10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

FOR THE QUARTERLY PERIOD ENDED September 30, 2020

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

FOR THE TRANSITION PERIOD FROM              TO             

COMMISSION FILE NUMBER: 001-35388

PROSPERITY BANCSHARES, INC.^®

(Exact name of registrant as specified in its charter)

Texas	74-2331986
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)

Prosperity Bank Plaza
4295 San Felipe, Houston, Texas	77027
(Address of principal executive offices)	(Zip Code)

(281) 269-7199

(Registrant’s telephone number, including area code)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common stock, par value $1.00 per share	PB	New York Stock Exchange, Inc.

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  ☒    No  ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).    Yes  ☒    No  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See definitions of “accelerated filer”, “large accelerated filer”, “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act:

Large Accelerated Filer	☒	Accelerated Filer	☐
Non-accelerated Filer	☐	Smaller Reporting Company	☐
		Emerging Growth Company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.    ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ☐    No  ☒

As of November 2, 2020, there were 92,558,558 outstanding shares of the registrant’s Common Stock, par value $1.00 per share.  

PROSPERITY BANCSHARES, INC.® AND SUBSIDIARIES

INDEX TO FORM 10-Q

PART I—FINANCIAL INFORMATION
Item 1.	Financial Statements	3
	Consolidated Balance Sheets as of September 30, 2020 (unaudited) and December 31, 2019	3
	Consolidated Statements of Income for the Three and Nine Months Ended September 30, 2020 and 2019 (unaudited)	4
	Consolidated Statements of Comprehensive Income for the Three and Nine Months Ended September 30, 2020 and 2019 (unaudited)	5
	Consolidated Statements of Changes in Shareholders’ Equity for the Three and Nine Months Ended September 30, 2020 and 2019 (unaudited)	6
	Consolidated Statements of Cash Flows for the Nine Months Ended September 30, 2020 and 2019 (unaudited)	7
	Notes to Consolidated Financial Statements (unaudited)	8
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	34
Item 3.	Quantitative and Qualitative Disclosures about Market Risk	58
Item 4.	Controls and Procedures	59
PART II—OTHER INFORMATION
Item 1.	Legal Proceedings	60
Item 1A.	Risk Factors	60
Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	61
Item 3.	Defaults Upon Senior Securities	61
Item 4.	Mine Safety Disclosures	61
Item 5.	Other Information	61
Item 6.	Exhibits	62
Signatures		63

2

PART I—FINANCIAL INFORMATION

ITEM 1. FINANCIAL STATEMENTS

PROSPERITY BANCSHARES, INC.^® AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

	September 30,			December 31,
	2020			2019
	(unaudited)
	(Dollars in thousands, except par value)
ASSETS
Cash and due from banks	$	1,031,193		$	573,589
Federal funds sold		56,469			519
Total cash and cash equivalents		1,087,662			574,108
Available for sale securities, at fair value		461,115			287,663
Held to maturity securities, at cost (fair value of $7,145,837 and $8,303,851, respectively)		6,970,380			8,282,393
Total securities		7,431,495			8,570,056
Loans held for sale		51,694			80,959
Loans held for investment		18,013,333			17,211,625
Loans held for investment - Warehouse Purchase Program		2,730,614			1,552,762
Total loans		20,795,641			18,845,346
Less: allowance for credit losses on loans		(323,635	)		(87,469	)
Loans, net		20,472,006			18,757,877
Accrued interest receivable		87,555			80,797
Goodwill		3,231,692			3,223,671
Core deposit intangibles, net		76,478			86,404
Bank premises and equipment, net		325,994			326,832
Other real estate owned		11,548			6,936
Bank owned life insurance (BOLI)		326,452			321,793
Federal Home Loan Bank of Dallas stock		8,901			83,945
Other assets		137,816			153,289
TOTAL ASSETS	$	33,197,599		$	32,185,708
LIABILITIES AND SHAREHOLDERS’ EQUITY
LIABILITIES:
Deposits:
Noninterest-bearing	$	8,998,328		$	7,763,894
Interest-bearing		17,460,878			16,435,838
Total deposits		26,459,206			24,199,732
Fed funds purchased and other borrowings		2,570			1,303,730
Securities sold under repurchase agreements		380,274			377,294
Subordinated notes		125,146			125,804
Accrued interest payable		6,592			8,585
Allowance for credit losses on off-balance sheet credit exposures		29,947			5,599
Other liabilities		158,987			194,129
Total liabilities		27,162,722			26,214,873
COMMITMENTS AND CONTINGENCIES		—			—
SHAREHOLDERS’ EQUITY:
Preferred stock, $1 par value; 20,000,000 shares authorized; none issued or outstanding		—			—
Common stock, $1 par value; 200,000,000 shares authorized; 92,562,434 shares issued and outstanding at September 30, 2020; 94,746,019 shares issued and outstanding at December 31, 2019		92,562			94,746
Capital surplus		3,631,213			3,734,519
Retained earnings		2,311,451			2,140,968
Accumulated other comprehensive (loss) income —net unrealized (loss) gain on available for sale securities, net of tax (benefit) expense of $(93) and $160, respectively		(349	)		602
Total shareholders’ equity		6,034,877			5,970,835
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$	33,197,599		$	32,185,708

See notes to consolidated financial statements.

3

PROSPERITY BANCSHARES, INC.^® AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME

(UNAUDITED)

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2020			2019			2020			2019
	(Dollars in thousands, except per share data)
INTEREST INCOME:
Loans, including fees	$	244,255		$	134,943		$	734,270		$	398,533
Securities		38,033			50,872			130,091			160,464
Federal funds sold and other earning assets		144			363			902			1,083
Total interest income		282,432			186,178			865,263			560,080
INTEREST EXPENSE:
Deposits		22,458			26,939			82,745			78,629
Other borrowings		52			4,335			3,517			15,208
Securities sold under repurchase agreements		309			914			1,403			2,504
Subordinated notes		1,500			—			4,499			—
Total interest expense		24,319			32,188			92,164			96,341
NET INTEREST INCOME		258,113			153,990			773,099			463,739
PROVISION FOR CREDIT LOSSES		10,000			1,100			20,000			2,600
NET INTEREST INCOME AFTER PROVISION FOR CREDIT LOSSES		248,113			152,890			753,099			461,139
NONINTEREST INCOME:
Nonsufficient funds (NSF) fees		7,156			8,835			22,244			24,624
Credit card, debit card and ATM card income		8,315			6,688			23,052			19,139
Service charges on deposit accounts		5,920			5,020			17,814			15,007
Trust income		2,502			2,492			7,406			7,645
Mortgage income		2,958			839			6,788			2,551
Brokerage income		628			522			1,862			1,736
Net (loss) gain on sale or write down of assets		(528	)		(3	)		(4,858	)		57
Other		7,973			6,280			20,679			18,016
Total noninterest income		34,924			30,673			94,987			88,775
NONINTEREST EXPENSE:
Salaries and employee benefits		75,068			52,978			231,459			156,992
Net occupancy and equipment		8,644			5,607			26,814			16,565
Credit and debit card, data processing and software amortization		8,776			4,989			31,887			14,466
Regulatory assessments and FDIC insurance		2,512			1,814			7,191			6,513
Core deposit intangibles amortization		3,270			1,248			9,926			3,832
Depreciation		4,605			3,286			13,971			9,501
Communications		3,027			2,214			9,546			6,667
Other real estate expense, net		121			(47	)		81			(75	)
Merger related expenses		—			—			8,018			—
Other		11,896			8,610			38,135			25,630
Total noninterest expense		117,919			80,699			377,028			240,091
INCOME BEFORE INCOME TAXES		165,118			102,864			471,058			309,823
PROVISION FOR INCOME TAXES		35,054			21,106			79,245			63,405
NET INCOME	$	130,064		$	81,758		$	391,813		$	246,418
EARNINGS PER SHARE:
Basic	$	1.40		$	1.19		$	4.20		$	3.55
Diluted	$	1.40		$	1.19		$	4.20		$	3.55

See notes to consolidated financial statements.

4

PROSPERITY BANCSHARES, INC.^® AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(UNAUDITED)

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2020			2019			2020			2019
	(Dollars in thousands)
Net income	$	130,064		$	81,758		$	391,813		$	246,418
Other comprehensive income (loss), before tax:
Securities available for sale:
Change in unrealized gains (losses) during the period		1,325			(1,563	)		(1,204	)		(344	)
Total other comprehensive income (loss)		1,325			(1,563	)		(1,204	)		(344	)
Deferred tax (expense) benefit related to other comprehensive income (loss)		(278	)		328			253			72
Other comprehensive income (loss), net of tax		1,047			(1,235	)		(951	)		(272	)
Comprehensive income	$	131,111		$	80,523		$	390,862		$	246,146

See notes to consolidated financial statements.

5

PROSPERITY BANCSHARES, INC.^® AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS’ EQUITY

(UNAUDITED)

													Accumulated
													Other			Total
	Common Stock						Capital			Retained			Comprehensive			Shareholders’
	Shares			Amount			Surplus			Earnings			Income (Loss)			Equity
	(In thousands, except share and per share data)
Three Months Ended
BALANCE AT JUNE 30, 2020		92,660,462		$	92,660		$	3,632,847		$	2,224,011		$	(1,396	)	$	5,948,122
Net income											130,064						130,064
Other comprehensive income														1,047			1,047
Common stock issued in connection with the issuance of restricted stock awards, net		—			—			—									—
Common stock repurchase		(98,028	)		(98	)		(4,805	)								(4,903	)
Stock based compensation expense								3,171									3,171
Cash dividends declared, $0.46 per share											(42,624	)					(42,624	)
BALANCE AT SEPTEMBER 30, 2020		92,562,434		$	92,562		$	3,631,213		$	2,311,451		$	(349	)	$	6,034,877
Nine Months Ended
BALANCE AT DECEMBER 31, 2019		94,746,019		$	94,746		$	3,734,519		$	2,140,968		$	602		$	5,970,835
Cumulative change in accounting principle upon adoption of ASU 2016-13(1) and other											(92,860	)					(92,860	)
BALANCE AT JANUARY 1, 2020 (AS ADJUSTED FOR CHANGE IN ACCOUNTING STANDARD)		94,746,019			94,746			3,734,519			2,048,108			602			5,877,975
Net income											391,813						391,813
Other comprehensive loss														(951	)		(951	)
Common stock issued in connection with the issuance of restricted stock awards, net		6,000			6			(6	)								—
Common stock repurchase		(2,189,585	)		(2,190	)		(112,774	)								(114,964	)
Stock based compensation expense								9,474									9,474
Cash dividends declared, $1.38 per share											(128,470	)					(128,470	)
BALANCE AT SEPTEMBER 30, 2020		92,562,434		$	92,562		$	3,631,213		$	2,311,451		$	(349	)	$	6,034,877

													Accumulated
													Other			Total
	Common Stock						Capital			Retained			Comprehensive			Shareholders’
	Shares			Amount			Surplus			Earnings			Income			Equity
	(In thousands, except share and per share data)
Three Months Ended
BALANCE AT JUNE 30, 2019		69,261,431		$	69,261		$	2,012,665		$	2,044,696		$	1,273		$	4,127,895
Net income											81,758						81,758
Other comprehensive loss														(1,235	)		(1,235	)
Common stock issued in connection with the issuance of restricted stock awards, net		9,750			10			(10	)								—
Common stock repurchase		(874,403	)		(874	)		(55,189	)								(56,063	)
Stock based compensation expense								2,494									2,494
Cash dividends declared, $0.41 per share											(28,043	)					(28,043	)
BALANCE AT SEPTEMBER 30, 2019		68,396,778			68,397			1,959,960			2,098,411			38			4,126,806
Nine Months Ended
BALANCE AT DECEMBER 31, 2018		69,846,825		$	69,847		$	2,045,351		$	1,937,316		$	310		$	4,052,824
Net income											246,418						246,418
Other comprehensive loss														(272	)		(272	)
Common stock issued in connection with the issuance of restricted stock awards, net		23,184			23			(23	)								—
Common stock repurchase		(1,473,231	)		(1,473	)		(93,011	)								(94,484	)
Stock based compensation expense								7,643									7,643
Cash dividends declared, $1.23 per share											(85,323	)					(85,323	)
BALANCE AT SEPTEMBER 30, 2019		68,396,778		$	68,397		$	1,959,960		$	2,098,411		$	38		$	4,126,806

(1) ASU 2016-13 became effective for the Company on January 1, 2020.

See notes to consolidated financial statements.

6

PROSPERITY BANCSHARES, INC.^® AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS

(UNAUDITED)

	Nine Months Ended
	September 30,
	2020			2019
	(Dollars in thousands)
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$	391,813		$	246,418
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and core deposit intangibles amortization		23,897			13,333
Provision for credit losses		20,000			2,600
Net amortization of premium on investments		27,318			22,223
Net gain on sale of other real estate and repossessed assets		(263	)		(346	)
Net loss on sale or write down of premises and equipment		2,506			—
Net loss (gain) on sale or write down of assets		2,352			(57	)
Net accretion of discount on loans		(75,282	)		(4,303	)
Net amortization of premium on deposits		(5,303	)		—
Gain on sale of loans		(4,957	)		(2,355	)
Proceeds from sale of loans held for sale		338,740			132,554
Originations of loans held for sale		(305,612	)		(121,212	)
Stock based compensation expense		9,474			7,643
Decrease in accrued interest receivable and other assets		97,047			13,860
(Decrease) increase in accrued interest payable and other liabilities		(24,834	)		38,840
Net cash provided by operating activities		496,896			349,198
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities and principal paydowns of held to maturity securities		1,751,229			1,328,559
Purchase of held to maturity securities		(466,474	)		(222,906	)
Proceeds from maturities and principal paydowns of available for sale securities		12,027,029			9,020,085
Purchase of available for sale securities		(12,201,746	)		(9,234,545	)
Originations of WPP loans		(30,474,590	)		—
Proceeds from pay-offs of WPP		29,296,738			—
Net increase in loans held for investment		(626,308	)		(312,461	)
Purchase of bank premises and equipment		(17,617	)		(16,253	)
Proceeds from sale of bank premises, equipment and other real estate		4,766			4,531
Proceeds from insurance claims		468			3,637
Net cash (used in) provided by investing activities		(706,505	)		570,647
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in noninterest-bearing deposits		1,234,434			117,887
Net increase (decrease) in interest-bearing deposits		1,030,343			(444,525	)
Net repayments of other short-term borrowings		(1,300,000	)		(430,000	)
Repayments of other long-term borrowings		(1,160	)		(331	)
Net increase in securities sold under repurchase agreements		2,980			26,684
Repurchase of common stock		(114,964	)		(94,484	)
Payments of cash dividends		(128,470	)		(85,323	)
Net cash provided by (used in) financing activities		723,163			(910,092	)
NET INCREASE IN CASH AND CASH EQUIVALENTS		513,554			9,753
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD		574,108			411,127
CASH AND CASH EQUIVALENTS, END OF PERIOD	$	1,087,662		$	420,880
NONCASH ACTIVITIES:
Acquisition of real estate through foreclosure of collateral	$	8,229		$	1,998
SUPPLEMENTAL INFORMATION:
Income taxes paid	$	132,185		$	63,250
Interest paid		94,157			95,104

See notes to consolidated financial statements

7

PROSPERITY BANCSHARES, INC.® AND SUBSIDIARIES

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

SEPTEMBER 30, 2020

(UNAUDITED)

1. BASIS OF PRESENTATION

The consolidated financial statements include the accounts of Prosperity Bancshares, Inc.^® (“Bancshares”) and its wholly-owned subsidiary, Prosperity Bank^® (the “Bank,” and together with Bancshares, the “Company”). All intercompany transactions and balances have been eliminated.

The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for financial information and with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, the statements reflect all adjustments necessary for a fair presentation of the financial position, results of operations and cash flows of the Company on a consolidated basis; and all such adjustments are of a normal recurring nature. These financial statements and the notes thereto should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Operating results for the nine-month period ended September 30, 2020 are not necessarily indicative of the results that may be expected for the year ending December 31, 2020 or any other period.

2. INCOME PER COMMON SHARE

The following table illustrates the computation of basic and diluted earnings per share:

	Three Months Ended September 30,								Nine Months Ended September 30,
	2020				2019				2020				2019
	Amount		Per Share Amount		Amount		Per Share Amount		Amount		Per Share Amount		Amount		Per Share Amount
	(Amounts in thousands, except per share data)
Net income	$	130,064			$	81,758			$	391,813			$	246,418
Basic:
Weighted average shares outstanding		92,656	$	1.40		68,738	$	1.19		93,226	$	4.20		69,463	$	3.55
Diluted:
Weighted average shares outstanding		92,656	$	1.40		68,738	$	1.19		93,226	$	4.20		69,463	$	3.55

As of September 30, 2020, all stock options have been exercised and there are no options outstanding. There were no stock options exercisable during the three and nine months ended September 30, 2020 or 2019 that would have had an anti-dilutive effect on the above computation.

3. NEW ACCOUNTING STANDARDS

Accounting Standards Updates (“ASU”)

ASU 2020-04, "Reference Rate Reform: Facilitation of the Effects of Reference Rate Reform on Financial Reporting - Accounting Standards Codification (“ASC”) Topic 848." ASU 2020-04 provides optional expedients and exceptions for applying GAAP to loan and lease agreements, derivative contracts, and other transactions affected by the anticipated transition away from LIBOR toward new interest rate benchmarks. The guidance allows for companies to: (i) account for certain contract modifications as a continuation of the existing contract without additional analysis; (ii) continue hedge accounting when certain critical terms of a hedging relationship change and assess effectiveness in ways that disregard certain potential sources of ineffectiveness; and (iii) make a one-time sale and/or transfer of certain debt securities from held-to-maturity to available-for-sale or trading. This ASU is available for adoption effective March 12, 2020 through December 31, 2022. An entity may elect to apply ASU 2020-04 for contract modifications as of January 1, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic within ASU 2020-04, the amendments must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The one-time election to sell and/or transfer debt securities classified as held-to-maturity may be made at any time after March 12, 2020. The Company anticipates this ASU will simplify any modifications it executes between the selected start date (yet to be determined) and December 31, 2022 that are directly related to the LIBOR transition by allowing prospective recognition of the continuation of the contract, rather than extinguishment of the old contract resulting in writing off unamortized fees and costs. ASU 2020-04 is not expected to have a significant impact on the Company’s financial statements.

8

ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326)—Measurement of Credit Losses on Financial Instruments (“ASC 326”).” On January 1, 2020, the Company adopted ASU 2016-13 which replaces the incurred loss methodology with an expected loss methodology that is referred to as the current expected credit loss (“CECL”) methodology. CECL requires a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The measurement of CECL is based on relevant information about past events including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount.

The Company adopted ASU 2016-13 using the modified-retrospective method for all financial assets measured at amortized cost and off-balance sheet credit exposures. Reporting periods beginning after January 1, 2020 are presented under ASC 326 while prior periods are reported with previously applicable GAAP. Upon adoption of ASU 2016-13, the Company recognized an increase in allowance for credit losses for loans of $108.7 million, of which $102.5 million was related to LegacyTexas Financial Group, Inc. (“LegacyTexas”), which merged into Bancshares on November 1, 2019, and an increase in allowance for credit losses for off-balance sheet credit exposures of $24.4 million, of which $6.3 million was related to LegacyTexas, with a corresponding decrease in retained earnings (pre-tax). Additionally, the Company adopted ASU 2016-13 using the prospective transition approach for financial assets purchased with credit deterioration. The Company recognized an increase in the allowance for credit losses for loans of $131.8 million, of which $130.3 million was related to LegacyTexas, due to the reclass of purchased credit deteriorated discounts as the result of adopting ASU 2016-13. See Note 5 “Loans and Allowance for Credit Losses” for additional information. The Company recognized no allowance for credit losses related to debt securities. See Note 4 “Securities” for additional information.

The following table illustrates the impact of adopting ASU 2016-13:

	January 1, 2020
	As Reported Under ASC 326		Pre-ASC 326 Adoption		Impact of ASC 326 Adoption
	(Dollars in thousands)
Assets:
Loans
Construction, land development and other land loans	$	28,729	$	14,654	$	14,075
Agriculture and agriculture real estate (includes farmland)		5,768		2,971		2,797
1-4 family (includes home equity)		23,544		15,277		8,267
Commercial real estate (includes multi-family residential)		61,322		12,332		48,990
Commercial and industrial		180,069		40,445		139,624
Consumer and other		28,575		1,790		26,785
Allowance for credit losses on loans	$	328,007	$	87,469	$	240,538
Liabilities:
Allowance for credit losses on off-balance sheet credit exposures	$	29,947	$	5,599	$	24,348

9

4. SECURITIES

The amortized cost and fair value of investment securities were as follows:

	September 30, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
Collateralized mortgage obligations	$	418,575	$	138	$	(525	)	$	418,188
Mortgage-backed securities		42,982		570		(625	)		42,927
Total	$	461,557	$	708	$	(1,150	)	$	461,115
Held to Maturity
U.S. Treasury securities and obligations of U.S. Government agencies	$	3,989	$	25	$	—		$	4,014
States and political subdivisions		170,427		9,288		(187	)		179,528
Collateralized mortgage obligations		123,309		2,080		(256	)		125,133
Mortgage-backed securities		6,672,655		165,665		(1,158	)		6,837,162
Total	$	6,970,380	$	177,058	$	(1,601	)	$	7,145,837

	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	470	$	1	$	—		$	471
Collateralized mortgage obligations		235,222		690		(139	)		235,773
Mortgage-backed securities		51,209		659		(449	)		51,419
Total	$	286,901	$	1,350	$	(588	)	$	287,663
Held to Maturity
U.S. Treasury securities and obligations of U.S. Government agencies	$	13,933	$	58	$	—		$	13,991
States and political subdivisions		238,347		7,632		(189	)		245,790
Collateralized mortgage obligations		203,470		1,115		(373	)		204,212
Mortgage-backed securities		7,826,643		48,060		(34,845	)		7,839,858
Total	$	8,282,393	$	56,865	$	(35,407	)	$	8,303,851

The investment securities portfolio is measured for expected credit losses by segregating the portfolio into two general segments and applying the appropriate expected credit losses methodology. Investment securities classified as available for sale or held to maturity are evaluated for expected credit losses under Financial Accounting Standards Board (“FASB”): ASC 326, “Financial Instruments – Credit Losses.”

Available for sale securities. For available for sale securities in an unrealized loss position, the amount of the expected credit losses recognized in earnings depends on whether an entity intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss. If an entity intends to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the expected credit losses will be recognized in earnings equal to the entire difference between the investment’s amortized cost basis and its fair value at the balance sheet date. If an entity does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis less any current-period loss, the expected credit losses will be separated into the amount representing the credit-related portion of the impairment loss (“credit loss”) and the noncredit portion of the impairment loss (“noncredit portion”). The amount of the total expected credit losses related to the credit loss is determined based on the difference between the present value of cash flows expected to be collected and the amortized cost basis and such difference is recognized in earnings. The amount of the total expected credit losses related to the noncredit portion is recognized in other comprehensive income, net of applicable taxes. The previous amortized cost basis less the expected credit losses recognized in earnings will become the new amortized cost basis of the investment.

10

As of September 30, 2020, management does not have the intent to sell any of the securities classified as available for sale before a recovery of cost. In addition, management believes it is more likely than not that the Company will not be required to sell any of its investment securities before a recovery of cost. The unrealized losses are largely due to changes in market interest rates and spread relationships since the time the underlying securities were purchased. The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline. Management does not believe any of the securities are impaired due to reasons of credit quality. Accordingly, as of September 30, 2020, management believes that there is no potential for credit losses on available for sale securities.

Held to maturity securities. The Company’s held to maturity investments include mortgage-related bonds issued by either the Government National Mortgage Corporation (“Ginnie Mae”), Federal National Mortgage Association (“Fannie Mae”) or Federal Home Loan Mortgage Corporation (“Freddie Mac”).  Ginnie Mae issued securities are explicitly guaranteed by the U.S. government, while Fannie Mae and Freddie Mac issued securities are fully guaranteed by those respective United States government-sponsored agencies, and conditionally guaranteed by the full faith and credit of the United States.  The Company’s held to maturity securities also include taxable and tax-exempt municipal securities issued primarily by school districts, utility districts and municipalities located in Texas. The Company’s investment in municipal securities is exposed to credit risk. The securities are highly rated by major rating agencies and regularly reviewed by management. A significant portion are guaranteed or insured by either the Texas Permanent School Fund, Assured Guaranty or Build America Mutual. As of September 30, 2020, the Company’s municipal securities represent 2.3% of the securities portfolio. Management has the ability and intent to hold the securities classified as held to maturity until they mature, at which time the Company will receive full value for the securities. Accordingly, as of September 30, 2020, management believes that there is no potential for material credit losses on held to maturity securities.

Securities with unrealized losses, segregated by length of time, that have been in a continuous loss position were as follows:

	September 30, 2020
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
	(Dollars in thousands)
Available for Sale
Collateralized mortgage obligations	$	188,671	$	(515	)	$	1,886	$	(10	)	$	190,557	$	(525	)
Mortgage-backed securities		16,298		(365	)		12,815		(260	)		29,113		(625	)
Total	$	204,969	$	(880	)	$	14,701	$	(270	)	$	219,670	$	(1,150	)
Held to Maturity
States and political subdivisions	$	1,689	$	(187	)	$	—	$	—		$	1,689	$	(187	)
Collateralized mortgage obligations		33,507		(256	)		—		—			33,507		(256	)
Mortgage-backed securities		118,159		(858	)		19,716		(300	)		137,875		(1,158	)
Total	$	153,355	$	(1,301	)	$	19,716	$	(300	)	$	173,071	$	(1,601	)

	December 31, 2019
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
	(Dollars in thousands)
Available for Sale
Collateralized mortgage obligations	$	50,245	$	(136	)	$	1,818	$	(3	)	$	52,063	$	(139	)
Mortgage-backed securities		34,901		(449	)		10		—			34,911		(449	)
Total	$	85,146	$	(585	)	$	1,828	$	(3	)	$	86,974	$	(588	)
Held to Maturity
States and political subdivisions	$	58,329	$	(183	)	$	3,241	$	(6	)	$	61,570	$	(189	)
Collateralized mortgage obligations		54,890		(373	)		—		—			54,890		(373	)
Mortgage-backed securities		947,314		(3,017	)		3,110,765		(31,828	)		4,058,079		(34,845	)
Total	$	1,060,533	$	(3,573	)	$	3,114,006	$	(31,834	)	$	4,174,539	$	(35,407	)

At September 30, 2020 and December 31, 2019, there were 44 securities and 138 securities, respectively, in an unrealized loss position for 12 months or more.

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The amortized cost and fair value of investment securities at September 30, 2020, by contractual maturity, are shown below. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations at any time with or without call or prepayment penalties.

	Held to Maturity				Available for Sale
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
Due in one year or less	$	26,715	$	26,744	$	—	$	—
Due after one year through five years		96,287		101,719		—		—
Due after five years through ten years		44,637		48,053		—		—
Due after ten years		6,777		7,026		—		—
Subtotal		174,416		183,542		—		—
Mortgage-backed securities and collateralized mortgage obligations		6,795,964		6,962,295		461,557		461,115
Total	$	6,970,380	$	7,145,837	$	461,557	$	461,115

The Company recorded no gain or loss on the sale of securities for the three and nine months ended September 30, 2020 and 2019. As of September 30, 2020, the Company did not own any non-agency collateralized mortgage obligations.

At September 30, 2020 and December 31, 2019, the Company did not own securities of any one issuer (other than the U.S. government and its agencies) for which aggregate adjusted cost exceeded 10% of the consolidated shareholders’ equity at such respective dates.

Securities with an amortized cost of $5.80 billion and $5.98 billion and a fair value of $5.94 billion and $5.99 billion at September 30, 2020 and December 31, 2019, respectively, were pledged to collateralize public deposits and for other purposes required or permitted by law.

5. LOANS AND ALLOWANCE FOR CREDIT LOSSES

The loan portfolio consists of various types of loans and is categorized by major type as follows:

	September 30, 2020		December 31, 2019
	(Dollars in thousands)
Residential mortgage loans held for sale	$	51,694	$	80,959
Commercial and industrial		4,150,189		3,205,595
Real estate:
Construction, land development and other land loans		2,081,762		2,064,167
1-4 family residential (includes home equity)		4,615,710		4,306,452
Commercial real estate (includes multi-family residential)		6,179,901		6,556,285
Farmland		419,126		495,558
Agriculture		179,846		185,297
Consumer and other		386,799		398,271
Total loans held for investment, excluding Warehouse Purchase Program		18,013,333		17,211,625
Warehouse Purchase Program		2,730,614		1,552,762
Total loans, including Warehouse Purchase Program	$	20,795,641	$	18,845,346

Concentrations of Credit. Most of the Company’s lending activity occurs within the states of Texas and Oklahoma. Commercial real estate loans, 1-4 family residential loans and construction, land development and other land loans make up 71.3% of the Company’s total loan portfolio, excluding Warehouse Purchase Program loans, at September 30, 2020. As of September 30, 2020 and December 31, 2019, excluding Warehouse Purchase Program loans, there were no concentrations of loans related to any single industry in excess of 10% of total loans.

12

Related Party Loans. As of September 30, 2020 and December 31, 2019, loans outstanding to directors, officers and their affiliates totaled $1.8 million and $4.2 million, respectively. All transactions between the Company and such related parties are conducted in the ordinary course of business and made on the same terms and conditions as similar transactions with unaffiliated persons.

An analysis of activity with respect to these related party loans is as follows:

	As of and for the nine months ended September 30, 2020			As of and for the year ended December 31, 2019
	(Dollars in thousands)
Beginning balance on January 1	$	4,152		$	1,923
New loans		813			1
Transfers		—			2,500
Repayments		(3,134	)		(272	)
Ending balance	$	1,831		$	4,152

Nonperforming Assets and Nonaccrual and Past Due Loans. The Company has several procedures in place to assist it in maintaining the overall quality of its loan portfolio. The Company has established underwriting guidelines to be followed by its officers, including requiring appraisals on loans collateralized by real estate. The Company also monitors its delinquency levels for any negative or adverse trends. Nevertheless, the Company’s loan portfolio could become subject to increasing pressures from deteriorating borrower credit due to general economic conditions.

The Company generally places a loan on nonaccrual status and ceases accruing interest when the payment of principal or interest is delinquent for 90 days, or earlier in some cases, unless the loan is in the process of collection and the underlying collateral fully supports the carrying value of the loan. A loan may be returned to accrual status when all the principal and interest amounts contractually due are brought current and future principal and interest amounts contractually due are reasonably assured, which is typically evidenced by a sustained period (at least six months) of repayment performance by the borrower.

With respect to potential problem loans, an evaluation of the borrower’s overall financial condition is made to determine the need, if any, for possible writedowns or appropriate additions to the allowance for credit losses.

An aging analysis of past due loans, segregated by category of loan, is presented below:

	September 30, 2020
	Loans Past Due and Still Accruing
	30-89 Days		90 or More Days		Total Past Due Loans		Nonaccrual Loans		Current Loans		Total Loans
	(Dollars in thousands)
Construction, land development and other land loans	$	24,592	$	422	$	25,014	$	2,211	$	2,054,537	$	2,081,762
Warehouse Purchase Program loans		—		—		—		—		2,730,614		2,730,614
Agriculture and agriculture real estate (includes farmland)		30		—		30		1,200		597,742		598,972
1-4 family (includes home equity) (1)		6,160		40		6,200		23,769		4,637,435		4,667,404
Commercial real estate (includes multi-family residential)		2,758		—		2,758		11,486		6,165,657		6,179,901
Commercial and industrial		4,958		—		4,958		17,153		4,128,078		4,150,189
Consumer and other		529		—		529		1,593		384,677		386,799
Total	$	39,027	$	462	$	39,489	$	57,412	$	20,698,740	$	20,795,641

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	December 31, 2019
	Loans Past Due and Still Accruing
	30-89 Days		90 or More Days		Total Past Due Loans		Nonaccrual Loans		Current Loans		Total Loans
	(Dollars in thousands)
Construction, land development and other land loans	$	16,470	$	—	$	16,470	$	1,142	$	2,046,555	$	2,064,167
Warehouse Purchase Program loans		—		—		—		—		1,552,762		1,552,762
Agriculture and agriculture real estate (includes farmland)		466		—		466		103		680,286		680,855
1-4 family (includes home equity) (1)		43,884		441		44,325		24,413		4,318,673		4,387,411
Commercial real estate (includes multi-family residential)		10,669		—		10,669		12,714		6,532,902		6,556,285
Commercial and industrial		7,249		—		7,249		16,809		3,181,537		3,205,595
Consumer and other		1,708		—		1,708		62		396,501		398,271
Total	$	80,446	$	441	$	80,887	$	55,243	$	18,709,216	$	18,845,346

(1) Includes $51.7 million and $81.0 million of residential mortgage loans held for sale at September 30, 2020 and December 31, 2019, respectively.

The following table presents information regarding nonperforming assets as of the dates indicated:

	September 30, 2020			December 31, 2019
	(Dollars in thousands)
Nonaccrual loans (1) (2)	$	57,412		$	55,243
Accruing loans 90 or more days past due		462			441
Total nonperforming loans		57,874			55,684
Repossessed assets		120			323
Other real estate		11,548			6,936
Total nonperforming assets	$	69,542		$	62,943
Nonperforming assets to total loans and other real estate		0.33	%		0.33	%
Nonperforming assets to total loans, excluding Warehouse Purchase Program loans, and other real estate		0.38	%		0.36	%

(1) Includes troubled debt restructurings of $13.2 million and $13.6 million as of September 30, 2020 and December 31, 2019, respectively.

(2) There were no nonperforming or troubled debt restructurings of warehouse lines of credit or Warehouse Purchase Program loans for the periods presented.

The Company had $69.5 million in nonperforming assets at September 30, 2020 compared with $62.9 million at December 31, 2019. Nonperforming assets were 0.33% of total loans and other real estate at September 30, 2020 and at December 31, 2019.

If interest on nonaccrual loans had been accrued under the original loan terms, approximately $2.3 million and $2.2 million would have been recorded as income for the nine months ended September 30, 2020 and 2019, respectively. The Company had $57.4 million in nonaccrual loans at September 30, 2020 compared with $50.0 million at September 30, 2019.

Acquired Loans.  Acquired loans were preliminarily recorded at fair value based on a discounted cash flow valuation methodology that considers, among other things, interest rates, projected default rates, loss given default, and recovery rates. During the valuation process, the Company identified purchased credit deteriorated (“PCD”) and Non-PCD loans in the acquired loan portfolios. Loans acquired with evidence of credit quality deterioration at acquisition for which it was probable that the Company would not be able to collect all contractual amounts due were accounted for as PCD. PCD loan identification considers the following factors: payment history and past due status, debt service coverage, loan grading, collateral values and other factors that may indicate deterioration of credit quality since origination. Non-PCD loan identification considers the following factors: account types, remaining terms, annual interest rates or coupons, current market rates, interest types, past delinquencies, timing of principal and interest payments, loan to value ratios, loss exposures and remaining balances. Accretion of purchased discounts on PCD loans will be based on future cash flows, taking into account contractual maturities. Accretion of purchased discounts on Non-PCD loans will be recognized on a level-yield basis based on contractual maturity of individual loans.

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PCD Loans.  The recorded investment in PCD loans included in the consolidated balance sheet and the related outstanding balance as of the dates indicated are presented in the table below. The outstanding balance represents the total amount owed as of September 30, 2020 and December 31, 2019.

	September 30, 2020			December 31, 2019
	(Dollars in thousands)
PCD loans:
Outstanding balance	$	226,080		$	410,785
Discount (1)		(16,760	)		(167,320	)	(2)
Recorded investment	$	209,320		$	243,465

(1) ASU 2016-13 became effective for the Company on January 1, 2020.

(2) Includes $131.8 million in PCD loans credit discount.

Changes in the accretable yield for acquired PCD loans for the three and nine months ended September 30, 2020 and 2019 were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
	(Dollars in thousands)
Balance at beginning of period	$	22,565		$	904		$	35,654		$	1,534
Adjustments		—			26			(449	)		62
Accretion charge-offs		—			—			(354	)		—
Accretion		(5,805	)		(277	)		(18,091	)		(943	)
Balance at September 30,	$	16,760		$	653		$	16,760		$	653

Income recognition on PCD loans is subject to the timing and amount of future cash flows. PCD loans for which the Company is accruing interest income are not considered non-performing or impaired. The adoption of ASU 2016-13, “Financial Instruments-Credit-Losses (ASC Topic 326) – Measurement of Credit Losses on Financial Instruments” (“CECL”) resulted in $131.8 million of the total PCD discount as of December 31, 2019 being reallocated to the allowance for credit losses. The PCD discount reflected above as of September 30, 2020, represents the amount of discount available to be recognized as income.

Non-PCD Loans. The recorded investment in Non-PCD loans included in the consolidated balance sheet and the related outstanding balance as of the dates indicated are presented in the table below. The outstanding balance represents the total amount owed as of September 30, 2020 and December 31, 2019.

	September 30, 2020			December 31, 2019
	(Dollars in thousands)
Non-PCD loans:
Outstanding balance	$	4,468,843		$	6,102,540
Discount		(53,115	)		(110,130	)
Recorded investment	$	4,415,728		$	5,992,410

Changes in the discount accretion for Non-PCD loans for the three and nine months ended September 30, 2020 and 2019 were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
	(Dollars in thousands)
Balance at beginning of period	$	69,860		$	12,479		$	110,130		$	14,833
Adjustments		(16	)		—			296			—
Accretion charge-offs		—			—			(120	)		—
Accretion		(16,729	)		(1,006	)		(57,191	)		(3,360	)
Balance at September 30,	$	53,115		$	11,473		$	53,115		$	11,473

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Credit Quality Indicators. As part of the on-going monitoring of the credit quality of the Company’s loan portfolio and methodology for calculating the allowance for credit losses, management assigns and tracks loan grades to be used as credit quality indicators. The following is a general description of the loan grades used:

Grade 1—Credits in this category have risk potential that is virtually nonexistent.  These loans may be secured by insured certificates of deposit, insured savings accounts, U.S. Government securities and highly rated municipal bonds.

Grade 2—Credits in this category are of the highest quality.  These borrowers represent top rated companies and individuals with unquestionable financial standing with excellent global cash flow coverage, net worth, liquidity and collateral coverage.

Grade 3—Credits in this category are not immune from risk but are well protected by the collateral and paying capacity of the borrower. These loans may exhibit a minor unfavorable credit factor, but the overall credit is sufficiently strong to minimize the possibility of loss.

Grade 4—Credits in this category are considered to be of acceptable credit quality with moderately greater risk than Grade 3 and receiving closer monitoring.  Loans in this category have sources of repayment that remain sufficient to preclude a larger than normal probability of default and secondary sources are likewise currently of sufficient quantity, quality, and liquidity to protect the Company against loss of principal and interest.  These borrowers have specific risk factors, but the overall strength of the credit is acceptable based on other mitigating credit and/or collateral factors and can repay the debt in the normal course of business.

Grade 5—Credits in this category constitute an undue and unwarranted credit risk; however, the factors do not rise to a level of substandard.  These credits have potential weaknesses and/or declining trends that, if not corrected, could expose the Company to risk at a future date.  These loans are monitored on the Company’s internally-generated watch list and evaluated on a quarterly basis.

Grade 6—Credits in this category are considered “substandard” but “non-impaired” loans in accordance with regulatory guidelines.  Loans in this category have well-defined weakness that, if not corrected, could make default of principal and interest possible.  Loans in this category are still accruing interest and may be dependent upon secondary sources of repayment and/or collateral liquidation.

Grade 7—Credits in this category are deemed “substandard” and “impaired” pursuant to regulatory guidelines. As such, the Company has determined that it is probable that less than 100% of the contractual principal and interest will be collected. These loans are individually evaluated for a specific reserve and will typically have the accrual of interest stopped.

Grade 8—Credits in this category include “doubtful” loans in accordance with regulatory guidance. Such loans are no longer accruing interest and factors indicate a loss is imminent.  These loans are also deemed “impaired.” While a specific reserve may be in place while the loan and collateral is being evaluated, these loans are typically charged down to an amount the Company estimates is collectible.

Grade 9—Credits in this category are deemed a “loss” in accordance with regulatory guidelines and have been charged off or charged down. The Company may continue collection efforts and may have partial recovery in the future.

16

The following table presents loans by risk grade, by category of loan and year of origination/renewal at September 30, 2020.

	Term Loans
	Amortized Cost Basis by Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
	(Dollars in thousands)
Construction, Land Development and Other Land Loans
Grade 1	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Grade 2		—		—		—		86		126		267		—		—		479
Grade 3		646,011		630,323		297,303		128,581		23,831		56,166		114,716		—		1,896,931
Grade 4		70,111		30,016		33,405		19,562		3,806		7,187		10,134		—		174,221
Grade 5		—		—		829		4,510		—		117		—		—		5,456
Grade 6		—		—		—		—		565		1,325		—		—		1,890
Grade 7		—		—		1,080		—		6		390		734		—		2,210
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		—		171		115		289		—		—		—		—		575
Total		716,122		660,510		332,732		153,028		28,334		65,452		125,584		—		2,081,762
Agriculture and Agriculture Real Estate (includes Farmland)
Grade 1	$	2,004	$	542	$	177	$	182		—		—	$	10,032	$	2	$	12,939
Grade 2		30		—		—		351		5		1,532		310		—		2,228
Grade 3		95,589		81,626		62,552		52,243		47,463		92,816		74,173		145		506,607
Grade 4		15,376		10,246		4,873		3,043		4,633		17,219		9,021		23		64,434
Grade 5		1,984		3,705		577		—		—		14		2,302		—		8,582
Grade 6		804		—		59		—		186		181		—		—		1,230
Grade 7		—		308		15		—		—		853		—		—		1,176
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		976		209		296		—		—		295		—		—		1,776
Total		116,763		96,636		68,549		55,819		52,287		112,910		95,838		170		598,972
1-4 Family (includes Home Equity) (1)
Grade 1	$	117	$	—	$	—	$	—	$	—	$	—	$	95	$	—	$	212
Grade 2		288		315		987		676		254		7,705		1,133		—		11,358
Grade 3		1,010,159		910,378		612,545		482,791		473,571		888,135		125,281		3,313		4,506,173
Grade 4		7,620		16,515		23,244		22,256		10,766		36,955		2,550		249		120,155
Grade 5		—		219		157		6		712		1,971		—		—		3,065
Grade 6		23		39		3		332		—		1,524		—		—		1,921
Grade 7		—		1,535		952		3,108		1,544		12,114		3,485		—		22,738
Grade 8		—		—		—		—		9		87		—		—		96
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		—		—		—		—		238		1,448		—		—		1,686
Total		1,018,207		929,001		637,888		509,169		487,094		949,939		132,544		3,562		4,667,404

17

	Term Loans
	Amortized Cost Basis by Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
	(Dollars in thousands)
Commercial Real Estate (includes Multi-Family Residential)
Grade 1	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Grade 2		10,046		2,006		—		7,450		201		1,386		—		—		21,089
Grade 3		468,230		986,980		983,614		824,609		464,007		1,018,983		63,247		2,072		4,811,742
Grade 4		89,339		79,177		209,634		214,653		156,972		318,504		8,505		6,597		1,083,381
Grade 5		6,120		7,556		16,457		2,771		35,280		43,836		1,306		—		113,326
Grade 6		10,014		174		—		10,587		3,176		14,906		—		—		38,857
Grade 7		19		—		1,238		15		7,840		847		1,485		—		11,444
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		48,199		21,935		5,361		6,278		200		18,089		—		—		100,062
Total		631,967		1,097,828		1,216,304		1,066,363		667,676		1,416,551		74,543		8,669		6,179,901
Commercial and Industrial
Grade 1	$	1,389,705	$	7,320	$	4,109	$	917	$	834	$	569	$	18,249	$	162	$	1,421,865
Grade 2		2,395		10,990		17,344		1,348		1,422		1,052		24,324		—		58,875
Grade 3		342,204		370,525		302,552		110,782		74,182		150,914		715,920		11,273		2,078,352
Grade 4		54,749		74,189		51,515		36,188		9,627		30,103		106,284		1,179		363,834
Grade 5		5,213		30,676		4,309		7		218		1,924		11,310		5,010		58,667
Grade 6		390		104		247		—		1,152		1,906		22,159		—		25,958
Grade 7		759		344		13,002		390		988		288		36,901		17		52,689
Grade 8		—		—		—		—		8		—		—		—		8
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		16,637		22,115		20,505		10,932		—		798		2,855		16,099		89,941
Total	$	1,812,052	$	516,263	$	413,583	$	160,564	$	88,431	$	187,554	$	938,002	$	33,740	$	4,150,189
Consumer and Other
Grade 1	$	37,213	$	11,159	$	4,170	$	2,469	$	1,370	$	157	$	1,523	$	—	$	58,061
Grade 2		2,350		1,036		407		31,450		1,583		—		1,204		—		38,030
Grade 3		39,858		50,310		31,445		22,314		7,615		16,122		74,327		73		242,064
Grade 4		4,237		2,052		964		75		84		118		14,148		—		21,678
Grade 5		—		—		66		18		—		—		9,997		—		10,081
Grade 6		—		—		—		—		—		—		—		—		—
Grade 7		2		1,569		7		4		—		21		2		—		1,605
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		3,800		—		—		—		—		—		11,480		—		15,280
Total	$	87,460	$	66,126	$	37,059	$	56,330	$	10,652	$	16,418	$	112,681	$	73	$	386,799

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	Term Loans
	Amortized Cost Basis by Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
	(Dollars in thousands)
Warehouse Purchase Program
Grade 1	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Grade 2		—		—		—		—		—		—		—		—		—
Grade 3		2,730,614		—		—		—		—		—		—		—		2,730,614
Grade 4		—		—		—		—		—		—		—		—		—
Grade 5		—		—		—		—		—		—		—		—		—
Grade 6		—		—		—		—		—		—		—		—		—
Grade 7		—		—		—		—		—		—		—		—		—
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		—		—		—		—		—		—		—		—		—
Total	$	2,730,614	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	2,730,614
Total
Grade 1	$	1,429,039	$	19,021	$	8,456	$	3,568	$	2,204	$	726	$	29,899	$	164	$	1,493,077
Grade 2		15,109		14,347		18,738		41,361		3,591		11,942		26,971		—		132,059
Grade 3		5,332,665		3,030,142		2,290,011		1,621,320		1,090,669		2,223,136		1,167,664		16,876		16,772,483
Grade 4		241,432		212,195		323,635		295,777		185,888		410,086		150,642		8,048		1,827,703
Grade 5		13,317		42,156		22,395		7,312		36,210		47,862		24,915		5,010		199,177
Grade 6		11,231		317		309		10,919		5,079		19,842		22,159		—		69,856
Grade 7		780		3,756		16,294		3,517		10,378		14,513		42,607		17		91,862
Grade 8		—		—		—		—		17		87		—		—		104
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		69,612		44,430		26,277		17,499		438		20,630		14,335		16,099		209,320
Total	$	7,113,185	$	3,366,364	$	2,706,115	$	2,001,273	$	1,334,474	$	2,748,824	$	1,479,192	$	46,214	$	20,795,641

(1) Includes $51.7 million of residential mortgage loans held for sale at September 30, 2020.

Allowance for Credit Losses on Loans. The allowance for credit losses is adjusted through charges to earnings in the form of a provision for credit losses. Management has established an allowance for credit losses which it believes is adequate as of September 30, 2020 for estimated losses in the Company’s loan portfolio. The amount of the allowance for credit losses is affected by the following: (1) charge-offs of loans that occur when loans are deemed uncollectible and decrease the allowance, (2) recoveries on loans previously charged off that increase the allowance and (3) provisions for credit losses charged to earnings that increase the allowance or provision releases returned to earnings that decrease the allowance. Based on an evaluation of the loan portfolio and consideration of the factors listed below, management presents a quarterly review of the allowance for credit losses to the Bank’s Board of Directors, indicating any change in the allowance since the last review and any recommendations as to adjustments in the allowance. Although management believes it uses the best information available to make determinations with respect to the allowance for credit losses, future adjustments may be necessary if economic conditions or the borrower’s performance differ from the assumptions used in making the initial determinations.

The Company’s allowance for credit losses on loans consists of two components: (1) a specific valuation allowance based on probable losses on specifically identified loans and (2) a general valuation allowance based on historical lifetime loan loss experience, general economic conditions and other qualitative risk factors both internal and external to the Company.

In setting the specific valuation allowance, the Company follows a loan review program to evaluate the credit risk in the total loan portfolio and assigns risk grades to each loan. Through this loan review process, the Company maintains an internal list of impaired loans, which along with the delinquency list of loans, helps management assess the overall quality of the loan portfolio and the adequacy of the allowance for credit losses. All loans that have been identified as impaired are reviewed on a quarterly basis in order to determine whether a specific reserve is required. For certain impaired loans, the Company allocates a specific loan loss reserve primarily based on the value of the collateral securing the impaired loan in accordance with ASC Topic 326-20, “Financial

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Instruments - Credit Losses.” The specific reserves are determined on an individual loan basis. Loans for which specific reserves are provided are excluded from the general valuation allowance described below.

In connection with this review of the loan portfolio, the Company considers risk elements attributable to particular loan types or categories in assessing the quality of individual loans. Some of the risk elements include:

• for 1-4 family residential mortgage loans, the borrower’s ability to repay the loan, including a consideration of the debt to income ratio and employment and income stability, the loan to value ratio, and the age, condition and marketability of collateral;

• for commercial real estate loans and multifamily residential loans, the debt service coverage ratio (income from the property in excess of operating expenses compared to loan payment requirements), operating results of the owner in the case of owner-occupied properties, the loan to value ratio, the age and condition of the collateral and the volatility of income, property value and future operating results typical of properties of that type;

• for construction, land development and other land loans, the perceived feasibility of the project including the ability to sell developed lots or improvements constructed for resale or the ability to lease property constructed for lease, the quality and nature of contracts for presale or prelease, if any, experience and ability of the developer and loan to value ratio;

• for commercial and industrial loans, the operating results of the commercial, industrial or professional enterprise, the borrower’s business, professional and financial ability and expertise, the specific risks and volatility of income and operating results typical for businesses in that category and the value, nature and marketability of collateral;

• for the Warehouse Purchase Program, the capitalization and liquidity of the mortgage banking client, the operating experience, the client’s satisfactory underwriting of purchased loans and the consistent timeliness by client of loan resale to investors;

• for agriculture real estate loans, the experience and financial capability of the borrower, projected debt service coverage of the operations of the borrower and loan to value ratio; and

• for non-real estate agriculture loans, the operating results, experience and financial capability of the borrower, historical and expected market conditions and the value, nature and marketability of collateral.

In addition, for each category, the Company considers secondary sources of income and the financial strength and credit history of the borrower and any guarantors.

In determining the amount of the general valuation allowance, management considers factors such as historical lifetime loan loss experience, concentration risk of specific loan types, the volume, growth and composition of the Company’s loan portfolio, current economic conditions and reasonable and supportable forecasted economic conditions that may affect the borrower’s ability to pay and the value of collateral, the evaluation of the Company’s loan portfolio through its internal loan review process, general economic conditions and other qualitative risk factors both internal and external to the Company and other relevant factors in accordance with ASC Topic 326, “Financial Instruments – Credit Losses.” Historical lifetime loan loss experience is determined by utilizing an open-pool (“cumulative loss rate”) methodology. Adjustments to the historical lifetime loan loss experience are made for differences in current loan pool risk characteristics such as portfolio concentrations, delinquency, non-accrual, and watch list levels, as well as changes in current and forecasted economic conditions such as unemployment rates, property and collateral values, and other indices relating to economic activity. The utilization of reasonable and supportable forecasts includes an immediate reversion to lifetime historical loss rates. Based on a review of these factors for each loan type, the Company applies an estimated percentage to the outstanding balance of each loan type, excluding any loan that has a specific reserve allocated to it. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. The Company uses this information to establish the amount of the general valuation allowance.

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The following table details activity in the allowance for credit losses on loans by category of loan for the three and nine months ended September 30, 2020 and 2019.

	Construction, Land Development and Other Land Loans			Agriculture and Agriculture Real Estate (includes Farmland)			1-4 Family (includes Home Equity)			Commercial Real Estate (includes Multi-Family Residential)			Commercial and Industrial			Consumer and Other			Total
	(Dollars in thousands)
Allowance for credit losses:
Three Months Ended
Balance June 30, 2020	$	39,862		$	6,898		$	33,021		$	78,207		$	149,884		$	16,333		$	324,205
Provision for credit losses		4,187			554			7,517			3,188			(4,982	)		(464	)		10,000
Charge-offs		(500	)		—			(436	)		(676	)		(8,444	)		(1,092	)		(11,148	)
Recoveries		22			17			184			—			99			256			578
Net charge-offs		(478	)		17			(252	)		(676	)		(8,345	)		(836	)		(10,570	)
Balance September 30, 2020	$	43,571		$	7,469		$	40,286		$	80,719		$	136,557		$	15,033		$	323,635
Nine Months Ended
Beginning balance, prior to adoption of ASC 326	$	14,654		$	2,971		$	15,277		$	12,332		$	40,445		$	1,790		$	87,469
Impact of adoption ASC 326		14,075			2,797			8,267			48,990			139,624			26,785			240,538
Provision for credit losses		15,302			1,680			17,050			19,992			(22,990	)		(11,034	)		20,000
Charge-offs		(500	)		(62	)		(611	)		(676	)		(21,733	)		(3,529	)		(27,111	)
Recoveries		40			83			303			81			1,211			1,021			2,739
Net charge-offs		(460	)		21			(308	)		(595	)		(20,522	)		(2,508	)		(24,372	)
Balance September 30, 2020	$	43,571		$	7,469		$	40,286		$	80,719		$	136,557		$	15,033		$	323,635
Allowance for credit losses:
Three Months Ended
Balance June 30, 2019	$	15,886		$	3,816		$	14,383		$	12,166		$	39,177		$	1,578		$	87,006
Provision for credit losses		290			188			543			452			(763	)		970			1,100
Charge-offs		—			(294	)		-			—			(419	)		(1,024	)		(1,737	)
Recoveries		6			16			9			1			502			158			692
Net charge-offs		6			(278	)		9			1			83			(866	)		(1,045	)
Balance September 30, 2019	$	15,602		$	3,726		$	14,935		$	12,619		$	38,497		$	1,682		$	87,061
Nine Months Ended
Balance December 31, 2018	$	15,582		$	2,693		$	14,135		$	11,220		$	40,223		$	1,587		$	86,440
Provision for credit losses		21			(921	)		799			1,396			(918	)		2,223			2,600
Charge-offs		(63	)		(358	)		(22	)		—			(2,501	)		(2,821	)		(5,765	)
Recoveries		62			1,312			23			3			1,693			693			3,786
Net charge-offs		(1	)		954			1			3			(808	)		(2,128	)		(1,979	)
Balance September 30, 2019	$	15,602		$	3,726		$	14,935		$	12,619		$	38,497		$	1,682		$	87,061

The allowance for credit losses on loans as of September 30, 2020 totaled $323.6 million or 1.56% of total loans, including acquired loans with discounts, an increase of $236.2 million or 270.0% compared to the allowance for credit losses on loans totaling $87.5 million or 0.46% of total loans, including acquired loans with discounts, for December 31, 2019. The increase in allowance for credit losses was primarily due to $240.5 million related to the Company’s adoption of CECL. The increase in allowance for loan losses was additionally driven by the anticipated impact of the on-going novel strain of coronavirus disease (“COVID-19”) pandemic, elevated unemployment levels and other internal and external environment factors, which resulted in a provision for credit losses of $10.0 million and $20.0 million for the three and nine months ended September 30, 2020, respectively.  Net charge-offs were $10.6 and $24.4 million for the three and nine months ended September 30, 2020, respectively. Net charge-offs for the third quarter of 2020 included $8.6 million related to PCD loans that had specific reserves of $15.7 million, of which $8.6 million was allocated to the charge-offs and $7.1 million moved to the general reserve. Additionally, $6.1 million of specific reserves on resolved PCD loans was released to the general reserve without taking any charge-off. Net charge-offs for the nine months ended September 30, 2020 included

21

$21.0 million related to PCD loans that had specific reserves of $44.2 million, of which $21.0 million was allocated to the charge-offs and $23.2 million moved to the general reserve.

The Company actively participated in the Paycheck Protection Program (“PPP”), under the provisions of the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) during the second quarter of 2020. As of September 30, 2020, the Company had 11,948 PPP loans totaling $1.39 billion. The loans have two year terms, are fully guaranteed by the SBA, and do not carry an allowance.

Allowance for Credit Losses on Off-Balance Sheet Credit Exposures. The allowance for credit losses on off-balance sheet credit exposures estimates expected credit losses over the contractual period in which there is exposure to credit risk via a contractual obligation to extend credit, unless that obligation is unconditionally cancellable by the Company. The allowance is adjusted as a provision for credit loss expense. The estimate includes consideration of the likelihood that funding will occur and an estimate of expected credit losses on the commitments expected to fund. The estimate of commitments expected to fund is affected by historical analysis looking at utilization rates. The expected credit loss rates applied to the commitments expected to fund are affected by the general valuation allowance utilized for outstanding balances with the same underlying assumptions and drivers. As of September 30, 2020, the Company had $29.9 million in allowance for credit losses on off-balance sheet credit exposures, compared with $5.6 million as of December 31, 2019. The allowance for credit losses on off-balance sheet credit exposures is a separate line item on the Company’s consolidated balance sheet. As of September 30, 2020, the Company had $1.75 billion in commitments expected to fund.

Troubled Debt Restructurings. The restructuring of a loan is considered a “troubled debt restructuring” if both (1) the borrower is experiencing financial difficulties and (2) the creditor has granted a concession. Concessions may include interest rate reductions or below market interest rates, principal forgiveness, restructuring amortization schedules and other actions intended to minimize potential losses.  Under ASC Topic 310-40 “Receivables—Troubled Debt Restructurings by Creditors,” the Company evaluates all loan modifications to identify whether the restructuring constitutes a troubled debt restructuring. As of September 30, 2020 and 2019, the Company had $13.2 million and $14.3 million, respectively, in outstanding troubled debt restructurings.

The following table presents information regarding the recorded investment of loans that were modified as troubled debt restructurings during the nine months ended September 30, 2020 and 2019.

	Nine Months Ended
	September 30,
	2020						2019
	Number of Loans		Pre-Modification Outstanding Recorded Investment		Post-Modification Outstanding Recorded Investment		Number of Loans		Pre-Modification Outstanding Recorded Investment		Post-Modification Outstanding Recorded Investment
	(Dollars in thousands)
Troubled Debt Restructurings
Construction, land development and other land loans		—	$	—	$	—		—	$	—	$	—
Agriculture and agriculture real estate (includes farmland)		—		—		—		—		—		—
1-4 Family (includes home equity)		1		23		12		—		—		—
Commercial real estate (includes multi-family residential)		—		—		—		—		—		—
Commercial and industrial		—		—		—		2		14,993		14,188
Consumer and other		—		—		—		—		—		—
Total		1	$	23	$	12		2	$	14,993	$	14,188

As of September 30, 2020, there have been no defaults on any loans that were modified as troubled debt restructurings during the preceding twelve months. Default is determined at 90 or more days past due. The modifications generally relate to extending the amortization periods of the loans, which includes loans modified during bankruptcy.

For the nine months ended September 30, 2020, the Company added one loan totaling $23 thousand as a new troubled debt restructuring, of which $12 thousand remained outstanding at September 30, 2020. For the nine months ended September 30, 2019, the Company added two loans totaling $15.0 million as new troubled debt restructurings, of which $14.2 million remained outstanding at September 30, 2019. The Company did not grant principal reductions on any restructured loans at the time of modification. These modifications did not have a material impact on the Company’s determination of the allowance for credit losses.

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Under the CARES Act, banks may elect to deem that loan modifications do not result in troubled debt restructurings if they are (1) related to COVID-19; (2) executed on a loan that was not more than 30 days past due as of December 31, 2019; and (3) executed between March 1, 2020, and the earlier of (A) 60 days after the date of termination of the COVID-19 national emergency declaration by the President of the United States or (B) December 31, 2020. Additionally, other short-term modifications made on a good faith basis in response to COVID-19 to borrowers who were current prior to any relief are not troubled debt restructurings under ASC Subtopic 310-40 and federal banking agencies’ interagency guidance. These modifications include short-term (e.g., up to six months) modifications such as payment deferrals, fee waivers, extensions of repayment terms, or delays in payment that are insignificant. Borrowers considered current are those that are less than 30 days past due on their contractual payments at the time a modification program is implemented. The Company's troubled debt restructurings noted above do not include loans that are short-term modifications related to COVID-19. 

6. FAIR VALUE

The Company uses fair value measurements to record fair value adjustments to certain assets and to determine fair value disclosures. Fair values represent the estimated price that would be received from selling an asset or paid to transfer a liability, otherwise known as an “exit price.” Securities available for sale are recorded at fair value on a recurring basis. Additionally, from time to time, the Company may be required to record at fair value other assets on a nonrecurring basis. These nonrecurring fair value adjustments typically involve application of lower-of-cost-or-market accounting or write downs of individual assets. ASC Topic 820, “Fair Value Measurements and Disclosures” establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows:

Fair Value Hierarchy

The Company groups financial assets and financial liabilities measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are:

• Level 1—Quoted prices in active markets for identical assets or liabilities.

• Level 2—Other significant observable inputs (including quoted prices in active markets for similar assets or liabilities) or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

• Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The fair value of an asset or liability is the price that would be received to sell that asset or paid to transfer that liability in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. In estimating fair value, the Company utilizes valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. Such valuation techniques are consistently applied. Inputs to valuation techniques include the assumptions that market participants would use in pricing an asset or liability.

The fair value disclosures below represent the Company’s estimates based on relevant market information and information about the financial instruments. Fair value estimates are based on judgments regarding current economic conditions, risk characteristics of the various instruments and other factors. These estimates are subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. Changes in the above methodologies and assumptions could significantly affect the estimates.

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The following tables present fair values for assets and liabilities measured at fair value on a recurring basis:

	As of September 30, 2020
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets:
Available for sale securities:
Collateralized mortgage obligations	$	—	$	418,188	$	—	$	418,188
Mortgage-backed securities		—		42,927		—		42,927
Total	$	—	$	461,115	$	—	$	461,115
Derivative financial instruments:
Loan customer counterparty	$	—	$	13,510	$	—	$	13,510
Financial institution counterparty		—		—		—		—
Liabilities:
Derivative financial instruments:
Loan customer counterparty	$	—	$	—	$	—	$	—
Financial institution counterparty		—		13,510		—		13,510

	As of December 31, 2019
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets:
Available for sale securities:
States and political subdivisions	$	—	$	471	$	—	$	471
Collateralized mortgage obligations		—		235,773		—		235,773
Mortgage-backed securities		—		51,419		—		51,419
Total available for sale securities	$	—	$	287,663	$	—	$	287,663
Derivative financial instruments:
Interest rate lock commitments	$	—		305	$	—		305
Forward mortgage-backed securities trades		—		3		—		3
Loan customer counterparty		—		4,829		—		4,829
Financial institution counterparty		—		240		—		240
Liabilities:
Derivative financial instruments:
Interest rate lock commitments	$	—	$	—	$	—	$	—
Forward mortgage-backed securities trades		—		83		—		83
Loan customer counterparty		—		240		—		240
Financial institution counterparty		—		4,829		—		4,829

Certain assets and liabilities are measured at fair value on a nonrecurring basis; that is, the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances (for example, when there is evidence of impairment). These instruments include other real estate owned, repossessed assets, held to maturity debt securities, loans held for sale and impaired loans, which are included as loans held for investment.  For the three and nine months ended September 30, 2020, the Company had additions to other real estate owned of $7.4 million and $8.2 million, respectively, of which $6.2 million and $6.9 million, respectively, were outstanding as of September 30, 2020. For the three and nine months ended September 30, 2020, the Company had additions to impaired loans of $8.9 million and $26.3 million, respectively, of which $8.9 million and $13.0 million, respectively, were outstanding as of September 30, 2020. The remaining financial assets and liabilities measured at fair value on a non-recurring basis that were recorded in 2020 and remained outstanding at September 30, 2020 were not significant.

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The following tables present carrying and fair value information of financial instruments as of the dates indicated:

	As of September 30, 2020
	Carrying		Estimated Fair Value
	Amount		Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets
Cash and due from banks	$	1,031,193	$	1,031,193	$	—	$	—	$	1,031,193
Federal funds sold		56,469		56,469		—		—		56,469
Held to maturity securities		6,970,380		—		7,145,837		—		7,145,837
Loans held for sale		51,694		—		51,694		—		51,694
Loans held for investment, net of allowance		17,689,698		—		—		17,704,208		17,704,208
Loans held for investment - Warehouse Purchase Program		2,730,614		—		2,730,614		—		2,730,614
Other real estate owned		11,548		—		11,548		—		11,548
Liabilities
Deposits:
Noninterest-bearing	$	8,998,328	$	—	$	8,998,328	$	—	$	8,998,328
Interest-bearing		17,460,878		—		17,485,431		—		17,485,431
Other borrowings		2,570		—		2,782		—		2,782
Securities sold under repurchase agreements		380,274		—		380,297		—		380,297
Subordinated notes		125,146		—		125,586		—		125,586

	As of December 31, 2019
	Carrying		Estimated Fair Value
	Amount		Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets
Cash and due from banks	$	573,589	$	573,589	$	—	$	—	$	573,589
Federal funds sold		519		519		—		—		519
Held to maturity securities		8,282,393		—		8,303,851		—		8,303,851
Loans held for sale		80,959		—		80,959		—		80,959
Loans held for investment, net of allowance		17,124,156		—		—		17,045,523		17,045,523
Loans held for investment - Warehouse Purchase Program		1,552,762		—		1,552,762		—		1,552,762
Other real estate owned		6,936		—		6,936		—		6,936
Liabilities
Deposits:
Noninterest-bearing	$	7,763,894	$	—	$	7,763,894	$	—	$	7,763,894
Interest-bearing		16,435,838		—		16,437,453		—		16,437,453
Other borrowings		1,303,730		—		1,303,941		—		1,303,941
Securities sold under repurchase agreements		377,294		—		377,302		—		377,302
Subordinated notes		125,804		—		125,743		—		125,743

The following is a description of the fair value estimates, methods and assumptions that are used by the Company in estimating the fair values of financial instruments.

Loans held for sale— Loans held for sale are carried at the lower of cost or estimated fair value. Fair value for consumer mortgages held for sale is based on commitments on hand from investors or prevailing market prices. As such, the Company classifies loans held for sale subjected to nonrecurring fair value adjustments as Level 2.

Loans held for investment— The Company does not record loans at fair value on a recurring basis. As such, valuation techniques discussed herein for loans are primarily for estimating fair value disclosures. The Company refined the calculation to estimate fair value for loans held for investment to be in accordance with ASU 2016-01. The refined discounted cash flow calculation to determine fair value considers internal and market-based information such as prepayment risk, cost of funds and liquidity. From time to time, the Company records nonrecurring fair value adjustments to impaired loans to reflect (1) partial write downs that are based on the observable market price or current appraised value of the collateral, or (2) the full charge-off of the loan carrying value.

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Where appraisals are not available, estimated cash flows are discounted using a rate commensurate with the credit risk associated with those cash flows. Assumptions regarding credit risk, cash flows and discount rates are judgmentally determined using available market information and specific borrower information.

The Company classifies the estimated fair value of loans held for investment as Level 3.

Other real estate owned— Other real estate owned is primarily foreclosed properties securing residential loans and commercial real estate. Foreclosed assets are adjusted to fair value less estimated costs to sell upon transfer of the loans to other real estate owned. Subsequently, these assets are carried at the lower of carrying value or fair value less estimated costs to sell. Other real estate carried at fair value based on an observable market price or a current appraised value is classified by the Company as Level 2. When management determines that the fair value of other real estate requires additional adjustments, either as a result of a non-current appraisal or when there is no observable market price, the Company classifies the other real estate as Level 3.

The fair value estimates presented herein are based on pertinent information available to management at September 30, 2020. Although management is not aware of any factors that would significantly affect the estimated fair value amounts, such amounts have not been comprehensively revalued for purposes of these financial statements since those dates and, therefore, current estimates of fair value may differ significantly from the amounts presented herein.

7. GOODWILL AND CORE DEPOSIT INTANGIBLES

Changes in the carrying amount of the Company’s goodwill and core deposit intangibles for the nine months ended September 30, 2020 and the year ended December 31, 2019 were as follows: 

	Goodwill		Core Deposit Intangibles
	(Dollars in thousands)
Balance as of December 31, 2018	$	1,900,845	$	32,883
Less:
Amortization		—		(6,537	)
Add:
LegacyTexas Merger		1,322,826		60,058
Balance as of December 31, 2019		3,223,671		86,404
Less:
Amortization		—		(9,926	)
Add:
Measurement period adjustment of LegacyTexas Merger		8,021		—
Balance as of September 30, 2020	$	3,231,692	$	76,478

Goodwill is recorded as of the acquisition date of each entity. The Company may record subsequent adjustments to goodwill for amounts undeterminable at acquisition date, such as deferred taxes and real estate valuations, and therefore the goodwill amounts may change accordingly. The Company initially records the total premium paid on acquisitions as goodwill. After finalizing the valuation, core deposit intangibles are identified and reclassified from goodwill to core deposit intangibles on the balance sheet. This reclassification has no effect on total assets, liabilities, shareholders’ equity, net income or cash flows. Management performs an evaluation annually, and more frequently if a triggering event occurs, of whether any impairment of the goodwill and core deposit intangibles has occurred. If any such impairment is determined, a write-down is recorded. As of September 30, 2020, there was no impairment recorded on goodwill and core deposit intangibles.

The measurement period for the Company to determine the fair value of acquired identifiable assets and assumed liabilities will be at the end of the earlier of (1) twelve months from the date of acquisition or (2) as soon as the Company receives the information it was seeking about facts and circumstances that existed as of the date of acquisition.

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Core deposit intangibles are being amortized on a non-pro rata basis over their estimated lives, which the Company believes is between 10 and 15 years. Amortization expense related to intangible assets totaled $3.3 million and $1.2 million for the three months ended September 30, 2020 and 2019, respectively, and $9.9 million and $3.8 million for the nine months ended September 30, 2020 and 2019, respectively. The estimated aggregate future amortization expense for core deposit intangibles remaining as of September 30, 2020 is as follows (dollars in thousands):

Remaining 2020	$	3,243
2021		11,551
2022		10,336
2023		9,360
2024		8,699
Thereafter		33,289
Total	$	76,478

8. INCOME TAXES

The amount of federal and state income tax expense is influenced by the amount of pre-tax income, the amount of tax-exempt income and the amount of other nondeductible expenses. Income tax expense totaled $35.1 million for the three months ended September 30, 2020 compared with $21.1 million for the same period in 2019, an increase of $13.9 million or 66.1%. The increase was primarily due the increase in pre-tax income related to the Merger. Income tax expense totaled $79.2 million for the nine months ended September 30, 2020 compared with $63.4 million for the same period in 2019, an increase of $15.8 million or 25.0%. The increase was primarily due to the increase in pre-tax income related to the Merger, partially offset by the tax benefit for net operating losses (“NOLs”) carryback of $20.1 million as a result of the CARES Act. The Company’s effective tax rate for the three months ended September 30, 2020 and 2019 was 21.2% and 20.5%, respectively. The Company’s effective tax rate for the nine months ended September 30, 2020 and 2019 was 16.8% and 20.5%, respectively.

In response to the COVID-19 pandemic, on March 27, 2020, the President of the United States signed the CARES Act into law. The CARES Act permits a five-year carryback period for NOLs, which allowed the Company to generate an anticipated tax refund and income tax benefit resulting from the tax rate differential between the current statutory tax rate of 21% and the 35% statutory tax rate in prior years during the carryback period. Pursuant to this provision of the CARES Act, the Company recorded a federal current benefit for taxes on income during the nine months ended September 30, 2020 due to the NOLs generated in 2019 by LegacyTexas that were used to offset taxable income generated between 2014 and 2017 taxed at 35% resulting in a tax benefit of $20.1 million, which is included in provision for income taxes in the accompanying condensed consolidated statements of income. This caused a reduction in the effective tax rate during the nine months ended September 30, 2020 as NOLs carried back to tax years 2014 through 2017 are applied at a federal tax rate of 35% applicable to those tax years, compared to a 21% tax rate effective at September 30, 2020. As a result, during the nine months ended September 30, 2020, the Company’s total deferred tax asset decreased by $31.9 million.

9. STOCK–BASED COMPENSATION

At September 30, 2020, the Company had two stock-based employee compensation plans with awards outstanding.

On March 3, 2020, Bancshares’ Board of Directors established the Prosperity Bancshares, Inc. 2020 Stock Incentive Plan (the “2020 Plan”), subject to approval by the Company’s shareholders. The Company’s shareholders approved the 2020 Plan at the annual meeting of shareholders on April 21, 2020. The 2020 Plan authorizes the issuance of up to 2,500,000 shares of common stock upon the exercise of options or pursuant to the grant or exercise, as the case may be, of other awards granted under the 2020 Plan, including incentive stock options, nonqualified stock options, stock appreciation rights, shares of restricted stock and restricted stock units. As of September 30, 2020, 12,500 shares of unvested restricted stock have been granted under the 2020 Plan.

During 2012, Bancshares’ Board of Directors established the Prosperity Bancshares, Inc. 2012 Stock Incentive Plan (the “2012 Plan”), which was approved by Bancshares’ shareholders and authorized the issuance of up to 1,250,000 shares of common stock upon the exercise of options granted under the 2012 Plan or pursuant to the grant or exercise, as the case may be, of other awards granted under the 2012 Plan, including restricted stock, stock appreciation rights, phantom stock awards and performance awards. As of September 30, 2020, 370,313 shares of common stock had been issued pursuant to vested awards and 489,312 shares of unvested restricted stock had been granted under the 2012 Plan prior to the adoption of the 2020 Plan by the Company’s shareholders. The Company does not plan to make any further awards pursuant to the 2012 Plan.

As of September 30, 2020, the Company had no stock options outstanding. Stock-based compensation expense related to restricted stock was $3.2 million and $2.5 million during the three months ended September 30, 2020 and 2019, respectively, and

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$9.5  million and $7.6 million during the nine months ended September 30, 2020 and 2019. As of September 30, 2020, there was $8.9  million of total unrecognized compensation expense related to stock-based compensation arrangements. That cost is expected to be recognized over a weighted average period of 1.90 years.

10. CONTRACTUAL OBLIGATIONS AND OFF-BALANCE SHEET ITEMS

Contractual Obligations

The Company’s contractual obligations and other commitments to make future payments as of September 30, 2020 (other than deposit obligations and securities sold under repurchase agreements) are summarized below. The Company’s future cash payments associated with its contractual obligations pursuant to its subordinated notes and Federal Home Loan Bank (“FHLB”) advances and notes payable as of September 30, 2020 are summarized below. The future interest payments were calculated using the current rate in effect at September 30, 2020. In September 2020, the Company gave irrevocable notice of its intent to redeem the outstanding subordinated notes on December 1, 2020. The $125.1 million outstanding balance of the subordinated notes and all accrued interest payable upon redemption is included in the “1 year or less” column below. Payments for the subordinated notes include interest of $1.1 million. Payments for FHLB notes payable include interest of $205 thousand that will be paid over the future periods. The payments do not include pre-payment options that may be available to the Company.

	1 year or less		More than 1 year but less than 3 years		3 years or more but less than 5 years		5 years or more		Total
	(Dollars in thousands)
Subordinated notes	$	126,292	$	—	$	—	$	—	$	126,292
Federal Home Loan Bank advances and notes payable		974		1,067		366		18		2,425
Total	$	127,266	$	1,067	$	366	$	18	$	128,717

Leases

The Company’s leases relate primarily to operating leases for office space and banking centers. The Company determines if an arrangement is a lease or contains a lease at inception. The Company’s leases have remaining lease terms of 1 to 18 years, which may include the option to extend the lease when it is reasonably certain for the Company to exercise that option. Operating lease right-of-use (ROU) assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. The Company uses its incremental collateralized borrowing rate to determine the present value of lease payments. Short-term leases and leases with variable lease costs are immaterial and the Company does not have any sublease arrangements. As of September 30, 2020, operating lease ROU assets and lease liabilities were approximately $54.0 million. ROU assets and lease liabilities were classified as other assets and other liabilities, respectively.

As of September 30, 2020, the weighted average remaining lease terms of the Company’s operating leases were 7.4 years. The weighted average discount rate used to determine the lease liabilities as of September 30, 2020 for the Company’s operating leases was 2.34%. Cash paid for the Company’s operating leases for the three months ended September 30, 2020 and 2019 was $3.3 million and $1.4 million, respectively. Cash paid for the Company’s operating leases for the nine months ended September 30, 2020 and 2019 was $10.5 million and $4.2 million, respectively. The Company obtained $5.6 million in ROU assets in exchange for lease liabilities for four operating leases during the nine months ended September 30, 2020.

The Company’s future undiscounted cash payments associated with its operating leases as of September 30, 2020 are summarized below (dollars in thousands).

Remaining 2020	$	2,637
2021		10,196
2022		9,671
2023		8,922
2024		8,042
2025		7,651
Thereafter		19,383
Total undiscounted lease payments	$	66,502

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The following table presents a summary of non-cancelable future operating lease commitments as of December 31, 2019 (dollars in thousands):

2020	$	10,137
2021		9,169
2022		8,641
2023		7,998
2024		7,119
Thereafter		24,996
Total non-cancelable lease payments	$	68,060

Off-Balance Sheet Items

In the normal course of business, the Company enters into various transactions that, in accordance with GAAP, are not included in its consolidated balance sheets. The Company enters into these transactions to meet the financing needs of its customers. These transactions include commitments to extend credit and standby letters of credit, which involve, to varying degrees, elements of credit risk and interest rate risk in excess of the amounts recognized in the consolidated balance sheets.

The Company’s commitments associated with outstanding standby letters of credit, unused capacity on Warehouse Purchase Program loans and commitments to extend credit expiring by period as of September 30, 2020 are summarized below. Since commitments associated with letters of credit, unused capacity of Warehouse Purchase Program loans, allowance for credit losses on off-balance sheet credit exposures and commitments to extend credit may expire unused, the amounts shown do not necessarily reflect the actual future cash funding requirements.

	1 year or less		More than 1 year but less than 3 years		3 years or more but less than 5 years		5 years or more		Total
	(Dollars in thousands)
Standby letters of credit	$	104,896	$	6,616	$	1,337	$	—	$	112,849
Unused capacity on Warehouse Purchase Program loans		803,386		—		—		—		803,386
Commitments to extend credit		1,743,194		852,081		342,756		1,245,988		4,184,019
Total	$	2,651,476	$	858,697	$	344,093	$	1,245,988	$	5,100,254

The Company funds an allowance for credit losses on off-balance sheet lending-related commitments and guarantees on credit card debt through a charge to provision for credit losses on the Company’s consolidated statement of income. At September 30, 2020 and December 31, 2019, this allowance for credit losses on off-balance sheet lending-related commitments and guarantees on credit card debt, included in “Allowance for credit losses on off-balance sheet credit exposures” on the Company’s consolidated balance sheet, totaled $29.9 million and $5.6 million, respectively.

11. OTHER COMPREHENSIVE INCOME

The tax effects allocated to each component of other comprehensive income were as follows:

	Three Months Ended September 30,
	2020							2019
	Before Tax Amount		Tax Effect			Net of Tax Amount		Before Tax Amount			Tax Effect		Net of Tax Amount
	(Dollars in thousands)
Other comprehensive income (loss):
Securities available for sale:
Change in unrealized gain (loss) during period	$	1,325	$	(278	)	$	1,047	$	(1,563	)	$	328	$	(1,235	)
Total securities available for sale		1,325		(278	)		1,047		(1,563	)		328		(1,235	)
Total other comprehensive income (loss)	$	1,325	$	(278	)	$	1,047	$	(1,563	)	$	328	$	(1,235	)

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	Nine Months Ended September 30,
	2020								2019
	Before Tax Amount			Tax Effect		Net of Tax Amount			Before Tax Amount			Tax Effect		Net of Tax Amount
	(Dollars in thousands)
Other comprehensive loss:
Securities available for sale:
Change in unrealized loss during period	$	(1,204	)	$	253	$	(951	)	$	(344	)	$	72	$	(272	)
Total securities available for sale		(1,204	)		253		(951	)		(344	)		72		(272	)
Total other comprehensive loss	$	(1,204	)	$	253	$	(951	)	$	(344	)	$	72	$	(272	)

Activity in accumulated other comprehensive income associated with securities available for sale, net of tax, was as follows:

	Securities Available for Sale			Accumulated Other Comprehensive Income (Loss)
	(Dollars in thousands)
Balance at December 31, 2019	$	602		$	602
Other comprehensive loss		(951	)		(951	)
Balance at September 30, 2020	$	(349	)	$	(349	)
Balance at December 31, 2018	$	310		$	310
Other comprehensive loss		(272	)		(272	)
Balance at September 30, 2019	$	38		$	38

12. DERIVATIVE FINANCIAL INSTRUMENTS

The following table provides the outstanding notional balances and fair values of outstanding derivative positions at September 30, 2020 and December 31, 2019.

	September 30, 2020						December 31, 2019
	Outstanding Notional Balance		Asset Derivative Fair Value		Liability Derivative Fair Value		Outstanding Notional Balance		Asset Derivative Fair Value		Liability Derivative Fair Value
	(Dollars in thousands)
Interest rate lock commitments	$	—	$	—	$	—	$	9,438	$	305	$	—
Forward mortgage-backed securities trades		—		—		—		40,750		3		83
Commercial loan interest rate swaps and caps:
Loan customer counterparty		224,928		13,510		—		231,345		4,829		240
Financial institution counterparty		224,928		—		13,510		231,345		240		4,829

These financial instruments are not designated as hedging instruments and are used for asset and liability management and commercial customers’ financing needs. All derivatives are carried at fair value in either other assets or other liabilities.

Interest rate lock commitments (“IRLCs”) — In the normal course of business, the Company enters into interest rate lock commitments with consumers to originate mortgage loans at a specified interest rate. These commitments, which contain fixed expiration dates, offer the borrower an interest rate guarantee provided the loan meets underwriting guidelines and closes within the timeframe established by the Company.

Forward mortgage-backed securities trades — The Company manages the changes in fair value associated with changes in interest rates related to IRLCs by using forward sold commitments known as forward mortgage-backed securities trades. These instruments are typically entered into at the time the interest rate lock commitment is made.

Interest rate swaps and caps — These derivative positions relate to transactions in which the Company enters into an interest rate swap or cap with a customer, while at the same time entering into an offsetting interest rate swap or cap with another financial institution. An interest rate swap transaction allows the Company’s customer to effectively convert a variable rate loan to a fixed rate.

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In connection with each swap, the Company agrees to pay interest to the customer on a notional amount at a variable interest rate and receive interest from the customer on a similar notional amount at a fixed interest rate. At the same time, the Company agrees to pay another financial institution the same fixed interest rate on the same notional amount and receive the same variable interest rate on the same notional amount. In connection with each interest rate cap, the Company sells a cap to the customer and agrees to pay interest if the underlying index exceeds the strike price defined in the cap agreement. Simultaneously the Company purchases a cap with matching terms from another financial institution that agrees to pay the Company if the underlying index exceeds the strike price.

The commercial loan customer counterparty weighted average received and paid interest rates for interest rate swaps outstanding at September 30, 2020 and December 31, 2019 are presented in the following table.

	Weighted-Average Interest Rate
	September 30, 2020						December 31, 2019
	Received			Paid			Received			Paid
Loan customer counterparty		0.58	%		2.83	%		3.42	%		2.86	%

The Company’s credit exposure on interest rate swaps is limited to the net favorable value of all swaps by each counterparty, which was approximately $13.5 million at September 30, 2020 and $4.8 million at December 31, 2019. This credit exposure is partly mitigated as transactions with customers are secured by the collateral, if any, securing the underlying transaction being hedged. The Company’s credit exposure, net of collateral pledged, relating to interest rate swaps with upstream financial institution counter-parties was zero at September 30, 2020. A credit support annex is in place and allows the Company to call collateral from upstream financial institution counter-parties. Collateral levels are monitored and adjusted on a regular basis for changes in interest rate swap values. The Company’s cash collateral pledged for interest rate swaps was $15.3 million at September 30, 2020 and $9.3 million at December 31, 2019.

The initial and subsequent changes in the fair value of IRLCs and the forward sales of mortgage-backed securities are recorded in net gain on sale of mortgage loans. These gains and losses were not attributable to instrument-specific credit risk. For interest rate swaps and caps, because the Company acts as an intermediary for its customer, changes in the fair value of the underlying derivative contracts substantially offset each other and do not have a material impact on its results of operations. Income (loss) for the three and nine months ended September 30, 2020 and 2019 was as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
Derivatives not designated as hedging instruments	2020		2019		2020			2019
	(Dollars in thousands)
Interest rate lock commitments	$	—	$	—	$	(305	)	$	—
Forward mortgage-backed securities trades		—		—		(2,398	)		—

13. ACQUISITIONS

Acquisitions are an integral part of the Company’s growth strategy. All acquisitions were accounted for using the acquisition method of accounting. Accordingly, the assets and liabilities of the acquired entities were recorded at their fair values at the acquisition date. The excess of the purchase price over the estimated fair value of the net assets for tax-free acquisitions was recorded as goodwill, none of which is deductible for tax purposes. The excess of the purchase price over the estimated fair value of the net assets for taxable acquisitions was also recorded as goodwill, and is deductible for tax purposes. The identified core deposit intangibles for each acquisition are being amortized using a non-pro rata basis over an estimated life of 10 to 15 years. The results of operations for each acquisition have been included in the Company’s consolidated financial results beginning on the respective acquisition date.

The measurement period for the Company to determine the fair values of acquired identifiable assets and assumed liabilities will end at the earlier of (1) twelve months from the date of the acquisition or (2) as soon as the Company receives the information it is seeking about facts and circumstances that existed as of the acquisition date or learns that more information is not obtainable. The following acquisitions were completed on the dates indicated:

2019 Acquisition

Merger with LegacyTexas Financial Group, Inc. — On November 1, 2019, LegacyTexas Financial Group, Inc. merged into Prosperity Bancshares and LegacyTexas Bank merged into the Bank. LegacyTexas was headquartered in Plano, Texas and operated 42 locations in 19 North Texas cities in and around the Dallas-Fort Worth area. As of September 30, 2019, LegacyTexas, on a consolidated basis, reported total assets of $10.5 billion, total gross loans of $9.1 billion, total deposits of $6.5 billion and shareholders’ equity of $1.2 billion.

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Pursuant to the terms of the merger agreement, Bancshares issued 26,228,148 shares of Bancshares common stock, with a closing price of $69.02 per share on November 1, 2019, plus $318.0 million in cash, comprised of $308.6 million in cash and $9.4 million in cash for taxes withheld, for all outstanding shares of LegacyTexas.

The assets and liabilities of LegacyTexas were recorded on the consolidated balance sheet at estimated fair value on the acquisition date. As of September 30, 2020, the following table presents the amounts recorded on the consolidated balance sheet on the acquisition date (dollars in thousands).

	Initially Recorded at Acquisition Date		Measurement Period Adjustments			Adjusted Values as of September 30, 2020
Fair value of consideration paid:
Common stock issued (26,228,148 shares)	$	1,810,267	$	—		$	1,810,267
Cash		318,018		—			318,018
Total consideration paid	$	2,128,285	$	—		$	2,128,285
Fair value of assets acquired:
Cash and due from banks	$	228,649	$	—		$	228,649
Securities held to maturity		472,933		—			472,933
Loans held for sale		60,818		—			60,818
Loans held for investment		6,771,080		—			6,771,080
Loans held for investment - Warehouse Purchase Program		1,693,049		—			1,693,049
Bank premises and equipment		67,347		(1,299	)		66,048
Other real estate owned		4,876		—			4,876
Core deposit intangibles		60,058		—			60,058
Federal Home Loan Bank stock		117,939		(113	)		117,826
Bank owned life insurance and other assets		242,592		(7,125	)		235,467
Total assets acquired		9,719,341		(8,537	)		9,710,804
Fair value of liabilities assumed:
Deposits		6,434,732		—			6,434,732
Other borrowings		2,078,682		—			2,078,682
Securities sold under repurchase agreements		57,670		—			57,670
Trust preferred securities		15,376		—			15,376
Subordinated notes		125,950		—			125,950
Other liabilities		201,472		(516	)		200,956
Total liabilities assumed		8,913,882		(516	)		8,913,366
Fair value of net assets acquired	$	805,459	$	(8,021	)	$	797,438
Goodwill resulting from acquisition	$	1,322,826	$	8,021		$	1,330,847

The measurement period adjustments noted in the table above were a result of information obtained subsequent to the Company’s initial reporting of provisional fair values but prior to finalizing the fair values in accordance with ASC 805, Business Combinations. Such information was determined to be a condition in existence as of acquisition date.

As of September 30, 2020, the Company recognized goodwill of $1.33 billion, which is subject to subsequent fair value adjustments. Goodwill represents the excess of the total purchase price paid over the fair value of the assets acquired, net of the fair value of liabilities assumed. The goodwill is not deductible for tax purposes. Additionally, as of September 30, 2020, total core deposit intangibles related to LegacyTexas were $52.1 million.

Merger Related Expenses: The Company incurred zero and $8.0 million of pre-tax merger related expenses during the three and nine months ended September 30, 2020, respectively. The Company incurred $46.4 million of pre-tax merger related expenses during the year ended December 31, 2019. The merger related expenses are reflected on the Company’s income statement for the applicable periods under “Merger related expenses” and consist of salaries and benefits, data processing and professional and legal fees.

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Pro Forma Information: Operations of LegacyTexas have been included in the consolidated financial statements since November 1, 2019.

The following pro forma information presents the results of operations for the three and nine months ended September 30, 2019, as if the Merger had occurred on January 1, 2019 (dollars in thousands, except per share amounts).

	Three Months Ended September 30, 2019		Nine Months Ended September 30, 2019
Net interest income	$	259,730	$	768,548
Net income		140,400		367,677
Basic earnings per share		1.47		3.85
Diluted earnings per share		1.47		3.85

The above pro forma results are presented for illustrative purposes and are not intended to represent or be indicative of the actual results of operations of the merged companies that would have been achieved had the Merger occurred on January 1, 2019, nor are they intended to represent or be indicative of future results of operations. The pro forma results do not include expected operating cost savings as a result of the acquisition. These pro forma results require significant estimates and judgments particularly as they relate to valuation and accretion of income associated with acquired loans. Pro forma adjustments principally included:

• Reversing interest income and interest expense as previously recorded by LegacyTexas and recording interest income and interest expense based on impact of estimated fair values of the acquired interest-earning assets and assumed interest-bearing liabilities;

• Reversing core deposit intangible amortization as previously recorded by LegacyTexas and recording amortization expense as it relates to the core deposit intangible recognized from the acquisition; and

• Reporting merger related expenses as if they were incurred on January 1, 2019.

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ITEM 2.MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

Special Cautionary Notice Regarding Forward-Looking Statements

Statements and financial discussion and analysis contained in this quarterly report on Form 10-Q that are not statements of historical fact constitute forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These forward-looking statements are based on assumptions and involve a number of risks and uncertainties, many of which are beyond the Company’s control. Forward-looking statements can be identified by words such as “believes,” “intends,” “expects,” “plans,” “will” and similar references to future periods. Many possible events or factors could affect the future financial results and performance of the Company and could cause such results or performance to differ materially from those expressed in the forward-looking statements. These possible events or factors include, but are not limited to:

• changes in the strength of the United States economy in general and the strength of the local economies in which the Company conducts operations resulting in, among other things, a deterioration in credit quality or reduced demand for credit, including the result and effect on the Company’s loan portfolio and allowance for credit losses;

• the effect, impact, potential duration or other implications of the COVID-19 pandemic, including any actions undertaken by federal, state and local governmental authorities in response to the pandemic;

• volatility in interest rates and market prices, which could reduce the Company’s net interest margins, asset valuations and expense expectations;

• changes in the levels of loan prepayments and the resulting effects on the value of the Company’s loan portfolio;

• changes in local economic and business conditions, including fluctuations in the price of oil, natural gas and other commodities, which adversely affect the Company’s customers and their ability to transact profitable business with the Company, including the ability of the Company’s borrowers to repay their loans according to their terms or a change in the value of the related collateral;

• increased competition for deposits and loans adversely affecting rates and terms;

• the expected cost savings, synergies and other financial and operational benefits from the LegacyTexas merger might not be realized within the expected time frames or at all, and costs or difficulties relating to the integration of LegacyTexas might be greater than expected;

• the timing, impact and other uncertainties of any future acquisitions, including the Company’s ability to identify suitable future acquisition candidates, the success or failure in the integration of their operations, and the ability to enter new markets successfully and capitalize on growth opportunities;

• the possible impairment of goodwill associated with an acquisition and possible adverse short-term effects on the results of operations;

• increased credit risk in the Company’s assets and increased operating risk caused by a material change in commercial, consumer and/or real estate loans as a percentage of the total loan portfolio;

• the concentration of the Company’s loan portfolio in loans collateralized by residential and commercial real estate;

• the failure of assumptions underlying the establishment of and provisions made to the allowance for credit losses, including such assumptions related to potential, pending or recent acquisitions;

• changes in the availability of funds resulting in increased costs or reduced liquidity;

• a deterioration or downgrade in the credit quality and credit agency ratings of the securities in the Company’s securities portfolio;

• increased asset levels and changes in the composition of assets and the resulting impact on the Company’s capital levels and regulatory capital ratios;

• the Company’s ability to acquire, operate and maintain cost effective and efficient systems without incurring unexpectedly difficult or expensive but necessary technological changes;

• the loss of senior management or operating personnel and the potential inability to hire qualified personnel at reasonable compensation levels;

• government intervention in the U.S. financial system;

34

• changes in statutes and government regulations or their interpretations applicable to financial holding companies and the Company’s present and future banking and other subsidiaries, including changes in tax requirements and tax rates;

• the effect of changes in accounting policies and practices, as may be adopted by the regulatory agencies, as well as the Public Company Accounting Oversight Board, the Financial Accounting Standards Board and other accounting standard setters;

• poor performance by external vendors;

• the cost and effects of a failure, interruption, or breach of security of the Company’s systems;

• the failure of analytical and forecasting models and tools used by the Company to estimate probable credit losses and to measure the fair value of financial instruments;

• additional risks from new lines of businesses or new products and services;

• claims or litigation related to intellectual property or fiduciary responsibilities;

• the failure of the Company’s enterprise risk management framework to identify or address risks adequately;

• a failure in or breach of operational or security systems of the Company’s infrastructure, or those of its third-party vendors and other service providers, including as a result of cyber attacks;

• potential risk of environmental liability associated with lending activities;

• acts of terrorism, an outbreak of hostilities or other international or domestic calamities, weather or other acts of God and other matters beyond the Company’s control, including the COVID-19 pandemic; and

• other risks and uncertainties described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, in this report under “Risk Factors” in Part II, Item 1A, or in the Company’s other reports and documents filed with the Securities and Exchange Commission.

A forward-looking statement may include a statement of the assumptions or bases underlying the forward-looking statement. The Company believes it has chosen these assumptions or bases in good faith and that they are reasonable. However, the Company cautions that assumptions or bases almost always vary from actual results, and the differences between assumptions or bases and actual results can be material. Therefore, the Company cautions against placing undue reliance on its forward-looking statements. The forward-looking statements speak only as of the date the statements are made. The Company undertakes no obligation to publicly update or otherwise revise any forward-looking statements, whether as a result of new information, future events or otherwise.

Management’s Discussion and Analysis of Financial Condition and Results of Operations analyzes the major elements of the Company’s balance sheets and statements of income. This section should be read in conjunction with the Company’s consolidated financial statements and accompanying notes included in Part I, Item 1 of this report and with the consolidated financial statements and accompanying notes and other detailed information appearing in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019.

OVERVIEW

Prosperity Bancshares, Inc., a Texas corporation, was formed in 1983 to acquire the former Allied First Bank in Edna, Texas, which was chartered in 1949 as The First National Bank of Edna and is now known as Prosperity Bank. The Company is a registered financial holding company that derives substantially all of its revenues and income from the operation of its bank subsidiary, Prosperity Bank. The Bank provides a wide array of financial products and services to businesses and consumers throughout Texas and Oklahoma. As of September 30, 2020, the Bank operated 275 full-service banking locations; with 65 in the Houston area, including The Woodlands; 30 in the South Texas area including Corpus Christi and Victoria; 65 in the Dallas/Fort Worth area; 22 in the East Texas area; 29 in the Central Texas area including Austin and San Antonio; 34 in the West Texas area including Lubbock, Midland-Odessa and Abilene; 16 in the Bryan/College Station area; 6 in the Central Oklahoma area; 8 in the Tulsa, Oklahoma area. The Company’s principal executive office is located at Prosperity Bank Plaza, 4295 San Felipe in Houston, Texas, and its telephone number is (281) 269-7199. The Company’s website address is www.prosperitybankusa.com. Information contained on the Company’s website is not incorporated by reference into this quarterly report on Form 10-Q and is not part of this or any other report.

The Company generates the majority of its revenues from interest income on loans, service charges and fees on customer accounts and income from investment in securities. The revenues are partially offset by interest expense paid on deposits and other borrowings and noninterest expenses such as administrative and occupancy expenses. Net interest income is the difference between interest income on earning assets such as loans and securities and interest expense on liabilities such as deposits and borrowings which

35

are used to fund those assets. Net interest income is the Company’s largest source of revenue. The level of interest rates and the volume and mix of earning assets and interest-bearing liabilities impact net interest income and margin.

Three principal components of the Company’s growth strategy are internal growth, efficient operations and acquisitions, including strategic merger transactions. The Company focuses on continual internal growth. The Company maintains separate data with respect to each banking center’s net interest income, efficiency ratio, deposit growth and loan growth for purposes of measuring its overall profitability. The Company also focuses on maintaining efficiency and stringent cost control practices and policies. The Company has centralized many of its critical operations, such as data processing and loan processing. Management believes that this centralized infrastructure can accommodate substantial additional growth and achieve necessary controls while enabling the Company to minimize operational costs through certain economies of scale.  The Company also intends to continue to seek expansion opportunities.

Total assets were $33.20 billion at September 30, 2020 compared with $32.19 billion at December 31, 2019, an increase of $1.01 billion or 3.1%. Total loans were $20.80 billion at September 30, 2020 compared with $18.85 billion at December 31, 2019, an increase of $1.95 billion or 10.3%. Total deposits were $26.46 billion at September 30, 2020 compared with $24.20 billion at December 31, 2019, an increase of $2.26 billion or 9.3%. Total shareholders’ equity was $6.03 billion at September 30, 2020 compared with $5.97 billion at December 31, 2019, an increase of $64.0 million or 1.1%.

CRITICAL ACCOUNTING POLICIES

The Company’s significant accounting policies are integral to understanding the results reported. The Company’s accounting policies are described in detail in Note 1 to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. The Company believes that of its significant accounting policies, the following may involve a higher degree of judgment and complexity:

Business Combinations—Generally, acquisitions are accounted for under the acquisition method of accounting in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 805, Business Combinations. A business combination occurs when the Company acquires net assets that constitute a business and obtains control over that business. Business combinations are effected through the transfer of consideration consisting of cash and/or common stock and are accounted for using the acquisition method. Accordingly, the assets and liabilities of the acquired business are recorded at their respective fair values at the acquisition date. Determining the fair value of assets and liabilities, especially the loan portfolio, is a process involving significant judgment regarding methods and assumptions used to calculate estimated fair values. Fair values are subject to refinement for up to one year after the closing date of the acquisition as information relative to closing date fair values becomes available. The results of operations of an acquired entity are included in the Company’s consolidated results from acquisition date, and prior periods are not restated. The fair value of acquired loans incorporates assumptions regarding future credit losses and therefore no allowance for loan losses related to the acquired loans is recorded on the acquisition date.

Allowance for Credit Losses on Loans— The allowance for credit losses is accounted for in accordance with FASB ASC 326, Measurement of Credit Losses on Financial Instruments. The allowance for credit losses is adjusted through charges to earnings in the form of a provision for credit losses. The Company’s allowance for credit losses consists of two elements: (1) specific valuation allowances based on probable losses on impaired loans; and (2) a general valuation allowance based on historical lifetime loan loss experience, general economic conditions and other qualitative risk factors both internal and external to the Company. Management has established an allowance for credit losses on loans which it believes is adequate for estimated losses in the Company’s loan portfolio. Based on an evaluation of the portfolio, management presents a quarterly review of the allowance for credit losses to the Bank’s Board of Directors, indicating any change in the allowance since the last review and any recommendations as to adjustments in the allowance. In making its evaluation, management considers factors such as historical lifetime loan loss experience, the amount of nonperforming assets and related collateral, the volume, growth and composition of the portfolio, current economic conditions and reasonable and supportable forecasted economic conditions that may affect the borrower’s ability to pay and the value of collateral, the evaluation of the portfolio through its internal loan review process and other relevant factors. Portions of the allowance may be allocated for specific credits; however, the entire allowance is available for any credit that, in management’s judgment, should be charged off. Charge-offs occur when loans are deemed to be uncollectible. For further discussion of the methodology used in the determination of the allowance for credit losses on loans, see “Accounting for Acquired Loans and the Allowance for Acquired Credit Losses”, “Financial Condition—Allowance for Credit Losses on Loans” sections below and Note 3 to the consolidated financial statements.

Accounting for Acquired Loans and the Allowance for Acquired Credit Losses — The Company accounts for its acquisitions using the acquisition method of accounting. Accordingly, the assets, including loans, and liabilities of the acquired entity were recorded at their fair values at the acquisition date. These fair value estimates associated with acquired loans, and based on a discounted cash flow model, include estimates related to market interest rates and undiscounted projections of future cash flows that

36

incorporate expectations of prepayments and the amount and timing of principal, interest and other cash flows, as well as any shortfalls thereof. On January 1, 2020, the Company adopted ASU 2016-13, “Financial Instruments-Credit Losses (Topic 326) – Measurement of Credit Losses on Financial Instruments” (“CECL”). Upon adoption of CECL, all loans accounted for under ASC 310-20 were included in the allowance for credit losses methodology, with no offset provided for any remaining fair value marks. In addition, all loans previously accounted for under ASC 310-30 had their credit marks reclassified to be included in the allowance for credit losses. For further discussion of the methodology used in the determination of the allowance for credit losses for acquired loans, see “Financial Condition—Allowance for Credit Losses on Loans” below. For further discussion of the Company’s acquisition and loan accounting, see Note 5 to the consolidated financial statements.

Fair Values of Financial Instruments—The Company determines the fair market values of financial instruments based on the fair value hierarchy established, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value. Level 1 inputs include quoted active market prices, where available. If such quoted market prices are not available, Level 2 inputs are used. These inputs are based upon internally developed analytical tools that primarily use observable, market-based parameters. Level 3 inputs are unobservable inputs which are typically based on an entity’s own assumptions, as there is little, if any, related market activity. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability.

RECENT ACQUISITIONS

Merger with LegacyTexas Financial Group, Inc.—On November 1, 2019, LegacyTexas Financial Group, Inc. (“LegacyTexas”), merged with Prosperity Bancshares and LegacyTexas Bank merged with the Bank (collectively, the “Merger”). LegacyTexas was headquartered in Plano, Texas and operated 42 locations in 19 North Texas cities in and around the Dallas-Fort Worth area. As of September 30, 2019, LegacyTexas, on a consolidated basis, reported total assets of $10.5 billion, total gross loans of $9.1 billion, total deposits of $6.5 billion and shareholders’ equity of $1.2 billion.

Pursuant to the terms of the merger agreement, Bancshares issued 26,228,148 shares of Bancshares common stock with a closing price of $69.02 per share plus $318.0 million in cash, made up of $308.6 million in cash and $9.4 million cash in taxes withheld, for all outstanding shares of LegacyTexas. This resulted in goodwill of $1.33 billion as of September 30, 2020, which was subject to subsequent fair value adjustments. Additionally, as of September 30, 2020, total core deposit intangibles related to LegacyTexas were $52.1 million.

RECENT DEVELOPMENTS

As of September 30, 2020, the Company had $125.0 million outstanding in Fixed-to-Floating Rate Subordinated Notes (the “Notes”) that were assumed in connection with the Merger. In September 2020, the Company notified the trustee with respect to the indenture under which the Notes were issued of the Company’s intent to redeem the Notes. The redemption will occur on December 1, 2020 and will be funded by dividends from the Bank.

COVID-19 PANDEMIC

In December 2019, a novel strain of coronavirus disease (“COVID-19”) was first reported in Wuhan, Hubei Province, China. On March 11, 2020, the World Health Organization declared COVID-19 a pandemic. On March 13, 2020, the U.S. President announced a national emergency relating to the pandemic, which has since been extended. On August 8, 2020, the Governor of Texas extended the proclamation certifying that COVID-19 poses an imminent threat of disaster in the state and declaring a state of disaster for all counties in Texas and on September 17, 2020, signed an Executive Order that detailed the ongoing plan to open businesses and activities in Texas. On September 25, 2020, the Governor of Oklahoma extended the executive order that declared an emergency caused by the impending threat of COVID-19 to the people of Oklahoma. The Bank is considered an essential business and is closely monitoring the latest developments regarding COVID-19. The COVID-19 pandemic has resulted in significant economic uncertainties that have had, and could continue to have, an adverse impact on the Company’s operating income, financial condition and cash flows. The extent to which the COVID-19 pandemic will impact the Company’s operations and financial results during the remainder of 2020 cannot be reasonably or reliably estimated at this time.

The health and safety of the Bank’s associates, customers, and communities are of utmost importance; and the Company has taken additional measures in an effort to ensure this safety, including restricting nonessential employee travel, expanding remote access availability, distancing work stations, professional cleaning of its facilities, and signs and distancing reminders for customers in

37

the banking centers. Further, the Company remains committed to providing uninterrupted and reliable banking service and has business continuity plans and protocols in place to ensure critical operations are able to continue without disruption.

In response to the COVID-19 pandemic, on March 27, 2020 the President of the United States signed the CARES Act into law.  The CARES Act provides assistance for American workers, families and small businesses. The Paycheck Protection Program (“PPP”), established by the CARES Act and implemented by the Small Business Administration (“SBA”) with support from the Department of the Treasury, provides small businesses with funds to pay payroll costs including benefits. Funds can also be used to pay interest on mortgages, rent, and utilities. On June 5, 2020, the President signed into law the Paycheck Protection Program Flexibility Act of 2020 (“PPP Flexibility Act”), which modified the covered expense period from eight weeks to 24 weeks, extended the maturity date of the loans out to five years and gave greater flexibility to employers having difficulty hiring workers. PPP loans originated prior to June 5, 2020, have a two year term and earn interest at 1%. PPP loans originated on and after June 5, 2020, have a five year term. The loans are eligible for early forgiveness by the SBA as provided by the CARES Act and the PPP Flexibility Act and related regulations and guidance. Additionally, the Bank is entitled to a per loan processing fee based on a tiered schedule ranging from 5% to 1% of the loan balance. The PPP application period expired on August 8, 2020.  As of September 30, 2020, the Company had 11,948 PPP loans totaling $1.39 billion. The Company has also provided relief to its loan customers through loan extensions and deferrals.

RESULTS OF OPERATIONS

Net income available to common shareholders was $130.1 million for the quarter ended September 30, 2020 compared with $81.8 million for the same period in 2019, an increase of $48.3 million or 59.1%. Net income per diluted common share was $1.40 for the quarter ended September 30, 2020 compared with $1.19 for the same period in 2019, an increase of 17.6%, primarily due to the Merger. The Company posted annualized returns on average common equity of 8.64% and 7.89%, annualized returns on average assets of 1.58% and 1.47% and efficiency ratios of 40.17% and 43.70% for the quarters ended September 30, 2020 and 2019, respectively. The efficiency ratio is calculated by dividing total noninterest expense by the sum of net interest income and noninterest income. Because the ratio is a measure of revenues and expenses resulting from the Company’s lending activities and fee-based banking services; net gains and losses on the sale of assets are not included. Additionally, taxes are not part of this calculation.

For the nine months ended September 30, 2020, net income available to common shareholders was $391.8 million compared with $246.4 million for the same period in 2019, an increase of $145.4 million or 59.0%. Net income per diluted common share was $4.20 for the nine months ended September 30, 2020 compared with $3.55 for the same period in 2019, an increase of 18.3%. The increase in net income and earnings per diluted common share for the nine months ended September 30, 2020 was primarily due to the Merger and a tax benefit for NOLs of $20.1 million, partially offset by merger related expenses of $8.0 million. The Company posted annualized returns on average common equity of 8.78% and 7.95%, annualized returns on average assets of 1.62% and 1.47% and efficiency ratios of 43.19% and 43.46% for the nine months ended September 30, 2020 and 2019, respectively.

Net Interest Income

The Company’s net interest income is affected by changes in the amount and mix of interest-earning assets and interest-bearing liabilities, referred to as a “volume change.” It is also affected by changes in yields earned on interest-earning assets and rates paid on interest-bearing deposits and other borrowed funds, referred to as a “rate change.”

For the Three Months Ended September 30, 2020

Net interest income before the provision for credit losses was $258.1 million for the quarter ended September 30, 2020, an increase of $104.1 million or 67.6%, compared with $154.0 million for the same period in 2019. The increase was primarily due to the Merger and the increase in loan discount accretion of $21.3 million.

Interest income on loans was $244.3 million for the quarter ended September 30, 2020, an increase of $109.3 million or 81.0%, compared with $134.9 million for the same period in 2019. The increase was primarily due to the Merger and the increase in loan discount accretion of $21.3 million.

Interest income on securities was $38.0 million for the quarter ended September 30, 2020, a decrease of $12.8 million or 25.2%, compared with $50.9 million for the same period in 2019. This decrease was primarily due to lower average securities balances and lower yields.

Average interest-bearing liabilities were $17.78 billion for the quarter ended September 30, 2020, an increase of $5.53 billion or 45.2%, compared with $12.25 billion for the same period in 2019, primarily due to the Merger. The net interest margin on a tax-equivalent basis was 3.57% for the quarter ended September 30, 2020, an increase of 41 basis points or 13.0% compared to 3.16% for the same period in 2019.

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For the Nine Months Ended September 30, 2020

Net interest income before the provision for credit losses was $773.1 million for the nine months ended September 30, 2020, an increase of $309.4 million or 66.7%, compared with $463.7 million for the same period in 2019.  The increase was primarily due to the Merger and the increase in loan discount accretion of $71.0 million.

Interest income on loans was $734.3 million for the nine months ended September 30, 2020, an increase of $335.7 million or 84.2%, compared with $398.5 million for the same period in 2019. The increase was primarily due to the Merger and the increase in loan discount accretion of $71.0 million. The Company had $69.9 million of total outstanding discounts on acquired loans, of which $69.9 million was accretable at September 30, 2020.

Interest income on securities was $130.1 million for the nine months ended September 30, 2020, a decrease of $30.4 million or 18.9%, compared with $160.5 million for the same period in 2019. This decrease was primarily due to lower average securities balances and lower yields.

Average interest-bearing liabilities were $17.71 billion for the nine months ended September 30, 2020, an increase of $5.17 billion or 41.2%, compared with $12.55 billion for the same period in 2019. The net interest margin on a tax-equivalent basis increased from 3.17% for the nine months ended September 30, 2019 to 3.69% for the nine months ended September 30, 2020, an increase of 52 basis points or 16.4%. This change was primarily due to the Merger and higher loan discount accretion for the nine months ended September 30, 2019.

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The following table presents, for the periods indicated, the total dollar amount of average balances, interest income from average interest-earning assets and the resultant yields, as well as the interest expense on average interest-bearing liabilities and the resultant rates.  Except as indicated in the footnotes, no tax-equivalent adjustments were made and all average balances are daily average balances. Any nonaccruing loans have been included in the table as loans carrying a zero yield.

	Three Months Ended September 30,
	2020								2019
	Average Outstanding Balance			Interest Earned/Paid		Average Yield/Rate (1)			Average Outstanding Balance			Interest Earned/Paid		Average Yield/Rate (1)
	(Dollars in thousands)
Assets
Interest-Earning Assets:
Loans held for sale	$	50,606		$	420		3.30	%	$	21,077		$	266		5.01	%
Loans held for investment		18,267,559			225,596		4.91	%		10,589,272			134,677		5.05	%
Loans held for investment - Warehouse Purchase Program		2,279,461			18,239		3.18	%		—			—		—
Total loans		20,597,626			244,255		4.72	%		10,610,349			134,943		5.05	%
Investment securities		7,603,762			38,033		1.99	%		8,758,056			50,872		2.30	%
Federal funds sold and other earning assets		618,228			144		0.09	%		74,751			363		1.93	%
Total interest-earning assets		28,819,616			282,432		3.90	%		19,443,156			186,178		3.80	%
Allowance for credit losses on loans (2)		(321,424	)							(86,996	)
Noninterest-earning assets		4,482,646								2,849,936
Total assets	$	32,980,838							$	22,206,096
Liabilities and Shareholders' Equity
Interest-Bearing Liabilities:
Interest-bearing demand deposits	$	5,221,722		$	5,028		0.38	%	$	3,575,249		$	5,602		0.62	%
Savings and money market deposits		8,937,751			7,833		0.35	%		5,524,277			12,588		0.90	%
Certificates and other time deposits		3,103,290			9,597		1.23	%		2,083,803			8,749		1.67	%
Federal funds purchased and other borrowings		13,898			52		1.49	%		749,814			4,335		2.29	%
Securities sold under repurchase agreements		378,888			309		0.32	%		315,277			914		1.15	%
Subordinated notes		125,256			1,500		4.76	%		—			—		—
Total interest-bearing liabilities		17,780,805			24,319		0.54	%		12,248,420			32,188		1.04	%
Noninterest-Bearing Liabilities:
Noninterest-bearing demand deposits		8,980,814								5,701,419
Allowance for credit losses on off-balance sheet credit exposures (2)		29,947								—
Other liabilities		167,532								11,526
Total liabilities		26,959,098								18,061,365
Shareholders' equity		6,021,740								4,144,731
Total liabilities and shareholders' equity	$	32,980,838							$	22,206,096
Net interest rate spread							3.36	%							2.76	%
Net interest income and margin (3) (4)				$	258,113		3.56	%				$	153,990		3.14	%
Net interest income and margin (tax equivalent) (5)				$	258,771		3.57	%				$	154,781		3.16	%

(1) Annualized and based on average balances on an actual 365-day or 366-day basis for the three months ended September 30, 2020 and 2019.

(2) ASU 2016-13 became effective for the Company on January 1, 2020.

(3) Yield is based on amortized cost and does not include any component of unrealized gains or losses.

(4) The net interest margin is equal to net interest income divided by average interest-earning assets.

(5) In order to make pretax income and resultant yields on tax-exempt investments and loans comparable to those on taxable investments and loans, a tax-equivalent adjustment has been computed using a federal income tax rate of 21%.

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	Nine Months Ended September 30,
	2020								2019
	Average Outstanding Balance			Interest Earned/Paid		Average Yield/Rate (1)			Average Outstanding Balance			Interest Earned/Paid		Average Yield/Rate (1)
	(Dollars in thousands)
Assets
Interest-Earning Assets:
Loans held for sale	$	60,256		$	1,575		3.49	%	$	23,605		$	887		5.02	%
Loans held for investment		17,890,010			690,175		5.15	%		10,484,864			397,646		5.07	%
Loans held for investment - Warehouse Purchase Program		1,749,568			42,520		3.25	%		—			—		—
Total loans		19,699,834			734,270		4.98	%		10,508,469			398,533		5.07	%
Investment securities		8,029,097			130,091		2.16	%		9,079,314			160,464		2.36	%
Federal funds sold and other earning assets		339,229			902		0.36	%		70,320			1,083		2.06	%
Total interest-earning assets		28,068,160			865,263		4.12	%		19,658,103			560,080		3.81	%
Allowance for credit losses on loans (2)		(325,036	)							(86,556	)
Noninterest-earning assets		4,540,440								2,853,098
Total assets	$	32,283,564							$	22,423,645
Liabilities and Shareholders' Equity
Interest-Bearing Liabilities:
Interest-bearing demand deposits	$	5,054,320		$	16,745		0.44	%	$	3,810,765		$	18,227		0.64	%
Savings and money market deposits		8,481,852			30,700		0.48	%		5,548,375			36,494		0.88	%
Certificates and other time deposits		3,243,564			35,300		1.45	%		2,067,940			23,908		1.55	%
Other borrowings		439,018			3,517		1.07	%		825,733			15,208		2.46	%
Securities sold under repurchase agreements		370,225			1,403		0.51	%		292,347			2,504		1.15	%
Subordinated notes		125,475			4,499		4.79	%		—			—		—
Total interest-bearing liabilities		17,714,454			92,164		0.69	%		12,545,160			96,341		1.03	%
Noninterest-Bearing Liabilities:
Noninterest-bearing demand deposits		8,354,410								5,645,145
Allowance for credit losses on off-balance sheet credit exposures (2)		24,321								—
Other liabilities		239,747								102,299
Total liabilities		26,332,932								18,292,604
Shareholders' equity		5,950,632								4,131,041
Total liabilities and shareholders' equity	$	32,283,564							$	22,423,645
Net interest rate spread							3.43	%							2.78	%
Net interest income and margin (3) (4)				$	773,099		3.68	%				$	463,739		3.15	%
Net interest income and margin (tax equivalent) (5)				$	775,170		3.69	%				$	466,220		3.17	%

(1) Annualized and based on average balances on an actual 365-day or 366-day basis for the nine months ended September 30, 2020 and 2019.

(2) ASU 2016-13 became effective for the Company on January 1, 2020.

(3) Yield is based on amortized cost and does not include any component of unrealized gains or losses.

(4) The net interest margin is equal to net interest income divided by average interest-earning assets.

(5) In order to make pretax income and resultant yields on tax-exempt investments and loans comparable to those on taxable investments and loans, a tax-equivalent adjustment has been computed using a federal income tax rate of 21%.

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The following table presents information regarding the dollar amount of changes in interest income and interest expense for the periods indicated for each major component of interest-earning assets and interest-bearing liabilities and distinguishes between the changes attributable to changes in volume and changes in interest rates.  For purposes of this table, changes attributable to both rate and volume which cannot be segregated have been allocated to rate.

	Three Months Ended September 30,									Nine Months Ended September 30,
	2020 vs. 2019									2020 vs. 2019
	Increase									Increase
	(Decrease)									(Decrease)
	Due to Change in									Due to Change in
	Volume			Rate			Total			Volume			Rate			Total
	(Dollars in thousands)
Interest-Earning Assets:
Loans held for sale	$	372		$	(218	)	$	154		$	1,377		$	(689	)	$	688
Loans held for investment (1)		97,468			(6,549	)		90,919			281,068			11,461			292,529
Loans held for investment - Warehouse Purchase Program		18,239			—			18,239			42,520			—			42,520
Investment securities (1)		(6,673	)		(6,166	)		(12,839	)		(18,555	)		(11,818	)		(30,373	)
Federal funds sold and other earning assets		2,637			(2,856	)		(219	)		4,147			(4,328	)		(181	)
Total increase (decrease) in interest income		112,043			(15,789	)		96,254			310,557			(5,374	)		305,183
Interest-Bearing Liabilities:
Interest-bearing demand deposits		2,566			(3,140	)		(574	)		5,958			(7,440	)		(1,482	)
Savings and money market deposits		7,722			(12,477	)		(4,755	)		19,326			(25,120	)		(5,794	)
Certificates and other time deposits (1)		4,280			(3,432	)		848			13,642			(2,250	)		11,392
Other borrowings		(4,236	)		(47	)		(4,283	)		(7,122	)		(4,569	)		(11,691	)
Securities sold under repurchase agreements		184			(789	)		(605	)		670			(1,771	)		(1,101	)
Subordinated notes		1,500			—			1,500			4,499			—			4,499
Total increase (decrease) in interest expense		12,016			(19,885	)		(7,869	)		36,973			(41,150	)		(4,177	)
Increase in net interest income	$	100,027		$	4,096		$	104,123		$	273,584		$	35,776		$	309,360

(1) Includes impact of purchase accounting adjustments.

Provision for Credit Losses

Management actively monitors the Company’s asset quality and provides specific loss provisions when necessary. Provisions for credit losses are charged to income to bring the total allowance for credit losses on loans and off-balance sheet credit exposures to a level deemed appropriate by management of the Company based on such factors as historical lifetime credit loss experience, the amount of nonperforming loans and related collateral, the volume growth and composition of the loan portfolio, current economic conditions and reasonable and supportable forecasted economic conditions that may affect the borrower’s ability to pay and the value of collateral, the evaluation of the loan portfolio through the internal loan review process and other relevant factors.

Loans are charged off against the allowance for credit losses when appropriate. Although management believes it uses the best information available to make determinations with respect to the provision for credit losses, future adjustments may be necessary if economic conditions differ from the assumptions used in making the initial determinations.

The Company made a $10.0 million provision for credit losses for the quarter ended September 30, 2020 and a $1.1 million provision for credit losses for the quarter ended September 30, 2019. The Company made a $20.0 million provision for credit losses for the nine months ended September 30, 2020 and a $2.6 million provision for credit losses for the nine months ended September 30, 2019.

Net charge-offs were $10.6 million for the quarter ended September 30, 2020 compared with net charge-offs of $1.0 million for the quarter ended September 30, 2019. Net charge-offs for the third quarter of 2020 included $8.6 million related to resolved PCD loans. These PCD loans had specific reserves of $15.7 million, of which $8.6 million was allocated to the charge-offs and $7.1 million was moved to the general reserve. Additionally, $6.1 million of specific reserves on resolved PCD loans was released to the general reserve without taking any charge-off. Net charge-offs were $24.4 million for the nine months ended September 30, 2020 compared with $2.0 million for the nine months ended September 30, 2019. Net charge-offs for the nine months ended September 30, 2020

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included $21.0 million related to resolved PCD loans. These PCD loans had specific reserves of $44.2 million, of which $21.0 million was allocated to the charge-offs and $23.2 million was moved to the general reserve. See “Financial Condition – Allowance for Credit Losses” below for more information.

Noninterest Income

The Company’s primary sources of recurring noninterest income are nonsufficient funds (“NSF”) fees, credit, debit and ATM card income, and service charges on deposit accounts. Additionally, the Company generates recurring noninterest income from its various additional products and services, including trust services, mortgage lending, brokerage and independent sales organization sponsorship operations. Noninterest income does not include loan origination fees, which are recognized over the life of the related loan as an adjustment to yield using the interest method.

Noninterest income totaled $34.9 million for the three months ended September 30, 2020 compared with $30.7 million for the same period in 2019, an increase of $4.3 million or 13.9%. This increase was primarily due to increases in mortgage income, which were due to the Merger and increased activity, and in credit card, debit card and ATM card income and other noninterest income due to the Merger, that was partially offset by a decrease in nonsufficient funds (“NSF”) fees. Noninterest income totaled $95.0 million for the nine months ended September 30, 2020 compared with $88.8 million for the same period in 2019, an increase of $6.2 million or 7.0%. This increase was primarily due to increases in mortgage income, which were due to the Merger and increased activity, and in credit card, debit card and ATM card income, other noninterest income and service charges on deposit accounts due to the Merger, partially offset by a net loss on write-down of assets of $4.9 million and decrease in NSF fees.

The following table presents, for the periods indicated, the major categories of noninterest income:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
	(Dollars in thousands)
Nonsufficient funds (NSF) fees	$	7,156		$	8,835		$	22,244		$	24,624
Credit card, debit card and ATM card income		8,315			6,688			23,052			19,139
Service charges on deposit accounts		5,920			5,020			17,814			15,007
Trust income		2,502			2,492			7,406			7,645
Mortgage income		2,958			839			6,788			2,551
Brokerage income		628			522			1,862			1,736
Bank owned life insurance income		1,449			1,314			4,502			3,924
Net (loss) gain on sale of assets		(528	)		(3	)		(4,858	)		57
Other		6,524			4,966			16,177			14,092
Total noninterest income	$	34,924		$	30,673		$	94,987		$	88,775

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Noninterest Expense

Noninterest expense totaled $117.9 million for the quarter ended September 30, 2020 compared with $80.7 million for the quarter ended September 30, 2019, an increase of $37.2 million or 46.1%, primarily due to the Merger. Noninterest expense totaled $377.0 million for the nine months ended September 30, 2020 compared with $240.1 million for the nine months ended September 30, 2019, an increase of $136.9 million or 57.0%. The change was primarily due to the increase in salaries and benefits, credit and debit card, data processing and software amortization, net occupancy and equipment and other noninterest expense due to the Merger and $8.0 million of merger related expenses.

The following table presents, for the periods indicated, the major categories of noninterest expense:

	Three Months Ended September 30,					Nine Months Ended September 30,
	2020		2019			2020		2019
	(Dollars in thousands)
Salaries and employee benefits (1)	$	75,068	$	52,978		$	231,459	$	156,992
Non-staff expenses:
Net occupancy and equipment		8,644		5,607			26,814		16,565
Credit and debit card, data processing and software amortization		8,776		4,989			31,887		14,466
Regulatory assessments and FDIC insurance		2,512		1,814			7,191		6,513
Core deposit intangibles amortization		3,270		1,248			9,926		3,832
Depreciation		4,605		3,286			13,971		9,501
Communications (2)		3,027		2,214			9,546		6,667
Other real estate expense, net (3)		121		(47	)		81		(75	)
Merger related expenses		—		—			8,018		—
Other		11,896		8,610			38,135		25,630
Total noninterest expense	$	117,919	$	80,699		$	377,028	$	240,091

(1) Includes stock-based compensation expense of $3.2 million and $2.5 million for the three months ended September 30, 2020 and 2019, respectively, and $9.5 million and $7.6 million for the nine months ended September 30, 2020 and 2019, respectively.

(2) Communications expense includes telephone, data circuits, postage and courier expenses.

(3) Other real estate expense is net of rental income and gains and losses on sales of real estate.

Income Taxes

The amount of federal and state income tax expense is influenced by the amount of pre-tax income, the amount of tax-exempt income and the amount of other nondeductible expenses. Income tax expense totaled $35.1 million for the three months ended September 30, 2020 compared with $21.1 million for the same period in 2019, an increase of $13.9 million or 66.1%. The increase was primarily due to the increase in pre-tax income related to the Merger. Income tax expense totaled $79.2 million for the nine months ended September 30, 2020 compared with $63.4 million for the same period in 2019, an increase of $15.8 million or 25.0%. The increase was primarily due to the increase in pre-tax income related to the Merger, partially offset by the tax benefit for net operating losses (“NOLs”) carryback of $20.1 million as a result of the CARES Act. The Company’s effective tax rate for the three months ended September 30, 2020 and 2019 was 21.2% and 20.5%, respectively. The Company’s effective tax rate for the nine months ended September 30, 2020 and 2019 was 16.8% and 20.5%, respectively.

In response to the COVID-19 pandemic, on March 27, 2020, the President of the United States signed the CARES Act into law. The CARES Act permits a five-year carryback period for NOLs, which allowed the Company to generate an anticipated tax refund and income tax benefit resulting from the tax rate differential between the current statutory tax rate of 21% and the 35% statutory tax rate in prior years during the carryback period. Pursuant to this provision of the CARES Act, the Company recorded a federal current benefit for taxes on income during the nine months ended September 30, 2020 due to the NOLs generated in 2019 by LegacyTexas that were used to offset taxable income generated between 2014 and 2017 taxed at 35% resulting in a tax benefit of $20.1 million, which is included in provision for income taxes in the accompanying condensed consolidated statements of income. This caused a reduction in the effective tax rate during the nine months ended September 30, 2020 as NOLs carried back to tax years 2014 through 2017 are applied at a federal tax rate of 35% applicable to those tax years, compared to a 21% tax rate effective at September 30, 2020. As a result, during the nine months ended September 30, 2020, the Company’s total deferred tax asset decreased by $31.9 million.

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FINANCIAL CONDITION

Loan Portfolio

The Company separates its loan portfolio into two general categories of loans: (1) “originated loans,” which are loans originated by Prosperity Bank and made pursuant to the Company’s loan policy and procedures in effect at the time the loan was made, and (2) “acquired loans,” which are loans acquired in a business combination and preliminarily recorded at fair value at acquisition date. Those acquired loans that are renewed or substantially modified after the date of the business combination are referred to as “re-underwritten acquired loans.” If a renewal or substantial modification of an acquired loan is underwritten by the Company with a new credit analysis, the loan may no longer be categorized as an acquired loan. For example, acquired loans to one borrower may be combined into a new loan with a new loan number and categorized as an originated loan. Acquired loans with a fair value discount or premium at the date of the business combination that remained at the reporting date are referred to as “fair-valued acquired loans.” All fair-valued acquired loans are further categorized into “PCD loans” (purchased credit-deteriorated loans) and “Non-PCD loans.” Acquired loans with evidence of more than insignificant credit quality deterioration since origination as of the acquisition date are classified as PCD loans.

The following tables summarize the Company’s originated and acquired loan portfolios broken out into originated loans, re-underwritten acquired loans, Non-PCD loans and PCD loans, as of the dates indicated.

	September 30, 2020
			Acquired Loans
	Originated Loans		Re-Underwritten Acquired Loans		Non-PCD Loans		PCD Loans		Total Loans
	(Dollars in thousands)
Residential mortgage loans held for sale	$	51,694	$	—	$	—	$	—	$	51,694
Commercial and industrial		2,302,053		925,213		832,982		89,941		4,150,189
Warehouse purchase program		2,730,614		—		—		—		2,730,614
Real estate:
Construction, land development and other land loans		1,812,183		165,641		103,363		575		2,081,762
1-4 family residential (includes home equity)		2,947,175		361,177		1,305,672		1,686		4,615,710
Commercial real estate (includes multi-family residential)		3,399,103		579,602		2,101,134		100,062		6,179,901
Farmland		379,626		10,910		26,814		1,776		419,126
Agriculture		147,084		32,191		571		—		179,846
Consumer and other		283,780		42,547		45,192		15,280		386,799
Total loans held for investment		14,001,618		2,117,281		4,415,728		209,320		20,743,947
Total	$	14,053,312	$	2,117,281	$	4,415,728	$	209,320	$	20,795,641

	December 31, 2019
			Acquired Loans
	Originated Loans		Re-Underwritten Acquired Loans		Non-PCD Loans		PCD Loans		Total Loans
	(Dollars in thousands)
Residential mortgage loans held for sale	$	80,959	$	—	$	—	$	—	$	80,959
Commercial and industrial		1,443,202		315,557		1,312,876		133,960		3,205,595
Warehouse purchase program		1,552,762		—		—		—		1,552,762
Real estate:
Construction, land development and other land loans		1,762,326		33,675		260,911		7,255		2,064,167
1-4 family residential (includes home equity)		2,640,228		126,588		1,533,809		5,827		4,306,452
Commercial real estate (includes multi-family residential)		3,300,663		381,326		2,779,681		94,615		6,556,285
Farmland		432,584		11,873		49,293		1,808		495,558
Agriculture		137,448		44,481		3,368		—		185,297
Consumer and other		311,985		33,814		52,472		—		398,271
Total loans held for investment		11,581,198		947,314		5,992,410		243,465		18,764,387
Total	$	11,662,157	$	947,314	$	5,992,410	$	243,465	$	18,845,346

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At September 30, 2020, total loans were $20.80 billion, an increase of $1.95 billion or 10.3%, compared with $18.85 billion at December 31, 2019. Loans at September 30, 2020 included $51.7 million of loans held for sale and $2.73 billion of Warehouse Purchase Program loans compared with $81.0 million and $1.55 billion at December 31, 2019. At September 30, 2020, loans represented 62.6% of total assets compared with 58.6% of total assets at December 31, 2019.

The loan portfolio consists of various types of loans categorized by major type as follows:

(i) Commercial and Industrial Loans. In nearly all cases, the Company’s commercial loans are made in the Company’s market areas and are underwritten on the basis of the borrower’s ability to service the debt from income. Working capital loans are primarily collateralized by short-term assets whereas term loans are primarily collateralized by long-term assets. As a general practice, term loans are secured by any available real estate, equipment or other assets owned by the borrower.  Both working capital and term loans are typically supported by a personal guaranty of a principal. In general, commercial loans involve more credit risk than residential mortgage loans and commercial mortgage loans and, therefore, usually yield a higher return. The increased risk in commercial loans is due to the type of collateral securing these loans as well as the expectation that commercial loans generally will be serviced principally from the operations of the business, and those operations may not be successful. Historical trends have shown these types of loans to have higher delinquencies than mortgage loans. As a result of these additional complexities, variables and risks, commercial loans require more thorough underwriting and servicing than other types of loans.

Included in commercial and industrial loans are (1) commitments to oil and gas producers largely secured by proven, developed and producing reserves and (2) commitments to service, equipment and midstream companies secured mainly by accounts receivable, inventory and equipment. Mineral reserve values supporting commitments to producers are normally re-determined semi-annually using reserve studies prepared by a third-party or the Company’s oil and gas engineer. Accounts receivable and inventory borrowing bases for service companies are typically re-determined monthly. Funding requests by both producers and service companies are monitored relative to the most recently determined borrowing base. As of September 30, 2020, oil and gas loans totaled $604.7 million (net of discount and excluding PPP loans totaling $115.3 million) or 2.9% of total loans, compared with total oil and gas loans of $698.3 million (net of discount) or 3.7% of total loans as of December 31, 2019. In addition, as of September 30, 2020, the Company had total unfunded commitments to oil and gas companies of $258.1 million compared with total unfunded commitments to oil and gas companies of $342.2 million as of December 31, 2019. Total unfunded commitments to producers include letters of credit issued in lieu of oil well plugging bonds.

(ii) Commercial Real Estate. The Company makes commercial real estate loans collateralized by owner-occupied and nonowner-occupied real estate to finance the purchase of real estate. The Company’s commercial real estate loans are collateralized by first liens on real estate, typically have variable interest rates (or five year or less fixed rates) and amortize over a 15- to 25-year period. Payments on loans secured by nonowner-occupied properties are often dependent on the successful operation or management of the properties. Accordingly, repayment of these loans may be subject to adverse conditions in the real estate market or the economy to a greater extent than other types of loans. The Company seeks to minimize these risks in a variety of ways, including giving careful consideration to the property’s operating history, future operating projections, current and projected occupancy, location and physical condition, in connection with underwriting these loans. The underwriting analysis also includes credit verification, analysis of global cash flow, appraisals and a review of the financial condition of the borrower and guarantor. Loans to hotels and restaurants are included in commercial real estate loans. As of September 30, 2020, loans to hotels totaled $386.3 million (excluding PPP loans totaling $8.8 million) or 1.9% of total loans; and loans to restaurants totaled $215.1 million (excluding PPP loans totaling $110.9 million) or 1.0% of total loans.

(iii) 1-4 Family Residential Loans. The Company’s lending activities also include the origination of 1-4 family residential mortgage loans (including home equity loans) collateralized by owner-occupied and nonowner-occupied residential properties located in the Company’s market areas. The Company offers a variety of mortgage loan portfolio products which generally are amortized over five to 30 years. Loans collateralized by 1-4 family residential real estate generally have been originated in amounts of no more than 89% of appraised value. The Company requires mortgage title insurance, as well as hazard, wind and/or flood insurance as appropriate. The Company prefers to retain residential mortgage loans for its own account rather than selling them into the secondary market. By doing so, the Company incurs interest rate risk as well as the risks associated with non-payments on such loans. The Company’s mortgage department also offers a variety of mortgage loan products which are generally amortized over 30 years, including FHA and VA loans, which are sold to secondary market investors.

(iv) Construction, Land Development and Other Land Loans. The Company makes loans to finance the construction of residential and nonresidential properties. Construction loans generally are collateralized by first liens on real estate and have floating interest rates. The Company conducts periodic inspections, either directly or through an agent, prior to approval of periodic draws on these loans. Underwriting guidelines similar to those described above are also used in the Company’s construction lending activities, with heightened analysis of construction and/or development costs. Construction loans involve additional risks attributable to the fact that loan funds are advanced upon the security of a project under construction, and the project is of uncertain value prior to its

46

completion. Because of uncertainties inherent in estimating construction costs, the market value of the completed project and the effects of governmental regulation on real property, it can be difficult to accurately evaluate the total funds required to complete a project and the related loan to value ratio. As a result of these uncertainties, construction lending often involves the disbursement of substantial funds with repayment dependent, in part, on the success of the ultimate project rather than the ability of a borrower or guarantor to repay the loan. If the Company is forced to foreclose on a project prior to completion, the Company may not be able to recover all of the unpaid portion of the loan. In addition, the Company may be required to fund additional amounts to complete a project and may have to hold the property for an indeterminate period of time. Although the Company has underwriting procedures designed to identify what it believes to be acceptable levels of risks in construction lending, these procedures may not prevent losses from the risks described above.

(v) Warehouse Purchase Program. The Company acquired the Warehouse Purchase Program as part of the merger with LegacyTexas. The Warehouse Purchase Program allows unaffiliated mortgage originators (“Clients”) to close 1-4 family real estate loans in their own name and manage their cash flow needs until the loans are sold to investors. The Company's Clients are strategically targeted for their experienced management teams and analyzed for the expected profitability of each Client’s business model over the long term. The Clients are located across the U.S. and originate mortgage loans primarily through traditional retail and/or wholesale business models using underwriting standards as required by the United States government-sponsored enterprise agencies such as Fannie Mae, the private investors to which the mortgage loans are ultimately sold and/or the mortgage insurers.

Although not subject to any legally binding commitment, when the Company makes a purchase decision, it acquires a 100% participation interest in the mortgage loans originated by its Clients. Individual mortgage loans are warehoused in the Company’s portfolio only for a short duration, averaging less than 30 days. When instructed by a Client that a warehoused loan has been sold to an investor, the Company delivers the note to the investor that pays the Company, which in turn remits the net sales proceeds to the Client.

(vi) Agriculture Loans. The Company provides agriculture loans for short-term livestock and crop production, including rice, cotton, milo and corn, farm equipment financing and agriculture real estate financing. The Company evaluates agriculture borrowers primarily based on their historical profitability, level of experience in their particular industry segment, overall financial capacity and the availability of secondary collateral to withstand economic and natural variations common to the industry. Because agriculture loans present a higher level of risk associated with events caused by nature, the Company routinely makes on-site visits and inspections in order to identify and monitor such risks.

(vii) Consumer Loans. Consumer loans made by the Company include direct “A”-credit automobile loans, recreational vehicle loans, boat loans, home improvement loans, personal loans (collateralized and uncollateralized) and deposit account collateralized loans. The terms of these loans typically range from 12 to 180 months and vary based upon the nature of collateral and size of loan. Generally, consumer loans entail greater risk than do real estate secured loans, particularly in the case of consumer loans that are unsecured or collateralized by rapidly depreciating assets such as automobiles. In such cases, any repossessed collateral for a defaulted consumer loan may not provide an adequate source of repayment for the outstanding loan balance. The remaining deficiency often does not warrant further substantial collection efforts against the borrower beyond obtaining a deficiency judgment. In addition, consumer loan collections are dependent on the borrower’s continuing financial stability, and thus are more likely to be adversely affected by job loss, divorce, illness, personal bankruptcy or death. Furthermore, the application of various federal and state laws may limit the amount which can be recovered on such loans.

The Company maintains an independent loan review department that reviews and validates the credit risk program on a periodic basis. Results of these reviews are presented to management. The loan review process complements and reinforces the risk identification and assessment decisions made by lenders and credit personnel, as well as the Company’s policies and procedures.

Nonperforming Assets

Nonperforming assets include loans on nonaccrual status, accruing loans 90 days or more past due, repossessed assets and real estate which has been acquired through foreclosure and is awaiting disposition. Nonperforming assets do not include PCD loans unless the loan has deteriorated since the acquisition date. PCD loans are reported as nonperforming assets when a deterioration in projected cash flows is identified.

The Company generally places a loan on nonaccrual status and ceases accruing interest when the payment of principal or interest is delinquent for 90 days, or earlier in some cases, unless the loan is in the process of collection and the underlying collateral fully supports the carrying value of the loan. A loan may be returned to accrual status when all the principal and interest amounts contractually due are brought current and future principal and interest amounts contractually due are reasonably assured, which is typically evidenced by a sustained period (at least six months) of repayment performance by the borrower.

47

Nonperforming assets increased $6.6 million, or 10.5%, to $69.5 million at September 30, 2020 compared with $62.9 million at December 31, 2019, of which $22.6 million and $18.2 million, respectively, were attributable to acquired loans. The increase in nonperforming assets was primarily due to $4.9 million in additions to other real estate owned from two 1-4 family loans and a $2.2 million increase in nonaccrual loans.

The following tables present information regarding nonperforming assets differentiated among originated loans, re-underwritten acquired loans, Non-PCD loans and PCD loans, as of the dates indicated:

	September 30, 2020
				Acquired Loans
	Originated Loans			Re-Underwritten Acquired Loans			Non-PCD Loans			PCD Loans			Total
	(Dollars in thousands)
Nonaccrual loans (1)(2)	$	45,653		$	1,930		$	9,635		$	194		$	57,412
Accruing loans 90 or more days past due		40			422			—			—			462
Total nonperforming loans		45,693			2,352			9,635			194			57,874
Repossessed assets		40			—			80			—			120
Other real estate		1,192			—			7,356			3,000			11,548
Total nonperforming assets	$	46,925		$	2,352		$	17,071		$	3,194		$	69,542
Nonperforming assets to total loans and other real estate by category		0.33	%		0.11	%		0.39	%		1.50	%		0.33	%
Nonperforming assets to total loans, excluding Warehouse Purchase Program loans, and other real estate by category		0.41	%		0.11	%		0.39	%		1.50	%		0.38	%

	December 31, 2019
				Acquired Loans
	Originated Loans			Re-Underwritten Acquired Loans			Non-PCD Loans			PCD Loans			Total
	(Dollars in thousands)
Nonaccrual loans (1)(2)	$	43,612		$	2,423		$	7,011		$	2,197		$	55,243
Accruing loans 90 or more days past due		441			—			—			—			441
Total nonperforming loans		44,053			2,423			7,011			2,197			55,684
Repossessed assets		—			—			323			—			323
Other real estate		718			—			6,218			—			6,936
Total nonperforming assets	$	44,771		$	2,423		$	13,552		$	2,197		$	62,943
Nonperforming assets to total loans and other real estate by category		0.38	%		0.26	%		0.23	%		0.90	%		0.33	%
Nonperforming assets to total loans, excluding Warehouse Purchase Program loans, and other real estate by category		0.44	%		0.26	%		0.23	%		0.90	%		0.36	%

(1) Includes troubled debt restructurings of $13.2 and $13.6 million as of September 30, 2020 and December 31, 2019, respectively.

(2) There were no non-performing or troubled debt restructurings of warehouse lines of credit or Warehouse Purchase Program loans for the periods presented.

Nonperforming assets were 0.33% of total loans and other real estate at September 30, 2020 and at December 31, 2019. The allowance for credit losses as a percentage of total nonperforming loans was 559.2% at September 30, 2020 and 157.1% at December 31, 2019.

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Allowance for Credit Losses on Loans

The allowance for credit losses is adjusted through charges to earnings in the form of a provision for credit losses. Management has established an allowance for credit losses on loans which it believes is adequate as of September 30, 2020 for estimated losses in the Company’s loan portfolio. The amount of the allowance for credit losses on loans is affected by the following: (1) charge-offs of loans that occur when loans are deemed uncollectible and decrease the allowance, (2) recoveries on loans previously charged off that increase the allowance and (3) provisions for credit losses charged to earnings that increase the allowance or provision releases returned to earnings that decrease the allowance. Based on an evaluation of the loan portfolio and consideration of the factors listed below, management presents a quarterly review of the allowance for credit losses to the Bank’s Board of Directors, indicating any change in the allowance since the last review and any recommendations as to adjustments in the allowance. Although management believes it uses the best information available to make determinations with respect to the allowance for credit losses, future adjustments may be necessary if economic conditions or the borrower’s performance differ from the assumptions used in making the initial determinations.

The Company’s allowance for credit losses on loans consists of two components: (1) a specific valuation allowance based on probable losses on specifically identified loans and (2) a general valuation allowance based on historical lifetime loan loss experience, general economic conditions and other qualitative risk factors both internal and external to the Company.

In setting the specific valuation allowance, the Company follows a loan review program to evaluate the credit risk in the total loan portfolio and assigns risk grades to each loan. Through this loan review process, the Company maintains an internal list of impaired loans which, along with the delinquency list of loans, helps management assess the overall quality of the loan portfolio and the adequacy of the allowance for credit losses. All loans that have been identified as impaired are reviewed on a quarterly basis in order to determine whether a specific reserve is required. For certain impaired loans, the Company allocates a specific loan loss reserve primarily based on the value of the collateral securing the impaired loan. The specific reserves are determined on an individual loan basis. Loans for which specific reserves are provided are excluded from the general valuation allowance described below.

In determining the amount of the general valuation allowance, management considers factors such as historical lifetime loan loss experience, concentration risk of specific loan types, the volume, growth and composition of the Company’s loan portfolio, current economic conditions and reasonable and supportable forecasted economic conditions that may affect the borrower’s ability to pay and the value of collateral, the evaluation of the Company’s loan portfolio through its internal loan review process, general economic conditions, other qualitative risk factors both internal and external to the Company and other relevant factors. Historical lifetime loan loss experience is determined by utilizing an open-pool (“cumulative loss rate”) methodology. Adjustments to the historical lifetime loan loss experience are made for differences in current loan pool risk characteristics such as portfolio concentrations, delinquency, non-accrual, and watch list levels, as well as changes in current and forecasted economic conditions such as unemployment rates, property and collateral values, and other indices relating to economic activity. The utilization of reasonable and supportable forecasts includes an immediate reversion to lifetime historical loss rates. Based on a review of these factors for each loan type, the Company applies an estimated percentage to the outstanding balance of each loan type, excluding any loan that has a specific reserve allocated to it. The Company uses this information to establish the amount of the general valuation allowance.

A change in the allowance for credit losses can be attributable to several factors, most notably (1) specific reserves identified for impaired loans, (2) historical lifetime credit loss information, (3) changes in environmental factors and (4) growth in the balance of loans.

Changes in the Company’s asset quality are reflected in the allowance in several ways. Specific reserves that are calculated on a loan-by-loan basis and the qualitative assessment of all other loans reflect current changes in the credit quality of the loan portfolio. Historical lifetime credit losses, on the other hand, are based on an open-pool (“cumulative loss rate”) methodology, which is then applied to estimate lifetime credit losses in the loan portfolio. A deterioration in the credit quality of the loan portfolio in the current period would increase the historical lifetime loss rate to be applied in future periods, just as an improvement in credit quality would decrease the historical lifetime loss rate.

The allowance for credit losses on loans is further determined by the size of the loan portfolio subject to the allowance methodology and environmental factors that include Company-specific risk indicators and general economic conditions, both of which are constantly changing. The Company evaluates the economic and portfolio-specific factors on a quarterly basis to determine a qualitative component of the general valuation allowance. The factors include current economic metrics, reasonable and supportable forecasted economic metrics, business conditions, delinquency trends, credit concentrations, nature and volume of the portfolio and other adjustments for items not covered by specific reserves and historical lifetime loss experience. Management’s assessment of qualitative factors is a statistically based approach to determine the loss rate adjustment associated with such factors. Based on the Company’s actual historical lifetime loan loss experience relative to economic and loan portfolio-specific factors at the time the losses occurred, management is able to identify the probable level of lifetime losses as of the date of measurement. The correlation of

49

historical loss experience with current and forecasted economic conditions provides an estimate of lifetime losses that has not been previously factored into the general valuation allowance by the determination of specific reserves and lifetime historical losses. Additionally, the Company considers qualitative factors not easily quantified and the possibility of model imprecision.

Utilizing the aggregation of specific reserves, historical loss experience and a qualitative component, management is able to determine the valuation allowance to reflect the full lifetime loss.

The Company accounts for its acquisitions using the acquisition method of accounting. Accordingly, the assets, including loans, and liabilities of the acquired entity were recorded at their fair values at the acquisition date. These fair value estimates associated with acquired loans, and based on a discounted cash flow model, include estimates related to market interest rates and undiscounted projections of future cash flows that incorporate expectations of prepayments and the amount and timing of principal, interest and other cash flows, as well as any shortfalls thereof. On January 1, 2020, the Company adopted ASU 2016-13, “Financial Instruments-Credit Losses (ASC Topic 326) – Measurement of Credit Losses on Financial Instruments” (“CECL”). Upon adoption of CECL, all loans accounted for under ASC 310-20 were included in the allowance for credit losses methodology, with no offset provided for any remaining fair value marks. In addition, all loans previously accounted for under ASC 310-30 had their credit marks reclassified to be included in the allowance for credit losses.

Non-PCD loans that were not deemed impaired subsequent to the acquisition date are considered non-impaired and are evaluated as part of the general valuation allowance. Non-PCD loans that have not become impaired subsequent to acquisition are included in the general valuation allowance.

Non-PCD loans that have deteriorated to an impaired status subsequent to acquisition are evaluated for a specific reserve on a quarterly basis which, when identified, is added to the allowance for credit losses. The Company reviews impaired Non-PCD loans on a loan-by-loan basis and determines the specific reserve based on the difference between the recorded investment in the loan and one of three factors: expected future cash flows, observable market price or fair value of the collateral. Because essentially all of the Company’s impaired Non-PCD loans have been collateral-dependent, the amount of the specific reserve historically has been determined by comparing the fair value of the collateral securing the Non-PCD loan with the recorded investment in such loan. In the future, the Company will continue to analyze impaired Non-PCD loans on a loan-by-loan basis and may use an alternative measurement method to determine the specific reserve, as appropriate and in accordance with applicable accounting standards.

PCD loans are individually monitored on a quarterly basis to assess for deterioration subsequent to acquisition and monitored for deterioration in expected cash flows. If a deterioration in cash flows is identified, an additional provision for credit losses is made. PCD loans were recorded at their acquisition date fair values, which were based on expected cash flows and included estimates of expected future credit losses. The Company’s estimates of loan fair values at the acquisition date may be adjusted for a period of up to one year as the Company continues to evaluate its estimate of expected future cash flows at the acquisition date. If the Company determines that losses arose after the acquisition date, the additional losses will be reflected as a provision for credit losses. See “Critical Accounting Policies” above for more information.

As described in the section captioned “Critical Accounting Policies” above, the Company’s determination of the allowance for credit losses involves a high degree of judgment and complexity. The Company’s analysis of qualitative, or environmental, factors on pools of loans with common risk characteristics, in combination with the quantitative historical lifetime loss information and specific reserves, provides the Company with an estimate of lifetime losses. The allowance must reflect changes in the balance of loans subject to the allowance methodology, as well as the estimated lifetime losses associated with those loans.

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The following tables present, as of and for the periods indicated, information regarding the allowance for credit losses on loans differentiated between originated loans and acquired loans. Reported net charge-offs may include those from Non-PCD loans and PCD loans, but only if the total charge-off required is greater than the remaining discount.

	As of and for the Nine Months Ended September 30, 2020
	Originated Loans			Acquired Loans			Total
	(Dollars in thousands)
Average loans outstanding	$	12,655,534		$	7,044,300		$	19,699,834
Gross loans outstanding at end of period	$	14,053,312		$	6,742,329		$	20,795,641
Allowance for credit losses at beginning of period	$	77,013		$	10,456		$	87,469
Cumulative effect from adoption of ASC 326		28,107			212,431			240,538
Provision for credit losses		32,519			(12,519	)		20,000
Charge-offs:
Commercial and industrial		(1,136	)		(20,597	)		(21,733	)
Real estate and agriculture		(167	)		(1,682	)		(1,849	)
Consumer and other		(3,043	)		(486	)		(3,529	)
Recoveries:
Commercial and industrial		295			916			1,211
Real estate and agriculture		447			60			507
Consumer and other		986			35			1,021
Net charge-offs(1)		(2,618	)		(21,754	)		(24,372	)
Allowance for credit losses at end of period	$	135,021		$	188,614		$	323,635
Ratio of allowance to end of period loans		0.96	%		2.80	%		1.56	%
Ratio of allowance to end of period loans, excluding Warehouse Purchase Program		1.19	%		2.80	%		1.79	%
Ratio of net charge-offs to average loans (annualized)		0.03	%		0.41	%		0.16	%
Ratio of allowance to end of period nonperforming loans		295.5	%		1548.4	%		559.2	%

	As of and for the Nine Months Ended September 30, 2019
	Originated Loans			Acquired Loans			Total
	(Dollars in thousands)
Average loans outstanding	$	9,473,642		$	1,034,827		$	10,508,469
Gross loans outstanding at end of period	$	9,739,399		$	933,946		$	10,673,345
Allowance for credit losses at beginning of period	$	78,956		$	7,484		$	86,440
Provision for credit losses		4,624			(2,024	)		2,600
Charge-offs:
Commercial and industrial		(2,496	)		(5	)		(2,501	)
Real estate and agriculture		(424	)		(19	)		(443	)
Consumer and other		(2,800	)		(21	)		(2,821	)
Recoveries:
Commercial and industrial		1,175			518			1,693
Real estate and agriculture		1,384			16			1,400
Consumer and other		675			18			693
Net (charge-offs) recoveries		(2,486	)		507			(1,979	)
Allowance for credit losses at end of period	$	81,094		$	5,967		$	87,061
Ratio of allowance to end of period loans		0.83	%		0.64	%		0.82	%
Ratio of net charge-offs (recoveries) to average loans (annualized)		0.03	%		(0.07	%)		0.03	%
Ratio of allowance to end of period nonperforming loans		182.3	%		102.5	%		173.0	%

(1) There was no net charge-off activity on Warehouse Purchase Program loans during the periods presented.

The Company had gross charge-offs on originated loans of $4.3 million during the nine months ended September 30, 2020. Partially offsetting these charge-offs were recoveries on originated loans of $1.7 million. Gross charge-offs on acquired loans were $22.8 million during the nine months ended September 30, 2020. Offsetting these charge-offs were recoveries on acquired loans of $1.0 million. Total charge-offs for the nine months ended September 30, 2020 were $27.1 million, partially offset by total recoveries of $2.7 million.

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The following tables show the allocation of the allowance for credit losses on loans among various categories of loans disaggregated between originated loans, re-underwritten acquired loans, Non-PCD loans and PCD loans at the dates indicated. The allocation is made for analytical purposes and is not necessarily indicative of the categories in which future losses may occur. The total allowance is available to absorb losses from any loan category, regardless of whether allocated to an originated loan or an acquired loan.

	September 30, 2020
			Acquired Loans
	Originated Loans		Re-Underwritten Acquired Loans		Non-PCD Loans		PCD Loans		Total Allowance		Percent of Loans to Total Loans(1)
	(Dollars in thousands)
Balance of allowance for credit losses applicable to:
Commercial and industrial	$	26,992	$	27,558	$	42,369	$	39,638	$	136,557		23.0	%
Real estate		95,675		10,909		29,840		28,152		164,576		71.6	%
Agriculture and agriculture real estate		6,259		817		220		173		7,469		3.3	%
Consumer and other		6,095		1,442		1,300		6,196		15,033		2.1	%
Total allowance for credit losses	$	135,021	$	40,726	$	73,729	$	74,159	$	323,635		100.0	%

	December 31, 2019
			Acquired Loans
	Originated Loans		Re-Underwritten Acquired Loans		Non-PCD Loans		PCD Loans		Total Allowance		Percent of Loans to Total Loans(1)
	(Dollars in thousands)
Balance of allowance for credit losses applicable to:
Commercial and industrial	$	32,723	$	7,722	$	—	$	—	$	40,445		18.5	%
Real estate		40,241		2,022		—		—		42,263		75.2	%
Agriculture and agriculture real estate		2,292		679		—		—		2,971		4.0	%
Consumer and other		1,757		33		—		—		1,790		2.3	%
Total allowance for credit losses	$	77,013	$	10,456	$	—	$	—	$	87,469		100.0	%

(1) Loans outstanding as of a percentage of total loans, excluding Warehouse Purchase Program loans.

On January 1, 2020, the Company adopted ASU 2016-13, “Financial Instruments-Credit Losses (ASC Topic 326) – Measurement of Credit Losses on Financial Instruments” (“CECL”). Upon adoption of CECL, the Company recognized an increase in allowance for credit losses for loans of $108.7 million, of which $102.5 million was related to LegacyTexas and an increase in allowance for credit losses for off-balance sheet credit exposures of $24.4 million, of which $6.3 million was related to LegacyTexas, with a corresponding decrease in retained earnings (pre-tax). Additionally, the Company recognized an increase in the allowance for credit losses for loans of $131.8 million, of which $130.3 million was related to LegacyTexas, due to the reclass of PCD discounts as result of adopting CECL. The allowance for credit losses totaled $323.6 million at September 30, 2020 and $87.5 million at December 31, 2019. The allowance for credit losses totaled 1.56% of total loans at September 30, 2020 and 0.46% of total loans at December 31, 2019.

At September 30, 2020, $135.0 million of the allowance for credit losses was attributable to originated loans, an increase of $58.0 million or 75.3% compared with $77.0 million of the allowance at December 31, 2019. At September 30, 2020, $40.7 million of the allowance for credit losses was attributable to re-underwritten acquired loans compared with $10.5 million of the allowance at December 31, 2019, an increase of $30.3 million or 289.5%. At September 30, 2020, $73.7 million of the allowance for credit losses was attributable to Non-PCD loans compared with a zero balance at December 31, 2019. At September 30, 2020, $74.2 million of the allowance for credit losses was attributable to PCD loans compared to a zero balance at December 31, 2019.  As stated above, the increase in allowance for credit losses was primarily due to the Company’s adoption of CECL.  

At September 30, 2020, the Company had $69.9 million of total outstanding discounts on Non-PCD and PCD loans, of which $69.9 million was accretable.  

The Company believes that the allowance for credit losses on loans at September 30, 2020 is adequate to cover estimated losses in the loan portfolio as of such date. Nevertheless, the Company could sustain losses in future periods which could be substantial in relation to the size of the allowance at September 30, 2020.

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Allowance for Credit Losses on Off-Balance Sheet Credit Exposures

The allowance estimates expected credit losses over the contractual period in which there is exposure to credit risk via a contractual obligation to extend credit, unless that obligation is unconditionally cancellable by the Company. The allowance is adjusted as a provision for credit loss expense. The estimate includes consideration of the likelihood that funding will occur and an estimate of expected credit losses on the commitments expected to fund. The estimate of commitments expected to fund is affected by historical analysis looking at utilization rates. The expected credit loss rates applied to the commitments expected to fund are affected by the general valuation allowance utilized for outstanding balances with the same underlying assumptions and drivers.

Securities

The carrying cost of securities totaled $7.43 billion at September 30, 2020 compared with $8.57 billion at December 31, 2019, a decrease of $1.14 billion or 13.3%. At September 30, 2020, securities represented 22.4% of total assets compared with 26.6% of total assets at December 31, 2019.

The amortized cost and fair value of investment securities were as follows:

	September 30, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
Collateralized mortgage obligations	$	418,575	$	138	$	(525	)	$	418,188
Mortgage-backed securities		42,982		570		(625	)		42,927
Total	$	461,557	$	708	$	(1,150	)	$	461,115
Held to Maturity
U.S. Treasury securities and obligations of U.S. Government agencies	$	3,989	$	25	$	—		$	4,014
States and political subdivisions		170,427		9,288		(187	)		179,528
Collateralized mortgage obligations		123,309		2,080		(256	)		125,133
Mortgage-backed securities		6,672,655		165,665		(1,158	)		6,837,162
Total	$	6,970,380	$	177,058	$	(1,601	)	$	7,145,837

	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	470	$	1	$	—		$	471
Collateralized mortgage obligations		235,222		690		(139	)		235,773
Mortgage-backed securities		51,209		659		(449	)		51,419
Total	$	286,901	$	1,350	$	(588	)	$	287,663
Held to Maturity
U.S. Treasury securities and obligations of U.S. Government agencies	$	13,933	$	58	$	—		$	13,991
States and political subdivisions		238,347		7,632		(189	)		245,790
Collateralized mortgage obligations		203,470		1,115		(373	)		204,212
Mortgage-backed securities		7,826,643		48,060		(34,845	)		7,839,858
Total	$	8,282,393	$	56,865	$	(35,407	)	$	8,303,851

The investment securities portfolio is measured for expected credit losses by segregating the portfolio into two general segments and applying the appropriate expected credit losses methodology. Investment securities classified as available for sale or held to maturity are evaluated for expected credit losses under FASB ASC 326, “Financial Instruments – Credit Losses.”

Available for sale securities. For available for sale securities in an unrealized loss position, the amount of the expected credit losses recognized in earnings depends on whether an entity intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss. If an entity intends to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the expected

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credit losses will be recognized in earnings equal to the entire difference between the investment’s amortized cost basis and its fair value at the balance sheet date. If an entity does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis less any current-period loss, the expected credit losses will be separated into the amount representing the credit-related portion of the impairment loss (“credit loss”) and the noncredit portion of the impairment loss (“noncredit portion”). The amount of the total expected credit losses related to the credit loss is determined based on the difference between the present value of cash flows expected to be collected and the amortized cost basis, and such difference is recognized in earnings. The amount of the total expected credit losses related to the noncredit portion is recognized in other comprehensive income, net of applicable taxes. The previous amortized cost basis less the expected credit losses recognized in earnings will become the new amortized cost basis of the investment.

As of September 30, 2020, management does not have the intent to sell any of the securities classified as available for sale before a recovery of cost. In addition, management believes it is more likely than not that the Company will not be required to sell any of its investment securities before a recovery of cost. The unrealized losses are largely due to changes in market interest rates and spread relationships since the time the underlying securities were purchased. The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline. Management does not believe any of the securities are impaired due to reasons of credit quality. Accordingly, as of September 30, 2020, management believes that there is no potential for credit losses on available for sale securities.

Held to maturity securities. The Company’s held to maturity investments include mortgage-related bonds issued by either the Government National Mortgage Corporation (“Ginnie Mae”), Federal National Mortgage Association (“Fannie Mae”) or Federal Home Loan Mortgage Corporation (“Freddie Mac”).  Ginnie Mae issued securities are explicitly guaranteed by the U.S. government, while Fannie Mae and Freddie Mac issued securities are fully guaranteed by those respective United States government-sponsored agencies, and conditionally guaranteed by the full faith and credit of the United States.  The Company’s held to maturity securities also include taxable and tax-exempt municipal securities issued primarily by school districts, utility districts and municipalities located in Texas. The Company’s investment in municipal securities is exposed to credit risk. The securities are highly rated by major rating agencies and regularly reviewed by management. A significant portion are guaranteed or insured by either the Texas Permanent School Fund, Assured Guaranty or Build America Mutual. As of September 30, 2020, the Company’s municipal securities represent 2.3% of the securities portfolio. Management has the ability and intent to hold the securities classified as held to maturity until they mature, at which time the Company will receive full value for the securities. Accordingly, as of September 30, 2020, management believes that there is no potential for material credit losses on held to maturity securities.

Deposits

Total deposits were $26.46 billion at September 30, 2020 compared with $24.20 billion at December 31, 2019, an increase of $2.26 billion or 9.3%. At September 30, 2020, noninterest-bearing deposits totaled $9.00 billion, an increase of $1.23 billion or 15.9% compared with $7.76 billion at December 31, 2019. Interest-bearing deposits totaled $17.46 billion at September 30, 2020 compared with $16.44 billion at December 31, 2019, an increase of $1.03 billion or 6.2%.

Average deposits for the nine months ended September 30, 2020 were $25.13 billion, an increase of $8.06 billion or 47.2%, compared with $17.07 billion for the nine months ended September 30, 2019. This increase was primarily due to the Merger. The ratio of average interest-bearing deposits to total average deposits was 66.8% and 66.9% during the first nine months of 2020 and 2019, respectively.

The following table summarizes the daily average balances and weighted average rates paid on deposits for the periods indicated below:

	Nine Months Ended September 30,
	2020					2019
	Average Balance		Average Rate (1)			Average Balance		Average Rate (1)
	(Dollars in thousands)
Interest-bearing demand deposits	$	5,054,320		0.44	%	$	3,810,765		0.64	%
Regular savings		2,791,252		0.22	%		2,179,441		0.46	%
Money market savings		5,690,600		0.61	%		3,368,934		1.15	%
Certificates, IRAs and other time deposits		3,243,564		1.45	%		2,067,940		1.55	%
Total interest-bearing deposits		16,779,736		0.66	%		11,427,080		0.92	%
Noninterest-bearing demand deposits		8,354,410					5,645,145
Total deposits	$	25,134,146		0.44	%	$	17,072,225		0.62	%

(1) Annualized and based on average balances on an actual 365-day or 366-day basis for the nine months ended September 30, 2020 and 2019.

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Other Borrowings

The following table presents the Company’s borrowings as of the dates indicated:

	September 30, 2020		December 31, 2019
	(Dollars in thousands)
FHLB advances	$	—	$	1,300,000
FHLB long-term notes payable		2,570		3,730
Total other borrowings		2,570		1,303,730
Securities sold under repurchase agreements		380,274		377,294
Subordinated notes - Fixed to floating rate notes maturing on December 1, 2025		125,146		125,804
Total	$	507,990	$	1,806,828

FHLB advances and long-term notes payable— The Company has an available line of credit with the FHLB of Dallas, which allows the Company to borrow on a collateralized basis. The Company’s FHLB advances are typically considered short-term borrowings and are used to manage liquidity as needed. Maturing advances are replaced by drawing on available cash, making additional borrowings or through increased customer deposits. At September 30, 2020, the Company had total funds of $7.63 billion available under this line. At September 30, 2020, the Company has zero FHLB advances. Long-term notes payable was $2.6 million at September 30, 2020, with a weighted average rate of 5.44%. The maturity dates on the FHLB notes payable range from the years 2020 to 2027 and have interest rates ranging from 4.75% to 5.99%.

Securities sold under repurchase agreements— At September 30, 2020, the Company had $380.3 million in securities sold under repurchase agreements with banking customers compared with $377.3 million at December 31, 2019, an increase of $3.0 million or 0.8%.  Repurchase agreements are generally settled on the following business day; however, approximately $5.4 million of the repurchase agreements outstanding at September 30, 2020 have maturity dates ranging from 6 to 24 months. All securities sold under repurchase agreements are collateralized by certain pledged securities.

Subordinated notes— On November 1, 2019, in connection with the Merger, the Company assumed the obligations related to a $75.0 million and a $50.0 million of Fixed-to-Floating Rate Subordinated Note (collectively, the “Notes”) that mature on December 1, 2025. The Notes, which qualify as Tier 2 capital for regulatory purposes, have an interest rate of 5.50% per annum, payable semi-annually on each December 1 and June 1 through December 1, 2020. From and including December 1, 2020 through maturity or earlier redemption, the interest rate will reset quarterly to an interest rate per annum equal to the then current three-month LIBOR rate plus 3.89%, payable on March 1, June 1, September 1, and December 1 of each year through the maturity date or earlier redemption. The Company may, at its option, beginning on December 1, 2020 and on any scheduled interest payment date thereafter, redeem the Notes, in whole or in part, at a redemption price equal to 100% of the principal amount of the Notes to be redeemed plus accrued and unpaid interest to, but excluding, the date of redemption. Any partial redemption will be made pro rata among all of the holders. The Notes are subordinated in right of payment to all of the Company’s senior indebtedness and effectively subordinated to all existing and future debt and all other liabilities of the Company’s subsidiaries. In September 2020, the Company gave irrevocable notice of its intent to redeem the Notes on December 1, 2020.

Liquidity

Liquidity involves the Company’s ability to raise funds to support asset growth or reduce assets to meet deposit withdrawals and other payment obligations, to maintain reserve requirements and otherwise to operate the Company on an ongoing basis. The Company’s largest source of funds is deposits and its largest use of funds is loans. The Company does not expect a change in the source or use of its funds in the future. Although access to purchased funds from correspondent banks is available and has been utilized on occasion to take advantage of investment opportunities, the Company does not generally rely on this external funding source. The cash and federal funds sold position, supplemented by amortizing investment and loan portfolios, has generally created an adequate liquidity position.

As of September 30, 2020, the Company had outstanding $4.18 billion in commitments to extend credit, $112.8 million in commitments associated with outstanding standby letters of credit, $29.9 million in allowance for credit losses on off-balance sheet credit exposures and $803.4 million in commitments associated with unused capacity on Warehouse Purchase Program loans. Since commitments associated with letters of credit and commitments to extend credit may expire unused, the total outstanding may not necessarily reflect the actual future cash funding requirements.

The Company has no exposure to future cash requirements associated with known uncertainties or capital expenditures of a material nature.

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Asset liquidity is provided by cash and assets which are readily marketable or which will mature in the near future. As of September 30, 2020, the Company had cash and cash equivalents of $1.09 billion compared with $574.1 million at December 31, 2019, an increase of $513.6 million or 89.5%. The increase was primarily due to the increase in deposits of $2.26 billion, increase in net proceeds and purchases of maturity securities and net cash provided by operating activities of $496.9 million, partially offset by the repurchase of common stock of $115.0 million, the payment of cash dividends of $128.5 million, net repayments of other short-term borrowing of $1.30 billion and $706.5 million used in investing activities.

Share Repurchases

On January 29, 2020, Bancshares announced a stock repurchase program that authorized the repurchase of up to 5%, or approximately 4.74 million shares, of the Bancshares’ outstanding common stock over a one-year period expiring on January 28, 2021, at the discretion of management. Under the stock repurchase program, Bancshares could repurchase shares from time to time at prevailing market prices, through open-market purchases or privately negotiated transactions, depending upon market conditions, and pursuant to any trading plan that may be adopted in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended. Repurchases under this program may also be made in transactions outside the safe harbor during a pending merger, acquisition or similar transaction. The timing and actual number of shares repurchased will depend on a variety of factors including price, corporate and regulatory requirements, market conditions, and other corporate liquidity requirements and priorities.  Shares of stock repurchased are held as authorized but unissued shares. Bancshares is not obligated to purchase any particular number of shares, and Bancshares may suspend, modify or terminate the program at any time and for any reason without prior notice. Bancshares repurchased 98.0 thousand shares of its common stock at an average weighted price of $49.99 during the three months ended September 30, 2020 and 2.2 million shares of its common stock at an average weighted price of $52.47 per share during the nine months ended September 30, 2020.

Contractual Obligations

The Company’s contractual obligations and other commitments to make future payments as of September 30, 2020 (other than deposit obligations and securities sold under repurchase agreements) are summarized below. The Company’s future cash payments associated with its contractual obligations pursuant to its subordinated notes and FHLB borrowings and notes payable as of September 30, 2020 are summarized below. The future interest payments were calculated using the current rate in effect at September 30, 2020. In September 2020, the Company gave irrevocable notice of its intent to redeem the outstanding subordinated notes on December 1, 2020. The $125.0 million outstanding principal balance of the subordinated notes and all accrued interest payable upon redemption is included in the “1 year or less” column below. Payments for the subordinated notes include interest of $1.1 million. Payments for FHLB borrowings include interest of $205 thousand that will be due over the future periods. The payments do not include pre-payment options that may be available to the Company.

	1 year or less		More than 1 year but less than 3 years		3 years or more but less than 5 years		5 years or more		Total
	(Dollars in thousands)
Subordinated notes	$	126,292	$	—	$	—	$	—	$	126,292
Federal Home Loan Bank advances and notes payable		974		1,067		366		18		2,425
Total	$	127,266	$	1,067	$	366	$	18	$	128,717

Leases

The Company’s leases relate primarily to operating leases for office space and banking centers. The Company determines if an arrangement is a lease or contains a lease at inception. The Company’s leases have remaining lease terms of 1 to 18 years, which may include the option to extend the lease when it is reasonably certain for the Company to exercise that option. Operating lease right-of-use (ROU) assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. The Company uses its incremental collateralized borrowing rate to determine the present value of lease payments. Short-term leases and leases with variable lease costs are immaterial, and the Company does not have any sublease arrangements. As of September 30, 2020, operating lease ROU assets and lease liabilities were approximately $54.0 million. ROU assets and lease liabilities were classified as other assets and other liabilities, respectively.

As of September 30, 2020, the weighted average remaining lease terms of the Company’s operating leases were 7.4 years. The weighted average discount rate used to determine the lease liabilities as of September 30, 2020 for the Company’s operating leases was 2.34%. Cash paid for the Company’s operating leases for the three months ended September 30, 2020 and September 30, 2019 was $3.3 million and $1.4 million, respectively. Cash paid for the Company’s operating leases for the nine months ended September 30, 2020 and September 30, 2019 was $10.5 million and $4.2 million, respectively. The Company obtained $5.6 million in ROU assets in exchange for lease liabilities for four operating leases during the nine months ended September 30, 2020.  

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The Company’s future undiscounted cash payments associated with its operating leases as of September 30, 2020 are summarized below (dollars in thousands).

Remaining 2020	$	2,637
2021		10,196
2022		9,671
2023		8,922
2024		8,042
2025		7,651
Thereafter		19,383
Total undiscounted lease payments	$	66,502

The following table presents a summary of non-cancelable future operating lease commitments as of December 31, 2019 (dollars in thousands):

2020	$	10,137
2021		9,169
2022		8,641
2023		7,998
2024		7,119
Thereafter		24,996
Total non-cancelable lease payments	$	68,060

Off-Balance Sheet Items

In the normal course of business, the Company enters into various transactions that, in accordance with GAAP, are not included in its consolidated balance sheets. The Company enters into these transactions to meet the financing needs of its customers. These transactions include commitments to extend credit and standby letters of credit, which involve, to varying degrees, elements of credit risk and interest rate risk in excess of the amounts recognized in the consolidated balance sheets.

The Company’s commitments associated with outstanding standby letters of credit, unused capacity of Warehouse Purchase Program loans and commitments to extend credit expiring by period as of September 30, 2020 are summarized below. Since commitments associated with letters of credit, unused capacity of Warehouse Purchase Program loans, allowance for credit losses on off-balance sheet credit exposures and commitments to extend credit may expire unused, the amounts shown do not necessarily reflect the actual future cash funding requirements.

	1 year or less		More than 1 year but less than 3 years		3 years or more but less than 5 years		5 years or more		Total
	(Dollars in thousands)
Standby letters of credit	$	104,896	$	6,616	$	1,337	$	—	$	112,849
Unused capacity on Warehouse Purchase Program loans		803,386		—		—		—		803,386
Commitments to extend credit		1,743,194		852,081		342,756		1,245,988		4,184,019
Total	$	2,651,476	$	858,697	$	344,093	$	1,245,988	$	5,100,254

The Company funds an allowance for credit losses on off-balance sheet lending-related commitments and guarantees on credit card debt through a charge to provision for credit losses on the Company’s consolidated statement of income. At September 30, 2020 and December 31, 2019, this allowance for credit losses on off-balance sheet lending-related commitments and guarantees on credit card debt, included in “Allowance for credit losses on off-balance sheet credit exposures” on the Company’s consolidated balance sheet, totaled $29.9 million and $5.6 million, respectively.

Capital Resources

Total shareholders’ equity was $6.03 billion at September 30, 2020 compared with $5.97 billion at December 31, 2019, an increase of $64.0 million or 1.1%. The increase was primarily the result of net income of $391.8 million partially offset by dividend payments of $128.5 million, the common stock repurchases totaling $112.8 million and the impact of the adoption ASC 326 and other of $92.9 million.

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The Basel III Capital Rules adopted by the federal regulatory authorities in 2013 substantially revised the risk-based capital requirements applicable to the Company and the Bank. The Basel III Capital Rules became effective for the Company on January 1, 2015, subject to a phase-in period for certain provisions. The Basel III Capital Rules require a capital conservation buffer with respect to each of the Common Equity Tier 1, Tier 1 risk-based and total risk-based capital ratios, which provides for capital levels that exceed the minimum risk-based capital adequacy requirements.  The capital conservation buffer of 2.5% was fully phased-in on January 1, 2019.  A financial institution with a conservation buffer of less than the required amount will be subject to limitations on capital distributions, including dividend payments and stock repurchases, and certain discretionary bonus payments to executive officers.

In response to the COVID-19 pandemic, in March 2020 the joint federal bank regulatory agencies issued an interim final rule that allows banking organizations that implement CECL in 2020 to mitigate the effects of the CECL accounting standard in their regulatory capital for two years. This two-year delay is in addition to the three-year transition period that the agencies had already made available. The Company has elected to adopt the option provided by the interim final rule, which will largely delay the effects of CECL on its regulatory capital for the next two years, after which the effects will be phased-in over a three-year period from January 1, 2022 through December 31, 2024. Under the interim final rule, the amount of adjustments to regulatory capital deferred until the phase-in period include both the initial impact of the Company’s adoption of CECL at January 1, 2020 and 25% of subsequent changes in the Company’s allowance for credit losses during each quarter of the two-year period ending December 31, 2021.

Financial institutions are categorized by the FDIC based on minimum Common Equity Tier 1, Tier 1 risk-based, total risk-based and Tier 1 leverage ratios. As of September 30, 2020, the Bank’s capital ratios were above the levels required for the Bank to be designated as “well capitalized.”

The following table provides a comparison of the Company’s and the Bank’s risk-weighted and leverage capital ratios to the minimum and well-capitalized regulatory standards as of September 30, 2020:

	Minimum Required For Capital Adequacy Purposes				Minimum Required Plus Capital Conservation Buffer			To Be Categorized As Well Capitalized Under Prompt Corrective Action Provisions			Actual Ratio as of September 30, 2020
The Company
CET1 capital (to risk weighted assets)		4.50	%			7.00	%	N/A				13.18	%
Tier 1 capital (to risk weighted assets)		6.00	%			8.50	%	N/A				13.18	%
Total capital (to risk weighted assets)		8.00	%			10.50	%	N/A				14.28	%
Tier 1 capital (to average assets)		4.00	%	(1)		4.00	%	N/A				9.57	%
The Bank
CET1 capital (to risk weighted assets)		4.50	%			7.00	%		6.50	%		13.67	%
Tier 1 capital (to risk weighted assets)		6.00	%			8.50	%		8.00	%		13.67	%
Total capital (to risk weighted assets)		8.00	%			10.50	%		10.00	%		14.19	%
Tier 1 capital (to average assets)		4.00	%	(2)		4.00	%		5.00	%		9.89	%

(1) The Federal Reserve Board may require the Company to maintain a leverage ratio above the required minimum.

(2) The FDIC may require the Bank to maintain a leverage ratio above the required minimum.

ITEM  3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

The Company manages market risk, which for the Company is primarily interest rate risk, through its Asset Liability Committee consisting of senior officers of the Company, in accordance with policies approved by the Company’s Board of Directors.

The Company uses simulation analysis to examine the potential effects of market changes on net interest income and market value. The Company considers macroeconomic variables, Company strategy, liquidity and other factors as it quantifies market risk. See Item 7 “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Interest Rate Sensitivity and Liquidity” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, filed on February 28, 2020 (the “2019 Form 10-K”), for further discussion. There have been no material changes in the Company’s market risk exposures that would affect the quantitative and qualitative disclosures from those disclosed in the 2019 Form 10-K and presented as of December 31, 2019.

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ITEM  4. CONTROLS AND PROCEDURES

Evaluation of disclosure controls and procedures. As of the end of the period covered by this report, the Company carried out an evaluation, under the supervision and with the participation of its management, including its Chief Executive Officer and Chief Financial Officer, of the effectiveness of the design and operation of its disclosure controls and procedures. In designing and evaluating the disclosure controls and procedures, management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objectives, and management was required to apply judgment in evaluating its controls and procedures. Based on this evaluation, the Company’s Chief Executive Officer and Chief Financial Officer concluded that the Company’s disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) were effective as of the end of the period covered by this report.

Changes in internal control over financial reporting. There were no changes in the Company’s internal control over financial reporting (as such term is defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) during the quarter ended September 30, 2020 that have materially affected, or are reasonably likely to materially affect, the Company’s internal control over financial reporting.

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PART II—OTHER INFORMATION

ITEM  1. LEGAL PROCEEDINGS

The Company and the Bank are defendants, from time to time, in legal actions arising from transactions conducted in the ordinary course of business. After consultations with legal counsel, the Company and the Bank believe that the ultimate liability, if any, arising from such actions will not have a material adverse effect on their financial statements.

ITEM  1A. RISK FACTORS

Except as provided below, there have been no material changes in the Company’s risk factors from those disclosed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019.

The novel Coronavirus ("COVID-19") pandemic could adversely affect the Company and its customers, associates and third-party service providers, and the adverse impacts on the Company’s business, financial position, operations and prospects could be significant.

The spread of COVID-19 has created a global public health crisis that has resulted in unprecedented uncertainty, volatility and disruption in financial markets and in governmental, commercial and consumer activity in the United States and globally. Governmental responses to the pandemic have included orders closing businesses not deemed essential and directing individuals to restrict their movements and observe social distancing. These actions, together with responses to the pandemic by businesses and individuals, have resulted in decreases in commercial and consumer activity, temporary closures of many businesses that have led to loss of revenues and an increase in unemployment, material decreases in oil and gas prices and in business valuations, disrupted global supply chains, market downturns and volatility, changes in consumer behavior related to pandemic fears and an expectation that Federal Reserve policy will maintain a low interest rate environment for the foreseeable future. These changes have had a significant adverse effect on the markets in which the Company conducts its business and on the demand for its products and services.

Business and consumer customers of the Company are experiencing varying degrees of financial distress, which is expected to continue to increase over coming months and could adversely affect their ability to timely pay interest and principal on their loans and the value of the collateral securing their obligations. Further, any disruption to our ability to deliver financial products or services to, or interact with, our customers could result in losses or increased operational costs, regulatory fines, penalties and other sanctions, or harm our reputation.

COVID-19 is not yet contained and could affect significantly more households and businesses. Given the ongoing and dynamic nature of the circumstances, it is not possible to accurately predict the extent, severity or duration of these conditions or when normal economic and operating conditions will resume. For this reason, the extent to which the COVID-19 pandemic affects the Company’s business, operations and financial condition, as well as its regulatory capital and liquidity, is highly uncertain and unpredictable and depends on, among other things, new information that may emerge concerning the scope, duration and severity of the COVID-19 pandemic and actions taken by governmental authorities and other parties in response to the pandemic. If the pandemic is prolonged, the adverse impact on the markets in which the Company operates and on its business, operations and financial condition could deepen.

The Federal Reserve has taken various actions and the U.S. government has enacted several fiscal stimulus measures to counteract the economic disruption caused by the COVID-19 pandemic and provide economic assistance to individual households and businesses, stabilize the markets and support economic growth. The success of these measures is unknown and they may not be sufficient to fully mitigate the negative impact of the COVID-19 pandemic. The Company faces an increased risk of litigation and governmental, regulatory and third-party scrutiny as a result of the effects of the COVID-19 pandemic on market and economic conditions and actions governmental authorities take in response to those conditions. Furthermore, various governmental programs such as the PPP are complex and the Company’s participation may lead to additional litigation and governmental, regulatory and third-party scrutiny, negative publicity and damage to the Company’s reputation. For example, the Company’s participation in the PPP as a lender may adversely affect the Company’s revenue and results of operations depending on the timing and amount of forgiveness, if any, to which its borrowers will be entitled.

To the extent the COVID-19 pandemic adversely affects the Company’s business, financial condition, results of operations and liquidity, it also may have the effect of exacerbating many of the other risks described under “Risk Factors” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019.

60

ITEM  2. UNREGISTERED SALES OF EQUITY SECURITIES AND USE OF PROCEEDS

a. None.

b. None.

c. The following table details the Company’s repurchases of shares of its common stock during the three months ended September 30, 2020:

Period	Total Number of Shares Purchased		Weighted Average Price Paid per Share		Total Number of Shares Purchased as Part of Publicly Announced Plans or Program		Maximum Number of Shares That May Yet Be Purchased Under the Plan at the End of the Period (1)
July 1 - July 31, 2020		—	$	—		—		2,645,744
August 1 - August 31, 2020		—		—		—		2,645,744
September 1 - September 30, 2020		98,028		49.99		98,028		2,547,716
Total		98,028	$	49.99		98,028

(1) On January 29, 2020, Bancshares announced a stock repurchase program under which up to 5%, or approximately

4.74 million shares, of its outstanding common stock may be acquired over a one-year period expiring on January 28, 2021, at the discretion of management. Under the stock repurchase program, Bancshares may repurchase shares from time to time at prevailing market prices, through open-market purchases or privately negotiated transactions, depending upon market conditions. See “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Financial Condition—Share Repurchases” for additional information.

ITEM  3. DEFAULTS UPON SENIOR SECURITIES

None.

ITEM  4. MINE SAFETY DISCLOSURES

Not applicable.

ITEM 5. OTHER INFORMATION

None.

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ITEM  6. EXHIBITS

Exhibit Number	Description of Exhibit
3.1	Amended and Restated Articles of Incorporation of Prosperity Bancshares, Inc. (incorporated herein by reference to Exhibit 3.1 to the Company’s Registration Statement on Form S-1 (Registration No. 333-63267) (the “Registration Statement”))
3.2	Articles of Amendment to Amended and Restated Articles of Incorporation of Prosperity Bancshares, Inc. (incorporated herein by reference to Exhibit 3.2 to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2006)
3.3	Amended and Restated Bylaws of Prosperity Bancshares, Inc. (incorporated herein by reference to Exhibit 3.1 to the Company’s Current Report on Form 8-K filed on June 20, 2019)
4.1	Form of certificate representing shares of the Company’s common stock (incorporated herein by reference to Exhibit 4 to the Registration Statement)
31.1*	Certification of the Chief Executive Officer pursuant to Rule 13a-14(a) of the Securities Exchange Act of 1934, as amended
31.2*	Certification of the Chief Financial Officer pursuant to Rule 13a-14(a) of the Securities Exchange Act of 1934, as amended
32.1**	Certification of the Chief Executive Officer pursuant to 18 U.S.C. Section 1350, adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
32.2**	Certification of the Chief Financial Officer pursuant to 18 U.S.C. Section 1350, adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
101.INS*	Inline XBRL Instance Document – The instance document does not appear in the interactive data file because its XBRL tags are embedded within the Inline XBRL document
101.SCH*	Inline XBRL Taxonomy Extension Schema Document
101.CAL*	Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.LAB*	Inline XBRL Taxonomy Extension Label Linkbase Document
101.PRE*	Inline XBRL Taxonomy Extension Presentation Linkbase Document
101.DEF*	Inline XBRL Taxonomy Extension Definition Linkbase Document
104	The cover page from the Company’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2020 (formatted as Inline XBRL and contained in Exhibits 101)

* Filed with this Quarterly Report on Form 10-Q.

** Furnished with this Quarterly Report on Form 10-Q.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

	PROSPERITY BANCSHARES, INC. ®         (Registrant)
Date: 11/5/2020	/S/    DAVID ZALMAN
	David Zalman
	Senior Chairman and Chief Executive Officer
Date: 11/5/2020	/S/    ASYLBEK OSMONOV
	Asylbek Osmonov
	Chief Financial Officer

63

EX-31.1

Exhibit 31.1

CERTIFICATION OF THE CHIEF EXECUTIVE OFFICER PURSUANT TO RULE 13a-14(a) OF THE

SECURITIES EXCHANGE ACT OF 1934, AS AMENDED

I, David Zalman, certify that:

1. I have reviewed this quarterly report on Form 10-Q of Prosperity Bancshares, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 5, 2020

/s/ David Zalman

David Zalman 

Chief Executive Officer

EX-31.2

Exhibit 31.2

CERTIFICATION OF THE CHIEF FINANCIAL OFFICER PURSUANT TO RULE 13a-14(a) OF THE

SECURITIES EXCHANGE ACT OF 1934, AS AMENDED

I, Asylbek Osmonov, certify that:

1. I have reviewed this quarterly report on Form 10-Q of Prosperity Bancshares, Inc.;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b) designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c) evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d) disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a) all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b) any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: November 5, 2020

/s/ Asylbek Osmonov

Asylbek Osmonov

Chief Financial Officer

EX-32.1

Exhibit 32.1

Certification Pursuant to 18 U.S.C. Section 1350, as adopted pursuant to

Section 906 of the Sarbanes-Oxley Act of 2002

In connection with the quarterly report of Prosperity Bancshares, Inc. (the “Company”) on Form 10-Q for the period ended September 30, 2020 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, David Zalman, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1. The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and operating results of the Company.

/s/ David Zalman

David Zalman 

Chief Executive Officer

November 5, 2020

EX-32.2

Exhibit 32.2

Certification Pursuant to 18 U.S.C. Section 1350, as adopted pursuant to

Section 906 of the Sarbanes-Oxley Act of 2002

In connection with the quarterly report of Prosperity Bancshares, Inc. (the “Company”) on Form 10-Q for the period ended September 30, 2020 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Asylbek Osmonov, Chief Financial Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1. The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material respects, the financial condition and operating results of the Company.

/s/ Asylbek Osmonov

Asylbek Osmonov

Chief Financial Officer

November 5, 2020

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Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 02, 2020
Cover [Abstract]
Entity Registrant Name	PROSPERITY BANCSHARES, INC.
Entity Central Index Key	0001068851
Trading Symbol	PB
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding (in shares)		92,558,558
Entity Current Reporting Status	Yes
Entity File Number	001-35388
Entity Incorporation, State or Country Code	TX
Entity Tax Identification Number	74-2331986
Entity Address, Address Line One	Prosperity Bank Plaza
Entity Address, Address Line Two	4295 San Felipe
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77027
City Area Code	281
Local Phone Number	269-7199
Entity Shell Company	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock, par value $1.00 per share
Security Exchange Name	NYSE
Document Quarterly Report	true
Document Transition Report	false

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Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
ASSETS
Cash and due from banks	$ 1,031,193	$ 573,589
Federal funds sold	56,469	519
Total cash and cash equivalents	1,087,662	574,108
Available for sale securities, at fair value	461,115	287,663
Held to maturity securities, at cost (fair value of $7,145,837 and $8,303,851, respectively)	6,970,380	8,282,393
Total securities	7,431,495	8,570,056
Loans held for sale	51,694	80,959
Loans held for investment	18,013,333	17,211,625
Total loans	20,795,641	18,845,346
Less: allowance for credit losses on loans	(323,635)	(87,469)
Loans, net	20,472,006	18,757,877
Accrued interest receivable	87,555	80,797
Goodwill	3,231,692	3,223,671
Core deposit intangibles, net	76,478	86,404
Bank premises and equipment, net	325,994	326,832
Other real estate owned	11,548	6,936
Bank owned life insurance (BOLI)	326,452	321,793
Federal Home Loan Bank of Dallas stock	8,901	83,945
Other assets	137,816	153,289
TOTAL ASSETS	33,197,599	32,185,708
Deposits:
Noninterest-bearing	8,998,328	7,763,894
Interest-bearing	17,460,878	16,435,838
Total deposits	26,459,206	24,199,732
Fed funds purchased and other borrowings	2,570	1,303,730
Securities sold under repurchase agreements	380,274	377,294
Subordinated notes	125,146	125,804
Accrued interest payable	6,592	8,585
Allowance for credit losses on off-balance sheet credit exposures	29,947	5,599
Other liabilities	158,987	194,129
Total liabilities	27,162,722	26,214,873
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS’ EQUITY:
Preferred stock, $1 par value; 20,000,000 shares authorized; none issued or outstanding
Common stock, $1 par value; 200,000,000 shares authorized; 92,562,434 shares issued and outstanding at September 30, 2020; 94,746,019 shares issued and outstanding at December 31, 2019	92,562	94,746
Capital surplus	3,631,213	3,734,519
Retained earnings	2,311,451	2,140,968
Accumulated other comprehensive (loss) income —net unrealized (loss) gain on available for sale securities, net of tax (benefit) expense of $(93) and $160, respectively	(349)	602
Total shareholders’ equity	6,034,877	5,970,835
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	33,197,599	32,185,708
Warehouse Purchase Program [Member]
ASSETS
Loans held for investment	2,730,614	1,552,762
Total loans	$ 2,730,614	$ 1,552,762

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Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Held to maturity securities, fair value	$ 7,145,837	$ 8,303,851
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	92,562,434	94,746,019
Common stock, shares outstanding (in shares)	92,562,434	94,746,019
Accumulated other comprehensive income net unrealized (loss) gain on available for sale securities, tax (benefit) expense	$ (93)	$ 160

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Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
INTEREST INCOME:
Loans, including fees	$ 244,255	$ 134,943	$ 734,270	$ 398,533
Securities	38,033	50,872	130,091	160,464
Federal funds sold and other earning assets	144	363	902	1,083
Total interest income	282,432	186,178	865,263	560,080
INTEREST EXPENSE:
Deposits	22,458	26,939	82,745	78,629
Other borrowings	52	4,335	3,517	15,208
Securities sold under repurchase agreements	309	914	1,403	2,504
Subordinated notes	1,500		4,499
Total interest expense	24,319	32,188	92,164	96,341
NET INTEREST INCOME	258,113	153,990	773,099	463,739
PROVISION FOR CREDIT LOSSES	10,000	1,100	20,000	2,600
NET INTEREST INCOME AFTER PROVISION FOR CREDIT LOSSES	248,113	152,890	753,099	461,139
NONINTEREST INCOME:
Nonsufficient funds (NSF) fees	7,156	8,835	22,244	24,624
Credit card, debit card and ATM card income	8,315	6,688	23,052	19,139
Service charges on deposit accounts	5,920	5,020	17,814	15,007
Trust income	2,502	2,492	7,406	7,645
Mortgage income	2,958	839	6,788	2,551
Brokerage income	628	522	1,862	1,736
Net (loss) gain on sale or write down of assets	(528)	(3)	(4,858)	57
Other	7,973	6,280	20,679	18,016
Total noninterest income	34,924	30,673	94,987	88,775
NONINTEREST EXPENSE:
Salaries and employee benefits	75,068	52,978	231,459	156,992
Net occupancy and equipment	8,644	5,607	26,814	16,565
Credit and debit card, data processing and software amortization	8,776	4,989	31,887	14,466
Regulatory assessments and FDIC insurance	2,512	1,814	7,191	6,513
Core deposit intangibles amortization	3,270	1,248	9,926	3,832
Depreciation	4,605	3,286	13,971	9,501
Communications	3,027	2,214	9,546	6,667
Other real estate expense, net	121	(47)	81	(75)
Merger related expenses			8,018
Other	11,896	8,610	38,135	25,630
Total noninterest expense	117,919	80,699	377,028	240,091
INCOME BEFORE INCOME TAXES	165,118	102,864	471,058	309,823
PROVISION FOR INCOME TAXES	35,054	21,106	79,245	63,405
NET INCOME	$ 130,064	$ 81,758	$ 391,813	$ 246,418
EARNINGS PER SHARE:
Basic	$ 1.40	$ 1.19	$ 4.20	$ 3.55
Diluted	$ 1.40	$ 1.19	$ 4.20	$ 3.55

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Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 130,064	$ 81,758	$ 391,813	$ 246,418
Securities available for sale:
Change in unrealized gains (losses) during the period	1,325	(1,563)	(1,204)	(344)
Total other comprehensive income (loss)	1,325	(1,563)	(1,204)	(344)
Deferred tax (expense) benefit related to other comprehensive income (loss)	(278)	328	253	72
Other comprehensive income (loss), net of tax	1,047	(1,235)	(951)	(272)
Comprehensive income	$ 131,111	$ 80,523	$ 390,862	$ 246,146

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Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	[1]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Common Stock [Member]	Common Stock [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Capital Surplus [Member]	Capital Surplus [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	[1]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
BALANCE at Dec. 31, 2018	$ 4,052,824				$ 69,847		$ 2,045,351		$ 1,937,316				$ 310
BALANCE (in shares) at Dec. 31, 2018					69,846,825
Net income	246,418								246,418
Other comprehensive income (loss)	(272)												(272)
Common stock issued in connection with the issuance of restricted stock awards, net					$ 23		(23)
Common stock issued in connection with the issuance of restricted stock awards, net (in shares)					23,184
Common stock repurchase	(94,484)				$ (1,473)		(93,011)
Common stock repurchase (in shares)					(1,473,231)
Stock based compensation expense	7,643						7,643
Cash dividends declared	(85,323)								(85,323)
BALANCE at Sep. 30, 2019	4,126,806				$ 68,397		1,959,960		2,098,411				38
BALANCE (in shares) at Sep. 30, 2019					68,396,778
BALANCE at Jun. 30, 2019	4,127,895				$ 69,261		2,012,665		2,044,696				1,273
BALANCE (in shares) at Jun. 30, 2019					69,261,431
Net income	81,758								81,758
Other comprehensive income (loss)	(1,235)												(1,235)
Common stock issued in connection with the issuance of restricted stock awards, net					$ 10		(10)
Common stock issued in connection with the issuance of restricted stock awards, net (in shares)					9,750
Common stock repurchase	(56,063)				$ (874)		(55,189)
Common stock repurchase (in shares)					(874,403)
Stock based compensation expense	2,494						2,494
Cash dividends declared	(28,043)								(28,043)
BALANCE at Sep. 30, 2019	4,126,806				$ 68,397		1,959,960		2,098,411				38
BALANCE (in shares) at Sep. 30, 2019					68,396,778
BALANCE at Dec. 31, 2019	$ 5,970,835	$ (92,860)		$ 5,877,975	$ 94,746	$ 94,746	3,734,519	$ 3,734,519	$ 2,140,968	$ (92,860)		$ 2,048,108	602	$ 602
BALANCE (in shares) at Dec. 31, 2019					94,746,019	94,746,019
Accounting Standards Update [Extensible List]	pb:AccountingStandardsUpdate201613AndOtherMember								pb:AccountingStandardsUpdate201613AndOtherMember
Net income	$ 391,813								$ 391,813
Other comprehensive income (loss)	(951)												(951)
Common stock issued in connection with the issuance of restricted stock awards, net					$ 6		(6)
Common stock issued in connection with the issuance of restricted stock awards, net (in shares)					6,000
Common stock repurchase	(114,964)				$ (2,190)		(112,774)
Common stock repurchase (in shares)					(2,189,585)
Stock based compensation expense	9,474						9,474
Cash dividends declared	(128,470)								(128,470)
BALANCE at Sep. 30, 2020	6,034,877				$ 92,562		3,631,213		2,311,451				(349)
BALANCE (in shares) at Sep. 30, 2020					92,562,434
BALANCE at Jun. 30, 2020	5,948,122				$ 92,660		3,632,847		2,224,011				(1,396)
BALANCE (in shares) at Jun. 30, 2020					92,660,462
Net income	130,064								130,064
Other comprehensive income (loss)	1,047												1,047
Common stock repurchase	(4,903)				$ (98)		(4,805)
Common stock repurchase (in shares)					(98,028)
Stock based compensation expense	3,171						3,171
Cash dividends declared	(42,624)								(42,624)
BALANCE at Sep. 30, 2020	$ 6,034,877				$ 92,562		$ 3,631,213		$ 2,311,451				$ (349)
BALANCE (in shares) at Sep. 30, 2020					92,562,434

[1] ASU 2016-13 became effective for the Company on January 1, 2020.

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Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Retained Earnings [Member]
Cash dividend declared, per share (in dollars per share)	$ 0.46	$ 0.41	$ 1.38	$ 1.23

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Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 391,813	$ 246,418
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and core deposit intangibles amortization	23,897	13,333
Provision for credit losses	20,000	2,600
Net amortization of premium on investments	27,318	22,223
Net gain on sale of other real estate and repossessed assets	(263)	(346)
Net loss on sale or write down of premises and equipment	2,506
Net loss (gain) on sale or write down of assets	2,352	(57)
Net accretion of discount on loans	(75,282)	(4,303)
Net amortization of premium on deposits	(5,303)
Gain on sale of loans	(4,957)	(2,355)
Proceeds from sale of loans held for sale	338,740	132,554
Originations of loans held for sale	(305,612)	(121,212)
Stock based compensation expense	9,474	7,643
Decrease in accrued interest receivable and other assets	97,047	13,860
(Decrease) increase in accrued interest payable and other liabilities	(24,834)	38,840
Net cash provided by operating activities	496,896	349,198
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities and principal paydowns of held to maturity securities	1,751,229	1,328,559
Purchase of held to maturity securities	(466,474)	(222,906)
Proceeds from maturities and principal paydowns of available for sale securities	12,027,029	9,020,085
Purchase of available for sale securities	(12,201,746)	(9,234,545)
Originations of WPP loans	(30,474,590)
Proceeds from pay-offs of WPP	29,296,738
Net increase in loans held for investment	(626,308)	(312,461)
Purchase of bank premises and equipment	(17,617)	(16,253)
Proceeds from sale of bank premises, equipment and other real estate	4,766	4,531
Proceeds from insurance claims	468	3,637
Net cash (used in) provided by investing activities	(706,505)	570,647
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in noninterest-bearing deposits	1,234,434	117,887
Net increase (decrease) in interest-bearing deposits	1,030,343	(444,525)
Net repayments of other short-term borrowings	(1,300,000)	(430,000)
Repayments of other long-term borrowings	(1,160)	(331)
Net increase in securities sold under repurchase agreements	2,980	26,684
Repurchase of common stock	(114,964)	(94,484)
Payments of cash dividends	(128,470)	(85,323)
Net cash provided by (used in) financing activities	723,163	(910,092)
NET INCREASE IN CASH AND CASH EQUIVALENTS	513,554	9,753
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	574,108	411,127
CASH AND CASH EQUIVALENTS, END OF PERIOD	1,087,662	420,880
NONCASH ACTIVITIES:
Acquisition of real estate through foreclosure of collateral	8,229	1,998
SUPPLEMENTAL INFORMATION:
Income taxes paid	132,185	63,250
Interest paid	$ 94,157	$ 95,104

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Basis of Presentation

9 Months Ended

Sep. 30, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Basis of Presentation

1. BASIS OF PRESENTATION

The consolidated financial statements include the accounts of Prosperity Bancshares, Inc.^® (“Bancshares”) and its wholly-owned subsidiary, Prosperity Bank^® (the “Bank,” and together with Bancshares, the “Company”). All intercompany transactions and balances have been eliminated.

The accompanying unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for financial information and with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, the statements reflect all adjustments necessary for a fair presentation of the financial position, results of operations and cash flows of the Company on a consolidated basis; and all such adjustments are of a normal recurring nature. These financial statements and the notes thereto should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Operating results for the nine-month period ended September 30, 2020 are not necessarily indicative of the results that may be expected for the year ending December 31, 2020 or any other period.

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Income Per Common Share

9 Months Ended

Sep. 30, 2020

Earnings Per Share [Abstract]

Income Per Common Share

2. INCOME PER COMMON SHARE

The following table illustrates the computation of basic and diluted earnings per share:

	Three Months Ended September 30,								Nine Months Ended September 30,
	2020				2019				2020				2019
	Amount		Per Share Amount		Amount		Per Share Amount		Amount		Per Share Amount		Amount		Per Share Amount
	(Amounts in thousands, except per share data)
Net income	$	130,064			$	81,758			$	391,813			$	246,418
Basic:
Weighted average shares outstanding		92,656	$	1.40		68,738	$	1.19		93,226	$	4.20		69,463	$	3.55
Diluted:
Weighted average shares outstanding		92,656	$	1.40		68,738	$	1.19		93,226	$	4.20		69,463	$	3.55

As of September 30, 2020, all stock options have been exercised and there are no options outstanding. There were no stock options exercisable during the three and nine months ended September 30, 2020 or 2019 that would have had an anti-dilutive effect on the above computation.

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New Accounting Standards

9 Months Ended

Sep. 30, 2020

New Accounting Pronouncements And Changes In Accounting Principles [Abstract]

New Accounting Standards

3. NEW ACCOUNTING STANDARDS

Accounting Standards Updates (“ASU”)

ASU 2020-04, "Reference Rate Reform: Facilitation of the Effects of Reference Rate Reform on Financial Reporting - Accounting Standards Codification (“ASC”) Topic 848." ASU 2020-04 provides optional expedients and exceptions for applying GAAP to loan and lease agreements, derivative contracts, and other transactions affected by the anticipated transition away from LIBOR toward new interest rate benchmarks. The guidance allows for companies to: (i) account for certain contract modifications as a continuation of the existing contract without additional analysis; (ii) continue hedge accounting when certain critical terms of a hedging relationship change and assess effectiveness in ways that disregard certain potential sources of ineffectiveness; and (iii) make a one-time sale and/or transfer of certain debt securities from held-to-maturity to available-for-sale or trading. This ASU is available for adoption effective March 12, 2020 through December 31, 2022. An entity may elect to apply ASU 2020-04 for contract modifications as of January 1, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic within ASU 2020-04, the amendments must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The one-time election to sell and/or transfer debt securities classified as held-to-maturity may be made at any time after March 12, 2020. The Company anticipates this ASU will simplify any modifications it executes between the selected start date (yet to be determined) and December 31, 2022 that are directly related to the LIBOR transition by allowing prospective recognition of the continuation of the contract, rather than extinguishment of the old contract resulting in writing off unamortized fees and costs. ASU 2020-04 is not expected to have a significant impact on the Company’s financial statements.

ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326)—Measurement of Credit Losses on Financial Instruments (“ASC 326”).” On January 1, 2020, the Company adopted ASU 2016-13 which replaces the incurred loss methodology with an expected loss methodology that is referred to as the current expected credit loss (“CECL”) methodology. CECL requires a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The measurement of CECL is based on relevant information about past events including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount.

The Company adopted ASU 2016-13 using the modified-retrospective method for all financial assets measured at amortized cost and off-balance sheet credit exposures. Reporting periods beginning after January 1, 2020 are presented under ASC 326 while prior periods are reported with previously applicable GAAP. Upon adoption of ASU 2016-13, the Company recognized an increase in allowance for credit losses for loans of $108.7 million, of which $102.5 million was related to LegacyTexas Financial Group, Inc. (“LegacyTexas”), which merged into Bancshares on November 1, 2019, and an increase in allowance for credit losses for off-balance sheet credit exposures of $24.4 million, of which $6.3 million was related to LegacyTexas, with a corresponding decrease in retained earnings (pre-tax). Additionally, the Company adopted ASU 2016-13 using the prospective transition approach for financial assets purchased with credit deterioration. The Company recognized an increase in the allowance for credit losses for loans of $131.8 million, of which $130.3 million was related to LegacyTexas, due to the reclass of purchased credit deteriorated discounts as the result of adopting ASU 2016-13. See Note 5 “Loans and Allowance for Credit Losses” for additional information. The Company recognized no allowance for credit losses related to debt securities. See Note 4 “Securities” for additional information.

The following table illustrates the impact of adopting ASU 2016-13:

	January 1, 2020
	As Reported Under ASC 326		Pre-ASC 326 Adoption		Impact of ASC 326 Adoption
	(Dollars in thousands)
Assets:
Loans
Construction, land development and other land loans	$	28,729	$	14,654	$	14,075
Agriculture and agriculture real estate (includes farmland)		5,768		2,971		2,797
1-4 family (includes home equity)		23,544		15,277		8,267
Commercial real estate (includes multi-family residential)		61,322		12,332		48,990
Commercial and industrial		180,069		40,445		139,624
Consumer and other		28,575		1,790		26,785
Allowance for credit losses on loans	$	328,007	$	87,469	$	240,538
Liabilities:
Allowance for credit losses on off-balance sheet credit exposures	$	29,947	$	5,599	$	24,348

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Securities

9 Months Ended

Sep. 30, 2020

Investments Debt And Equity Securities [Abstract]

Securities

4. SECURITIES

The amortized cost and fair value of investment securities were as follows:

	September 30, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
Collateralized mortgage obligations	$	418,575	$	138	$	(525	)	$	418,188
Mortgage-backed securities		42,982		570		(625	)		42,927
Total	$	461,557	$	708	$	(1,150	)	$	461,115
Held to Maturity
U.S. Treasury securities and obligations of U.S. Government agencies	$	3,989	$	25	$	—		$	4,014
States and political subdivisions		170,427		9,288		(187	)		179,528
Collateralized mortgage obligations		123,309		2,080		(256	)		125,133
Mortgage-backed securities		6,672,655		165,665		(1,158	)		6,837,162
Total	$	6,970,380	$	177,058	$	(1,601	)	$	7,145,837

	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	470	$	1	$	—		$	471
Collateralized mortgage obligations		235,222		690		(139	)		235,773
Mortgage-backed securities		51,209		659		(449	)		51,419
Total	$	286,901	$	1,350	$	(588	)	$	287,663
Held to Maturity
U.S. Treasury securities and obligations of U.S. Government agencies	$	13,933	$	58	$	—		$	13,991
States and political subdivisions		238,347		7,632		(189	)		245,790
Collateralized mortgage obligations		203,470		1,115		(373	)		204,212
Mortgage-backed securities		7,826,643		48,060		(34,845	)		7,839,858
Total	$	8,282,393	$	56,865	$	(35,407	)	$	8,303,851

The investment securities portfolio is measured for expected credit losses by segregating the portfolio into two general segments and applying the appropriate expected credit losses methodology. Investment securities classified as available for sale or held to maturity are evaluated for expected credit losses under Financial Accounting Standards Board (“FASB”): ASC 326, “Financial Instruments – Credit Losses.”

Available for sale securities. For available for sale securities in an unrealized loss position, the amount of the expected credit losses recognized in earnings depends on whether an entity intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss. If an entity intends to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the expected credit losses will be recognized in earnings equal to the entire difference between the investment’s amortized cost basis and its fair value at the balance sheet date. If an entity does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis less any current-period loss, the expected credit losses will be separated into the amount representing the credit-related portion of the impairment loss (“credit loss”) and the noncredit portion of the impairment loss (“noncredit portion”). The amount of the total expected credit losses related to the credit loss is determined based on the difference between the present value of cash flows expected to be collected and the amortized cost basis and such difference is recognized in earnings. The amount of the total expected credit losses related to the noncredit portion is recognized in other comprehensive income, net of applicable taxes. The previous amortized cost basis less the expected credit losses recognized in earnings will become the new amortized cost basis of the investment.

As of September 30, 2020, management does not have the intent to sell any of the securities classified as available for sale before a recovery of cost. In addition, management believes it is more likely than not that the Company will not be required to sell any of its investment securities before a recovery of cost. The unrealized losses are largely due to changes in market interest rates and spread relationships since the time the underlying securities were purchased. The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline. Management does not believe any of the securities are impaired due to reasons of credit quality. Accordingly, as of September 30, 2020, management believes that there is no potential for credit losses on available for sale securities.

Held to maturity securities. The Company’s held to maturity investments include mortgage-related bonds issued by either the Government National Mortgage Corporation (“Ginnie Mae”), Federal National Mortgage Association (“Fannie Mae”) or Federal Home Loan Mortgage Corporation (“Freddie Mac”).  Ginnie Mae issued securities are explicitly guaranteed by the U.S. government, while Fannie Mae and Freddie Mac issued securities are fully guaranteed by those respective United States government-sponsored agencies, and conditionally guaranteed by the full faith and credit of the United States.  The Company’s held to maturity securities also include taxable and tax-exempt municipal securities issued primarily by school districts, utility districts and municipalities located in Texas. The Company’s investment in municipal securities is exposed to credit risk. The securities are highly rated by major rating agencies and regularly reviewed by management. A significant portion are guaranteed or insured by either the Texas Permanent School Fund, Assured Guaranty or Build America Mutual. As of September 30, 2020, the Company’s municipal securities represent 2.3% of the securities portfolio. Management has the ability and intent to hold the securities classified as held to maturity until they mature, at which time the Company will receive full value for the securities. Accordingly, as of September 30, 2020, management believes that there is no potential for material credit losses on held to maturity securities.

Securities with unrealized losses, segregated by length of time, that have been in a continuous loss position were as follows:

	September 30, 2020
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
	(Dollars in thousands)
Available for Sale
Collateralized mortgage obligations	$	188,671	$	(515	)	$	1,886	$	(10	)	$	190,557	$	(525	)
Mortgage-backed securities		16,298		(365	)		12,815		(260	)		29,113		(625	)
Total	$	204,969	$	(880	)	$	14,701	$	(270	)	$	219,670	$	(1,150	)
Held to Maturity
States and political subdivisions	$	1,689	$	(187	)	$	—	$	—		$	1,689	$	(187	)
Collateralized mortgage obligations		33,507		(256	)		—		—			33,507		(256	)
Mortgage-backed securities		118,159		(858	)		19,716		(300	)		137,875		(1,158	)
Total	$	153,355	$	(1,301	)	$	19,716	$	(300	)	$	173,071	$	(1,601	)

	December 31, 2019
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
	(Dollars in thousands)
Available for Sale
Collateralized mortgage obligations	$	50,245	$	(136	)	$	1,818	$	(3	)	$	52,063	$	(139	)
Mortgage-backed securities		34,901		(449	)		10		—			34,911		(449	)
Total	$	85,146	$	(585	)	$	1,828	$	(3	)	$	86,974	$	(588	)
Held to Maturity
States and political subdivisions	$	58,329	$	(183	)	$	3,241	$	(6	)	$	61,570	$	(189	)
Collateralized mortgage obligations		54,890		(373	)		—		—			54,890		(373	)
Mortgage-backed securities		947,314		(3,017	)		3,110,765		(31,828	)		4,058,079		(34,845	)
Total	$	1,060,533	$	(3,573	)	$	3,114,006	$	(31,834	)	$	4,174,539	$	(35,407	)

At September 30, 2020 and December 31, 2019, there were 44 securities and 138 securities, respectively, in an unrealized loss position for 12 months or more.

The amortized cost and fair value of investment securities at September 30, 2020, by contractual maturity, are shown below. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations at any time with or without call or prepayment penalties.

	Held to Maturity				Available for Sale
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
Due in one year or less	$	26,715	$	26,744	$	—	$	—
Due after one year through five years		96,287		101,719		—		—
Due after five years through ten years		44,637		48,053		—		—
Due after ten years		6,777		7,026		—		—
Subtotal		174,416		183,542		—		—
Mortgage-backed securities and collateralized mortgage obligations		6,795,964		6,962,295		461,557		461,115
Total	$	6,970,380	$	7,145,837	$	461,557	$	461,115

The Company recorded no gain or loss on the sale of securities for the three and nine months ended September 30, 2020 and 2019. As of September 30, 2020, the Company did not own any non-agency collateralized mortgage obligations.

At September 30, 2020 and December 31, 2019, the Company did not own securities of any one issuer (other than the U.S. government and its agencies) for which aggregate adjusted cost exceeded 10% of the consolidated shareholders’ equity at such respective dates.

Securities with an amortized cost of $5.80 billion and $5.98 billion and a fair value of $5.94 billion and $5.99 billion at September 30, 2020 and December 31, 2019, respectively, were pledged to collateralize public deposits and for other purposes required or permitted by law.

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Loans and Allowance for Credit Losses

9 Months Ended

Sep. 30, 2020

Receivables [Abstract]

Loans and Allowance for Credit Losses

5. LOANS AND ALLOWANCE FOR CREDIT LOSSES

The loan portfolio consists of various types of loans and is categorized by major type as follows:

	September 30, 2020		December 31, 2019
	(Dollars in thousands)
Residential mortgage loans held for sale	$	51,694	$	80,959
Commercial and industrial		4,150,189		3,205,595
Real estate:
Construction, land development and other land loans		2,081,762		2,064,167
1-4 family residential (includes home equity)		4,615,710		4,306,452
Commercial real estate (includes multi-family residential)		6,179,901		6,556,285
Farmland		419,126		495,558
Agriculture		179,846		185,297
Consumer and other		386,799		398,271
Total loans held for investment, excluding Warehouse Purchase Program		18,013,333		17,211,625
Warehouse Purchase Program		2,730,614		1,552,762
Total loans, including Warehouse Purchase Program	$	20,795,641	$	18,845,346

Concentrations of Credit. Most of the Company’s lending activity occurs within the states of Texas and Oklahoma. Commercial real estate loans, 1-4 family residential loans and construction, land development and other land loans make up 71.3% of the Company’s total loan portfolio, excluding Warehouse Purchase Program loans, at September 30, 2020. As of September 30, 2020 and December 31, 2019, excluding Warehouse Purchase Program loans, there were no concentrations of loans related to any single industry in excess of 10% of total loans.

Related Party Loans. As of September 30, 2020 and December 31, 2019, loans outstanding to directors, officers and their affiliates totaled $1.8 million and $4.2 million, respectively. All transactions between the Company and such related parties are conducted in the ordinary course of business and made on the same terms and conditions as similar transactions with unaffiliated persons.

An analysis of activity with respect to these related party loans is as follows:

	As of and for the nine months ended September 30, 2020			As of and for the year ended December 31, 2019
	(Dollars in thousands)
Beginning balance on January 1	$	4,152		$	1,923
New loans		813			1
Transfers		—			2,500
Repayments		(3,134	)		(272	)
Ending balance	$	1,831		$	4,152

Nonperforming Assets and Nonaccrual and Past Due Loans. The Company has several procedures in place to assist it in maintaining the overall quality of its loan portfolio. The Company has established underwriting guidelines to be followed by its officers, including requiring appraisals on loans collateralized by real estate. The Company also monitors its delinquency levels for any negative or adverse trends. Nevertheless, the Company’s loan portfolio could become subject to increasing pressures from deteriorating borrower credit due to general economic conditions.

The Company generally places a loan on nonaccrual status and ceases accruing interest when the payment of principal or interest is delinquent for 90 days, or earlier in some cases, unless the loan is in the process of collection and the underlying collateral fully supports the carrying value of the loan. A loan may be returned to accrual status when all the principal and interest amounts contractually due are brought current and future principal and interest amounts contractually due are reasonably assured, which is typically evidenced by a sustained period (at least six months) of repayment performance by the borrower.

With respect to potential problem loans, an evaluation of the borrower’s overall financial condition is made to determine the need, if any, for possible writedowns or appropriate additions to the allowance for credit losses.

An aging analysis of past due loans, segregated by category of loan, is presented below:

	September 30, 2020
	Loans Past Due and Still Accruing
	30-89 Days		90 or More Days		Total Past Due Loans		Nonaccrual Loans		Current Loans		Total Loans
	(Dollars in thousands)
Construction, land development and other land loans	$	24,592	$	422	$	25,014	$	2,211	$	2,054,537	$	2,081,762
Warehouse Purchase Program loans		—		—		—		—		2,730,614		2,730,614
Agriculture and agriculture real estate (includes farmland)		30		—		30		1,200		597,742		598,972
1-4 family (includes home equity) (1)		6,160		40		6,200		23,769		4,637,435		4,667,404
Commercial real estate (includes multi-family residential)		2,758		—		2,758		11,486		6,165,657		6,179,901
Commercial and industrial		4,958		—		4,958		17,153		4,128,078		4,150,189
Consumer and other		529		—		529		1,593		384,677		386,799
Total	$	39,027	$	462	$	39,489	$	57,412	$	20,698,740	$	20,795,641

	December 31, 2019
	Loans Past Due and Still Accruing
	30-89 Days		90 or More Days		Total Past Due Loans		Nonaccrual Loans		Current Loans		Total Loans
	(Dollars in thousands)
Construction, land development and other land loans	$	16,470	$	—	$	16,470	$	1,142	$	2,046,555	$	2,064,167
Warehouse Purchase Program loans		—		—		—		—		1,552,762		1,552,762
Agriculture and agriculture real estate (includes farmland)		466		—		466		103		680,286		680,855
1-4 family (includes home equity) (1)		43,884		441		44,325		24,413		4,318,673		4,387,411
Commercial real estate (includes multi-family residential)		10,669		—		10,669		12,714		6,532,902		6,556,285
Commercial and industrial		7,249		—		7,249		16,809		3,181,537		3,205,595
Consumer and other		1,708		—		1,708		62		396,501		398,271
Total	$	80,446	$	441	$	80,887	$	55,243	$	18,709,216	$	18,845,346

(1) Includes $51.7 million and $81.0 million of residential mortgage loans held for sale at September 30, 2020 and December 31, 2019, respectively.

The following table presents information regarding nonperforming assets as of the dates indicated:

	September 30, 2020			December 31, 2019
	(Dollars in thousands)
Nonaccrual loans (1) (2)	$	57,412		$	55,243
Accruing loans 90 or more days past due		462			441
Total nonperforming loans		57,874			55,684
Repossessed assets		120			323
Other real estate		11,548			6,936
Total nonperforming assets	$	69,542		$	62,943
Nonperforming assets to total loans and other real estate		0.33	%		0.33	%
Nonperforming assets to total loans, excluding Warehouse Purchase Program loans, and other real estate		0.38	%		0.36	%

(1) Includes troubled debt restructurings of $13.2 million and $13.6 million as of September 30, 2020 and December 31, 2019, respectively.

(2) There were no nonperforming or troubled debt restructurings of warehouse lines of credit or Warehouse Purchase Program loans for the periods presented.

The Company had $69.5 million in nonperforming assets at September 30, 2020 compared with $62.9 million at December 31, 2019. Nonperforming assets were 0.33% of total loans and other real estate at September 30, 2020 and at December 31, 2019.

If interest on nonaccrual loans had been accrued under the original loan terms, approximately $2.3 million and $2.2 million would have been recorded as income for the nine months ended September 30, 2020 and 2019, respectively. The Company had $57.4 million in nonaccrual loans at September 30, 2020 compared with $50.0 million at September 30, 2019.

Acquired Loans.  Acquired loans were preliminarily recorded at fair value based on a discounted cash flow valuation methodology that considers, among other things, interest rates, projected default rates, loss given default, and recovery rates. During the valuation process, the Company identified purchased credit deteriorated (“PCD”) and Non-PCD loans in the acquired loan portfolios. Loans acquired with evidence of credit quality deterioration at acquisition for which it was probable that the Company would not be able to collect all contractual amounts due were accounted for as PCD. PCD loan identification considers the following factors: payment history and past due status, debt service coverage, loan grading, collateral values and other factors that may indicate deterioration of credit quality since origination. Non-PCD loan identification considers the following factors: account types, remaining terms, annual interest rates or coupons, current market rates, interest types, past delinquencies, timing of principal and interest payments, loan to value ratios, loss exposures and remaining balances. Accretion of purchased discounts on PCD loans will be based on future cash flows, taking into account contractual maturities. Accretion of purchased discounts on Non-PCD loans will be recognized on a level-yield basis based on contractual maturity of individual loans.

PCD Loans.  The recorded investment in PCD loans included in the consolidated balance sheet and the related outstanding balance as of the dates indicated are presented in the table below. The outstanding balance represents the total amount owed as of September 30, 2020 and December 31, 2019.

	September 30, 2020			December 31, 2019
	(Dollars in thousands)
PCD loans:
Outstanding balance	$	226,080		$	410,785
Discount (1)		(16,760	)		(167,320	)	(2)
Recorded investment	$	209,320		$	243,465

(1) ASU 2016-13 became effective for the Company on January 1, 2020.

(2) Includes $131.8 million in PCD loans credit discount.

Changes in the accretable yield for acquired PCD loans for the three and nine months ended September 30, 2020 and 2019 were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
	(Dollars in thousands)
Balance at beginning of period	$	22,565		$	904		$	35,654		$	1,534
Adjustments		—			26			(449	)		62
Accretion charge-offs		—			—			(354	)		—
Accretion		(5,805	)		(277	)		(18,091	)		(943	)
Balance at September 30,	$	16,760		$	653		$	16,760		$	653

Income recognition on PCD loans is subject to the timing and amount of future cash flows. PCD loans for which the Company is accruing interest income are not considered non-performing or impaired. The adoption of ASU 2016-13, “Financial Instruments-Credit-Losses (ASC Topic 326) – Measurement of Credit Losses on Financial Instruments” (“CECL”) resulted in $131.8 million of the total PCD discount as of December 31, 2019 being reallocated to the allowance for credit losses. The PCD discount reflected above as of September 30, 2020, represents the amount of discount available to be recognized as income.

Non-PCD Loans. The recorded investment in Non-PCD loans included in the consolidated balance sheet and the related outstanding balance as of the dates indicated are presented in the table below. The outstanding balance represents the total amount owed as of September 30, 2020 and December 31, 2019.

	September 30, 2020			December 31, 2019
	(Dollars in thousands)
Non-PCD loans:
Outstanding balance	$	4,468,843		$	6,102,540
Discount		(53,115	)		(110,130	)
Recorded investment	$	4,415,728		$	5,992,410

Changes in the discount accretion for Non-PCD loans for the three and nine months ended September 30, 2020 and 2019 were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
	(Dollars in thousands)
Balance at beginning of period	$	69,860		$	12,479		$	110,130		$	14,833
Adjustments		(16	)		—			296			—
Accretion charge-offs		—			—			(120	)		—
Accretion		(16,729	)		(1,006	)		(57,191	)		(3,360	)
Balance at September 30,	$	53,115		$	11,473		$	53,115		$	11,473

Credit Quality Indicators. As part of the on-going monitoring of the credit quality of the Company’s loan portfolio and methodology for calculating the allowance for credit losses, management assigns and tracks loan grades to be used as credit quality indicators. The following is a general description of the loan grades used:

Grade 1—Credits in this category have risk potential that is virtually nonexistent.  These loans may be secured by insured certificates of deposit, insured savings accounts, U.S. Government securities and highly rated municipal bonds.

Grade 2—Credits in this category are of the highest quality.  These borrowers represent top rated companies and individuals with unquestionable financial standing with excellent global cash flow coverage, net worth, liquidity and collateral coverage.

Grade 3—Credits in this category are not immune from risk but are well protected by the collateral and paying capacity of the borrower. These loans may exhibit a minor unfavorable credit factor, but the overall credit is sufficiently strong to minimize the possibility of loss.

Grade 4—Credits in this category are considered to be of acceptable credit quality with moderately greater risk than Grade 3 and receiving closer monitoring.  Loans in this category have sources of repayment that remain sufficient to preclude a larger than normal probability of default and secondary sources are likewise currently of sufficient quantity, quality, and liquidity to protect the Company against loss of principal and interest.  These borrowers have specific risk factors, but the overall strength of the credit is acceptable based on other mitigating credit and/or collateral factors and can repay the debt in the normal course of business.

Grade 5—Credits in this category constitute an undue and unwarranted credit risk; however, the factors do not rise to a level of substandard.  These credits have potential weaknesses and/or declining trends that, if not corrected, could expose the Company to risk at a future date.  These loans are monitored on the Company’s internally-generated watch list and evaluated on a quarterly basis.

Grade 6—Credits in this category are considered “substandard” but “non-impaired” loans in accordance with regulatory guidelines.  Loans in this category have well-defined weakness that, if not corrected, could make default of principal and interest possible.  Loans in this category are still accruing interest and may be dependent upon secondary sources of repayment and/or collateral liquidation.

Grade 7—Credits in this category are deemed “substandard” and “impaired” pursuant to regulatory guidelines. As such, the Company has determined that it is probable that less than 100% of the contractual principal and interest will be collected. These loans are individually evaluated for a specific reserve and will typically have the accrual of interest stopped.

Grade 8—Credits in this category include “doubtful” loans in accordance with regulatory guidance. Such loans are no longer accruing interest and factors indicate a loss is imminent.  These loans are also deemed “impaired.” While a specific reserve may be in place while the loan and collateral is being evaluated, these loans are typically charged down to an amount the Company estimates is collectible.

Grade 9—Credits in this category are deemed a “loss” in accordance with regulatory guidelines and have been charged off or charged down. The Company may continue collection efforts and may have partial recovery in the future.

The following table presents loans by risk grade, by category of loan and year of origination/renewal at September 30, 2020.

	Term Loans
	Amortized Cost Basis by Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
	(Dollars in thousands)
Construction, Land Development and Other Land Loans
Grade 1	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Grade 2		—		—		—		86		126		267		—		—		479
Grade 3		646,011		630,323		297,303		128,581		23,831		56,166		114,716		—		1,896,931
Grade 4		70,111		30,016		33,405		19,562		3,806		7,187		10,134		—		174,221
Grade 5		—		—		829		4,510		—		117		—		—		5,456
Grade 6		—		—		—		—		565		1,325		—		—		1,890
Grade 7		—		—		1,080		—		6		390		734		—		2,210
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		—		171		115		289		—		—		—		—		575
Total		716,122		660,510		332,732		153,028		28,334		65,452		125,584		—		2,081,762
Agriculture and Agriculture Real Estate (includes Farmland)
Grade 1	$	2,004	$	542	$	177	$	182		—		—	$	10,032	$	2	$	12,939
Grade 2		30		—		—		351		5		1,532		310		—		2,228
Grade 3		95,589		81,626		62,552		52,243		47,463		92,816		74,173		145		506,607
Grade 4		15,376		10,246		4,873		3,043		4,633		17,219		9,021		23		64,434
Grade 5		1,984		3,705		577		—		—		14		2,302		—		8,582
Grade 6		804		—		59		—		186		181		—		—		1,230
Grade 7		—		308		15		—		—		853		—		—		1,176
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		976		209		296		—		—		295		—		—		1,776
Total		116,763		96,636		68,549		55,819		52,287		112,910		95,838		170		598,972
1-4 Family (includes Home Equity) (1)
Grade 1	$	117	$	—	$	—	$	—	$	—	$	—	$	95	$	—	$	212
Grade 2		288		315		987		676		254		7,705		1,133		—		11,358
Grade 3		1,010,159		910,378		612,545		482,791		473,571		888,135		125,281		3,313		4,506,173
Grade 4		7,620		16,515		23,244		22,256		10,766		36,955		2,550		249		120,155
Grade 5		—		219		157		6		712		1,971		—		—		3,065
Grade 6		23		39		3		332		—		1,524		—		—		1,921
Grade 7		—		1,535		952		3,108		1,544		12,114		3,485		—		22,738
Grade 8		—		—		—		—		9		87		—		—		96
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		—		—		—		—		238		1,448		—		—		1,686
Total		1,018,207		929,001		637,888		509,169		487,094		949,939		132,544		3,562		4,667,404

	Term Loans
	Amortized Cost Basis by Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
	(Dollars in thousands)
Commercial Real Estate (includes Multi-Family Residential)
Grade 1	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Grade 2		10,046		2,006		—		7,450		201		1,386		—		—		21,089
Grade 3		468,230		986,980		983,614		824,609		464,007		1,018,983		63,247		2,072		4,811,742
Grade 4		89,339		79,177		209,634		214,653		156,972		318,504		8,505		6,597		1,083,381
Grade 5		6,120		7,556		16,457		2,771		35,280		43,836		1,306		—		113,326
Grade 6		10,014		174		—		10,587		3,176		14,906		—		—		38,857
Grade 7		19		—		1,238		15		7,840		847		1,485		—		11,444
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		48,199		21,935		5,361		6,278		200		18,089		—		—		100,062
Total		631,967		1,097,828		1,216,304		1,066,363		667,676		1,416,551		74,543		8,669		6,179,901
Commercial and Industrial
Grade 1	$	1,389,705	$	7,320	$	4,109	$	917	$	834	$	569	$	18,249	$	162	$	1,421,865
Grade 2		2,395		10,990		17,344		1,348		1,422		1,052		24,324		—		58,875
Grade 3		342,204		370,525		302,552		110,782		74,182		150,914		715,920		11,273		2,078,352
Grade 4		54,749		74,189		51,515		36,188		9,627		30,103		106,284		1,179		363,834
Grade 5		5,213		30,676		4,309		7		218		1,924		11,310		5,010		58,667
Grade 6		390		104		247		—		1,152		1,906		22,159		—		25,958
Grade 7		759		344		13,002		390		988		288		36,901		17		52,689
Grade 8		—		—		—		—		8		—		—		—		8
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		16,637		22,115		20,505		10,932		—		798		2,855		16,099		89,941
Total	$	1,812,052	$	516,263	$	413,583	$	160,564	$	88,431	$	187,554	$	938,002	$	33,740	$	4,150,189
Consumer and Other
Grade 1	$	37,213	$	11,159	$	4,170	$	2,469	$	1,370	$	157	$	1,523	$	—	$	58,061
Grade 2		2,350		1,036		407		31,450		1,583		—		1,204		—		38,030
Grade 3		39,858		50,310		31,445		22,314		7,615		16,122		74,327		73		242,064
Grade 4		4,237		2,052		964		75		84		118		14,148		—		21,678
Grade 5		—		—		66		18		—		—		9,997		—		10,081
Grade 6		—		—		—		—		—		—		—		—		—
Grade 7		2		1,569		7		4		—		21		2		—		1,605
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		3,800		—		—		—		—		—		11,480		—		15,280
Total	$	87,460	$	66,126	$	37,059	$	56,330	$	10,652	$	16,418	$	112,681	$	73	$	386,799

	Term Loans
	Amortized Cost Basis by Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
	(Dollars in thousands)
Warehouse Purchase Program
Grade 1	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Grade 2		—		—		—		—		—		—		—		—		—
Grade 3		2,730,614		—		—		—		—		—		—		—		2,730,614
Grade 4		—		—		—		—		—		—		—		—		—
Grade 5		—		—		—		—		—		—		—		—		—
Grade 6		—		—		—		—		—		—		—		—		—
Grade 7		—		—		—		—		—		—		—		—		—
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		—		—		—		—		—		—		—		—		—
Total	$	2,730,614	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	2,730,614
Total
Grade 1	$	1,429,039	$	19,021	$	8,456	$	3,568	$	2,204	$	726	$	29,899	$	164	$	1,493,077
Grade 2		15,109		14,347		18,738		41,361		3,591		11,942		26,971		—		132,059
Grade 3		5,332,665		3,030,142		2,290,011		1,621,320		1,090,669		2,223,136		1,167,664		16,876		16,772,483
Grade 4		241,432		212,195		323,635		295,777		185,888		410,086		150,642		8,048		1,827,703
Grade 5		13,317		42,156		22,395		7,312		36,210		47,862		24,915		5,010		199,177
Grade 6		11,231		317		309		10,919		5,079		19,842		22,159		—		69,856
Grade 7		780		3,756		16,294		3,517		10,378		14,513		42,607		17		91,862
Grade 8		—		—		—		—		17		87		—		—		104
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		69,612		44,430		26,277		17,499		438		20,630		14,335		16,099		209,320
Total	$	7,113,185	$	3,366,364	$	2,706,115	$	2,001,273	$	1,334,474	$	2,748,824	$	1,479,192	$	46,214	$	20,795,641

(1) Includes $51.7 million of residential mortgage loans held for sale at September 30, 2020.

Allowance for Credit Losses on Loans. The allowance for credit losses is adjusted through charges to earnings in the form of a provision for credit losses. Management has established an allowance for credit losses which it believes is adequate as of September 30, 2020 for estimated losses in the Company’s loan portfolio. The amount of the allowance for credit losses is affected by the following: (1) charge-offs of loans that occur when loans are deemed uncollectible and decrease the allowance, (2) recoveries on loans previously charged off that increase the allowance and (3) provisions for credit losses charged to earnings that increase the allowance or provision releases returned to earnings that decrease the allowance. Based on an evaluation of the loan portfolio and consideration of the factors listed below, management presents a quarterly review of the allowance for credit losses to the Bank’s Board of Directors, indicating any change in the allowance since the last review and any recommendations as to adjustments in the allowance. Although management believes it uses the best information available to make determinations with respect to the allowance for credit losses, future adjustments may be necessary if economic conditions or the borrower’s performance differ from the assumptions used in making the initial determinations.

The Company’s allowance for credit losses on loans consists of two components: (1) a specific valuation allowance based on probable losses on specifically identified loans and (2) a general valuation allowance based on historical lifetime loan loss experience, general economic conditions and other qualitative risk factors both internal and external to the Company.

In setting the specific valuation allowance, the Company follows a loan review program to evaluate the credit risk in the total loan portfolio and assigns risk grades to each loan. Through this loan review process, the Company maintains an internal list of impaired loans, which along with the delinquency list of loans, helps management assess the overall quality of the loan portfolio and the adequacy of the allowance for credit losses. All loans that have been identified as impaired are reviewed on a quarterly basis in order to determine whether a specific reserve is required. For certain impaired loans, the Company allocates a specific loan loss reserve primarily based on the value of the collateral securing the impaired loan in accordance with ASC Topic 326-20, “Financial

Instruments - Credit Losses.” The specific reserves are determined on an individual loan basis. Loans for which specific reserves are provided are excluded from the general valuation allowance described below.

In connection with this review of the loan portfolio, the Company considers risk elements attributable to particular loan types or categories in assessing the quality of individual loans. Some of the risk elements include:

• for 1-4 family residential mortgage loans, the borrower’s ability to repay the loan, including a consideration of the debt to income ratio and employment and income stability, the loan to value ratio, and the age, condition and marketability of collateral;

• for commercial real estate loans and multifamily residential loans, the debt service coverage ratio (income from the property in excess of operating expenses compared to loan payment requirements), operating results of the owner in the case of owner-occupied properties, the loan to value ratio, the age and condition of the collateral and the volatility of income, property value and future operating results typical of properties of that type;

• for construction, land development and other land loans, the perceived feasibility of the project including the ability to sell developed lots or improvements constructed for resale or the ability to lease property constructed for lease, the quality and nature of contracts for presale or prelease, if any, experience and ability of the developer and loan to value ratio;

• for commercial and industrial loans, the operating results of the commercial, industrial or professional enterprise, the borrower’s business, professional and financial ability and expertise, the specific risks and volatility of income and operating results typical for businesses in that category and the value, nature and marketability of collateral;

• for the Warehouse Purchase Program, the capitalization and liquidity of the mortgage banking client, the operating experience, the client’s satisfactory underwriting of purchased loans and the consistent timeliness by client of loan resale to investors;

• for agriculture real estate loans, the experience and financial capability of the borrower, projected debt service coverage of the operations of the borrower and loan to value ratio; and

• for non-real estate agriculture loans, the operating results, experience and financial capability of the borrower, historical and expected market conditions and the value, nature and marketability of collateral.

In addition, for each category, the Company considers secondary sources of income and the financial strength and credit history of the borrower and any guarantors.

In determining the amount of the general valuation allowance, management considers factors such as historical lifetime loan loss experience, concentration risk of specific loan types, the volume, growth and composition of the Company’s loan portfolio, current economic conditions and reasonable and supportable forecasted economic conditions that may affect the borrower’s ability to pay and the value of collateral, the evaluation of the Company’s loan portfolio through its internal loan review process, general economic conditions and other qualitative risk factors both internal and external to the Company and other relevant factors in accordance with ASC Topic 326, “Financial Instruments – Credit Losses.” Historical lifetime loan loss experience is determined by utilizing an open-pool (“cumulative loss rate”) methodology. Adjustments to the historical lifetime loan loss experience are made for differences in current loan pool risk characteristics such as portfolio concentrations, delinquency, non-accrual, and watch list levels, as well as changes in current and forecasted economic conditions such as unemployment rates, property and collateral values, and other indices relating to economic activity. The utilization of reasonable and supportable forecasts includes an immediate reversion to lifetime historical loss rates. Based on a review of these factors for each loan type, the Company applies an estimated percentage to the outstanding balance of each loan type, excluding any loan that has a specific reserve allocated to it. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. The Company uses this information to establish the amount of the general valuation allowance.

The following table details activity in the allowance for credit losses on loans by category of loan for the three and nine months ended September 30, 2020 and 2019.

	Construction, Land Development and Other Land Loans			Agriculture and Agriculture Real Estate (includes Farmland)			1-4 Family (includes Home Equity)			Commercial Real Estate (includes Multi-Family Residential)			Commercial and Industrial			Consumer and Other			Total
	(Dollars in thousands)
Allowance for credit losses:
Three Months Ended
Balance June 30, 2020	$	39,862		$	6,898		$	33,021		$	78,207		$	149,884		$	16,333		$	324,205
Provision for credit losses		4,187			554			7,517			3,188			(4,982	)		(464	)		10,000
Charge-offs		(500	)		—			(436	)		(676	)		(8,444	)		(1,092	)		(11,148	)
Recoveries		22			17			184			—			99			256			578
Net charge-offs		(478	)		17			(252	)		(676	)		(8,345	)		(836	)		(10,570	)
Balance September 30, 2020	$	43,571		$	7,469		$	40,286		$	80,719		$	136,557		$	15,033		$	323,635
Nine Months Ended
Beginning balance, prior to adoption of ASC 326	$	14,654		$	2,971		$	15,277		$	12,332		$	40,445		$	1,790		$	87,469
Impact of adoption ASC 326		14,075			2,797			8,267			48,990			139,624			26,785			240,538
Provision for credit losses		15,302			1,680			17,050			19,992			(22,990	)		(11,034	)		20,000
Charge-offs		(500	)		(62	)		(611	)		(676	)		(21,733	)		(3,529	)		(27,111	)
Recoveries		40			83			303			81			1,211			1,021			2,739
Net charge-offs		(460	)		21			(308	)		(595	)		(20,522	)		(2,508	)		(24,372	)
Balance September 30, 2020	$	43,571		$	7,469		$	40,286		$	80,719		$	136,557		$	15,033		$	323,635
Allowance for credit losses:
Three Months Ended
Balance June 30, 2019	$	15,886		$	3,816		$	14,383		$	12,166		$	39,177		$	1,578		$	87,006
Provision for credit losses		290			188			543			452			(763	)		970			1,100
Charge-offs		—			(294	)		-			—			(419	)		(1,024	)		(1,737	)
Recoveries		6			16			9			1			502			158			692
Net charge-offs		6			(278	)		9			1			83			(866	)		(1,045	)
Balance September 30, 2019	$	15,602		$	3,726		$	14,935		$	12,619		$	38,497		$	1,682		$	87,061
Nine Months Ended
Balance December 31, 2018	$	15,582		$	2,693		$	14,135		$	11,220		$	40,223		$	1,587		$	86,440
Provision for credit losses		21			(921	)		799			1,396			(918	)		2,223			2,600
Charge-offs		(63	)		(358	)		(22	)		—			(2,501	)		(2,821	)		(5,765	)
Recoveries		62			1,312			23			3			1,693			693			3,786
Net charge-offs		(1	)		954			1			3			(808	)		(2,128	)		(1,979	)
Balance September 30, 2019	$	15,602		$	3,726		$	14,935		$	12,619		$	38,497		$	1,682		$	87,061

The allowance for credit losses on loans as of September 30, 2020 totaled $323.6 million or 1.56% of total loans, including acquired loans with discounts, an increase of $236.2 million or 270.0% compared to the allowance for credit losses on loans totaling $87.5 million or 0.46% of total loans, including acquired loans with discounts, for December 31, 2019. The increase in allowance for credit losses was primarily due to $240.5 million related to the Company’s adoption of CECL. The increase in allowance for loan losses was additionally driven by the anticipated impact of the on-going novel strain of coronavirus disease (“COVID-19”) pandemic, elevated unemployment levels and other internal and external environment factors, which resulted in a provision for credit losses of $10.0 million and $20.0 million for the three and nine months ended September 30, 2020, respectively.  Net charge-offs were $10.6 and $24.4 million for the three and nine months ended September 30, 2020, respectively. Net charge-offs for the third quarter of 2020 included $8.6 million related to PCD loans that had specific reserves of $15.7 million, of which $8.6 million was allocated to the charge-offs and $7.1 million moved to the general reserve. Additionally, $6.1 million of specific reserves on resolved PCD loans was released to the general reserve without taking any charge-off. Net charge-offs for the nine months ended September 30, 2020 included

$21.0 million related to PCD loans that had specific reserves of $44.2 million, of which $21.0 million was allocated to the charge-offs and $23.2 million moved to the general reserve.

The Company actively participated in the Paycheck Protection Program (“PPP”), under the provisions of the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) during the second quarter of 2020. As of September 30, 2020, the Company had 11,948 PPP loans totaling $1.39 billion. The loans have two year terms, are fully guaranteed by the SBA, and do not carry an allowance.

Allowance for Credit Losses on Off-Balance Sheet Credit Exposures. The allowance for credit losses on off-balance sheet credit exposures estimates expected credit losses over the contractual period in which there is exposure to credit risk via a contractual obligation to extend credit, unless that obligation is unconditionally cancellable by the Company. The allowance is adjusted as a provision for credit loss expense. The estimate includes consideration of the likelihood that funding will occur and an estimate of expected credit losses on the commitments expected to fund. The estimate of commitments expected to fund is affected by historical analysis looking at utilization rates. The expected credit loss rates applied to the commitments expected to fund are affected by the general valuation allowance utilized for outstanding balances with the same underlying assumptions and drivers. As of September 30, 2020, the Company had $29.9 million in allowance for credit losses on off-balance sheet credit exposures, compared with $5.6 million as of December 31, 2019. The allowance for credit losses on off-balance sheet credit exposures is a separate line item on the Company’s consolidated balance sheet. As of September 30, 2020, the Company had $1.75 billion in commitments expected to fund.

Troubled Debt Restructurings. The restructuring of a loan is considered a “troubled debt restructuring” if both (1) the borrower is experiencing financial difficulties and (2) the creditor has granted a concession. Concessions may include interest rate reductions or below market interest rates, principal forgiveness, restructuring amortization schedules and other actions intended to minimize potential losses.  Under ASC Topic 310-40 “Receivables—Troubled Debt Restructurings by Creditors,” the Company evaluates all loan modifications to identify whether the restructuring constitutes a troubled debt restructuring. As of September 30, 2020 and 2019, the Company had $13.2 million and $14.3 million, respectively, in outstanding troubled debt restructurings.

The following table presents information regarding the recorded investment of loans that were modified as troubled debt restructurings during the nine months ended September 30, 2020 and 2019.

	Nine Months Ended
	September 30,
	2020						2019
	Number of Loans		Pre-Modification Outstanding Recorded Investment		Post-Modification Outstanding Recorded Investment		Number of Loans		Pre-Modification Outstanding Recorded Investment		Post-Modification Outstanding Recorded Investment
	(Dollars in thousands)
Troubled Debt Restructurings
Construction, land development and other land loans		—	$	—	$	—		—	$	—	$	—
Agriculture and agriculture real estate (includes farmland)		—		—		—		—		—		—
1-4 Family (includes home equity)		1		23		12		—		—		—
Commercial real estate (includes multi-family residential)		—		—		—		—		—		—
Commercial and industrial		—		—		—		2		14,993		14,188
Consumer and other		—		—		—		—		—		—
Total		1	$	23	$	12		2	$	14,993	$	14,188

As of September 30, 2020, there have been no defaults on any loans that were modified as troubled debt restructurings during the preceding twelve months. Default is determined at 90 or more days past due. The modifications generally relate to extending the amortization periods of the loans, which includes loans modified during bankruptcy.

For the nine months ended September 30, 2020, the Company added one loan totaling $23 thousand as a new troubled debt restructuring, of which $12 thousand remained outstanding at September 30, 2020. For the nine months ended September 30, 2019, the Company added two loans totaling $15.0 million as new troubled debt restructurings, of which $14.2 million remained outstanding at September 30, 2019. The Company did not grant principal reductions on any restructured loans at the time of modification. These modifications did not have a material impact on the Company’s determination of the allowance for credit losses.

Under the CARES Act, banks may elect to deem that loan modifications do not result in troubled debt restructurings if they are (1) related to COVID-19; (2) executed on a loan that was not more than 30 days past due as of December 31, 2019; and (3) executed between March 1, 2020, and the earlier of (A) 60 days after the date of termination of the COVID-19 national emergency declaration by the President of the United States or (B) December 31, 2020. Additionally, other short-term modifications made on a good faith basis in response to COVID-19 to borrowers who were current prior to any relief are not troubled debt restructurings under ASC Subtopic 310-40 and federal banking agencies’ interagency guidance. These modifications include short-term (e.g., up to six months) modifications such as payment deferrals, fee waivers, extensions of repayment terms, or delays in payment that are insignificant. Borrowers considered current are those that are less than 30 days past due on their contractual payments at the time a modification program is implemented. The Company's troubled debt restructurings noted above do not include loans that are short-term modifications related to COVID-19. 

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Fair Value

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value

6. FAIR VALUE

The Company uses fair value measurements to record fair value adjustments to certain assets and to determine fair value disclosures. Fair values represent the estimated price that would be received from selling an asset or paid to transfer a liability, otherwise known as an “exit price.” Securities available for sale are recorded at fair value on a recurring basis. Additionally, from time to time, the Company may be required to record at fair value other assets on a nonrecurring basis. These nonrecurring fair value adjustments typically involve application of lower-of-cost-or-market accounting or write downs of individual assets. ASC Topic 820, “Fair Value Measurements and Disclosures” establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows:

Fair Value Hierarchy

The Company groups financial assets and financial liabilities measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are:

• Level 1—Quoted prices in active markets for identical assets or liabilities.

• Level 2—Other significant observable inputs (including quoted prices in active markets for similar assets or liabilities) or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

• Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The fair value of an asset or liability is the price that would be received to sell that asset or paid to transfer that liability in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. In estimating fair value, the Company utilizes valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. Such valuation techniques are consistently applied. Inputs to valuation techniques include the assumptions that market participants would use in pricing an asset or liability.

The fair value disclosures below represent the Company’s estimates based on relevant market information and information about the financial instruments. Fair value estimates are based on judgments regarding current economic conditions, risk characteristics of the various instruments and other factors. These estimates are subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. Changes in the above methodologies and assumptions could significantly affect the estimates.

The following tables present fair values for assets and liabilities measured at fair value on a recurring basis:

	As of September 30, 2020
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets:
Available for sale securities:
Collateralized mortgage obligations	$	—	$	418,188	$	—	$	418,188
Mortgage-backed securities		—		42,927		—		42,927
Total	$	—	$	461,115	$	—	$	461,115
Derivative financial instruments:
Loan customer counterparty	$	—	$	13,510	$	—	$	13,510
Financial institution counterparty		—		—		—		—
Liabilities:
Derivative financial instruments:
Loan customer counterparty	$	—	$	—	$	—	$	—
Financial institution counterparty		—		13,510		—		13,510

	As of December 31, 2019
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets:
Available for sale securities:
States and political subdivisions	$	—	$	471	$	—	$	471
Collateralized mortgage obligations		—		235,773		—		235,773
Mortgage-backed securities		—		51,419		—		51,419
Total available for sale securities	$	—	$	287,663	$	—	$	287,663
Derivative financial instruments:
Interest rate lock commitments	$	—		305	$	—		305
Forward mortgage-backed securities trades		—		3		—		3
Loan customer counterparty		—		4,829		—		4,829
Financial institution counterparty		—		240		—		240
Liabilities:
Derivative financial instruments:
Interest rate lock commitments	$	—	$	—	$	—	$	—
Forward mortgage-backed securities trades		—		83		—		83
Loan customer counterparty		—		240		—		240
Financial institution counterparty		—		4,829		—		4,829

Certain assets and liabilities are measured at fair value on a nonrecurring basis; that is, the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances (for example, when there is evidence of impairment). These instruments include other real estate owned, repossessed assets, held to maturity debt securities, loans held for sale and impaired loans, which are included as loans held for investment.  For the three and nine months ended September 30, 2020, the Company had additions to other real estate owned of $7.4 million and $8.2 million, respectively, of which $6.2 million and $6.9 million, respectively, were outstanding as of September 30, 2020. For the three and nine months ended September 30, 2020, the Company had additions to impaired loans of $8.9 million and $26.3 million, respectively, of which $8.9 million and $13.0 million, respectively, were outstanding as of September 30, 2020. The remaining financial assets and liabilities measured at fair value on a non-recurring basis that were recorded in 2020 and remained outstanding at September 30, 2020 were not significant.

The following tables present carrying and fair value information of financial instruments as of the dates indicated:

	As of September 30, 2020
	Carrying		Estimated Fair Value
	Amount		Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets
Cash and due from banks	$	1,031,193	$	1,031,193	$	—	$	—	$	1,031,193
Federal funds sold		56,469		56,469		—		—		56,469
Held to maturity securities		6,970,380		—		7,145,837		—		7,145,837
Loans held for sale		51,694		—		51,694		—		51,694
Loans held for investment, net of allowance		17,689,698		—		—		17,704,208		17,704,208
Loans held for investment - Warehouse Purchase Program		2,730,614		—		2,730,614		—		2,730,614
Other real estate owned		11,548		—		11,548		—		11,548
Liabilities
Deposits:
Noninterest-bearing	$	8,998,328	$	—	$	8,998,328	$	—	$	8,998,328
Interest-bearing		17,460,878		—		17,485,431		—		17,485,431
Other borrowings		2,570		—		2,782		—		2,782
Securities sold under repurchase agreements		380,274		—		380,297		—		380,297
Subordinated notes		125,146		—		125,586		—		125,586

	As of December 31, 2019
	Carrying		Estimated Fair Value
	Amount		Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets
Cash and due from banks	$	573,589	$	573,589	$	—	$	—	$	573,589
Federal funds sold		519		519		—		—		519
Held to maturity securities		8,282,393		—		8,303,851		—		8,303,851
Loans held for sale		80,959		—		80,959		—		80,959
Loans held for investment, net of allowance		17,124,156		—		—		17,045,523		17,045,523
Loans held for investment - Warehouse Purchase Program		1,552,762		—		1,552,762		—		1,552,762
Other real estate owned		6,936		—		6,936		—		6,936
Liabilities
Deposits:
Noninterest-bearing	$	7,763,894	$	—	$	7,763,894	$	—	$	7,763,894
Interest-bearing		16,435,838		—		16,437,453		—		16,437,453
Other borrowings		1,303,730		—		1,303,941		—		1,303,941
Securities sold under repurchase agreements		377,294		—		377,302		—		377,302
Subordinated notes		125,804		—		125,743		—		125,743

The following is a description of the fair value estimates, methods and assumptions that are used by the Company in estimating the fair values of financial instruments.

Loans held for sale— Loans held for sale are carried at the lower of cost or estimated fair value. Fair value for consumer mortgages held for sale is based on commitments on hand from investors or prevailing market prices. As such, the Company classifies loans held for sale subjected to nonrecurring fair value adjustments as Level 2.

Loans held for investment— The Company does not record loans at fair value on a recurring basis. As such, valuation techniques discussed herein for loans are primarily for estimating fair value disclosures. The Company refined the calculation to estimate fair value for loans held for investment to be in accordance with ASU 2016-01. The refined discounted cash flow calculation to determine fair value considers internal and market-based information such as prepayment risk, cost of funds and liquidity. From time to time, the Company records nonrecurring fair value adjustments to impaired loans to reflect (1) partial write downs that are based on the observable market price or current appraised value of the collateral, or (2) the full charge-off of the loan carrying value.

Where appraisals are not available, estimated cash flows are discounted using a rate commensurate with the credit risk associated with those cash flows. Assumptions regarding credit risk, cash flows and discount rates are judgmentally determined using available market information and specific borrower information.

The Company classifies the estimated fair value of loans held for investment as Level 3.

Other real estate owned— Other real estate owned is primarily foreclosed properties securing residential loans and commercial real estate. Foreclosed assets are adjusted to fair value less estimated costs to sell upon transfer of the loans to other real estate owned. Subsequently, these assets are carried at the lower of carrying value or fair value less estimated costs to sell. Other real estate carried at fair value based on an observable market price or a current appraised value is classified by the Company as Level 2. When management determines that the fair value of other real estate requires additional adjustments, either as a result of a non-current appraisal or when there is no observable market price, the Company classifies the other real estate as Level 3.

The fair value estimates presented herein are based on pertinent information available to management at September 30, 2020. Although management is not aware of any factors that would significantly affect the estimated fair value amounts, such amounts have not been comprehensively revalued for purposes of these financial statements since those dates and, therefore, current estimates of fair value may differ significantly from the amounts presented herein.

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Goodwill and Core Deposit Intangibles

9 Months Ended

Sep. 30, 2020

Goodwill And Intangible Assets Disclosure [Abstract]

Goodwill and Core Deposit Intangibles

7. GOODWILL AND CORE DEPOSIT INTANGIBLES

Changes in the carrying amount of the Company’s goodwill and core deposit intangibles for the nine months ended September 30, 2020 and the year ended December 31, 2019 were as follows: 

	Goodwill		Core Deposit Intangibles
	(Dollars in thousands)
Balance as of December 31, 2018	$	1,900,845	$	32,883
Less:
Amortization		—		(6,537	)
Add:
LegacyTexas Merger		1,322,826		60,058
Balance as of December 31, 2019		3,223,671		86,404
Less:
Amortization		—		(9,926	)
Add:
Measurement period adjustment of LegacyTexas Merger		8,021		—
Balance as of September 30, 2020	$	3,231,692	$	76,478

Goodwill is recorded as of the acquisition date of each entity. The Company may record subsequent adjustments to goodwill for amounts undeterminable at acquisition date, such as deferred taxes and real estate valuations, and therefore the goodwill amounts may change accordingly. The Company initially records the total premium paid on acquisitions as goodwill. After finalizing the valuation, core deposit intangibles are identified and reclassified from goodwill to core deposit intangibles on the balance sheet. This reclassification has no effect on total assets, liabilities, shareholders’ equity, net income or cash flows. Management performs an evaluation annually, and more frequently if a triggering event occurs, of whether any impairment of the goodwill and core deposit intangibles has occurred. If any such impairment is determined, a write-down is recorded. As of September 30, 2020, there was no impairment recorded on goodwill and core deposit intangibles.

The measurement period for the Company to determine the fair value of acquired identifiable assets and assumed liabilities will be at the end of the earlier of (1) twelve months from the date of acquisition or (2) as soon as the Company receives the information it was seeking about facts and circumstances that existed as of the date of acquisition.

Core deposit intangibles are being amortized on a non-pro rata basis over their estimated lives, which the Company believes is between 10 and 15 years. Amortization expense related to intangible assets totaled $3.3 million and $1.2 million for the three months ended September 30, 2020 and 2019, respectively, and $9.9 million and $3.8 million for the nine months ended September 30, 2020 and 2019, respectively. The estimated aggregate future amortization expense for core deposit intangibles remaining as of September 30, 2020 is as follows (dollars in thousands):

Remaining 2020	$	3,243
2021		11,551
2022		10,336
2023		9,360
2024		8,699
Thereafter		33,289
Total	$	76,478

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Income Taxes

9 Months Ended

Sep. 30, 2020

Income Tax Disclosure [Abstract]

Income Taxes

8. INCOME TAXES

The amount of federal and state income tax expense is influenced by the amount of pre-tax income, the amount of tax-exempt income and the amount of other nondeductible expenses. Income tax expense totaled $35.1 million for the three months ended September 30, 2020 compared with $21.1 million for the same period in 2019, an increase of $13.9 million or 66.1%. The increase was primarily due the increase in pre-tax income related to the Merger. Income tax expense totaled $79.2 million for the nine months ended September 30, 2020 compared with $63.4 million for the same period in 2019, an increase of $15.8 million or 25.0%. The increase was primarily due to the increase in pre-tax income related to the Merger, partially offset by the tax benefit for net operating losses (“NOLs”) carryback of $20.1 million as a result of the CARES Act. The Company’s effective tax rate for the three months ended September 30, 2020 and 2019 was 21.2% and 20.5%, respectively. The Company’s effective tax rate for the nine months ended September 30, 2020 and 2019 was 16.8% and 20.5%, respectively.

In response to the COVID-19 pandemic, on March 27, 2020, the President of the United States signed the CARES Act into law. The CARES Act permits a five-year carryback period for NOLs, which allowed the Company to generate an anticipated tax refund and income tax benefit resulting from the tax rate differential between the current statutory tax rate of 21% and the 35% statutory tax rate in prior years during the carryback period. Pursuant to this provision of the CARES Act, the Company recorded a federal current benefit for taxes on income during the nine months ended September 30, 2020 due to the NOLs generated in 2019 by LegacyTexas that were used to offset taxable income generated between 2014 and 2017 taxed at 35% resulting in a tax benefit of $20.1 million, which is included in provision for income taxes in the accompanying condensed consolidated statements of income. This caused a reduction in the effective tax rate during the nine months ended September 30, 2020 as NOLs carried back to tax years 2014 through 2017 are applied at a federal tax rate of 35% applicable to those tax years, compared to a 21% tax rate effective at September 30, 2020. As a result, during the nine months ended September 30, 2020, the Company’s total deferred tax asset decreased by $31.9 million.

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Stock-Based Compensation

9 Months Ended

Sep. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

9. STOCK–BASED COMPENSATION

At September 30, 2020, the Company had two stock-based employee compensation plans with awards outstanding.

On March 3, 2020, Bancshares’ Board of Directors established the Prosperity Bancshares, Inc. 2020 Stock Incentive Plan (the “2020 Plan”), subject to approval by the Company’s shareholders. The Company’s shareholders approved the 2020 Plan at the annual meeting of shareholders on April 21, 2020. The 2020 Plan authorizes the issuance of up to 2,500,000 shares of common stock upon the exercise of options or pursuant to the grant or exercise, as the case may be, of other awards granted under the 2020 Plan, including incentive stock options, nonqualified stock options, stock appreciation rights, shares of restricted stock and restricted stock units. As of September 30, 2020, 12,500 shares of unvested restricted stock have been granted under the 2020 Plan.

During 2012, Bancshares’ Board of Directors established the Prosperity Bancshares, Inc. 2012 Stock Incentive Plan (the “2012 Plan”), which was approved by Bancshares’ shareholders and authorized the issuance of up to 1,250,000 shares of common stock upon the exercise of options granted under the 2012 Plan or pursuant to the grant or exercise, as the case may be, of other awards granted under the 2012 Plan, including restricted stock, stock appreciation rights, phantom stock awards and performance awards. As of September 30, 2020, 370,313 shares of common stock had been issued pursuant to vested awards and 489,312 shares of unvested restricted stock had been granted under the 2012 Plan prior to the adoption of the 2020 Plan by the Company’s shareholders. The Company does not plan to make any further awards pursuant to the 2012 Plan.

As of September 30, 2020, the Company had no stock options outstanding. Stock-based compensation expense related to restricted stock was $3.2 million and $2.5 million during the three months ended September 30, 2020 and 2019, respectively, and

$9.5  million and $7.6 million during the nine months ended September 30, 2020 and 2019. As of September 30, 2020, there was $8.9  million of total unrecognized compensation expense related to stock-based compensation arrangements. That cost is expected to be recognized over a weighted average period of 1.90 years.

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Contractual Obligations and Off-Balance Sheet Items

9 Months Ended

Sep. 30, 2020

Commitments And Contingencies Disclosure [Abstract]

Contractual Obligations and Off-Balance Sheet Items

10. CONTRACTUAL OBLIGATIONS AND OFF-BALANCE SHEET ITEMS

Contractual Obligations

The Company’s contractual obligations and other commitments to make future payments as of September 30, 2020 (other than deposit obligations and securities sold under repurchase agreements) are summarized below. The Company’s future cash payments associated with its contractual obligations pursuant to its subordinated notes and Federal Home Loan Bank (“FHLB”) advances and notes payable as of September 30, 2020 are summarized below. The future interest payments were calculated using the current rate in effect at September 30, 2020. In September 2020, the Company gave irrevocable notice of its intent to redeem the outstanding subordinated notes on December 1, 2020. The $125.1 million outstanding balance of the subordinated notes and all accrued interest payable upon redemption is included in the “1 year or less” column below. Payments for the subordinated notes include interest of $1.1 million. Payments for FHLB notes payable include interest of $205 thousand that will be paid over the future periods. The payments do not include pre-payment options that may be available to the Company.

	1 year or less		More than 1 year but less than 3 years		3 years or more but less than 5 years		5 years or more		Total
	(Dollars in thousands)
Subordinated notes	$	126,292	$	—	$	—	$	—	$	126,292
Federal Home Loan Bank advances and notes payable		974		1,067		366		18		2,425
Total	$	127,266	$	1,067	$	366	$	18	$	128,717

Leases

The Company’s leases relate primarily to operating leases for office space and banking centers. The Company determines if an arrangement is a lease or contains a lease at inception. The Company’s leases have remaining lease terms of 1 to 18 years, which may include the option to extend the lease when it is reasonably certain for the Company to exercise that option. Operating lease right-of-use (ROU) assets and liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. The Company uses its incremental collateralized borrowing rate to determine the present value of lease payments. Short-term leases and leases with variable lease costs are immaterial and the Company does not have any sublease arrangements. As of September 30, 2020, operating lease ROU assets and lease liabilities were approximately $54.0 million. ROU assets and lease liabilities were classified as other assets and other liabilities, respectively.

As of September 30, 2020, the weighted average remaining lease terms of the Company’s operating leases were 7.4 years. The weighted average discount rate used to determine the lease liabilities as of September 30, 2020 for the Company’s operating leases was 2.34%. Cash paid for the Company’s operating leases for the three months ended September 30, 2020 and 2019 was $3.3 million and $1.4 million, respectively. Cash paid for the Company’s operating leases for the nine months ended September 30, 2020 and 2019 was $10.5 million and $4.2 million, respectively. The Company obtained $5.6 million in ROU assets in exchange for lease liabilities for four operating leases during the nine months ended September 30, 2020.

The Company’s future undiscounted cash payments associated with its operating leases as of September 30, 2020 are summarized below (dollars in thousands).

Remaining 2020	$	2,637
2021		10,196
2022		9,671
2023		8,922
2024		8,042
2025		7,651
Thereafter		19,383
Total undiscounted lease payments	$	66,502

The following table presents a summary of non-cancelable future operating lease commitments as of December 31, 2019 (dollars in thousands):

2020	$	10,137
2021		9,169
2022		8,641
2023		7,998
2024		7,119
Thereafter		24,996
Total non-cancelable lease payments	$	68,060

Off-Balance Sheet Items

In the normal course of business, the Company enters into various transactions that, in accordance with GAAP, are not included in its consolidated balance sheets. The Company enters into these transactions to meet the financing needs of its customers. These transactions include commitments to extend credit and standby letters of credit, which involve, to varying degrees, elements of credit risk and interest rate risk in excess of the amounts recognized in the consolidated balance sheets.

The Company’s commitments associated with outstanding standby letters of credit, unused capacity on Warehouse Purchase Program loans and commitments to extend credit expiring by period as of September 30, 2020 are summarized below. Since commitments associated with letters of credit, unused capacity of Warehouse Purchase Program loans, allowance for credit losses on off-balance sheet credit exposures and commitments to extend credit may expire unused, the amounts shown do not necessarily reflect the actual future cash funding requirements.

	1 year or less		More than 1 year but less than 3 years		3 years or more but less than 5 years		5 years or more		Total
	(Dollars in thousands)
Standby letters of credit	$	104,896	$	6,616	$	1,337	$	—	$	112,849
Unused capacity on Warehouse Purchase Program loans		803,386		—		—		—		803,386
Commitments to extend credit		1,743,194		852,081		342,756		1,245,988		4,184,019
Total	$	2,651,476	$	858,697	$	344,093	$	1,245,988	$	5,100,254

The Company funds an allowance for credit losses on off-balance sheet lending-related commitments and guarantees on credit card debt through a charge to provision for credit losses on the Company’s consolidated statement of income. At September 30, 2020 and December 31, 2019, this allowance for credit losses on off-balance sheet lending-related commitments and guarantees on credit card debt, included in “Allowance for credit losses on off-balance sheet credit exposures” on the Company’s consolidated balance sheet, totaled $29.9 million and $5.6 million, respectively.

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Other Comprehensive Income

9 Months Ended

Sep. 30, 2020

Equity [Abstract]

Other Comprehensive Income

11. OTHER COMPREHENSIVE INCOME

The tax effects allocated to each component of other comprehensive income were as follows:

	Three Months Ended September 30,
	2020							2019
	Before Tax Amount		Tax Effect			Net of Tax Amount		Before Tax Amount			Tax Effect		Net of Tax Amount
	(Dollars in thousands)
Other comprehensive income (loss):
Securities available for sale:
Change in unrealized gain (loss) during period	$	1,325	$	(278	)	$	1,047	$	(1,563	)	$	328	$	(1,235	)
Total securities available for sale		1,325		(278	)		1,047		(1,563	)		328		(1,235	)
Total other comprehensive income (loss)	$	1,325	$	(278	)	$	1,047	$	(1,563	)	$	328	$	(1,235	)

	Nine Months Ended September 30,
	2020								2019
	Before Tax Amount			Tax Effect		Net of Tax Amount			Before Tax Amount			Tax Effect		Net of Tax Amount
	(Dollars in thousands)
Other comprehensive loss:
Securities available for sale:
Change in unrealized loss during period	$	(1,204	)	$	253	$	(951	)	$	(344	)	$	72	$	(272	)
Total securities available for sale		(1,204	)		253		(951	)		(344	)		72		(272	)
Total other comprehensive loss	$	(1,204	)	$	253	$	(951	)	$	(344	)	$	72	$	(272	)

Activity in accumulated other comprehensive income associated with securities available for sale, net of tax, was as follows:

	Securities Available for Sale			Accumulated Other Comprehensive Income (Loss)
	(Dollars in thousands)
Balance at December 31, 2019	$	602		$	602
Other comprehensive loss		(951	)		(951	)
Balance at September 30, 2020	$	(349	)	$	(349	)
Balance at December 31, 2018	$	310		$	310
Other comprehensive loss		(272	)		(272	)
Balance at September 30, 2019	$	38		$	38

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Derivative Financial Instruments

9 Months Ended

Sep. 30, 2020

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Derivative Financial Instruments

12. DERIVATIVE FINANCIAL INSTRUMENTS

The following table provides the outstanding notional balances and fair values of outstanding derivative positions at September 30, 2020 and December 31, 2019.

	September 30, 2020						December 31, 2019
	Outstanding Notional Balance		Asset Derivative Fair Value		Liability Derivative Fair Value		Outstanding Notional Balance		Asset Derivative Fair Value		Liability Derivative Fair Value
	(Dollars in thousands)
Interest rate lock commitments	$	—	$	—	$	—	$	9,438	$	305	$	—
Forward mortgage-backed securities trades		—		—		—		40,750		3		83
Commercial loan interest rate swaps and caps:
Loan customer counterparty		224,928		13,510		—		231,345		4,829		240
Financial institution counterparty		224,928		—		13,510		231,345		240		4,829

These financial instruments are not designated as hedging instruments and are used for asset and liability management and commercial customers’ financing needs. All derivatives are carried at fair value in either other assets or other liabilities.

Interest rate lock commitments (“IRLCs”) — In the normal course of business, the Company enters into interest rate lock commitments with consumers to originate mortgage loans at a specified interest rate. These commitments, which contain fixed expiration dates, offer the borrower an interest rate guarantee provided the loan meets underwriting guidelines and closes within the timeframe established by the Company.

Forward mortgage-backed securities trades — The Company manages the changes in fair value associated with changes in interest rates related to IRLCs by using forward sold commitments known as forward mortgage-backed securities trades. These instruments are typically entered into at the time the interest rate lock commitment is made.

Interest rate swaps and caps — These derivative positions relate to transactions in which the Company enters into an interest rate swap or cap with a customer, while at the same time entering into an offsetting interest rate swap or cap with another financial institution. An interest rate swap transaction allows the Company’s customer to effectively convert a variable rate loan to a fixed rate.

In connection with each swap, the Company agrees to pay interest to the customer on a notional amount at a variable interest rate and receive interest from the customer on a similar notional amount at a fixed interest rate. At the same time, the Company agrees to pay another financial institution the same fixed interest rate on the same notional amount and receive the same variable interest rate on the same notional amount. In connection with each interest rate cap, the Company sells a cap to the customer and agrees to pay interest if the underlying index exceeds the strike price defined in the cap agreement. Simultaneously the Company purchases a cap with matching terms from another financial institution that agrees to pay the Company if the underlying index exceeds the strike price.

The commercial loan customer counterparty weighted average received and paid interest rates for interest rate swaps outstanding at September 30, 2020 and December 31, 2019 are presented in the following table.

	Weighted-Average Interest Rate
	September 30, 2020						December 31, 2019
	Received			Paid			Received			Paid
Loan customer counterparty		0.58	%		2.83	%		3.42	%		2.86	%

The Company’s credit exposure on interest rate swaps is limited to the net favorable value of all swaps by each counterparty, which was approximately $13.5 million at September 30, 2020 and $4.8 million at December 31, 2019. This credit exposure is partly mitigated as transactions with customers are secured by the collateral, if any, securing the underlying transaction being hedged. The Company’s credit exposure, net of collateral pledged, relating to interest rate swaps with upstream financial institution counter-parties was zero at September 30, 2020. A credit support annex is in place and allows the Company to call collateral from upstream financial institution counter-parties. Collateral levels are monitored and adjusted on a regular basis for changes in interest rate swap values. The Company’s cash collateral pledged for interest rate swaps was $15.3 million at September 30, 2020 and $9.3 million at December 31, 2019.

The initial and subsequent changes in the fair value of IRLCs and the forward sales of mortgage-backed securities are recorded in net gain on sale of mortgage loans. These gains and losses were not attributable to instrument-specific credit risk. For interest rate swaps and caps, because the Company acts as an intermediary for its customer, changes in the fair value of the underlying derivative contracts substantially offset each other and do not have a material impact on its results of operations. Income (loss) for the three and nine months ended September 30, 2020 and 2019 was as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
Derivatives not designated as hedging instruments	2020		2019		2020			2019
	(Dollars in thousands)
Interest rate lock commitments	$	—	$	—	$	(305	)	$	—
Forward mortgage-backed securities trades		—		—		(2,398	)		—

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Acquisitions

9 Months Ended

Sep. 30, 2020

Business Combinations [Abstract]

Acquisitions

13. ACQUISITIONS

Acquisitions are an integral part of the Company’s growth strategy. All acquisitions were accounted for using the acquisition method of accounting. Accordingly, the assets and liabilities of the acquired entities were recorded at their fair values at the acquisition date. The excess of the purchase price over the estimated fair value of the net assets for tax-free acquisitions was recorded as goodwill, none of which is deductible for tax purposes. The excess of the purchase price over the estimated fair value of the net assets for taxable acquisitions was also recorded as goodwill, and is deductible for tax purposes. The identified core deposit intangibles for each acquisition are being amortized using a non-pro rata basis over an estimated life of 10 to 15 years. The results of operations for each acquisition have been included in the Company’s consolidated financial results beginning on the respective acquisition date.

The measurement period for the Company to determine the fair values of acquired identifiable assets and assumed liabilities will end at the earlier of (1) twelve months from the date of the acquisition or (2) as soon as the Company receives the information it is seeking about facts and circumstances that existed as of the acquisition date or learns that more information is not obtainable. The following acquisitions were completed on the dates indicated:

2019 Acquisition

Merger with LegacyTexas Financial Group, Inc. — On November 1, 2019, LegacyTexas Financial Group, Inc. merged into Prosperity Bancshares and LegacyTexas Bank merged into the Bank. LegacyTexas was headquartered in Plano, Texas and operated 42 locations in 19 North Texas cities in and around the Dallas-Fort Worth area. As of September 30, 2019, LegacyTexas, on a consolidated basis, reported total assets of $10.5 billion, total gross loans of $9.1 billion, total deposits of $6.5 billion and shareholders’ equity of $1.2 billion.

Pursuant to the terms of the merger agreement, Bancshares issued 26,228,148 shares of Bancshares common stock, with a closing price of $69.02 per share on November 1, 2019, plus $318.0 million in cash, comprised of $308.6 million in cash and $9.4 million in cash for taxes withheld, for all outstanding shares of LegacyTexas.

The assets and liabilities of LegacyTexas were recorded on the consolidated balance sheet at estimated fair value on the acquisition date. As of September 30, 2020, the following table presents the amounts recorded on the consolidated balance sheet on the acquisition date (dollars in thousands).

	Initially Recorded at Acquisition Date		Measurement Period Adjustments			Adjusted Values as of September 30, 2020
Fair value of consideration paid:
Common stock issued (26,228,148 shares)	$	1,810,267	$	—		$	1,810,267
Cash		318,018		—			318,018
Total consideration paid	$	2,128,285	$	—		$	2,128,285
Fair value of assets acquired:
Cash and due from banks	$	228,649	$	—		$	228,649
Securities held to maturity		472,933		—			472,933
Loans held for sale		60,818		—			60,818
Loans held for investment		6,771,080		—			6,771,080
Loans held for investment - Warehouse Purchase Program		1,693,049		—			1,693,049
Bank premises and equipment		67,347		(1,299	)		66,048
Other real estate owned		4,876		—			4,876
Core deposit intangibles		60,058		—			60,058
Federal Home Loan Bank stock		117,939		(113	)		117,826
Bank owned life insurance and other assets		242,592		(7,125	)		235,467
Total assets acquired		9,719,341		(8,537	)		9,710,804
Fair value of liabilities assumed:
Deposits		6,434,732		—			6,434,732
Other borrowings		2,078,682		—			2,078,682
Securities sold under repurchase agreements		57,670		—			57,670
Trust preferred securities		15,376		—			15,376
Subordinated notes		125,950		—			125,950
Other liabilities		201,472		(516	)		200,956
Total liabilities assumed		8,913,882		(516	)		8,913,366
Fair value of net assets acquired	$	805,459	$	(8,021	)	$	797,438
Goodwill resulting from acquisition	$	1,322,826	$	8,021		$	1,330,847

The measurement period adjustments noted in the table above were a result of information obtained subsequent to the Company’s initial reporting of provisional fair values but prior to finalizing the fair values in accordance with ASC 805, Business Combinations. Such information was determined to be a condition in existence as of acquisition date.

As of September 30, 2020, the Company recognized goodwill of $1.33 billion, which is subject to subsequent fair value adjustments. Goodwill represents the excess of the total purchase price paid over the fair value of the assets acquired, net of the fair value of liabilities assumed. The goodwill is not deductible for tax purposes. Additionally, as of September 30, 2020, total core deposit intangibles related to LegacyTexas were $52.1 million.

Merger Related Expenses: The Company incurred zero and $8.0 million of pre-tax merger related expenses during the three and nine months ended September 30, 2020, respectively. The Company incurred $46.4 million of pre-tax merger related expenses during the year ended December 31, 2019. The merger related expenses are reflected on the Company’s income statement for the applicable periods under “Merger related expenses” and consist of salaries and benefits, data processing and professional and legal fees.

Pro Forma Information: Operations of LegacyTexas have been included in the consolidated financial statements since November 1, 2019.

The following pro forma information presents the results of operations for the three and nine months ended September 30, 2019, as if the Merger had occurred on January 1, 2019 (dollars in thousands, except per share amounts).

	Three Months Ended September 30, 2019		Nine Months Ended September 30, 2019
Net interest income	$	259,730	$	768,548
Net income		140,400		367,677
Basic earnings per share		1.47		3.85
Diluted earnings per share		1.47		3.85

The above pro forma results are presented for illustrative purposes and are not intended to represent or be indicative of the actual results of operations of the merged companies that would have been achieved had the Merger occurred on January 1, 2019, nor are they intended to represent or be indicative of future results of operations. The pro forma results do not include expected operating cost savings as a result of the acquisition. These pro forma results require significant estimates and judgments particularly as they relate to valuation and accretion of income associated with acquired loans. Pro forma adjustments principally included:

• Reversing interest income and interest expense as previously recorded by LegacyTexas and recording interest income and interest expense based on impact of estimated fair values of the acquired interest-earning assets and assumed interest-bearing liabilities;

• Reversing core deposit intangible amortization as previously recorded by LegacyTexas and recording amortization expense as it relates to the core deposit intangible recognized from the acquisition; and

• Reporting merger related expenses as if they were incurred on January 1, 2019.

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New Accounting Standards (Policies)

9 Months Ended

Sep. 30, 2020

New Accounting Pronouncements And Changes In Accounting Principles [Abstract]

Accounting Standards Updates (''ASU'')

Accounting Standards Updates (“ASU”)

ASU 2020-04, "Reference Rate Reform: Facilitation of the Effects of Reference Rate Reform on Financial Reporting - Accounting Standards Codification (“ASC”) Topic 848." ASU 2020-04 provides optional expedients and exceptions for applying GAAP to loan and lease agreements, derivative contracts, and other transactions affected by the anticipated transition away from LIBOR toward new interest rate benchmarks. The guidance allows for companies to: (i) account for certain contract modifications as a continuation of the existing contract without additional analysis; (ii) continue hedge accounting when certain critical terms of a hedging relationship change and assess effectiveness in ways that disregard certain potential sources of ineffectiveness; and (iii) make a one-time sale and/or transfer of certain debt securities from held-to-maturity to available-for-sale or trading. This ASU is available for adoption effective March 12, 2020 through December 31, 2022. An entity may elect to apply ASU 2020-04 for contract modifications as of January 1, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic within ASU 2020-04, the amendments must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The one-time election to sell and/or transfer debt securities classified as held-to-maturity may be made at any time after March 12, 2020. The Company anticipates this ASU will simplify any modifications it executes between the selected start date (yet to be determined) and December 31, 2022 that are directly related to the LIBOR transition by allowing prospective recognition of the continuation of the contract, rather than extinguishment of the old contract resulting in writing off unamortized fees and costs. ASU 2020-04 is not expected to have a significant impact on the Company’s financial statements.

ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326)—Measurement of Credit Losses on Financial Instruments (“ASC 326”).” On January 1, 2020, the Company adopted ASU 2016-13 which replaces the incurred loss methodology with an expected loss methodology that is referred to as the current expected credit loss (“CECL”) methodology. CECL requires a financial asset (or a group of financial assets) measured at amortized cost basis to be presented at the net amount expected to be collected. The measurement of CECL is based on relevant information about past events including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount.

The Company adopted ASU 2016-13 using the modified-retrospective method for all financial assets measured at amortized cost and off-balance sheet credit exposures. Reporting periods beginning after January 1, 2020 are presented under ASC 326 while prior periods are reported with previously applicable GAAP. Upon adoption of ASU 2016-13, the Company recognized an increase in allowance for credit losses for loans of $108.7 million, of which $102.5 million was related to LegacyTexas Financial Group, Inc. (“LegacyTexas”), which merged into Bancshares on November 1, 2019, and an increase in allowance for credit losses for off-balance sheet credit exposures of $24.4 million, of which $6.3 million was related to LegacyTexas, with a corresponding decrease in retained earnings (pre-tax). Additionally, the Company adopted ASU 2016-13 using the prospective transition approach for financial assets purchased with credit deterioration. The Company recognized an increase in the allowance for credit losses for loans of $131.8 million, of which $130.3 million was related to LegacyTexas, due to the reclass of purchased credit deteriorated discounts as the result of adopting ASU 2016-13. See Note 5 “Loans and Allowance for Credit Losses” for additional information. The Company recognized no allowance for credit losses related to debt securities. See Note 4 “Securities” for additional information.

The following table illustrates the impact of adopting ASU 2016-13:

	January 1, 2020
	As Reported Under ASC 326		Pre-ASC 326 Adoption		Impact of ASC 326 Adoption
	(Dollars in thousands)
Assets:
Loans
Construction, land development and other land loans	$	28,729	$	14,654	$	14,075
Agriculture and agriculture real estate (includes farmland)		5,768		2,971		2,797
1-4 family (includes home equity)		23,544		15,277		8,267
Commercial real estate (includes multi-family residential)		61,322		12,332		48,990
Commercial and industrial		180,069		40,445		139,624
Consumer and other		28,575		1,790		26,785
Allowance for credit losses on loans	$	328,007	$	87,469	$	240,538
Liabilities:
Allowance for credit losses on off-balance sheet credit exposures	$	29,947	$	5,599	$	24,348

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Income Per Common Share (Tables)

9 Months Ended

Sep. 30, 2020

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The following table illustrates the computation of basic and diluted earnings per share:

	Three Months Ended September 30,								Nine Months Ended September 30,
	2020				2019				2020				2019
	Amount		Per Share Amount		Amount		Per Share Amount		Amount		Per Share Amount		Amount		Per Share Amount
	(Amounts in thousands, except per share data)
Net income	$	130,064			$	81,758			$	391,813			$	246,418
Basic:
Weighted average shares outstanding		92,656	$	1.40		68,738	$	1.19		93,226	$	4.20		69,463	$	3.55
Diluted:
Weighted average shares outstanding		92,656	$	1.40		68,738	$	1.19		93,226	$	4.20		69,463	$	3.55

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New Accounting Standards (Tables)

9 Months Ended

Sep. 30, 2020

New Accounting Pronouncements And Changes In Accounting Principles [Abstract]

Schedule of Impact of Adopting ASU 2016-13

The following table illustrates the impact of adopting ASU 2016-13:

	January 1, 2020
	As Reported Under ASC 326		Pre-ASC 326 Adoption		Impact of ASC 326 Adoption
	(Dollars in thousands)
Assets:
Loans
Construction, land development and other land loans	$	28,729	$	14,654	$	14,075
Agriculture and agriculture real estate (includes farmland)		5,768		2,971		2,797
1-4 family (includes home equity)		23,544		15,277		8,267
Commercial real estate (includes multi-family residential)		61,322		12,332		48,990
Commercial and industrial		180,069		40,445		139,624
Consumer and other		28,575		1,790		26,785
Allowance for credit losses on loans	$	328,007	$	87,469	$	240,538
Liabilities:
Allowance for credit losses on off-balance sheet credit exposures	$	29,947	$	5,599	$	24,348

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Securities (Tables)

9 Months Ended

Sep. 30, 2020

Investments Debt And Equity Securities [Abstract]

Schedule of Amortized Cost and Fair Value of Investment Securities

The amortized cost and fair value of investment securities were as follows:

	September 30, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
Collateralized mortgage obligations	$	418,575	$	138	$	(525	)	$	418,188
Mortgage-backed securities		42,982		570		(625	)		42,927
Total	$	461,557	$	708	$	(1,150	)	$	461,115
Held to Maturity
U.S. Treasury securities and obligations of U.S. Government agencies	$	3,989	$	25	$	—		$	4,014
States and political subdivisions		170,427		9,288		(187	)		179,528
Collateralized mortgage obligations		123,309		2,080		(256	)		125,133
Mortgage-backed securities		6,672,655		165,665		(1,158	)		6,837,162
Total	$	6,970,380	$	177,058	$	(1,601	)	$	7,145,837

	December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	470	$	1	$	—		$	471
Collateralized mortgage obligations		235,222		690		(139	)		235,773
Mortgage-backed securities		51,209		659		(449	)		51,419
Total	$	286,901	$	1,350	$	(588	)	$	287,663
Held to Maturity
U.S. Treasury securities and obligations of U.S. Government agencies	$	13,933	$	58	$	—		$	13,991
States and political subdivisions		238,347		7,632		(189	)		245,790
Collateralized mortgage obligations		203,470		1,115		(373	)		204,212
Mortgage-backed securities		7,826,643		48,060		(34,845	)		7,839,858
Total	$	8,282,393	$	56,865	$	(35,407	)	$	8,303,851

Securities in Continuous Loss Position

Securities with unrealized losses, segregated by length of time, that have been in a continuous loss position were as follows:

	September 30, 2020
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
	(Dollars in thousands)
Available for Sale
Collateralized mortgage obligations	$	188,671	$	(515	)	$	1,886	$	(10	)	$	190,557	$	(525	)
Mortgage-backed securities		16,298		(365	)		12,815		(260	)		29,113		(625	)
Total	$	204,969	$	(880	)	$	14,701	$	(270	)	$	219,670	$	(1,150	)
Held to Maturity
States and political subdivisions	$	1,689	$	(187	)	$	—	$	—		$	1,689	$	(187	)
Collateralized mortgage obligations		33,507		(256	)		—		—			33,507		(256	)
Mortgage-backed securities		118,159		(858	)		19,716		(300	)		137,875		(1,158	)
Total	$	153,355	$	(1,301	)	$	19,716	$	(300	)	$	173,071	$	(1,601	)

	December 31, 2019
	Less than 12 Months					12 Months or More					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
	(Dollars in thousands)
Available for Sale
Collateralized mortgage obligations	$	50,245	$	(136	)	$	1,818	$	(3	)	$	52,063	$	(139	)
Mortgage-backed securities		34,901		(449	)		10		—			34,911		(449	)
Total	$	85,146	$	(585	)	$	1,828	$	(3	)	$	86,974	$	(588	)
Held to Maturity
States and political subdivisions	$	58,329	$	(183	)	$	3,241	$	(6	)	$	61,570	$	(189	)
Collateralized mortgage obligations		54,890		(373	)		—		—			54,890		(373	)
Mortgage-backed securities		947,314		(3,017	)		3,110,765		(31,828	)		4,058,079		(34,845	)
Total	$	1,060,533	$	(3,573	)	$	3,114,006	$	(31,834	)	$	4,174,539	$	(35,407	)

Investment Securities by Contractual Maturity

The amortized cost and fair value of investment securities at September 30, 2020, by contractual maturity, are shown below. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations at any time with or without call or prepayment penalties.

	Held to Maturity				Available for Sale
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
Due in one year or less	$	26,715	$	26,744	$	—	$	—
Due after one year through five years		96,287		101,719		—		—
Due after five years through ten years		44,637		48,053		—		—
Due after ten years		6,777		7,026		—		—
Subtotal		174,416		183,542		—		—
Mortgage-backed securities and collateralized mortgage obligations		6,795,964		6,962,295		461,557		461,115
Total	$	6,970,380	$	7,145,837	$	461,557	$	461,115

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Loans and Allowance for Credit Losses (Tables)

9 Months Ended

Sep. 30, 2020

Receivables [Abstract]

Types of Loans in Loan Portfolio

The loan portfolio consists of various types of loans and is categorized by major type as follows:

	September 30, 2020		December 31, 2019
	(Dollars in thousands)
Residential mortgage loans held for sale	$	51,694	$	80,959
Commercial and industrial		4,150,189		3,205,595
Real estate:
Construction, land development and other land loans		2,081,762		2,064,167
1-4 family residential (includes home equity)		4,615,710		4,306,452
Commercial real estate (includes multi-family residential)		6,179,901		6,556,285
Farmland		419,126		495,558
Agriculture		179,846		185,297
Consumer and other		386,799		398,271
Total loans held for investment, excluding Warehouse Purchase Program		18,013,333		17,211,625
Warehouse Purchase Program		2,730,614		1,552,762
Total loans, including Warehouse Purchase Program	$	20,795,641	$	18,845,346

Related Party Loans

An analysis of activity with respect to these related party loans is as follows:

	As of and for the nine months ended September 30, 2020			As of and for the year ended December 31, 2019
	(Dollars in thousands)
Beginning balance on January 1	$	4,152		$	1,923
New loans		813			1
Transfers		—			2,500
Repayments		(3,134	)		(272	)
Ending balance	$	1,831		$	4,152

Aging Analysis of Past Due Loans

An aging analysis of past due loans, segregated by category of loan, is presented below:

	September 30, 2020
	Loans Past Due and Still Accruing
	30-89 Days		90 or More Days		Total Past Due Loans		Nonaccrual Loans		Current Loans		Total Loans
	(Dollars in thousands)
Construction, land development and other land loans	$	24,592	$	422	$	25,014	$	2,211	$	2,054,537	$	2,081,762
Warehouse Purchase Program loans		—		—		—		—		2,730,614		2,730,614
Agriculture and agriculture real estate (includes farmland)		30		—		30		1,200		597,742		598,972
1-4 family (includes home equity) (1)		6,160		40		6,200		23,769		4,637,435		4,667,404
Commercial real estate (includes multi-family residential)		2,758		—		2,758		11,486		6,165,657		6,179,901
Commercial and industrial		4,958		—		4,958		17,153		4,128,078		4,150,189
Consumer and other		529		—		529		1,593		384,677		386,799
Total	$	39,027	$	462	$	39,489	$	57,412	$	20,698,740	$	20,795,641

	December 31, 2019
	Loans Past Due and Still Accruing
	30-89 Days		90 or More Days		Total Past Due Loans		Nonaccrual Loans		Current Loans		Total Loans
	(Dollars in thousands)
Construction, land development and other land loans	$	16,470	$	—	$	16,470	$	1,142	$	2,046,555	$	2,064,167
Warehouse Purchase Program loans		—		—		—		—		1,552,762		1,552,762
Agriculture and agriculture real estate (includes farmland)		466		—		466		103		680,286		680,855
1-4 family (includes home equity) (1)		43,884		441		44,325		24,413		4,318,673		4,387,411
Commercial real estate (includes multi-family residential)		10,669		—		10,669		12,714		6,532,902		6,556,285
Commercial and industrial		7,249		—		7,249		16,809		3,181,537		3,205,595
Consumer and other		1,708		—		1,708		62		396,501		398,271
Total	$	80,446	$	441	$	80,887	$	55,243	$	18,709,216	$	18,845,346

(1) Includes $51.7 million and $81.0 million of residential mortgage loans held for sale at September 30, 2020 and December 31, 2019, respectively.

Non-performing Assets

The following table presents information regarding nonperforming assets as of the dates indicated:

	September 30, 2020			December 31, 2019
	(Dollars in thousands)
Nonaccrual loans (1) (2)	$	57,412		$	55,243
Accruing loans 90 or more days past due		462			441
Total nonperforming loans		57,874			55,684
Repossessed assets		120			323
Other real estate		11,548			6,936
Total nonperforming assets	$	69,542		$	62,943
Nonperforming assets to total loans and other real estate		0.33	%		0.33	%
Nonperforming assets to total loans, excluding Warehouse Purchase Program loans, and other real estate		0.38	%		0.36	%

(1) Includes troubled debt restructurings of $13.2 million and $13.6 million as of September 30, 2020 and December 31, 2019, respectively.

(2) There were no nonperforming or troubled debt restructurings of warehouse lines of credit or Warehouse Purchase Program loans for the periods presented.

Recorded Investment and Outstanding Balance for Purchased Credit Deteriorated Loans and Non Purchased Credit Deteriorated Loans

The recorded investment in PCD loans included in the consolidated balance sheet and the related outstanding balance as of the dates indicated are presented in the table below. The outstanding balance represents the total amount owed as of September 30, 2020 and December 31, 2019.

	September 30, 2020			December 31, 2019
	(Dollars in thousands)
PCD loans:
Outstanding balance	$	226,080		$	410,785
Discount (1)		(16,760	)		(167,320	)	(2)
Recorded investment	$	209,320		$	243,465

(1) ASU 2016-13 became effective for the Company on January 1, 2020.

(2) Includes $131.8 million in PCD loans credit discount.

The recorded investment in Non-PCD loans included in the consolidated balance sheet and the related outstanding balance as of the dates indicated are presented in the table below. The outstanding balance represents the total amount owed as of September 30, 2020 and December 31, 2019.

	September 30, 2020			December 31, 2019
	(Dollars in thousands)
Non-PCD loans:
Outstanding balance	$	4,468,843		$	6,102,540
Discount		(53,115	)		(110,130	)
Recorded investment	$	4,415,728		$	5,992,410

Summary of Changes in Accretable Yields of Acquired Loans

Changes in the accretable yield for acquired PCD loans for the three and nine months ended September 30, 2020 and 2019 were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
	(Dollars in thousands)
Balance at beginning of period	$	22,565		$	904		$	35,654		$	1,534
Adjustments		—			26			(449	)		62
Accretion charge-offs		—			—			(354	)		—
Accretion		(5,805	)		(277	)		(18,091	)		(943	)
Balance at September 30,	$	16,760		$	653		$	16,760		$	653

Changes in the discount accretion for Non-PCD loans for the three and nine months ended September 30, 2020 and 2019 were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
	(Dollars in thousands)
Balance at beginning of period	$	69,860		$	12,479		$	110,130		$	14,833
Adjustments		(16	)		—			296			—
Accretion charge-offs		—			—			(120	)		—
Accretion		(16,729	)		(1,006	)		(57,191	)		(3,360	)
Balance at September 30,	$	53,115		$	11,473		$	53,115		$	11,473

Risk Grade by Category of Loan and Year of Origination/Renewal

The following table presents loans by risk grade, by category of loan and year of origination/renewal at September 30, 2020.

	Term Loans
	Amortized Cost Basis by Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
	(Dollars in thousands)
Construction, Land Development and Other Land Loans
Grade 1	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Grade 2		—		—		—		86		126		267		—		—		479
Grade 3		646,011		630,323		297,303		128,581		23,831		56,166		114,716		—		1,896,931
Grade 4		70,111		30,016		33,405		19,562		3,806		7,187		10,134		—		174,221
Grade 5		—		—		829		4,510		—		117		—		—		5,456
Grade 6		—		—		—		—		565		1,325		—		—		1,890
Grade 7		—		—		1,080		—		6		390		734		—		2,210
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		—		171		115		289		—		—		—		—		575
Total		716,122		660,510		332,732		153,028		28,334		65,452		125,584		—		2,081,762
Agriculture and Agriculture Real Estate (includes Farmland)
Grade 1	$	2,004	$	542	$	177	$	182		—		—	$	10,032	$	2	$	12,939
Grade 2		30		—		—		351		5		1,532		310		—		2,228
Grade 3		95,589		81,626		62,552		52,243		47,463		92,816		74,173		145		506,607
Grade 4		15,376		10,246		4,873		3,043		4,633		17,219		9,021		23		64,434
Grade 5		1,984		3,705		577		—		—		14		2,302		—		8,582
Grade 6		804		—		59		—		186		181		—		—		1,230
Grade 7		—		308		15		—		—		853		—		—		1,176
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		976		209		296		—		—		295		—		—		1,776
Total		116,763		96,636		68,549		55,819		52,287		112,910		95,838		170		598,972
1-4 Family (includes Home Equity) (1)
Grade 1	$	117	$	—	$	—	$	—	$	—	$	—	$	95	$	—	$	212
Grade 2		288		315		987		676		254		7,705		1,133		—		11,358
Grade 3		1,010,159		910,378		612,545		482,791		473,571		888,135		125,281		3,313		4,506,173
Grade 4		7,620		16,515		23,244		22,256		10,766		36,955		2,550		249		120,155
Grade 5		—		219		157		6		712		1,971		—		—		3,065
Grade 6		23		39		3		332		—		1,524		—		—		1,921
Grade 7		—		1,535		952		3,108		1,544		12,114		3,485		—		22,738
Grade 8		—		—		—		—		9		87		—		—		96
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		—		—		—		—		238		1,448		—		—		1,686
Total		1,018,207		929,001		637,888		509,169		487,094		949,939		132,544		3,562		4,667,404

	Term Loans
	Amortized Cost Basis by Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
	(Dollars in thousands)
Commercial Real Estate (includes Multi-Family Residential)
Grade 1	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Grade 2		10,046		2,006		—		7,450		201		1,386		—		—		21,089
Grade 3		468,230		986,980		983,614		824,609		464,007		1,018,983		63,247		2,072		4,811,742
Grade 4		89,339		79,177		209,634		214,653		156,972		318,504		8,505		6,597		1,083,381
Grade 5		6,120		7,556		16,457		2,771		35,280		43,836		1,306		—		113,326
Grade 6		10,014		174		—		10,587		3,176		14,906		—		—		38,857
Grade 7		19		—		1,238		15		7,840		847		1,485		—		11,444
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		48,199		21,935		5,361		6,278		200		18,089		—		—		100,062
Total		631,967		1,097,828		1,216,304		1,066,363		667,676		1,416,551		74,543		8,669		6,179,901
Commercial and Industrial
Grade 1	$	1,389,705	$	7,320	$	4,109	$	917	$	834	$	569	$	18,249	$	162	$	1,421,865
Grade 2		2,395		10,990		17,344		1,348		1,422		1,052		24,324		—		58,875
Grade 3		342,204		370,525		302,552		110,782		74,182		150,914		715,920		11,273		2,078,352
Grade 4		54,749		74,189		51,515		36,188		9,627		30,103		106,284		1,179		363,834
Grade 5		5,213		30,676		4,309		7		218		1,924		11,310		5,010		58,667
Grade 6		390		104		247		—		1,152		1,906		22,159		—		25,958
Grade 7		759		344		13,002		390		988		288		36,901		17		52,689
Grade 8		—		—		—		—		8		—		—		—		8
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		16,637		22,115		20,505		10,932		—		798		2,855		16,099		89,941
Total	$	1,812,052	$	516,263	$	413,583	$	160,564	$	88,431	$	187,554	$	938,002	$	33,740	$	4,150,189
Consumer and Other
Grade 1	$	37,213	$	11,159	$	4,170	$	2,469	$	1,370	$	157	$	1,523	$	—	$	58,061
Grade 2		2,350		1,036		407		31,450		1,583		—		1,204		—		38,030
Grade 3		39,858		50,310		31,445		22,314		7,615		16,122		74,327		73		242,064
Grade 4		4,237		2,052		964		75		84		118		14,148		—		21,678
Grade 5		—		—		66		18		—		—		9,997		—		10,081
Grade 6		—		—		—		—		—		—		—		—		—
Grade 7		2		1,569		7		4		—		21		2		—		1,605
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		3,800		—		—		—		—		—		11,480		—		15,280
Total	$	87,460	$	66,126	$	37,059	$	56,330	$	10,652	$	16,418	$	112,681	$	73	$	386,799

	Term Loans
	Amortized Cost Basis by Origination Year
	2020		2019		2018		2017		2016		Prior		Revolving Loans		Revolving Loans Converted to Term Loans		Total
	(Dollars in thousands)
Warehouse Purchase Program
Grade 1	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Grade 2		—		—		—		—		—		—		—		—		—
Grade 3		2,730,614		—		—		—		—		—		—		—		2,730,614
Grade 4		—		—		—		—		—		—		—		—		—
Grade 5		—		—		—		—		—		—		—		—		—
Grade 6		—		—		—		—		—		—		—		—		—
Grade 7		—		—		—		—		—		—		—		—		—
Grade 8		—		—		—		—		—		—		—		—		—
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		—		—		—		—		—		—		—		—		—
Total	$	2,730,614	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	2,730,614
Total
Grade 1	$	1,429,039	$	19,021	$	8,456	$	3,568	$	2,204	$	726	$	29,899	$	164	$	1,493,077
Grade 2		15,109		14,347		18,738		41,361		3,591		11,942		26,971		—		132,059
Grade 3		5,332,665		3,030,142		2,290,011		1,621,320		1,090,669		2,223,136		1,167,664		16,876		16,772,483
Grade 4		241,432		212,195		323,635		295,777		185,888		410,086		150,642		8,048		1,827,703
Grade 5		13,317		42,156		22,395		7,312		36,210		47,862		24,915		5,010		199,177
Grade 6		11,231		317		309		10,919		5,079		19,842		22,159		—		69,856
Grade 7		780		3,756		16,294		3,517		10,378		14,513		42,607		17		91,862
Grade 8		—		—		—		—		17		87		—		—		104
Grade 9		—		—		—		—		—		—		—		—		—
PCD Loans		69,612		44,430		26,277		17,499		438		20,630		14,335		16,099		209,320
Total	$	7,113,185	$	3,366,364	$	2,706,115	$	2,001,273	$	1,334,474	$	2,748,824	$	1,479,192	$	46,214	$	20,795,641

(1) Includes $51.7 million of residential mortgage loans held for sale at September 30, 2020.

Allowance for Credit Losses on Loans by Category of Loan

The following table details activity in the allowance for credit losses on loans by category of loan for the three and nine months ended September 30, 2020 and 2019.

	Construction, Land Development and Other Land Loans			Agriculture and Agriculture Real Estate (includes Farmland)			1-4 Family (includes Home Equity)			Commercial Real Estate (includes Multi-Family Residential)			Commercial and Industrial			Consumer and Other			Total
	(Dollars in thousands)
Allowance for credit losses:
Three Months Ended
Balance June 30, 2020	$	39,862		$	6,898		$	33,021		$	78,207		$	149,884		$	16,333		$	324,205
Provision for credit losses		4,187			554			7,517			3,188			(4,982	)		(464	)		10,000
Charge-offs		(500	)		—			(436	)		(676	)		(8,444	)		(1,092	)		(11,148	)
Recoveries		22			17			184			—			99			256			578
Net charge-offs		(478	)		17			(252	)		(676	)		(8,345	)		(836	)		(10,570	)
Balance September 30, 2020	$	43,571		$	7,469		$	40,286		$	80,719		$	136,557		$	15,033		$	323,635
Nine Months Ended
Beginning balance, prior to adoption of ASC 326	$	14,654		$	2,971		$	15,277		$	12,332		$	40,445		$	1,790		$	87,469
Impact of adoption ASC 326		14,075			2,797			8,267			48,990			139,624			26,785			240,538
Provision for credit losses		15,302			1,680			17,050			19,992			(22,990	)		(11,034	)		20,000
Charge-offs		(500	)		(62	)		(611	)		(676	)		(21,733	)		(3,529	)		(27,111	)
Recoveries		40			83			303			81			1,211			1,021			2,739
Net charge-offs		(460	)		21			(308	)		(595	)		(20,522	)		(2,508	)		(24,372	)
Balance September 30, 2020	$	43,571		$	7,469		$	40,286		$	80,719		$	136,557		$	15,033		$	323,635
Allowance for credit losses:
Three Months Ended
Balance June 30, 2019	$	15,886		$	3,816		$	14,383		$	12,166		$	39,177		$	1,578		$	87,006
Provision for credit losses		290			188			543			452			(763	)		970			1,100
Charge-offs		—			(294	)		-			—			(419	)		(1,024	)		(1,737	)
Recoveries		6			16			9			1			502			158			692
Net charge-offs		6			(278	)		9			1			83			(866	)		(1,045	)
Balance September 30, 2019	$	15,602		$	3,726		$	14,935		$	12,619		$	38,497		$	1,682		$	87,061
Nine Months Ended
Balance December 31, 2018	$	15,582		$	2,693		$	14,135		$	11,220		$	40,223		$	1,587		$	86,440
Provision for credit losses		21			(921	)		799			1,396			(918	)		2,223			2,600
Charge-offs		(63	)		(358	)		(22	)		—			(2,501	)		(2,821	)		(5,765	)
Recoveries		62			1,312			23			3			1,693			693			3,786
Net charge-offs		(1	)		954			1			3			(808	)		(2,128	)		(1,979	)
Balance September 30, 2019	$	15,602		$	3,726		$	14,935		$	12,619		$	38,497		$	1,682		$	87,061

Troubled Debt Restructurings

The following table presents information regarding the recorded investment of loans that were modified as troubled debt restructurings during the nine months ended September 30, 2020 and 2019.

	Nine Months Ended
	September 30,
	2020						2019
	Number of Loans		Pre-Modification Outstanding Recorded Investment		Post-Modification Outstanding Recorded Investment		Number of Loans		Pre-Modification Outstanding Recorded Investment		Post-Modification Outstanding Recorded Investment
	(Dollars in thousands)
Troubled Debt Restructurings
Construction, land development and other land loans		—	$	—	$	—		—	$	—	$	—
Agriculture and agriculture real estate (includes farmland)		—		—		—		—		—		—
1-4 Family (includes home equity)		1		23		12		—		—		—
Commercial real estate (includes multi-family residential)		—		—		—		—		—		—
Commercial and industrial		—		—		—		2		14,993		14,188
Consumer and other		—		—		—		—		—		—
Total		1	$	23	$	12		2	$	14,993	$	14,188

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Fair Value (Tables)

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value Assets and Liabilities Measured on Recurring Basis

The following tables present fair values for assets and liabilities measured at fair value on a recurring basis:

	As of September 30, 2020
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets:
Available for sale securities:
Collateralized mortgage obligations	$	—	$	418,188	$	—	$	418,188
Mortgage-backed securities		—		42,927		—		42,927
Total	$	—	$	461,115	$	—	$	461,115
Derivative financial instruments:
Loan customer counterparty	$	—	$	13,510	$	—	$	13,510
Financial institution counterparty		—		—		—		—
Liabilities:
Derivative financial instruments:
Loan customer counterparty	$	—	$	—	$	—	$	—
Financial institution counterparty		—		13,510		—		13,510

	As of December 31, 2019
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets:
Available for sale securities:
States and political subdivisions	$	—	$	471	$	—	$	471
Collateralized mortgage obligations		—		235,773		—		235,773
Mortgage-backed securities		—		51,419		—		51,419
Total available for sale securities	$	—	$	287,663	$	—	$	287,663
Derivative financial instruments:
Interest rate lock commitments	$	—		305	$	—		305
Forward mortgage-backed securities trades		—		3		—		3
Loan customer counterparty		—		4,829		—		4,829
Financial institution counterparty		—		240		—		240
Liabilities:
Derivative financial instruments:
Interest rate lock commitments	$	—	$	—	$	—	$	—
Forward mortgage-backed securities trades		—		83		—		83
Loan customer counterparty		—		240		—		240
Financial institution counterparty		—		4,829		—		4,829

Summary of Carrying and Fair Value Information of Financial Instruments

The following tables present carrying and fair value information of financial instruments as of the dates indicated:

	As of September 30, 2020
	Carrying		Estimated Fair Value
	Amount		Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets
Cash and due from banks	$	1,031,193	$	1,031,193	$	—	$	—	$	1,031,193
Federal funds sold		56,469		56,469		—		—		56,469
Held to maturity securities		6,970,380		—		7,145,837		—		7,145,837
Loans held for sale		51,694		—		51,694		—		51,694
Loans held for investment, net of allowance		17,689,698		—		—		17,704,208		17,704,208
Loans held for investment - Warehouse Purchase Program		2,730,614		—		2,730,614		—		2,730,614
Other real estate owned		11,548		—		11,548		—		11,548
Liabilities
Deposits:
Noninterest-bearing	$	8,998,328	$	—	$	8,998,328	$	—	$	8,998,328
Interest-bearing		17,460,878		—		17,485,431		—		17,485,431
Other borrowings		2,570		—		2,782		—		2,782
Securities sold under repurchase agreements		380,274		—		380,297		—		380,297
Subordinated notes		125,146		—		125,586		—		125,586

	As of December 31, 2019
	Carrying		Estimated Fair Value
	Amount		Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Assets
Cash and due from banks	$	573,589	$	573,589	$	—	$	—	$	573,589
Federal funds sold		519		519		—		—		519
Held to maturity securities		8,282,393		—		8,303,851		—		8,303,851
Loans held for sale		80,959		—		80,959		—		80,959
Loans held for investment, net of allowance		17,124,156		—		—		17,045,523		17,045,523
Loans held for investment - Warehouse Purchase Program		1,552,762		—		1,552,762		—		1,552,762
Other real estate owned		6,936		—		6,936		—		6,936
Liabilities
Deposits:
Noninterest-bearing	$	7,763,894	$	—	$	7,763,894	$	—	$	7,763,894
Interest-bearing		16,435,838		—		16,437,453		—		16,437,453
Other borrowings		1,303,730		—		1,303,941		—		1,303,941
Securities sold under repurchase agreements		377,294		—		377,302		—		377,302
Subordinated notes		125,804		—		125,743		—		125,743

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Goodwill and Core Deposit Intangibles (Tables)

9 Months Ended

Sep. 30, 2020

Goodwill And Intangible Assets Disclosure [Abstract]

Goodwill and Core Deposit Intangibles

Changes in the carrying amount of the Company’s goodwill and core deposit intangibles for the nine months ended September 30, 2020 and the year ended December 31, 2019 were as follows: 

	Goodwill		Core Deposit Intangibles
	(Dollars in thousands)
Balance as of December 31, 2018	$	1,900,845	$	32,883
Less:
Amortization		—		(6,537	)
Add:
LegacyTexas Merger		1,322,826		60,058
Balance as of December 31, 2019		3,223,671		86,404
Less:
Amortization		—		(9,926	)
Add:
Measurement period adjustment of LegacyTexas Merger		8,021		—
Balance as of September 30, 2020	$	3,231,692	$	76,478

Estimated Aggregate Future Amortization Expense for Core Deposit Intangibles

The estimated aggregate future amortization expense for core deposit intangibles remaining as of September 30, 2020 is as follows (dollars in thousands):

Remaining 2020	$	3,243
2021		11,551
2022		10,336
2023		9,360
2024		8,699
Thereafter		33,289
Total	$	76,478

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Contractual Obligations and Off-Balance Sheet Items (Tables)

9 Months Ended

Sep. 30, 2020

Commitments And Contingencies Disclosure [Abstract]

Schedule of Contractual Obligations and Other Commitments

The Company’s contractual obligations and other commitments to make future payments as of September 30, 2020 (other than deposit obligations and securities sold under repurchase agreements) are summarized below.

	1 year or less		More than 1 year but less than 3 years		3 years or more but less than 5 years		5 years or more		Total
	(Dollars in thousands)
Subordinated notes	$	126,292	$	—	$	—	$	—	$	126,292
Federal Home Loan Bank advances and notes payable		974		1,067		366		18		2,425
Total	$	127,266	$	1,067	$	366	$	18	$	128,717

Future Undiscounted Cash Payments Associated with its Operating Leases

The Company’s future undiscounted cash payments associated with its operating leases as of September 30, 2020 are summarized below (dollars in thousands).

Remaining 2020	$	2,637
2021		10,196
2022		9,671
2023		8,922
2024		8,042
2025		7,651
Thereafter		19,383
Total undiscounted lease payments	$	66,502

Summary of Non-Cancelable Future Operating Lease Commitments

The following table presents a summary of non-cancelable future operating lease commitments as of December 31, 2019 (dollars in thousands):

2020	$	10,137
2021		9,169
2022		8,641
2023		7,998
2024		7,119
Thereafter		24,996
Total non-cancelable lease payments	$	68,060

Summary of Commitments Associated with Outstanding Standby Letters of Credit, Unused Capacity on Warehouse Purchase Program Loans and Commitments to Extend Credit

The Company’s commitments associated with outstanding standby letters of credit, unused capacity on Warehouse Purchase Program loans and commitments to extend credit expiring by period as of September 30, 2020 are summarized below. Since commitments associated with letters of credit, unused capacity of Warehouse Purchase Program loans, allowance for credit losses on off-balance sheet credit exposures and commitments to extend credit may expire unused, the amounts shown do not necessarily reflect the actual future cash funding requirements.

	1 year or less		More than 1 year but less than 3 years		3 years or more but less than 5 years		5 years or more		Total
	(Dollars in thousands)
Standby letters of credit	$	104,896	$	6,616	$	1,337	$	—	$	112,849
Unused capacity on Warehouse Purchase Program loans		803,386		—		—		—		803,386
Commitments to extend credit		1,743,194		852,081		342,756		1,245,988		4,184,019
Total	$	2,651,476	$	858,697	$	344,093	$	1,245,988	$	5,100,254

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Other Comprehensive Income (Tables)

9 Months Ended

Sep. 30, 2020

Equity [Abstract]

Tax Effects Allocated to Each Component of Other Comprehensive Income

The tax effects allocated to each component of other comprehensive income were as follows:

	Three Months Ended September 30,
	2020							2019
	Before Tax Amount		Tax Effect			Net of Tax Amount		Before Tax Amount			Tax Effect		Net of Tax Amount
	(Dollars in thousands)
Other comprehensive income (loss):
Securities available for sale:
Change in unrealized gain (loss) during period	$	1,325	$	(278	)	$	1,047	$	(1,563	)	$	328	$	(1,235	)
Total securities available for sale		1,325		(278	)		1,047		(1,563	)		328		(1,235	)
Total other comprehensive income (loss)	$	1,325	$	(278	)	$	1,047	$	(1,563	)	$	328	$	(1,235	)

	Nine Months Ended September 30,
	2020								2019
	Before Tax Amount			Tax Effect		Net of Tax Amount			Before Tax Amount			Tax Effect		Net of Tax Amount
	(Dollars in thousands)
Other comprehensive loss:
Securities available for sale:
Change in unrealized loss during period	$	(1,204	)	$	253	$	(951	)	$	(344	)	$	72	$	(272	)
Total securities available for sale		(1,204	)		253		(951	)		(344	)		72		(272	)
Total other comprehensive loss	$	(1,204	)	$	253	$	(951	)	$	(344	)	$	72	$	(272	)

Activity in Accumulated Other Comprehensive Income Associated with Securities Available for Sale, Net of Tax

Activity in accumulated other comprehensive income associated with securities available for sale, net of tax, was as follows:

	Securities Available for Sale			Accumulated Other Comprehensive Income (Loss)
	(Dollars in thousands)
Balance at December 31, 2019	$	602		$	602
Other comprehensive loss		(951	)		(951	)
Balance at September 30, 2020	$	(349	)	$	(349	)
Balance at December 31, 2018	$	310		$	310
Other comprehensive loss		(272	)		(272	)
Balance at September 30, 2019	$	38		$	38

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Derivative Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2020

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Schedule of Notional Balances and Fair Value of Derivative Positions

The following table provides the outstanding notional balances and fair values of outstanding derivative positions at September 30, 2020 and December 31, 2019.

	September 30, 2020						December 31, 2019
	Outstanding Notional Balance		Asset Derivative Fair Value		Liability Derivative Fair Value		Outstanding Notional Balance		Asset Derivative Fair Value		Liability Derivative Fair Value
	(Dollars in thousands)
Interest rate lock commitments	$	—	$	—	$	—	$	9,438	$	305	$	—
Forward mortgage-backed securities trades		—		—		—		40,750		3		83
Commercial loan interest rate swaps and caps:
Loan customer counterparty		224,928		13,510		—		231,345		4,829		240
Financial institution counterparty		224,928		—		13,510		231,345		240		4,829

Schedule of Weighted Average Received and Paid Interest Rates for Interest Rate Swaps Outstanding

The commercial loan customer counterparty weighted average received and paid interest rates for interest rate swaps outstanding at September 30, 2020 and December 31, 2019 are presented in the following table.

	Weighted-Average Interest Rate
	September 30, 2020						December 31, 2019
	Received			Paid			Received			Paid
Loan customer counterparty		0.58	%		2.83	%		3.42	%		2.86	%

Schedule of Income (Loss) from Derivatives Not Designated as Hedging Instruments

Income (loss) for the three and nine months ended September 30, 2020 and 2019 was as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
Derivatives not designated as hedging instruments	2020		2019		2020			2019
	(Dollars in thousands)
Interest rate lock commitments	$	—	$	—	$	(305	)	$	—
Forward mortgage-backed securities trades		—		—		(2,398	)		—

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Acquisitions (Tables)

9 Months Ended

Sep. 30, 2020

Business Combinations [Abstract]

Amounts Recorded on Consolidated Balance Sheet on Acquisition Date

The assets and liabilities of LegacyTexas were recorded on the consolidated balance sheet at estimated fair value on the acquisition date. As of September 30, 2020, the following table presents the amounts recorded on the consolidated balance sheet on the acquisition date (dollars in thousands).

	Initially Recorded at Acquisition Date		Measurement Period Adjustments			Adjusted Values as of September 30, 2020
Fair value of consideration paid:
Common stock issued (26,228,148 shares)	$	1,810,267	$	—		$	1,810,267
Cash		318,018		—			318,018
Total consideration paid	$	2,128,285	$	—		$	2,128,285
Fair value of assets acquired:
Cash and due from banks	$	228,649	$	—		$	228,649
Securities held to maturity		472,933		—			472,933
Loans held for sale		60,818		—			60,818
Loans held for investment		6,771,080		—			6,771,080
Loans held for investment - Warehouse Purchase Program		1,693,049		—			1,693,049
Bank premises and equipment		67,347		(1,299	)		66,048
Other real estate owned		4,876		—			4,876
Core deposit intangibles		60,058		—			60,058
Federal Home Loan Bank stock		117,939		(113	)		117,826
Bank owned life insurance and other assets		242,592		(7,125	)		235,467
Total assets acquired		9,719,341		(8,537	)		9,710,804
Fair value of liabilities assumed:
Deposits		6,434,732		—			6,434,732
Other borrowings		2,078,682		—			2,078,682
Securities sold under repurchase agreements		57,670		—			57,670
Trust preferred securities		15,376		—			15,376
Subordinated notes		125,950		—			125,950
Other liabilities		201,472		(516	)		200,956
Total liabilities assumed		8,913,882		(516	)		8,913,366
Fair value of net assets acquired	$	805,459	$	(8,021	)	$	797,438
Goodwill resulting from acquisition	$	1,322,826	$	8,021		$	1,330,847

Summary of Pro Forma Information

The following pro forma information presents the results of operations for the three and nine months ended September 30, 2019, as if the Merger had occurred on January 1, 2019 (dollars in thousands, except per share amounts).

	Three Months Ended September 30, 2019		Nine Months Ended September 30, 2019
Net interest income	$	259,730	$	768,548
Net income		140,400		367,677
Basic earnings per share		1.47		3.85
Diluted earnings per share		1.47		3.85

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Income Per Common Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net income	$ 130,064	$ 81,758	$ 391,813	$ 246,418
Basic, Weighted average shares outstanding (in shares)	92,656	68,738	93,226	69,463
Basic	$ 1.40	$ 1.19	$ 4.20	$ 3.55
Diluted, Weighted average shares outstanding (in shares)	92,656	68,738	93,226	69,463
Diluted	$ 1.40	$ 1.19	$ 4.20	$ 3.55

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Income Per Common Share - Additional Information (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Number of options outstanding	0		0
Antidilutive Securities excluded from computation of earnings per share, amount	0	0	0	0

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New Accounting Standards - Additional Information (Details)	9 Months Ended
	Sep. 30, 2020 USD ($)
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Increase in allowance for credit losses for loans	$ 236,200,000
Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Increase in allowance for credit losses for loans	108,700,000
Increase in allowance for credit losses for off-balance sheet credit exposures	24,400,000
Increase in allowance for credit losses for loans	131,800,000
Allowance for credit losses related to debt securities	0
Legacy Texas [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Increase in allowance for credit losses for loans	102,500,000
Increase in allowance for credit losses for off-balance sheet credit exposures	6,300,000
Increase in allowance for credit losses for loans	$ 130,300,000

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New Accounting Standards - Schedule of Impact of Adopting ASU 2016-13 (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	$ 323,635	$ 324,205	$ 328,007	$ 87,469	$ 87,061	$ 87,006	$ 86,440
Allowance for credit losses on off-balance sheet credit exposures	29,947		29,947	5,599
Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			240,538
Allowance for credit losses on off-balance sheet credit exposures			24,348
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	7,469	6,898		2,971	3,726	3,816	2,693
Pre-ASC 326 Adoption [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			87,469
Allowance for credit losses on off-balance sheet credit exposures			5,599
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	43,571	39,862	28,729	14,654	15,602	15,886	15,582
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			14,075
Real Estate [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			5,768
Real Estate [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			2,797
Real Estate [Member] | 1-4 Family [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	40,286	33,021	23,544	15,277	14,935	14,383	14,135
Real Estate [Member] | 1-4 Family [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			8,267
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	80,719	78,207	61,322	12,332	12,619	12,166	11,220
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			48,990
Real Estate [Member] | Pre-ASC 326 Adoption [Member] | Construction, Land Development and Other Land Loans [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			14,654
Real Estate [Member] | Pre-ASC 326 Adoption [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			2,971
Real Estate [Member] | Pre-ASC 326 Adoption [Member] | 1-4 Family [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			15,277
Real Estate [Member] | Pre-ASC 326 Adoption [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			12,332
Commercial and Industrial [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	136,557	149,884	180,069	40,445	38,497	39,177	40,223
Commercial and Industrial [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			139,624
Commercial and Industrial [Member] | Pre-ASC 326 Adoption [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			40,445
Consumer and Other [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	$ 15,033	$ 16,333	28,575	$ 1,790	$ 1,682	$ 1,578	$ 1,587
Consumer and Other [Member] | Accounting Standards Update 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			26,785
Consumer and Other [Member] | Pre-ASC 326 Adoption [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			$ 1,790

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Securities - Schedule of Amortized Cost and Fair Value of Investment Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Amortized Cost	$ 461,557	$ 286,901
Available for Sale, Gross Unrealized Gains	708	1,350
Available for Sale, Gross Unrealized Losses	(1,150)	(588)
Available for Sale	461,115	287,663
Held to Maturity, Amortized Cost	6,970,380	8,282,393
Held to Maturity, Gross Unrealized Gains	177,058	56,865
Held to Maturity, Gross Unrealized Losses	(1,601)	(35,407)
Held to Maturity	7,145,837	8,303,851
States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Amortized Cost		470
Available for Sale, Gross Unrealized Gains		1
Available for Sale		471
Held to Maturity, Amortized Cost	170,427	238,347
Held to Maturity, Gross Unrealized Gains	9,288	7,632
Held to Maturity, Gross Unrealized Losses	(187)	(189)
Held to Maturity	179,528	245,790
Collateralized Mortgage Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Amortized Cost	418,575	235,222
Available for Sale, Gross Unrealized Gains	138	690
Available for Sale, Gross Unrealized Losses	(525)	(139)
Available for Sale	418,188	235,773
Held to Maturity, Amortized Cost	123,309	203,470
Held to Maturity, Gross Unrealized Gains	2,080	1,115
Held to Maturity, Gross Unrealized Losses	(256)	(373)
Held to Maturity	125,133	204,212
Mortgage-backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Amortized Cost	42,982	51,209
Available for Sale, Gross Unrealized Gains	570	659
Available for Sale, Gross Unrealized Losses	(625)	(449)
Available for Sale	42,927	51,419
Held to Maturity, Amortized Cost	6,672,655	7,826,643
Held to Maturity, Gross Unrealized Gains	165,665	48,060
Held to Maturity, Gross Unrealized Losses	(1,158)	(34,845)
Held to Maturity	6,837,162	7,839,858
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Schedule Of Available For Sale Securities [Line Items]
Held to Maturity, Amortized Cost	3,989	13,933
Held to Maturity, Gross Unrealized Gains	25	58
Held to Maturity	$ 4,014	$ 13,991

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Securities - Additional Information (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020 USD ($) Security	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) Segment Security	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) Security
Schedule Of Held To Maturity Securities [Line Items]
Number of Investment Securities Segments | Segment			2
Credit losses			$ 0
Municipal securities percentage of securities portfolio	2.30%		2.30%
Securities in Unrealized Loss Positions Qualitative Disclosure Number of Positions Greater Than or Equal to One Year | Security	44		44		138
Gain (loss) on sale of securities	$ 0	$ 0	$ 0	$ 0
Available for sale securities, at fair value	461,115,000		461,115,000		$ 287,663,000
Collateralized Securities [Member]
Schedule Of Held To Maturity Securities [Line Items]
Available for Sale Securities, Amortized Cost Basis	5,800,000,000		5,800,000,000		5,980,000,000
Available for sale securities, at fair value	$ 5,940,000,000		$ 5,940,000,000		$ 5,990,000,000
Securities Concentration Risk [Member] | Stockholders' Equity, Total [Member]
Schedule Of Held To Maturity Securities [Line Items]
Concentration Risk, Percentage			10.00%		10.00%

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Securities - Securities in Continuous Loss Position (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Estimated Fair Value, Less than 12 Months	$ 204,969	$ 85,146
Available for Sale, Unrealized Losses, Less than 12 Months	(880)	(585)
Available for Sale, Estimated Fair Value, 12 Months or More	14,701	1,828
Available for Sale, Unrealized Losses, 12 Months or More	(270)	(3)
Available for Sale, Estimated Fair Value, Total	219,670	86,974
Available for Sale, Unrealized Losses, Total	(1,150)	(588)
Held to Maturity, Estimated Fair Value, Less than 12 Months	153,355	1,060,533
Held to Maturity, Unrealized Losses, Less than 12 Months	(1,301)	(3,573)
Held to Maturity, Estimated Fair Value, 12 Months or More	19,716	3,114,006
Held to Maturity, Unrealized Losses, 12 Months or More	(300)	(31,834)
Held to Maturity, Estimated Fair Value, Total	173,071	4,174,539
Held to Maturity, Unrealized Losses, Total	(1,601)	(35,407)
Collateralized Mortgage Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Estimated Fair Value, Less than 12 Months	188,671	50,245
Available for Sale, Unrealized Losses, Less than 12 Months	(515)	(136)
Available for Sale, Estimated Fair Value, 12 Months or More	1,886	1,818
Available for Sale, Unrealized Losses, 12 Months or More	(10)	(3)
Available for Sale, Estimated Fair Value, Total	190,557	52,063
Available for Sale, Unrealized Losses, Total	(525)	(139)
Held to Maturity, Estimated Fair Value, Less than 12 Months	33,507	54,890
Held to Maturity, Unrealized Losses, Less than 12 Months	(256)	(373)
Held to Maturity, Estimated Fair Value, Total	33,507	54,890
Held to Maturity, Unrealized Losses, Total	(256)	(373)
Mortgage-backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Available for Sale, Estimated Fair Value, Less than 12 Months	16,298	34,901
Available for Sale, Unrealized Losses, Less than 12 Months	(365)	(449)
Available for Sale, Estimated Fair Value, 12 Months or More	12,815	10
Available for Sale, Unrealized Losses, 12 Months or More	(260)
Available for Sale, Estimated Fair Value, Total	29,113	34,911
Available for Sale, Unrealized Losses, Total	(625)	(449)
Held to Maturity, Estimated Fair Value, Less than 12 Months	118,159	947,314
Held to Maturity, Unrealized Losses, Less than 12 Months	(858)	(3,017)
Held to Maturity, Estimated Fair Value, 12 Months or More	19,716	3,110,765
Held to Maturity, Unrealized Losses, 12 Months or More	(300)	(31,828)
Held to Maturity, Estimated Fair Value, Total	137,875	4,058,079
Held to Maturity, Unrealized Losses, Total	(1,158)	(34,845)
States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities [Line Items]
Held to Maturity, Estimated Fair Value, Less than 12 Months	1,689	58,329
Held to Maturity, Unrealized Losses, Less than 12 Months	(187)	(183)
Held to Maturity, Estimated Fair Value, 12 Months or More		3,241
Held to Maturity, Unrealized Losses, 12 Months or More		(6)
Held to Maturity, Estimated Fair Value, Total	1,689	61,570
Held to Maturity, Unrealized Losses, Total	$ (187)	$ (189)

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Securities - Investment Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Investments Debt And Equity Securities [Abstract]
Held to Maturity, amortized cost, due in one year or less	$ 26,715
Held to Maturity, amortized cost, due after one year through five years	96,287
Held to Maturity, amortized cost, due after five years through ten years	44,637
Held to Maturity, amortized cost, due after ten years	6,777
Held to Maturity, amortized cost, subtotal	174,416
Held to Maturity, amortized cost, mortgage-backed securities and collateralized mortgage obligations	6,795,964
Held to Maturity, Amortized Cost	6,970,380	$ 8,282,393
Held to Maturity, fair value, due in one year or less	26,744
Held to Maturity, fair value, due after one year through five years	101,719
Held to Maturity, fair value, due after five years through ten years	48,053
Held to Maturity, fair value, due after ten years	7,026
Held to Maturity, fair value, subtotal	183,542
Held to Maturity, fair value, mortgage-backed securities and collateralized mortgage obligations	6,962,295
Held to Maturity, fair value, total	7,145,837	8,303,851
Available for Sale, amortized cost, mortgage-backed securities and collateralized mortgage obligations	461,557
Available for Sale, Amortized Cost	461,557	286,901
Available for Sale, fair value, mortgage-backed securities and collateralized mortgage obligations	461,115
Available for Sale securities, at fair value	$ 461,115	$ 287,663

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Loans and Allowance for Credit Losses - Types of Loans in Loan Portfolio (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans held for sale		$ 51,694	$ 80,959
Total loans held for investment		18,013,333	17,211,625
Total loans, including Warehouse Purchase Program		20,795,641	18,845,346
Residential Mortgage Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for sale		51,694	80,959
Warehouse Purchase Program [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		2,730,614	1,552,762
Total loans, including Warehouse Purchase Program		2,730,614	1,552,762
Commercial and Industrial [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		4,150,189	3,205,595
Total loans, including Warehouse Purchase Program		4,150,189	3,205,595
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		2,081,762	2,064,167
Total loans, including Warehouse Purchase Program		2,081,762	2,064,167
Real Estate [Member] | 1-4 Family [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		4,615,710	4,306,452
Total loans, including Warehouse Purchase Program	[1]	4,667,404	4,387,411
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		6,179,901	6,556,285
Total loans, including Warehouse Purchase Program		6,179,901	6,556,285
Real Estate [Member] | Farmland [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		419,126	495,558
Agriculture [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		179,846	185,297
Consumer and Other [Member]
Accounts Notes And Loans Receivable [Line Items]
Total loans held for investment		386,799	398,271
Total loans, including Warehouse Purchase Program		$ 386,799	$ 398,271

[1] Includes $51.7 million and $81.0 million of residential mortgage loans held for sale at September 30, 2020 and December 31, 2019, respectively.

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Loans and Allowance for Credit Losses - Additional Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) Loan contract	Sep. 30, 2019 USD ($) contract	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Accounts Notes And Loans Receivable [Line Items]
Percentage of Loans Related to Single Industry on Loans	10.00%		10.00%			10.00%
Percentage of real estate loans aggregating to company loan portfolio, excluding Warehouse Purchase Program loans	71.30%		71.30%
Loans and Leases Receivable, Related Parties	$ 1,831		$ 1,831			$ 4,152	$ 1,923
Loans held for investment	$ 18,013,333		$ 18,013,333			$ 17,211,625
Financing Receivable Ratio of Nonperforming Loans to All Loans and Other Real Estate	0.33%		0.33%			0.33%
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans			$ 2,300	$ 2,200
Loans and leases receivable, nonaccrual loans	$ 57,400	$ 50,000	57,400	50,000
Financing Receivable, Allowance for Credit Losses on Loans	$ 323,600		$ 323,600			$ 87,500
Allowance for Credit Losses as Percentage of Loans	1.56%		1.56%			0.46%
Increase in allowance for credit losses for loans			$ 236,200
Increase in allowance for credit losses for loans, percentage			270.00%
Provision for credit losses	$ 10,000	1,100	$ 20,000	2,600
Net charge-offs	10,570	1,045	24,372	$ 1,979
Allowance for credit losses on off-balance sheet credit exposures	29,947		29,947		$ 29,947	$ 5,599
Commitments expected to fund	1,750,000		1,750,000
Nonaccrual loans	57,412		$ 57,412			55,243
Troubled debt restructurings, number of loans | contract			1	2
Financing receivable, number of loans with default | contract			0
Financing receivable, modifications, recorded investment	12	14,200	$ 12	$ 14,200
Troubled debt restructuring, recorded investment at date of restructure			$ 23	14,993
Loan to be Considered as Payment Default in Period			90 days
Troubled Debt Restructuring [Member]
Accounts Notes And Loans Receivable [Line Items]
Allowance for credit losses on off-balance sheet credit exposures	29,900		$ 29,900			5,600
Nonaccrual loans	13,200	$ 14,300	13,200	$ 14,300
COVID-19 [Member]
Accounts Notes And Loans Receivable [Line Items]
Provision for credit losses	10,000		20,000
Net charge-offs	$ 10,600		$ 24,400
CARES Act [Member] | Paycheck Protection Program [Member]
Accounts Notes And Loans Receivable [Line Items]
Number of loans | Loan			11,948
Funded amount			$ 1,390,000
Term period of loans	2 years		2 years
PCD Loans [Member] | COVID-19 [Member]
Accounts Notes And Loans Receivable [Line Items]
Net charge-offs	$ 8,600		$ 21,000
Specific reserves	15,700		44,200
General reserve	7,100		23,200
Additional specific reserves			6,100
Accounting Standards Update 2016-13 [Member]
Accounts Notes And Loans Receivable [Line Items]
Increase in allowance for credit losses for loans			108,700
Increase in allowance for credit losses due to adoption of CECL	240,538		240,538
Allowance for credit losses on off-balance sheet credit exposures					$ 24,348
Accounting Standards Update 2016-13 [Member] | PCD Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
PCD discount reallocated to allowance for credit losses						131,800
Nonperforming Financial Instruments [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	$ 69,500		$ 69,500			$ 62,900

XML

Loans and Allowance for Credit Losses - Related Party Loans (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Receivables [Abstract]
Beginning balance on January 1	$ 4,152	$ 1,923
New loans	813	1
Transfers		2,500
Repayments	(3,134)	(272)
Ending balance	$ 1,831	$ 4,152

XML

Loans and Allowance for Credit Losses - Aging Analysis of Past Due Loans (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		$ 39,489	$ 80,887
Nonaccrual loans		57,412	55,243
Current loans		20,698,740	18,709,216
Total loans		20,795,641	18,845,346
Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		39,027	80,446
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		462	441
Warehouse Purchase Program Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Current loans		2,730,614	1,552,762
Total loans		2,730,614	1,552,762
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		30	466
Nonaccrual loans		1,200	103
Current loans		597,742	680,286
Total loans		598,972	680,855
Agriculture and Agriculture Real Estate (Includes Farmland) [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		30	466
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		25,014	16,470
Nonaccrual loans		2,211	1,142
Current loans		2,054,537	2,046,555
Total loans		2,081,762	2,064,167
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		24,592	16,470
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		422
Real Estate [Member] | 1-4 Family Residential (Includes Home Equity) [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing	[1]	6,200	44,325
Nonaccrual loans	[1]	23,769	24,413
Current loans	[1]	4,637,435	4,318,673
Total loans	[1]	4,667,404	4,387,411
Real Estate [Member] | 1-4 Family Residential (Includes Home Equity) [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing	[1]	6,160	43,884
Real Estate [Member] | 1-4 Family Residential (Includes Home Equity) [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing	[1]	40	441
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		2,758	10,669
Nonaccrual loans		11,486	12,714
Current loans		6,165,657	6,532,902
Total loans		6,179,901	6,556,285
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		2,758	10,669
Commercial and Industrial [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		4,958	7,249
Nonaccrual loans		17,153	16,809
Current loans		4,128,078	3,181,537
Total loans		4,150,189	3,205,595
Commercial and Industrial [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		4,958	7,249
Consumer and Other [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		529	1,708
Nonaccrual loans		1,593	62
Current loans		384,677	396,501
Total loans		386,799	398,271
Consumer and Other [Member] | Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans past due and still accruing		$ 529	$ 1,708

[1] Includes $51.7 million and $81.0 million of residential mortgage loans held for sale at September 30, 2020 and December 31, 2019, respectively.

XML

Loans and Allowance for Credit Losses - Aging Analysis of Past Due Loans (Parenthetical) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans held for sale	$ 51,694	$ 80,959
Residential Mortgage Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for sale	$ 51,694	$ 80,959

XML

Loans and Allowance for Credit Losses - Nonperforming Assets (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		$ 18,013,333	$ 17,211,625
Other real estate owned		$ 11,548	$ 6,936
Nonperforming assets to total loans and other real estate		0.33%	0.33%
Nonperforming assets to total loans, excluding Warehouse Purchase Program loans, and other real estate		0.38%	0.36%
Nonperforming Financial Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		$ 57,874	$ 55,684
Repossessed assets		120	323
Other real estate owned		11,548	6,936
Total nonperforming assets		69,542	62,943
Nonperforming Financial Loans [Member] | Finance Receivable Nonaccrual Status [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	[1],[2]	57,412	55,243
Nonperforming Financial Loans [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		$ 462	$ 441

[1] Includes troubled debt restructurings of $13.2 million and $13.6 million as of September 30, 2020 and December 31, 2019, respectively.

[2] There were no nonperforming or troubled debt restructurings of warehouse lines of credit or Warehouse Purchase Program loans for the periods presented.

XML

Loans and Allowance for Credit Losses - Nonperforming Assets (Parenthetical) (Details) - USD ($)		Sep. 30, 2020	Dec. 31, 2019
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		$ 18,013,333,000	$ 17,211,625,000
Nonperforming Financial Loans [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		57,874,000	55,684,000
Nonperforming Financial Loans [Member] | Finance Receivable Nonaccrual Status [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment	[1],[2]	57,412,000	55,243,000
Troubled Debt Restructuring [Member] | Nonperforming Financial Loans [Member] | Finance Receivable Nonaccrual Status [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		13,200,000	13,600,000
Troubled Debt Restructuring [Member] | Nonperforming Financial Loans [Member] | Finance Receivable Nonaccrual Status [Member] | Warehouse Purchase Program [Member]
Accounts Notes And Loans Receivable [Line Items]
Loans held for investment		$ 0	$ 0

[1] Includes troubled debt restructurings of $13.2 million and $13.6 million as of September 30, 2020 and December 31, 2019, respectively.

[2] There were no nonperforming or troubled debt restructurings of warehouse lines of credit or Warehouse Purchase Program loans for the periods presented.

XML

Loans and Allowance for Credit Losses - Recorded Investment and Outstanding Balance for Purchased Credit Deteriorated Loans and Non Purchased Credit Deteriorated Loans (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
PCD Loans [Member]
Purchased And Non Purchased Credit Impaired Loans [Line Items]
Outstanding balance		$ 226,080	$ 410,785
Discount	[1]	(16,760)	(167,320)	[2]
Recorded investment		209,320	243,465
Non-PCD Loans [Member]
Purchased And Non Purchased Credit Impaired Loans [Line Items]
Outstanding balance		4,468,843	6,102,540
Discount		(53,115)	(110,130)
Recorded investment		$ 4,415,728	$ 5,992,410

[1] ASU 2016-13 became effective for the Company on January 1, 2020.

[2] Includes $131.8 million in PCD loans credit discount.

XML

Loans and Allowance for Credit Losses - Recorded Investment and Outstanding Balance for Purchased Credit Deteriorated Loans and Non Purchased Credit Deteriorated Loans (Parenthetical) (Details) $ in Millions	Dec. 31, 2019 USD ($)
PCD Loans [Member]
Purchased And Non Purchased Credit Impaired Loans [Line Items]
PCD loans credit discount	$ 131.8

XML

Loans and Allowance for Credit Losses - Summary of Changes in Accretable Yields of Acquired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
PCD Loans [Member]
Changes In Accretable Yield for PCI And Non PCI Loans [Line Items]
Balance at beginning of period	$ 22,565	$ 904	$ 35,654	$ 1,534
Adjustments		26	(449)	62
Accretion charge-offs			(354)
Accretion	(5,805)	(277)	(18,091)	(943)
Balance at September 30,	16,760	653	16,760	653
Non-PCD Loans [Member]
Changes In Accretable Yield for PCI And Non PCI Loans [Line Items]
Balance at beginning of period	69,860	12,479	110,130	14,833
Adjustments	(16)		296
Accretion charge-offs			(120)
Accretion	(16,729)	(1,006)	(57,191)	(3,360)
Balance at September 30,	$ 53,115	$ 11,473	$ 53,115	$ 11,473

XML

Loans and Allowance for Credit Losses - Risk Grade by Category of Loan and Year of Origination/Renewal (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Financing Receivable Impaired [Line Items]
2020		$ 7,113,185
2019		3,366,364
2018		2,706,115
2017		2,001,273
2016		1,334,474
Prior		2,748,824
Revolving Loans		1,479,192
Revolving Loans Converted to Term Loans		46,214
Total loans		20,795,641	$ 18,845,346
PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2020		69,612
2019		44,430
2018		26,277
2017		17,499
2016		438
Prior		20,630
Revolving Loans		14,335
Revolving Loans Converted to Term Loans		16,099
Total loans		209,320
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020		116,763
2019		96,636
2018		68,549
2017		55,819
2016		52,287
Prior		112,910
Revolving Loans		95,838
Revolving Loans Converted to Term Loans		170
Total loans		598,972	680,855
Agriculture and Agriculture Real Estate (Includes Farmland) [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2020		976
2019		209
2018		296
Prior		295
Total loans		1,776
Warehouse Purchase Program [Member]
Financing Receivable Impaired [Line Items]
2020		2,730,614
Total loans		2,730,614	1,552,762
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2020		716,122
2019		660,510
2018		332,732
2017		153,028
2016		28,334
Prior		65,452
Revolving Loans		125,584
Total loans		2,081,762	2,064,167
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2019		171
2018		115
2017		289
Total loans		575
Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2020		1,018,207
2019		929,001
2018		637,888
2017		509,169
2016		487,094
Prior		949,939
Revolving Loans		132,544
Revolving Loans Converted to Term Loans		3,562
Total loans	[1]	4,667,404	4,387,411
Real Estate [Member] | 1-4 Family [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2016		238
Prior		1,448
Total loans		1,686
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020		631,967
2019		1,097,828
2018		1,216,304
2017		1,066,363
2016		667,676
Prior		1,416,551
Revolving Loans		74,543
Revolving Loans Converted to Term Loans		8,669
Total loans		6,179,901	6,556,285
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2020		48,199
2019		21,935
2018		5,361
2017		6,278
2016		200
Prior		18,089
Total loans		100,062
Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020		1,812,052
2019		516,263
2018		413,583
2017		160,564
2016		88,431
Prior		187,554
Revolving Loans		938,002
Revolving Loans Converted to Term Loans		33,740
Total loans		4,150,189	3,205,595
Commercial and Industrial [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2020		16,637
2019		22,115
2018		20,505
2017		10,932
Prior		798
Revolving Loans		2,855
Revolving Loans Converted to Term Loans		16,099
Total loans		89,941
Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2020		87,460
2019		66,126
2018		37,059
2017		56,330
2016		10,652
Prior		16,418
Revolving Loans		112,681
Revolving Loans Converted to Term Loans		73
Total loans		386,799	$ 398,271
Consumer and Other [Member] | PCD Loans [Member]
Financing Receivable Impaired [Line Items]
2020		3,800
Revolving Loans		11,480
Total loans		15,280
Grade 1 [Member]
Financing Receivable Impaired [Line Items]
2020		1,429,039
2019		19,021
2018		8,456
2017		3,568
2016		2,204
Prior		726
Revolving Loans		29,899
Revolving Loans Converted to Term Loans		164
Total loans		1,493,077
Grade 1 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020		2,004
2019		542
2018		177
2017		182
Revolving Loans		10,032
Revolving Loans Converted to Term Loans		2
Total loans		12,939
Grade 1 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2020		117
Revolving Loans		95
Total loans		212
Grade 1 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020		1,389,705
2019		7,320
2018		4,109
2017		917
2016		834
Prior		569
Revolving Loans		18,249
Revolving Loans Converted to Term Loans		162
Total loans		1,421,865
Grade 1 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2020		37,213
2019		11,159
2018		4,170
2017		2,469
2016		1,370
Prior		157
Revolving Loans		1,523
Total loans		58,061
Grade 2 [Member]
Financing Receivable Impaired [Line Items]
2020		15,109
2019		14,347
2018		18,738
2017		41,361
2016		3,591
Prior		11,942
Revolving Loans		26,971
Total loans		132,059
Grade 2 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020		30
2017		351
2016		5
Prior		1,532
Revolving Loans		310
Total loans		2,228
Grade 2 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2017		86
2016		126
Prior		267
Total loans		479
Grade 2 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2020		288
2019		315
2018		987
2017		676
2016		254
Prior		7,705
Revolving Loans		1,133
Total loans		11,358
Grade 2 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020		10,046
2019		2,006
2017		7,450
2016		201
Prior		1,386
Total loans		21,089
Grade 2 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020		2,395
2019		10,990
2018		17,344
2017		1,348
2016		1,422
Prior		1,052
Revolving Loans		24,324
Total loans		58,875
Grade 2 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2020		2,350
2019		1,036
2018		407
2017		31,450
2016		1,583
Revolving Loans		1,204
Total loans		38,030
Grade 3 [Member]
Financing Receivable Impaired [Line Items]
2020		5,332,665
2019		3,030,142
2018		2,290,011
2017		1,621,320
2016		1,090,669
Prior		2,223,136
Revolving Loans		1,167,664
Revolving Loans Converted to Term Loans		16,876
Total loans		16,772,483
Grade 3 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020		95,589
2019		81,626
2018		62,552
2017		52,243
2016		47,463
Prior		92,816
Revolving Loans		74,173
Revolving Loans Converted to Term Loans		145
Total loans		506,607
Grade 3 [Member] | Warehouse Purchase Program [Member]
Financing Receivable Impaired [Line Items]
2020		2,730,614
Total loans		2,730,614
Grade 3 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2020		646,011
2019		630,323
2018		297,303
2017		128,581
2016		23,831
Prior		56,166
Revolving Loans		114,716
Total loans		1,896,931
Grade 3 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2020		1,010,159
2019		910,378
2018		612,545
2017		482,791
2016		473,571
Prior		888,135
Revolving Loans		125,281
Revolving Loans Converted to Term Loans		3,313
Total loans		4,506,173
Grade 3 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020		468,230
2019		986,980
2018		983,614
2017		824,609
2016		464,007
Prior		1,018,983
Revolving Loans		63,247
Revolving Loans Converted to Term Loans		2,072
Total loans		4,811,742
Grade 3 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020		342,204
2019		370,525
2018		302,552
2017		110,782
2016		74,182
Prior		150,914
Revolving Loans		715,920
Revolving Loans Converted to Term Loans		11,273
Total loans		2,078,352
Grade 3 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2020		39,858
2019		50,310
2018		31,445
2017		22,314
2016		7,615
Prior		16,122
Revolving Loans		74,327
Revolving Loans Converted to Term Loans		73
Total loans		242,064
Grade 4 [Member]
Financing Receivable Impaired [Line Items]
2020		241,432
2019		212,195
2018		323,635
2017		295,777
2016		185,888
Prior		410,086
Revolving Loans		150,642
Revolving Loans Converted to Term Loans		8,048
Total loans		1,827,703
Grade 4 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020		15,376
2019		10,246
2018		4,873
2017		3,043
2016		4,633
Prior		17,219
Revolving Loans		9,021
Revolving Loans Converted to Term Loans		23
Total loans		64,434
Grade 4 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2020		70,111
2019		30,016
2018		33,405
2017		19,562
2016		3,806
Prior		7,187
Revolving Loans		10,134
Total loans		174,221
Grade 4 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2020		7,620
2019		16,515
2018		23,244
2017		22,256
2016		10,766
Prior		36,955
Revolving Loans		2,550
Revolving Loans Converted to Term Loans		249
Total loans		120,155
Grade 4 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020		89,339
2019		79,177
2018		209,634
2017		214,653
2016		156,972
Prior		318,504
Revolving Loans		8,505
Revolving Loans Converted to Term Loans		6,597
Total loans		1,083,381
Grade 4 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020		54,749
2019		74,189
2018		51,515
2017		36,188
2016		9,627
Prior		30,103
Revolving Loans		106,284
Revolving Loans Converted to Term Loans		1,179
Total loans		363,834
Grade 4 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2020		4,237
2019		2,052
2018		964
2017		75
2016		84
Prior		118
Revolving Loans		14,148
Total loans		21,678
Grade 5 [Member]
Financing Receivable Impaired [Line Items]
2020		13,317
2019		42,156
2018		22,395
2017		7,312
2016		36,210
Prior		47,862
Revolving Loans		24,915
Revolving Loans Converted to Term Loans		5,010
Total loans		199,177
Grade 5 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020		1,984
2019		3,705
2018		577
Prior		14
Revolving Loans		2,302
Total loans		8,582
Grade 5 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2018		829
2017		4,510
Prior		117
Total loans		5,456
Grade 5 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2019		219
2018		157
2017		6
2016		712
Prior		1,971
Total loans		3,065
Grade 5 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020		6,120
2019		7,556
2018		16,457
2017		2,771
2016		35,280
Prior		43,836
Revolving Loans		1,306
Total loans		113,326
Grade 5 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020		5,213
2019		30,676
2018		4,309
2017		7
2016		218
Prior		1,924
Revolving Loans		11,310
Revolving Loans Converted to Term Loans		5,010
Total loans		58,667
Grade 5 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2018		66
2017		18
Revolving Loans		9,997
Total loans		10,081
Grade 6 [Member]
Financing Receivable Impaired [Line Items]
2020		11,231
2019		317
2018		309
2017		10,919
2016		5,079
Prior		19,842
Revolving Loans		22,159
Total loans		69,856
Grade 6 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2020		804
2018		59
2016		186
Prior		181
Total loans		1,230
Grade 6 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2016		565
Prior		1,325
Total loans		1,890
Grade 6 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2020		23
2019		39
2018		3
2017		332
Prior		1,524
Total loans		1,921
Grade 6 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020		10,014
2019		174
2017		10,587
2016		3,176
Prior		14,906
Total loans		38,857
Grade 6 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020		390
2019		104
2018		247
2016		1,152
Prior		1,906
Revolving Loans		22,159
Total loans		25,958
Grade 7 [Member]
Financing Receivable Impaired [Line Items]
2020		780
2019		3,756
2018		16,294
2017		3,517
2016		10,378
Prior		14,513
Revolving Loans		42,607
Revolving Loans Converted to Term Loans		17
Total loans		91,862
Grade 7 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Financing Receivable Impaired [Line Items]
2019		308
2018		15
Prior		853
Total loans		1,176
Grade 7 [Member] | Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Financing Receivable Impaired [Line Items]
2018		1,080
2016		6
Prior		390
Revolving Loans		734
Total loans		2,210
Grade 7 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2019		1,535
2018		952
2017		3,108
2016		1,544
Prior		12,114
Revolving Loans		3,485
Total loans		22,738
Grade 7 [Member] | Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Financing Receivable Impaired [Line Items]
2020		19
2018		1,238
2017		15
2016		7,840
Prior		847
Revolving Loans		1,485
Total loans		11,444
Grade 7 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2020		759
2019		344
2018		13,002
2017		390
2016		988
Prior		288
Revolving Loans		36,901
Revolving Loans Converted to Term Loans		17
Total loans		52,689
Grade 7 [Member] | Consumer and Other [Member]
Financing Receivable Impaired [Line Items]
2020		2
2019		1,569
2018		7
2017		4
Prior		21
Revolving Loans		2
Total loans		1,605
Grade 8 [Member]
Financing Receivable Impaired [Line Items]
2016		17
Prior		87
Total loans		104
Grade 8 [Member] | Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Impaired [Line Items]
2016		9
Prior		87
Total loans		96
Grade 8 [Member] | Commercial and Industrial [Member]
Financing Receivable Impaired [Line Items]
2016		8
Total loans		$ 8

[1] Includes $51.7 million and $81.0 million of residential mortgage loans held for sale at September 30, 2020 and December 31, 2019, respectively.

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Loans and Allowance for Credit Losses - Risk Grade by Category of Loan and Year of Origination/Renewal (Parenthetical) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable Impaired [Line Items]
Loans held for sale	$ 51,694	$ 80,959
Residential Mortgage Loans [Member]
Financing Receivable Impaired [Line Items]
Loans held for sale	$ 51,694	$ 80,959

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Loans and Allowance for Credit Losses - Allowance for Credit Losses on Loans by Category of Loan (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Allowance for credit losses:
Allowance for credit losses, beginning balance	$ 324,205	$ 87,006	$ 87,469	$ 86,440
Provision for credit losses	10,000	1,100	20,000	2,600
Charge-offs	(11,148)	(1,737)	(27,111)	(5,765)
Recoveries	578	692	2,739	3,786
Net charge-offs	(10,570)	(1,045)	(24,372)	(1,979)
Allowance for credit losses, ending balance	323,635	87,061	323,635	87,061
Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	240,538		240,538
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	6,898	3,816	2,971	2,693
Provision for credit losses	554	188	1,680	(921)
Charge-offs		(294)	(62)	(358)
Recoveries	17	16	83	1,312
Net charge-offs	17	(278)	21	954
Allowance for credit losses, ending balance	7,469	3,726	7,469	3,726
Agriculture and Agriculture Real Estate (Includes Farmland) [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	2,797		2,797
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	39,862	15,886	14,654	15,582
Provision for credit losses	4,187	290	15,302	21
Charge-offs	(500)		(500)	(63)
Recoveries	22	6	40	62
Net charge-offs	(478)	6	(460)	(1)
Allowance for credit losses, ending balance	43,571	15,602	43,571	15,602
Real Estate [Member] | Construction, Land Development and Other Land Loans [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	14,075		14,075
Real Estate [Member] | 1-4 Family [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	33,021	14,383	15,277	14,135
Provision for credit losses	7,517	543	17,050	799
Charge-offs	(436)		(611)	(22)
Recoveries	184	9	303	23
Net charge-offs	(252)	9	(308)	1
Allowance for credit losses, ending balance	40,286	14,935	40,286	14,935
Real Estate [Member] | 1-4 Family [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	8,267		8,267
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	78,207	12,166	12,332	11,220
Provision for credit losses	3,188	452	19,992	1,396
Charge-offs	(676)		(676)
Recoveries		1	81	3
Net charge-offs	(676)	1	(595)	3
Allowance for credit losses, ending balance	80,719	12,619	80,719	12,619
Real Estate [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	48,990		48,990
Commercial and Industrial [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	149,884	39,177	40,445	40,223
Provision for credit losses	(4,982)	(763)	(22,990)	(918)
Charge-offs	(8,444)	(419)	(21,733)	(2,501)
Recoveries	99	502	1,211	1,693
Net charge-offs	(8,345)	83	(20,522)	(808)
Allowance for credit losses, ending balance	136,557	38,497	136,557	38,497
Commercial and Industrial [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	139,624		139,624
Consumer and Other [Member]
Allowance for credit losses:
Allowance for credit losses, beginning balance	16,333	1,578	1,790	1,587
Provision for credit losses	(464)	970	(11,034)	2,223
Charge-offs	(1,092)	(1,024)	(3,529)	(2,821)
Recoveries	256	158	1,021	693
Net charge-offs	(836)	(866)	(2,508)	(2,128)
Allowance for credit losses, ending balance	15,033	$ 1,682	15,033	$ 1,682
Consumer and Other [Member] | Accounting Standards Update 2016-13 [Member]
Allowance for credit losses:
Impact of adoption ASC 326	$ 26,785		$ 26,785

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Loans and Allowance for Credit Losses - Troubled Debt Restructurings (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($) contract	Sep. 30, 2019 USD ($) contract
Financing Receivable Modifications [Line Items]
Troubled debt restructurings, number of loans | contract	1	2
Troubled debt restructurings, pre-modification outstanding recorded investment	$ 23	$ 14,993
Troubled debt restructurings, post-modification outstanding recorded investment	$ 12	$ 14,188
Real Estate [Member] | 1-4 Family [Member]
Financing Receivable Modifications [Line Items]
Troubled debt restructurings, number of loans | contract	1
Troubled debt restructurings, pre-modification outstanding recorded investment	$ 23
Troubled debt restructurings, post-modification outstanding recorded investment	$ 12
Commercial and Industrial [Member]
Financing Receivable Modifications [Line Items]
Troubled debt restructurings, number of loans | contract		2
Troubled debt restructurings, pre-modification outstanding recorded investment		$ 14,993
Troubled debt restructurings, post-modification outstanding recorded investment		$ 14,188

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Fair Value - Fair Value Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Available for sale securities:
Available for sale securities, at fair value	$ 461,115	$ 287,663
Fair Value, Measurements, Recurring [Member]
Available for sale securities:
Available for sale securities, at fair value	461,115	287,663
Fair Value, Measurements, Recurring [Member] | Loan Customer Counterparty [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value	13,510	4,829
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value		240
Fair Value, Measurements, Recurring [Member] | Financial Institution Counterparty [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		240
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value	13,510	4,829
Fair Value, Measurements, Recurring [Member] | Interest Rate Lock Commitments [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		305
Fair Value, Measurements, Recurring [Member] | Forward Mortgage-Backed Securities Trades [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		3
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value		83
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Available for sale securities:
Available for sale securities, at fair value	461,115	287,663
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Loan Customer Counterparty [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value	13,510	4,829
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value		240
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Financial Institution Counterparty [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		240
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value	13,510	4,829
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Interest Rate Lock Commitments [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		305
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Forward Mortgage-Backed Securities Trades [Member]
Derivative financial instruments:
Derivative financial instruments, assets at fair value		3
Derivative financial instruments:
Derivative financial instruments, liabilities at fair value		83
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member]
Available for sale securities:
Available for sale securities, at fair value	418,188	235,773
Fair Value, Measurements, Recurring [Member] | Collateralized Mortgage Obligations [Member] | Level 2 [Member]
Available for sale securities:
Available for sale securities, at fair value	418,188	235,773
Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities [Member]
Available for sale securities:
Available for sale securities, at fair value	42,927	51,419
Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities [Member] | Level 2 [Member]
Available for sale securities:
Available for sale securities, at fair value	$ 42,927	51,419
Fair Value, Measurements, Recurring [Member] | States and Political Subdivisions [Member]
Available for sale securities:
Available for sale securities, at fair value		471
Fair Value, Measurements, Recurring [Member] | States and Political Subdivisions [Member] | Level 2 [Member]
Available for sale securities:
Available for sale securities, at fair value		$ 471

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Fair Value - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Other real estate, additions	$ 7.4	$ 8.2
Real estate owned outstanding	6.2	6.9
Additions to impaired loans	8.9	26.3
Impaired loans outstanding	$ 8.9	$ 13.0

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Fair Value - Summary of Carrying and Fair Value Information of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets
Cash and due from banks	$ 1,031,193	$ 573,589
Federal funds sold	56,469	519
Held to maturity securities	7,145,837	8,303,851
Loans held for sale	51,694	80,959
Loans held for investment	18,013,333	17,211,625
Other real estate owned	11,548	6,936
Liabilities
Noninterest-bearing	8,998,328	7,763,894
Interest-bearing	17,460,878	16,435,838
Other borrowings	2,570	1,303,730
Securities sold under repurchase agreements	380,274	377,294
Subordinated notes	125,146	125,804
Carrying Amount [Member]
Assets
Cash and due from banks	1,031,193	573,589
Federal funds sold	56,469	519
Held to maturity securities	6,970,380	8,282,393
Loans held for sale	51,694	80,959
Loans held for investment, net of allowance	17,689,698	17,124,156
Other real estate owned	11,548	6,936
Liabilities
Noninterest-bearing	8,998,328	7,763,894
Interest-bearing	17,460,878	16,435,838
Other borrowings	2,570	1,303,730
Securities sold under repurchase agreements	380,274	377,294
Subordinated notes	125,146	125,804
Carrying Amount [Member] | Warehouse Purchase Program [Member]
Assets
Loans held for investment	2,730,614	1,552,762
Estimated Fair Value [Member]
Assets
Cash and due from banks	1,031,193	573,589
Federal funds sold	56,469	519
Held to maturity securities	7,145,837	8,303,851
Loans held for sale	51,694	80,959
Loans held for investment, net of allowance	17,704,208	17,045,523
Other real estate owned	11,548	6,936
Liabilities
Noninterest-bearing	8,998,328	7,763,894
Interest-bearing	17,485,431	16,437,453
Other borrowings	2,782	1,303,941
Securities sold under repurchase agreements	380,297	377,302
Subordinated notes	125,586	125,743
Estimated Fair Value [Member] | Level 1 [Member]
Assets
Cash and due from banks	1,031,193	573,589
Federal funds sold	56,469	519
Estimated Fair Value [Member] | Level 2 [Member]
Assets
Held to maturity securities	7,145,837	8,303,851
Loans held for sale	51,694	80,959
Other real estate owned	11,548	6,936
Liabilities
Noninterest-bearing	8,998,328	7,763,894
Interest-bearing	17,485,431	16,437,453
Other borrowings	2,782	1,303,941
Securities sold under repurchase agreements	380,297	377,302
Subordinated notes	125,586	125,743
Estimated Fair Value [Member] | Level 3 [Member]
Assets
Loans held for investment, net of allowance	17,704,208	17,045,523
Estimated Fair Value [Member] | Warehouse Purchase Program [Member]
Assets
Loans held for investment	2,730,614	1,552,762
Estimated Fair Value [Member] | Warehouse Purchase Program [Member] | Level 2 [Member]
Assets
Loans held for investment	$ 2,730,614	$ 1,552,762

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Goodwill and Core Deposit Intangibles - Goodwill and Core Deposit Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill, Beginning balance			$ 3,223,671	$ 1,900,845	$ 1,900,845
Goodwill, LegacyTexas Merger					1,322,826
Goodwill, Measurement period adjustment of LegacyTexas Merger			8,021
Goodwill, Ending balance	$ 3,231,692		3,231,692		3,223,671
Core Deposit Intangibles, Beginning balance			86,404	32,883	32,883
Core Deposit Intangibles, Amortization	(3,270)	$ (1,248)	(9,926)	$ (3,832)	(6,537)
Core Deposit Intangibles, LegacyTexas Merger					60,058
Core Deposit Intangibles, Ending balance	$ 76,478		$ 76,478		$ 86,404

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Goodwill and Core Deposit Intangibles - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Schedule Of Intangible Assets And Goodwill [Line Items]
Impairment recorded on goodwill and core deposit intangibles			$ 0
Amortization expense related to intangible assets	$ 3,270,000	$ 1,248,000	$ 9,926,000	$ 3,832,000	$ 6,537,000
Minimum [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Finite-lived intangible assets, useful life			10 years
Maximum [Member]
Schedule Of Intangible Assets And Goodwill [Line Items]
Finite-lived intangible assets, useful life			15 years

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Goodwill and Core Deposit Intangibles - Estimated Aggregate Future Amortization Expense for Core Deposit Intangibles (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Remaining 2020	$ 3,243
2021	11,551
2022	10,336
2023	9,360
2024	8,699
Thereafter	33,289
Total	$ 76,478	$ 86,404	$ 32,883

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Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense	$ 35,054	$ 21,106	$ 79,245	$ 63,405
Increase (decrease) in income tax expense	$ 13,900		$ 15,800
Increase (decrease) in income tax expense, Percentage	66.10%		25.00%
Income taxes receivable, net operating loss, CARES Act.			$ 20,100
Effective income tax rate	21.20%	20.50%	16.80%	20.50%
Effective income tax rate reconciliation, at federal statutory income tax rate, percent			21.00%		35.00%
Decrease in deferred tax asset			$ 31,900

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Stock-Based Compensation - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) Plan shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) Plan shares	Sep. 30, 2019 USD ($)	Dec. 31, 2012 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock-based employee compensation plans | Plan	2		2
Total unrecognized compensation expense related to stock-based compensation arrangements | $	$ 8.9		$ 8.9
Weighted-average period of cost expected to be recognized			1 year 10 months 24 days
Number of shares outstanding	0		0
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense | $	$ 3.2	$ 2.5	$ 9.5	$ 7.6
2020 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares authorized for issuance	2,500,000		2,500,000
Number of restricted shares granted			12,500
2012 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common shares authorized for issuance					1,250,000
Number of restricted shares granted			489,312
Shares issued			370,313

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Contractual Obligations and Off-Balance Sheet Items - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jan. 01, 2020	Dec. 31, 2019
Contractual Obligations And Off Balance Sheet Items [Line Items]
Subordinated notes	$ 125,146		$ 125,146			$ 125,804
Operating lease, right-of-use asset	54,000		54,000
Operating lease, liability	$ 54,000		$ 54,000
Operating lease, weighted average remaining lease term	7 years 4 months 24 days		7 years 4 months 24 days
Operating lease, weighted average discount rate, percent	2.34%		2.34%
Operating lease, payments	$ 3,300	$ 1,400	$ 10,500	$ 4,200
Right-of-Use asset obtained in exchange for operating lease liability			5,600
Allowance for credit losses on off-balance sheet credit exposures	$ 29,947		$ 29,947		$ 29,947	$ 5,599
Minimum [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
Lessee operating lease remaining lease term	1 year		1 year
Maximum [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
Lessee operating lease remaining lease term	18 years		18 years
Subordinated Notes Payable [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
Interest payable	$ 1,100		$ 1,100
Federal Home Loan Bank Advance And Notes Payable [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
Interest payable	$ 205		$ 205

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Contractual Obligations and Off-Balance Sheet Items - Contractual Obligations and Other Commitments (Details) - Lease Total [Member] $ in Thousands	Sep. 30, 2020 USD ($)
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	$ 127,266
More than 1 year but less than 3 years	1,067
3 years or more but less than 5 years	366
5 years or more	18
Total	128,717
Subordinated Notes Payable [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	126,292
Total	126,292
Federal Home Loan Bank Advance And Notes Payable [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	974
More than 1 year but less than 3 years	1,067
3 years or more but less than 5 years	366
5 years or more	18
Total	$ 2,425

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Contractual Obligations and Off-Balance Sheet Items - Future Undiscounted Cash Payments Associated with its Operating Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Remaining 2020	$ 2,637
2021	10,196	$ 10,137
2022	9,671	9,169
2023	8,922	8,641
2024	8,042	7,998
2025	7,651	7,119
Thereafter	19,383	24,996
Total undiscounted lease payments	$ 66,502	$ 68,060

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Contractual Obligations and Off-Balance Sheet Items - Summary of Non-Cancelable Future Operating Lease Commitments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Leases [Abstract]
2020	$ 10,196	$ 10,137
2021	9,671	9,169
2022	8,922	8,641
2023	8,042	7,998
2024	7,651	7,119
Thereafter	19,383	24,996
Total undiscounted lease payments	$ 66,502	$ 68,060

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Contractual Obligations and Off-Balance Sheet Items - Summary of Commitments Associated with Outstanding Standby Letters of Credit and Commitments to Extend Credit (Details) - Guarantee Obligations [Member] $ in Thousands	Sep. 30, 2020 USD ($)
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	$ 2,651,476
More than 1 year but less than 3 years	858,697
3 years or more but less than 5 years	344,093
5 years or more	1,245,988
Total	5,100,254
Unused capacity on Warehouse Purchase Program loans [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	803,386
Total	803,386
Commitments to Extend Credit [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	1,743,194
More than 1 year but less than 3 years	852,081
3 years or more but less than 5 years	342,756
5 years or more	1,245,988
Total	4,184,019
Standby Letters of Credit [Member]
Contractual Obligations And Off Balance Sheet Items [Line Items]
1 year or less	104,896
More than 1 year but less than 3 years	6,616
3 years or more but less than 5 years	1,337
5 years or more	0
Total	$ 112,849

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Other Comprehensive Income - Tax Effects Allocated to Each Component of Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Equity [Abstract]
Change in unrealized gain (loss) during period, before tax amount	$ 1,325	$ (1,563)	$ (1,204)	$ (344)
Change in unrealized gain (loss) during period, tax effect	(278)	328	253	72
Change in unrealized gain (loss) during period, net of tax amount	1,047	(1,235)	(951)	(272)
Total securities available for sale, before tax amount	1,325	(1,563)	(1,204)	(344)
Total securities available for sale, tax effect	(278)	328	253	72
Total securities available for sale, net of tax amount	1,047	(1,235)	(951)	(272)
Total other comprehensive income (loss), before tax amount	1,325	(1,563)	(1,204)	(344)
Total other comprehensive income (loss), tax effect	(278)	328	253	72
Other comprehensive income (loss), net of tax	$ 1,047	$ (1,235)	$ (951)	$ (272)

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Other Comprehensive Income - Activity in Accumulated Other Comprehensive Income Associated with Securities Available for Sale, Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Beginning balance, accumulated other comprehensive income			$ 602	$ 310
Other comprehensive loss	$ 1,047	$ (1,235)	(951)	(272)
Ending balance, accumulated other comprehensive income	(349)	38	(349)	38
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Beginning balance, accumulated other comprehensive income			602	310
Other comprehensive loss			(951)	(272)
Ending balance, accumulated other comprehensive income	$ (349)	$ 38	$ (349)	$ 38

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Derivative Financial Instruments - Schedule of Notional Balances and Fair Value of Derivative Positions (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Interest Rate Lock Commitments [Member]
Derivatives Fair Value [Line Items]
Outstanding Notional Balance		$ 9,438
Derivative financial instruments, assets at fair value		305
Forward Mortgage-Backed Securities Trades [Member]
Derivatives Fair Value [Line Items]
Outstanding Notional Balance		40,750
Derivative financial instruments, assets at fair value		3
Derivative financial instruments, liabilities at fair value		83
Commercial Loan Interest Rate Swaps and Caps [Member] | Loan Customer Counterparty [Member]
Derivatives Fair Value [Line Items]
Outstanding Notional Balance	$ 224,928	231,345
Derivative financial instruments, assets at fair value	13,510	4,829
Derivative financial instruments, liabilities at fair value		240
Commercial Loan Interest Rate Swaps and Caps [Member] | Financial Institution Counterparty [Member]
Derivatives Fair Value [Line Items]
Outstanding Notional Balance	224,928	231,345
Derivative financial instruments, assets at fair value		240
Derivative financial instruments, liabilities at fair value	$ 13,510	$ 4,829

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Derivative Financial Instruments - Schedule of Weighted Average Received and Paid Interest Rates for Interest Rate Swaps Outstanding (Details) - Commercial Loan Interest Rate Swaps and Caps [Member] - Loan Customer Counterparty [Member]	Sep. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Weighted-Average Interest Rate Received	0.0058	0.0342
Weighted-Average Interest Rate Paid	0.0283	0.0286

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Derivative Financial Instruments - Additional Information (Details) - Interest Rate Swap - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Credit exposure	$ 13,500,000	$ 4,800,000
Cash collateral pledged	15,300,000	$ 9,300,000
Financial Institution Counterparty [Member]
Derivative [Line Items]
Credit exposure	$ 0

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Derivative Financial Instruments - Schedule of Income (Loss) from Derivatives (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Interest Rate Lock Commitments [Member]
Derivative Instruments Gain Loss [Line Items]
Derivatives not designated as hedging instruments	$ (305)
Forward Mortgage-Backed Securities Trades [Member]
Derivative Instruments Gain Loss [Line Items]
Derivatives not designated as hedging instruments	$ (2,398)

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Acquisitions (Summary) - Additional Information (Details)	9 Months Ended
	Sep. 30, 2020
Minimum [Member]
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	10 years
Maximum [Member]
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	15 years

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Acquisitions (2019 Acquisitions) - Additional Information (Details) $ / shares in Units, $ in Thousands		3 Months Ended	9 Months Ended	12 Months Ended
	Nov. 01, 2019 USD ($) Location City $ / shares shares	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($) shares	Dec. 31, 2019 USD ($)	Jun. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Total assets		$ 33,197,599	$ 33,197,599	$ 32,185,708
Total deposits		26,459,206	26,459,206	24,199,732
Shareholders’ equity		6,034,877	6,034,877	5,970,835	$ 5,948,122	$ 4,126,806	$ 4,127,895	$ 4,052,824
Goodwill		3,231,692	3,231,692	3,223,671				$ 1,900,845
Finite-lived intangible assets acquired				60,058
Merger-related expenses			$ 8,018
Legacy Texas [Member]
Business Acquisition [Line Items]
Total assets						10,500,000
Total gross loans						9,100,000
Total deposits						6,500,000
Shareholders’ equity						$ 1,200,000
Legacy Texas [Member]
Business Acquisition [Line Items]
Business acquisition, equity interest issued or issuable, number of shares | shares	26,228,148		26,228,148
Business acquisition, closing share price | $ / shares	$ 69.02
Payments to acquire businesses in cash	$ 318,000		$ 318,018
Payments to acquire businesses in cash, cash	308,600
Payments to acquire businesses in cash, cash for taxes withheld	$ 9,400
Goodwill		1,330,847	1,330,847
Finite-lived intangible assets acquired			52,100
Merger-related expenses		$ 0	$ 8,000	$ 46,400
Legacy Texas [Member] | North Texas [Member]
Business Acquisition [Line Items]
Number of bank operating locations | Location	42
Number of bank operating cities | City	19

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Acquisitions - Amounts Recorded on Consolidated Balance Sheet on Acquisition Date (Details) - USD ($) $ in Thousands		9 Months Ended
	Nov. 01, 2019	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair value of liabilities assumed:
Goodwill		$ 3,231,692	$ 3,223,671	$ 1,900,845
Legacy Texas [Member]
Fair value of consideration paid:
Common stock issued (26,228,148 shares)		1,810,267
Payments to acquire businesses in cash	$ 318,000	318,018
Total consideration paid		2,128,285
Fair value of assets acquired:
Cash and due from banks		228,649
Securities held to maturity		472,933
Loans held for sale		60,818
Loans held for investment		6,771,080
Loans held for investment - Warehouse Purchase Program		1,693,049
Bank premises and equipment		66,048
Other real estate owned		4,876
Core deposit intangibles		60,058
Federal Home Loan Bank stock		117,826
Bank owned life insurance and other assets		235,467
Total assets acquired		9,710,804
Fair value of liabilities assumed:
Deposits		6,434,732
Other borrowings		2,078,682
Securities sold under repurchase agreements		57,670
Trust preferred securities		15,376
Subordinated notes		125,950
Other liabilities		200,956
Total liabilities assumed		8,913,366
Fair value of net assets acquired		797,438
Goodwill		1,330,847
ASC 805 [Member] | Legacy Texas [Member]
Fair value of consideration paid:
Common stock issued (26,228,148 shares)	1,810,267
Payments to acquire businesses in cash	318,018
Total consideration paid	2,128,285
Fair value of assets acquired:
Cash and due from banks	228,649
Securities held to maturity	472,933
Loans held for sale	60,818
Loans held for investment	6,771,080
Loans held for investment - Warehouse Purchase Program	1,693,049
Bank premises and equipment	67,347
Other real estate owned	4,876
Core deposit intangibles	60,058
Federal Home Loan Bank stock	117,939
Bank owned life insurance and other assets	242,592
Total assets acquired	9,719,341
Fair value of liabilities assumed:
Deposits	6,434,732
Other borrowings	2,078,682
Securities sold under repurchase agreements	57,670
Trust preferred securities	15,376
Subordinated notes	125,950
Other liabilities	201,472
Total liabilities assumed	8,913,882
Fair value of net assets acquired	805,459
Goodwill	$ 1,322,826
Measurement Period Adjustments [Member] | ASC 805 [Member] | Legacy Texas [Member]
Fair value of assets acquired:
Bank premises and equipment		(1,299)
Federal Home Loan Bank stock		(113)
Bank owned life insurance and other assets		(7,125)
Total assets acquired		(8,537)
Fair value of liabilities assumed:
Other liabilities		(516)
Total liabilities assumed		(516)
Fair value of net assets acquired		(8,021)
Goodwill		$ 8,021

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Acquisitions - Amounts Recorded on Consolidated Balance Sheet on Acquisition Date (Parenthetical) (Details) - shares		9 Months Ended
	Nov. 01, 2019	Sep. 30, 2020
Legacy Texas [Member]
Business Acquisition [Line Items]
Business acquisition, equity interest issued or issuable, number of shares	26,228,148	26,228,148

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Acquisitions - Summary of Pro Forma Information (Details) - Legacy Texas [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Changes In Accretable Yield for PCI And Non PCI Loans [Line Items]
Net interest income	$ 259,730	$ 768,548
Net income	$ 140,400	$ 367,677
Basic earnings per share	$ 1.47	$ 3.85
Diluted earnings per share	$ 1.47	$ 3.85