10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF

THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2017

Commission file number 0-7674

FIRST FINANCIAL BANKSHARES, INC.

(Exact name of registrant as specified in its charter)

Texas	75-0944023
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)
400 Pine Street, Abilene, Texas	79601
(Address of principal executive offices)	(Zip Code)

(325) 627-7155

(Registrant’s telephone number, including area code)

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 and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulations S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post 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 the definitions of “large accelerated filer,” “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	☐  (Do not check if a smaller reporting company)	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 Act).    Yes  ☐    No  ☒

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date:

Class	Outstanding at October 31, 2017
Common Stock, $0.01 par value per share	66,226,057

TABLE OF CONTENTS

Item		Page
1.	Financial Statements		3
	Consolidated Balance Sheets – Unaudited		4
	Consolidated Statements of Earnings – Unaudited		5
	Consolidated Statements of Comprehensive Earnings – Unaudited		6
	Consolidated Statements of Shareholders’ Equity – Unaudited		7
	Consolidated Statements of Cash Flows – Unaudited		8
	Notes to Consolidated Financial Statements – Unaudited		9
2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations		33
3.	Quantitative and Qualitative Disclosures About Market Risk		52
4.	Controls and Procedures		52
PART II
OTHER INFORMATION
1.	Legal Proceedings		53
1A.	Risk Factors		53
2.	Unregistered Sales of Equity Securities and Use of Proceeds		53
3.	Defaults Upon Senior Securities		53
4.	Mine Safety Disclosures		53
5.	Other Information		53
6.	Exhibits		54
	Signatures		55

2

PART I

FINANCIAL INFORMATION

Item 1. Financial Statements.

The consolidated balance sheets of First Financial Bankshares, Inc. (the “Company” or “we”) at September 30, 2017 and 2016 and December 31, 2016, and the consolidated statements of earnings and comprehensive earnings for the three and nine months ended September 30, 2017 and 2016, and the consolidated statements of shareholders’ equity and cash flows for the nine months ended September 30, 2017 and 2016, follow on pages 4 through 8.

3

FIRST FINANCIAL BANKSHARES, INC. AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

(Dollars in thousands, except per share amounts)

	Septembere 30,						December 31,
	2017			2016			2016
ASSETS	(Unaudited)
CASH AND DUE FROM BANKS	$	177,615		$	166,981		$	204,782
FEDERAL FUNDS SOLD		—			3,400			3,130
INTEREST-BEARING DEPOSITS IN BANKS		166,820			117,334			48,574
Total cash and cash equivalents		344,435			287,715			256,486
INTEREST-BEARING TIME DEPOSITS IN BANKS		1,458			1,707			1,707
SECURITIES AVAILABLE-FOR-SALE, at fair value		2,885,483			2,729,030			2,860,837
SECURITIES HELD-TO-MATURITY (fair value of $133 and $124 at September 30, 2016, and December 31, 2016, respectively)		—			129			121
LOANS:
Held for investment		3,472,227			3,337,793			3,357,307
Less - allowance for loan losses		(47,922	)		(45,298	)		(45,779	)
Net loans held for investment		3,424,305			3,292,495			3,311,528
Held for sale		19,119			31,591			26,898
Net loans		3,443,424			3,324,086			3,338,426
BANK PREMISES AND EQUIPMENT, net		125,668			122,725			122,685
INTANGIBLE ASSETS		141,355			143,729			143,603
OTHER ASSETS		67,341			77,615			86,066
Total assets	$	7,009,164		$	6,686,736		$	6,809,931
LIABILITIES AND SHAREHOLDERS’ EQUITY
NONINTEREST-BEARING DEPOSITS	$	1,949,174		$	1,702,993		$	1,717,722
INTEREST-BEARING DEPOSITS		3,748,286			3,532,471			3,760,817
Total deposits		5,697,460			5,235,464			5,478,539
DIVIDENDS PAYABLE		12,580			11,891			11,897
BORROWINGS		351,435			513,759			445,770
OTHER LIABILITIES		41,133			57,678			35,840
Total liabilities		6,102,608			5,818,792			5,972,046
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS’ EQUITY:
Common stock - ($0.01 par value, authorized 120,000,000 shares; 66,223,957, 66,063,285, and 66,094,695 shares issued at September 30, 2017 and 2016, and December 31, 2016, respectively)		662			661			661
Capital surplus		376,286			371,170			372,245
Retained earnings		493,706			431,765			446,534
Treasury stock (shares at cost: 498,459, 510,955, and 507,409 at September 30, 2017 and 2016, and December 31, 2016, respectively)		(7,028	)		(6,566	)		(6,671	)
Deferred compensation		7,028			6,566			6,671
Accumulated other comprehensive earnings		35,902			64,348			18,445
Total shareholders’ equity		906,556			867,944			837,885
Total liabilities and shareholders’ equity	$	7,009,164		$	6,686,736		$	6,809,931

See notes to consolidated financial statements.

4

FIRST FINANCIAL BANKSHARES, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF EARNINGS - (UNAUDITED)

(Dollars in thousands, except per share amounts)

	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
INTEREST INCOME:
Interest and fees on loans	$	42,749		$	40,411		$	123,643		$	120,700
Interest on investment securities:
Taxable		8,074			6,775			23,848			21,167
Exempt from federal income tax		11,091			10,808			33,991			32,220
Interest on federal funds sold and interest-bearing deposits in banks		640			99			1,037			222
Total interest income		62,554			58,093			182,519			174,309
INTEREST EXPENSE:
Interest on deposits		2,228			1,112			5,748			3,197
Other		638			254			978			811
Total interest expense		2,866			1,366			6,726			4,008
Net interest income		59,688			56,727			175,793			170,301
PROVISION FOR LOAN LOSSES		1,415			3,833			5,090			8,219
Net interest income after provision for loan losses		58,273			52,894			170,703			162,082
NONINTEREST INCOME:
Trust fees		6,040			5,066			17,804			14,446
Service charges on deposit accounts		5,083			4,796			14,517			13,614
ATM, interchange and credit card fees		6,340			6,000			19,102			17,521
Real estate mortgage operations		3,891			4,697			11,496			11,849
Net gain on sale of available-for-sale securities (includes $1,075 and $239 for the three months ended September 30, 2017 and 2016, respectively, and $1,825 and $1,153 for the nine months ended September 30, 2017 and 2016, respectively, related to accumulated other comprehensive earnings reclassifications)		1,075			239			1,825			1,153
Net gain (loss) on sale of foreclosed assets		(11	)		(10	)		(42	)		343
Net gain (loss) on sale of assets		(15	)		(168	)		(211	)		271
Interest on loan recoveries		405			709			896			1,970
Other		1,452			823			3,328			2,243
Total noninterest income		24,260			22,152			68,715			63,410
NONINTEREST EXPENSE:
Salaries and employee benefits		24,143			22,931			70,867			67,668
Net occupancy expense		2,711			2,672			8,081			7,886
Equipment expense		3,294			3,420			10,397			10,186
FDIC insurance premiums		561			513			1,657			2,155
ATM, interchange and credit card expenses		2,001			1,859			5,517			5,352
Professional and service fees		2,036			1,883			5,878			5,099
Printing, stationery and supplies		449			536			1,423			1,504
Operational and other losses		1,081			533			2,639			1,452
Amortization of intangible assets		143			172			477			570
Other		7,545			7,484			22,955			21,968
Total noninterest expense		43,964			42,003			129,891			123,840
EARNINGS BEFORE INCOME TAXES		38,569			33,043			109,527			101,652
INCOME TAX EXPENSE (includes $376 and $84 for the three months ended September 30, 2017 and 2016, respectively, and $639 and $404 for the nine months ended September 30, 2017 and 2016, respectively, related to income tax expense from reclassification items)		9,195			7,440			25,300			23,544
NET EARNINGS	$	29,374		$	25,603		$	84,227		$	78,108
EARNINGS PER SHARE, BASIC	$	0.44		$	0.39		$	1.27		$	1.18
EARNINGS PER SHARE, ASSUMING DILUTION	$	0.44		$	0.39		$	1.27		$	1.18
DIVIDENDS PER SHARE	$	0.19		$	0.18		$	0.56		$	0.52

See notes to consolidated financial statements.

5

FIRST FINANCIAL BANKSHARES, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS - (UNAUDITED)

(Dollars in thousands)

	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
NET EARNINGS	$	29,374		$	25,603		$	84,227		$	78,108
OTHER ITEMS OF COMPREHENSIVE EARNINGS (LOSS):
Change in unrealized gain on investment securities available-for-sale, before income taxes		1,729			(18,984	)		28,682			27,235
Reclassification adjustment for realized gains on investment securities included in net earnings, before income tax		(1,075	)		(239	)		(1,825	)		(1,153	)
Total other items of comprehensive earnings		654			(19,223	)		26,857			26,082
Income tax benefit (expense) related to other items of comprehensive earnings		(229	)		6,728			(9,400	)		(9,129	)
COMPREHENSIVE EARNINGS	$	29,799		$	13,108		$	101,684		$	95,061

See notes to consolidated financial statements.

6

FIRST FINANCIAL BANKSHARES, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF SHAREHOLDERS’ EQUITY

(Dollars in thousands, except per share amounts)

																		Accumulated
																		Other		Total
	Common Stock				Capital		Retained			Treasury Stock						Deferred		Comprehensive		Shareholders’
	Shares		Amount		Surplus		Earnings			Shares			Amounts			Compensation		Earnings		Equity
Balances at December 31, 2015		65,990,234	$	660	$	368,925	$	388,006			(520,651	)	$	(6,296	)	$	6,296	$	47,395	$	804,986
Net earnings (unaudited)		—		—		—		78,108			—			—			—		—		78,108
Stock option exercises (unaudited)		66,866		1		988		—			—			—			—		—		989
Restricted stock grant (unaudited)		6,185		—		250		—			—			—			—		—		250
Cash dividends declared, $0.52 per share (unaudited)		—		—		—		(34,349	)		—			—			—		—		(34,349	)
Change in unrealized gain in investment securities available-for-sale, net of related income taxes (unaudited)		—		—		—		—			—			—			—		16,953		16,953
Additional tax benefit related to directors’ deferred compensation plan (unaudited)		—		—		345		—			—			—			—		—		345
Shares purchased in connection with directors’ deferred compensation plan, net (unaudited)		—		—		—		—			9,696			(270	)		270		—		—
Stock option expense (unaudited)		—		—		662		—			—			—			—		—		662
Balances at September 30, 2016 (unaudited)		66,063,285	$	661	$	371,170	$	431,765			(510,955	)	$	(6,566	)	$	6,566	$	64,348	$	867,944
Balances at December 31, 2016		66,094,695	$	661	$	372,245	$	446,534			(507,409	)	$	(6,671	)	$	6,671	$	18,445	$	837,885
Net earnings (unaudited)		—		—		—		84,227			—			—			—		—		84,227
Stock option exercises (unaudited)		114,612		1		2,259		—			—			—			—		—		2,260
Restricted stock grant (unaudited)		14,650		—		600		—			—			—			—		—		600
Cash dividends declared, $.056 per share (unaudited)		—		—		—		(37,055	)		—			—			—		—		(37,055	)
Change in unrealized gain in investment securities available-for-sale, net of related income taxes (unaudited)		—		—		—		—			—			—			—		17,457		17,457
Shares purchased in connection with directors’ deferred compensation plan, net (unaudited)		—		—		—		—			8,950			(357	)		357		—		—
Stock option expense (unaudited)		—		—		1,182		—			—			—			—		—		1,182
Balances at September 30, 2017 (unaudited)		66,223,957	$	662	$	376,286	$	493,706			(498,459	)	$	(7,028	)	$	7,028	$	35,902	$	906,556

See notes to consolidated financial statements.    

7

FIRST FINANCIAL BANKSHARES, INC. AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS - (UNAUDITED)

(Dollars in thousands)

	Nine Months Ended September 30,
	2017			2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net earnings	$	84,227		$	78,108
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization		9,447			8,627
Provision for loan losses		5,090			8,219
Securities premium amortization (discount accretion), net		23,009			21,275
Gain on sale of assets, net		(1,572	)		(1,767	)
Deferred federal income tax benefit		1,290			825
Change in loans held-for-sale		7,779			1,952
Change in other assets		18,703			10,059
Change in other liabilities		7,172			530
Total adjustments		70,918			49,720
Net cash provided by operating activities		155,145			127,828
CASH FLOWS FROM INVESTING ACTIVITIES:
Net decrease in interest-bearing time deposits in banks		249			1,788
Activity in available-for-sale securities:
Sales		120,576			20,792
Maturities		4,299,781			2,830,522
Purchases		(4,450,719	)		(2,835,964	)
Activity in held-to-maturity securities - maturities		124			148
Net increase in loans		(119,911	)		(27,446	)
Purchases of bank premises and equipment and other assets		(12,626	)		(17,151	)
Proceeds from sale of other assets		4,857			2,960
Net cash used in investing activities		(157,669	)		(24,351	)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase (decrease) in noninterest-bearing deposits		231,452			(42,959	)
Net increase (decrease) in interest-bearing deposits		(12,531	)		88,254
Net decrease in borrowings		(94,335	)		(101,916	)
Common stock transactions:
Proceeds from stock issuances		2,260			989
Dividends paid		(36,373	)		(33,016	)
Net cash provided by (used in) financing activities		90,473			(88,648	)
NET DECREASE IN CASH AND CASH EQUIVALENTS		87,949			14,829
CASH AND CASH EQUIVALENTS, beginning of period		256,486			272,886
CASH AND CASH EQUIVALENTS, end of period	$	344,435		$	287,715
SUPPLEMENTAL INFORMATION AND NONCASH TRANSACTIONS:
Interest paid	$	6,772		$	4,018
Federal income tax paid		21,896			21,631
Transfer of loans and bank premises to other real estate owned		2,044			1,905
Investment securities purchased but not settled		993			4,521
Restricted stock grant to officers and directors		600			250

See notes to consolidated financial statements.

8

FIRST FINANCIAL BANKSHARES, INC. AND SUBSIDIARIES

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)

Note 1 - Basis of Presentation

The unaudited interim consolidated financial statements include the accounts of the Company, a Texas corporation and a financial holding company registered under the Bank Holding Company Act of 1956, as amended, or BHCA, and its wholly-owned subsidiaries: First Financial Bank, National Association, Abilene, Texas; First Technology Services, Inc.; First Financial Trust & Asset Management Company, National Association; First Financial Investments, Inc.; and First Financial Insurance Agency, Inc.

Through our subsidiary bank, we conduct a full-service commercial banking business. Our banking centers are located primarily in Central, North Central, Southeast and West Texas. As of September 30, 2017, we had 69 financial centers across Texas, with eleven locations in Abilene, three locations in San Angelo and Weatherford, two locations in Cleburne, Conroe, Stephenville and Granbury, and one location each in Acton, Albany, Aledo, Alvarado, Beaumont, Boyd, Bridgeport, Brock, Burleson, Cisco, Clyde, Cut and Shoot, Decatur, Eastland, Fort Worth, Glen Rose, Grapevine, Hereford, Huntsville, Keller, Magnolia, Mauriceville, Merkel, Midlothian, Mineral Wells, Montgomery, Moran, New Waverly, Newton, Odessa, Orange, Port Arthur, Ranger, Rising Star, Roby, Southlake, Sweetwater, Tomball, Trent, Trophy Club, Vidor, Waxahachie, Willis and Willow Park, all in Texas. Our trust subsidiary has seven locations which are located in Abilene, Fort Worth, Odessa, Beaumont, San Angelo, Stephenville and Sweetwater.

In the opinion of management, the unaudited interim consolidated financial statements reflect all adjustments necessary for a fair presentation of the Company’s financial position and unaudited results of operations and should be read in conjunction with the Company’s audited consolidated financial statements, and notes thereto in the Company’s Annual Report on Form 10-K, for the year ended December 31, 2016. All adjustments were of a normal recurring nature. However, the results of operations for the three and nine months ended September 30, 2017, are not necessarily indicative of the results to be expected for the year ending December 31, 2017, due to seasonality, changes in economic conditions and loan credit quality, interest rate fluctuations, regulatory and legislative changes and other factors. The preparation of financial statements in conformity with United States generally accepted accounting principles (“GAAP”) require management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the financial statement date. Actual results could vary. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted under U.S. Securities and Exchange Commission (“SEC”) rules and regulations. The Company evaluated subsequent events for potential recognition and/or disclosure through the date the consolidated financial statements were issued.

Goodwill and other intangible assets are evaluated annually for impairment as of the end of the second quarter. No such impairment has been noted in connection with the current or any prior evaluations.

9

Note 2 - Stock Repurchase

On July 25, 2017, the Company’s Board of Directors authorized the repurchase of up to 2,000,000 common shares through September 30, 2020. Previously, the Board had authorized the repurchase of up to 1,500,000 common shares through September 30, 2017. The shares buyback plan authorizes management to repurchase the shares at such time as repurchases are considered beneficial to shareholders. Any repurchase of shares will be made through the open market, block trades or in privately negotiated transactions in accordance with applicable laws and regulations. Under the repurchase plan, there is no minimum number of shares that the Company is required to repurchase. Through October 27, 2017, no shares were repurchased under this authorization or the previous authorization.

Note 3 - Earnings Per Share

Basic earnings per common share is computed by dividing net income available to common shareholders by the weighted average number of shares outstanding during the periods presented. In computing diluted earnings per common share for the three months and nine months ended September 30, 2017 and 2016, the Company assumes that all dilutive outstanding options to purchase common shares have been exercised at the beginning of the period (or the time of issuance, if later). The dilutive effect of the outstanding options and the restricted shares is reflected by application of the treasury stock method, whereby the proceeds from exercised options and restricted shares are assumed to be used to purchase common stock at the average market price during the respective periods. The weighted average common shares outstanding used in computing basic earnings per common share for the three months ended September 30, 2017 and 2016 were 66,140,518 and 66,023,069 shares, respectively. The weighted average common shares outstanding used in computing basic earnings per common share for the nine months ended September 30, 2017 and 2016 were 66,104,914 and 66,004,797 shares, respectively. The weighted average common shares outstanding used in computing fully diluted earnings per common share for the three months ended September 30, 2017 and 2016 were 66,417,281 and 66,147,202 shares, respectively. The weighted average common shares outstanding used in computing fully diluted earnings per common share for the nine months ended September 30, 2017 and 2016 were 66,392,210 and 66,135,918 shares, respectively.

Note 4 - Interest-bearing Time Deposits in Banks and Securities

Interest-bearing time deposits in banks totaled $1,458,000, $1,707,000 and $1,707,000 at September 30, 2017 and 2016 and December 31, 2016, respectively, and have original maturities generally ranging from one to two years.

Management classifies debt and equity securities as held-to-maturity, available-for-sale, or trading based on its intent. Debt securities that management has the positive intent and ability to hold to maturity are classified as held-to-maturity and recorded at cost, adjusted for amortization of premiums and accretion of discounts, which are recognized as adjustments to interest income using the interest method. Securities not classified as held-to-maturity or trading are classified as available-for-sale and recorded at fair value, with all unrealized gains and unrealized losses judged to be temporary, net of deferred income taxes, excluded from earnings and reported in the consolidated statements of comprehensive earnings. Available-for-sale securities that have unrealized losses that are judged other-than-temporary are included in gain (loss) on sale of securities and a new cost basis is established. Securities classified as trading are recorded at fair value with unrealized gains and losses included in earnings.

The Company records its available-for-sale and trading securities portfolio at fair value. Fair values of these securities are determined based on methodologies in accordance with current authoritative accounting guidance. Fair values are volatile and may be influenced by a number of factors, including market interest rates, prepayment speeds, discount rates, credit ratings and yield curves. Fair values for investment securities are based on quoted market prices, where available. If quoted market prices are not available, fair values are based on the quoted prices of similar instruments or an estimate of fair value by using a range of fair value estimates in the market place as a result of the illiquid market specific to the type of security.

10

When the fair value of a security is below its amortized cost, and depending on the length of time the condition exists and the extent the fair value is below amortized cost, additional analysis is performed to determine whether an other-than-temporary impairment condition exists. Available-for-sale and held-to-maturity securities are analyzed quarterly for possible other-than-temporary impairment. The analysis considers (i) whether we have the intent to sell our securities prior to recovery and/or maturity, (ii) whether it is more likely than not that we will have to sell our securities prior to recovery and/or maturity, (iii) the length of time and extent to which the fair value has been less than amortized cost, and (iv) the financial condition of the issuer. Often, the information available to conduct these assessments is limited and rapidly changing, making estimates of fair value subject to judgment. If actual information or conditions are different than estimated, the extent of the impairment of the security may be different than previously estimated, which could have a material effect on the Company’s results of operations and financial condition.

The Company’s investment portfolio consists of U.S. Treasury securities, obligations of U.S. government sponsored enterprises and agencies, obligations of states and political subdivisions, mortgage pass-through securities, corporate bonds and general obligation or revenue based municipal bonds. Pricing for such securities is generally readily available and transparent in the market. The Company utilizes independent third-party pricing services to value its investment securities, which the Company reviews as well as the underlying pricing methodologies for reasonableness and to ensure such prices are aligned with pricing matrices. The Company validates quarterly, on a sample basis, prices supplied by the independent pricing services by comparison to prices obtained from other third-party sources.

A summary of the Company’s available-for-sale securities follows (in thousands):

	September 30, 2017
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Obligations of U.S. government sponsored enterprises and agencies	$	73,583	$	35	$	(30	)	$	73,588
Obligations of states and political subdivisions		1,379,117		56,671		(1,594	)		1,434,194
Corporate bonds and other		19,439		118		(2	)		19,555
Residential mortgage-backed securities		1,024,615		8,466		(3,797	)		1,029,284
Commercial mortgage-backed securities		328,806		945		(889	)		328,862
Total securities available-for-sale	$	2,825,560	$	66,235	$	(6,312	)	$	2,885,483

11

	September 30, 2016
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
U.S. Treasury securities	$	10,685	$	54	$	—		$	10,739
Obligations of U.S. government sponsored enterprises and agencies		114,918		802		—			115,720
Obligations of states and political subdivisions		1,419,737		83,694		(715	)		1,502,716
Corporate bonds and other		68,285		1,325		(1	)		69,609
Residential mortgage-backed securities		750,673		17,125		(1,299	)		766,499
Commercial mortgage-backed securities		259,636		4,200		(89	)		263,747
Total securities available-for-sale	$	2,623,934	$	107,200	$	(2,104	)	$	2,729,030

	December 31, 2016
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
U.S. Treasury securities	$	10,649	$	19	$	—		$	10,668
Obligations of U.S. government sponsored enterprises and agencies		113,450		253		—			113,703
Obligations of states and political subdivisions		1,534,095		40,194		(10,013	)		1,564,276
Corporate bonds and other		51,920		476		(3	)		52,393
Residential mortgage-backed securities		848,614		8,260		(5,513	)		851,361
Commercial mortgage-backed securities		269,044		622		(1,230	)		268,436
Total securities available-for-sale	$	2,827,772	$	49,824	$	(16,759	)	$	2,860,837

Disclosures related to the Company’s held-to-maturity securities, which totaled $129,000 and $121,000 at September 30, 2016, and December 31, 2016, respectively, have not been presented due to insignificance. There were no held-to-maturity securities owned by the Company at September 30, 2017.

The Company invests in mortgage-backed securities that have expected maturities that differ from their contractual maturities. These differences arise because borrowers may have the right to call or prepay obligations with or without a prepayment penalty. These securities include collateralized mortgage obligations (CMOs) and other asset backed securities. The expected maturities of these securities at September 30, 2017 were computed by using scheduled amortization of balances and historical prepayment rates. At September 30, 2017 and 2016, and December 31, 2016, the Company did not hold CMOs that entail higher risks than standard mortgage-backed securities.

The amortized cost and estimated fair value of available-for-sale securities at September 30, 2017, by contractual and expected maturity, are shown below (in thousands):

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	Amortized Cost Basis		Estimated Fair Value
Due within one year	$	187,370	$	189,136
Due after one year through five years		650,523		679,535
Due after five years through ten years		632,562		656,623
Due after ten years		1,684		2,043
Mortgage-backed securities		1,353,421		1,358,146
Total	$	2,825,560	$	2,885,483

The following tables disclose, as of September 30, 2017 and 2016, and December 31, 2016, the Company’s investment securities that have been in a continuous unrealized-loss position for less than 12 months and for 12 or more months (in thousands):

	Less than 12 Months				12 Months or Longer				Total
September 30, 2017	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of U.S.government sponsored enterprises and agencies	$	45,050	$	30	$	—	$	—	$	45,050	$	30
Obligations of states and political subdivisions		54,983		309		45,217		1,285		100,200		1,594
Corporate bonds and other		—		—		240		2		240		2
Residential mortgage-backed securities		225,369		1,531		131,849		2,266		357,218		3,797
Commercial mortgage-backed securities		170,146		751		21,001		138		191,147		889
Total	$	495,548	$	2,621	$	198,307	$	3,691	$	693,855	$	6,312
	Less than 12 Months				12 Months or Longer				Total
September 30, 2016	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of states and political subdivisions	$	82,131	$	711	$	741	$	4	$	82,872	$	715
Corporate bonds and other		12,257		1		—		—		12,257		1
Residential mortgage-backed securities		80,015		267		57,334		1,032		137,349		1,299
Commercial mortgage-backed securities		10,213		25		13,692		64		23,905		89
Total	$	184,616	$	1,004	$	71,767	$	1,100	$	256,383	$	2,104
	Less than 12 Months				12 Months or Longer				Total
December 31, 2016	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of state and political subdivisions	$	446,052	$	9,997	$	1,209	$	16	$	447,261	$	10,013
Corporate bonds and other		244		3		—		—		244		3
Residential mortgage-backed securities		372,331		4,532		33,227		981		405,558		5,513
Commercial mortgage-backed securities		193,495		1,180		13,263		50		206,758		1,230
Total	$	1,012,122	$	15,712	$	47,699	$	1,047	$	1,059,821	$	16,759

13

The number of investments in an unrealized loss position totaled 179 at September 30, 2017. We do not believe these unrealized losses are “other-than-temporary” as (i) we do not have the intent to sell our securities prior to recovery and/or maturity and (ii) it is more likely than not that we will not have to sell our securities prior to recovery and/or maturity. In making this determination, we also consider the length of time and extent to which fair value has been less than cost and the financial condition of the issuer. The unrealized losses noted are interest rate related due to the level of interest rates at September 30, 2017 compared to the time of purchase. We have reviewed the ratings of the issuers and have not identified any issues related to the ultimate repayment of principal as a result of credit concerns on these securities. Our mortgage related securities are backed by GNMA, FNMA and FHLMC or are collateralized by securities backed by these agencies. At September 30, 2017, 82.70% of our available-for-sale securities that are obligations of states and political subdivisions were issued within the State of Texas, of which 31.16% are guaranteed by the Texas Permanent School Fund.

At September 30, 2017, $1,787,958,000 of the Company’s securities were pledged as collateral for public or trust fund deposits, repurchase agreements and for other purposes required or permitted by law.

During the quarters ended September 30, 2017 and 2016, sales of investment securities that were classified as available-for-sale totaled $83,605,000 and $7,410,000, respectively. Gross realized gains from security sales during the third quarter of 2017 and 2016 totaled $1,750,000 and $239,000, respectively. Gross realized losses from security sales during the third quarter of 2017 totaled $675,000. There were no gross realized losses during the third quarter of 2016.

During the nine months ended September 30, 2017 and 2016, sale of investment securities were classified as available-for-sale totaled $120,576,000 and $20,792,000, respectively. Gross realized gains from security sales during the nine-month period ended September 30, 2017 and 2016 totaled $2,550,000 and $1,158,000, respectively. Gross realized losses from security sales during the nine-month periods ended September 30, 2017 and 2016 totaled $725,000 and $5,000, respectively.

The specific identification method was used to determine cost in order to compute the realized gains and losses.

Note 5 - Loans and Allowance for Loan Losses

Loans held for investment are stated at the amount of unpaid principal, reduced by unearned income and an allowance for loan losses. Interest on loans is calculated by using the simple interest method on daily balances of the principal amounts outstanding. The Company defers and amortizes net loan origination fees and costs as an adjustment to yield. The allowance for loan losses is established through a provision for loan losses charged to expense. Loans are charged against the allowance for loan losses when management believes the collectability of the principal is unlikely.

The Company has certain lending policies and procedures in place that are designed to maximize loan income with an acceptable level of risk. Management reviews and approves these policies and procedures on an annual basis and makes changes as appropriate. Management receives and reviews monthly reports related to loan originations, quality, concentrations, delinquencies, nonperforming and potential problem loans. Diversification in the loan portfolio is a means of managing risk associated with fluctuations in economic conditions, both by type of loan and geographic location.

Commercial loans are underwritten after evaluating and understanding the borrower’s ability to operate profitably and effectively. Underwriting standards are designed to determine whether the borrower possesses sound business ethics and practices and to evaluate current and projected cash flows to determine the ability of the borrower to repay their obligations as agreed. Commercial loans are primarily made based on the identified cash flows of the borrower and, secondarily, on the underlying collateral provided by the borrower. Most commercial loans are secured by the assets being financed or other business assets, such as accounts receivable or inventory, and include personal guarantees.

Agricultural loans are subject to underwriting standards and processes similar to commercial loans. These agricultural loans are based primarily on the identified cash flows of the borrower and secondarily on the underlying collateral provided by the borrower. Most agricultural loans are secured by the agriculture related assets being financed, such as farm land, cattle or equipment, and include personal guarantees.

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Real estate loans are also subject to underwriting standards and processes similar to commercial and agricultural loans. These loans are underwritten primarily based on projected cash flows and, secondarily, as loans secured by real estate. The repayment of real estate loans is generally largely dependent on the successful operation of the property securing the loans or the business conducted on the property securing the loan. Real estate loans may be more adversely affected by conditions in the real estate markets or in the general economy. The properties securing the Company’s real estate portfolio are generally diverse in terms of type and geographic location within Texas. This diversity helps reduce the exposure to adverse economic events that affect any single market or industry. Generally, real estate loans are owner occupied which further reduces the Company’s risk.

Consumer loan underwriting utilizes methodical credit standards and analysis to supplement the Company’s underwriting policies and procedures. The Company’s loan policy addresses types of consumer loans that may be originated and the collateral, if secured, which must be perfected. The relatively smaller individual dollar amounts of consumer loans that are spread over numerous individual borrowers also minimize the Company’s risk.

The allowance for loan losses is an amount which represents management’s best estimate of probable losses that are inherent in the Company’s loan portfolio as of the balance sheet date. The allowance for loan losses is comprised of three elements: (i) specific reserves determined based on probable losses on specific classified loans; (ii) a historical valuation reserve component that considers historical loss rates; and (iii) qualitative reserves based upon general economic conditions and other qualitative risk factors both internal and external to the Company. The allowance for loan losses is increased by charges to income and decreased by charge-offs (net of recoveries). Management’s periodic evaluation of the appropriateness of the allowance is based on general economic conditions, the financial condition of borrowers, the value and liquidity of collateral, delinquency, prior loan loss experience, and the results of periodic reviews of the portfolio. For purposes of determining our historical valuation reserve, the loan portfolio, less cash secured loans, government guaranteed loans and classified loans, is multiplied by the Company’s historical loss rate. Specific allocations are increased or decreased in accordance with deterioration or improvement in credit quality and a corresponding increase or decrease in risk of loss on a particular loan. In addition, we adjust our allowance for qualitative factors such as current local economic conditions and trends, including, without limitations, unemployment, oil and gas prices, flood and drought conditions, changes in lending staff, policies and procedures, changes in credit concentrations, changes in the trends and severity of problem loans and changes in trends in volume and terms of loans. This qualitative reserve serves to estimate for additional areas of losses inherent in our portfolio that are not reflected in our historic loss factors.

Although we believe we use the best information available to make loan loss allowance determinations, future adjustments could be necessary if circumstances or economic conditions differ substantially from the assumptions used in making our initial determinations. A decline in the economy and employment rates could result in increased levels of non-performing assets and charge-offs, increased loan provisions and reductions in income. Additionally, bank regulatory agencies periodically review our allowance for loan losses and methodology and could require, in accordance with generally accepted accounting principles, additional provisions to the allowance for loan losses based on their judgment of information available to them at the time of their examination as well as changes to our methodology.

Accrual of interest is discontinued on a loan and payments are applied to principal when management believes, after considering economic and business conditions and collection efforts, the borrower’s financial condition is such that collection of interest is doubtful. Except consumer loans, generally all loans past due greater than 90 days, based on contractual terms, are placed on non-accrual. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured. Consumer loans are generally charged-off when a loan becomes past due 90 days. For other loans in the portfolio, facts and circumstances are evaluated in making charge-off decisions.

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Loans are considered impaired when, based on current information and events, management determines that it is probable we will be unable to collect all amounts due in accordance with the loan agreement, including scheduled principal and interest payments. If a loan is impaired, a specific valuation allowance is allocated, if necessary. Interest payments on impaired loans are typically applied to principal unless collectability of the principal amount is reasonably assured, in which case interest is recognized on a cash basis. Impaired loans, or portions thereof, are charged off when deemed uncollectable.

The Company’s policy requires measurement of the allowance for an impaired, collateral dependent loan based on the fair value of the collateral. Other loan impairments for non-collateral dependent loans are measured based on the present value of expected future cash flows or the loan’s observable market price. At September 30, 2017 and 2016, and December 31, 2016, all significant impaired loans have been determined to be collateral dependent and the allowance for loss has been measured utilizing the estimated fair value of the collateral less costs to sell.

From time to time, the Company modifies its loan agreement with a borrower. A modified loan is considered a troubled debt restructuring when two conditions are met: (i) the borrower is experiencing financial difficulty and (ii) concessions are made by the Company that would not otherwise be considered for a borrower with similar credit risk characteristics. Modifications to loan terms may include a lower interest rate, a reduction of principal, or a longer term to maturity. For all impaired loans, including the Company’s troubled debt restructurings, the Company performs a periodic, well-documented credit evaluation of the borrower’s financial condition and prospects for repayment to assess the likelihood that all principal and interest payments required under the terms of the agreement will be collected in full. When doubt exists about the ultimate collectability of principal and interest, the troubled debt restructuring remains on non-accrual status and payments received are applied to reduce principal to the extent necessary to eliminate such doubt. This determination of accrual status is judgmental and is based on facts and circumstances related to each troubled debt restructuring. Each of these loans is individually evaluated for impairment and a specific reserve is recorded based on probable losses, taking into consideration the related collateral, modified loan terms and cash flow. As of September 30, 2017 and 2016, and December 31, 2016, substantially all of the Company’s troubled debt restructured loans are included in the non-accrual totals.

The Company originates certain mortgage loans for sale in the secondary market. Accordingly, these loans are classified as held-for-sale and are carried at the lower of cost or fair value on an aggregate basis. The mortgage loan sales contracts contain indemnification clauses should the loans default, generally in the first three to nine months, or if documentation is determined not to be in compliance with regulations. The Company’s historic losses as a result of these indemnities have been insignificant.

Loans acquired, including loans acquired in a business combination, are initially recorded at fair value with no valuation allowance. Acquired loans are segregated between those considered to be credit impaired and those deemed performing. To make this determination, management considers such factors as past due status, non-accrual status and credit risk ratings. The fair value of acquired performing loans is determined by discounting expected cash flows, both principal and interest, at prevailing market interest rates. The difference between the fair value and principal balances at acquisition date, the fair value discount, is accreted into interest income over the estimated life of the acquired loan portfolio.

Purchased credit impaired loans are those loans that showed evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all amounts contractually owed. Their acquisition fair value, which includes a credit component at the acquisition date, was based on the estimate of cash flows, both principal and interest, expected to be collected or estimated collateral values if cash flows are not estimable, discounted at prevailing market rates of interest. The difference between the discounted cash flows expected at acquisition and the investment in the loan is recognized as interest income on a level-yield method over the life of the loan, unless management was unable to reasonably forecast cash flows in which case the loans were placed on

16

nonaccrual. Contractually required payments for interest and principal that exceed the cash flows expected at acquisition are not recognized as a yield adjustment. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows subsequent to acquisition are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition. The carrying amount of purchased credit impaired loans at September 30, 2017 and 2016, and December 31, 2016, was $736,000, $1,853,000 and $1,256,000, respectively, compared to a contractual balance of $932,000, $2,528,000, and $1,865,000, respectively. Other purchased credit impaired loan disclosures were omitted due to immateriality.

Loans held-for-investment by class of financing receivables are as follows (in thousands):    

	September 30,				December 31,
	2017		2016		2016
Commercial	$	674,947	$	663,581	$	674,410
Agricultural		83,005		84,716		84,021
Real estate		2,297,556		2,191,260		2,189,844
Consumer		416,719		398,236		409,032
Total loans held-for-investment	$	3,472,227	$	3,337,793	$	3,357,307

Loans held for sale totaled $19,119,000, $31,591,000 and $26,898,000 at September 30, 2017 and 2016, and December 31, 2016, respectively, which are valued using the lower of cost or fair value.

The Company’s non-accrual loans, loans still accruing and past due 90 days or more and restructured loans are as follows (in thousands):

	September 30,				December 31,
	2017		2016		2016
Non-accrual loans*	$	18,750	$	33,712	$	27,371
Loans still accruing and past due 90 days or more		257		107		284
Troubled debt restructured loans**		668		750		701
Total	$	19,675	$	34,569	$	28,356

*Includes $736,000, $1,853,000 and $1,256,000 of purchased credit impaired loans as of September 30, 2017 and 2016, and December 31, 2016, respectively.

**Troubled debt restructured loans of $5,277,000, $7,513,000 and $6,863,000, whose interest collection, after considering economic and business conditions and collection efforts, is doubtful are included in non-accrual loans at September 30, 2017 and 2016, and December 31, 2016, respectively.

The Company’s recorded investment in impaired loans and the related valuation allowance are as follows (in thousands):

September 30, 2017		September 30, 2016		December 31, 2016
Recorded Investment	Valuation Allowance	Recorded Investment	Valuation Allowance	Recorded Investment	Valuation Allowance
$18,750	$4,177	$33,712	$7,042	$27,371	$5,012

The Company had $22,076,000, $34,938,000 and $29,000,000 in non-accrual, past due 90 days or more and still accruing, restructured loans and foreclosed assets at September 30, 2017 and 2016, and December 31, 2016, respectively. Non-accrual loans at September 30, 2017 and 2016, and December 31, 2016, consisted of the following by class of financing receivables (in thousands):

17

	September 30,				December 31,
	2017		2016		2016
Commercial	$	4,133	$	12,714	$	7,284
Agricultural		60		167		99
Real estate		13,386		19,582		18,754
Consumer		1,171		1,249		1,234
Total	$	18,750	$	33,712	$	27,371

No significant additional funds are committed to be advanced in connection with impaired loans as of September 30, 2017.

The Company’s impaired loans and related allowance as of September 30, 2017 and 2016, and December 31, 2016, are summarized in the following tables by class of financing receivables (in thousands). No interest income was recognized on impaired loans subsequent to their classification as impaired.

September 30, 2017	Unpaid Contractual Principal Balance		Recorded Investment With No Allowance*		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance		Year-to- Date Average Recorded Investment		Three- Month Average Recorded Investment
Commercial	$	10,989	$	617	$	3,516	$	4,133	$	1,671	$	7,313	$	5,866
Agricultural		66		—		60		60		17		66		60
Real Estate		17,306		3,742		9,644		13,386		1,984		14,279		13,829
Consumer		1,388		262		909		1,171		505		1,341		1,238
Total	$	29,749	$	4,621	$	14,129	$	18,750	$	4,177	$	22,999	$	20,993

*Includes $736,000 of purchased credit impaired loans.

September 30, 2016	Unpaid Contractual Principal Balance		Recorded Investment With No Allowance*		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance		Year-to- Date Average Recorded Investment		Three- Month Average Recorded Investment
Commercial	$	21,696	$	1,067	$	11,647	$	12,714	$	3,983	$	8,421	$	14,238
Agricultural		168		—		167		167		41		83		84
Real Estate		24,130		5,626		13,956		19,582		2,566		17,021		19,436
Consumer		1,479		324		925		1,249		452		989		1,166
Total	$	47,473	$	7,017	$	26,695	$	33,712	$	7,042	$	26,514	$	34,924

*Includes $1,853,000 of purchased credit impaired loans.

December 31, 2016	Unpaid Contractual Principal Balance		Recorded Investment With No Allowance*		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance		Year Average Recorded Investment
Commercial	$	13,389	$	1,148	$	6,136	$	7,284	$	2,128	$	4,921
Agricultural		103		—		99		99		25		50
Real Estate		23,466		6,229		12,525		18,754		2,428		16,170
Consumer		1,421		280		954		1,234		431		914
Total	$	38,379	$	7,657	$	19,714	$	27,371	$	5,012	$	22,055

*Includes $1,256,000 of purchased credit impaired loans.

The Company recognized interest income on impaired loans prior to being recognized as impaired of approximately $829,000 during the year ended December 31, 2016. Such amounts for the three-month and nine-month periods ended September 30, 2017 and 2016 were not significant.

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From a credit risk standpoint, the Company rates its loans in one of four categories: (i) pass, (ii) special mention, (iii) substandard or (iv) doubtful. Loans rated as loss are charged-off.

The ratings of loans reflect a judgment about the risks of default and loss associated with the loan. The Company reviews the ratings on our credits as part of our on-going monitoring of the credit quality of our loan portfolio. Ratings are adjusted to reflect the degree of risk and loss that are felt to be inherent in each credit as of each reporting period. Our methodology is structured so that specific allocations are increased in accordance with deterioration in credit quality (and a corresponding increase in risk and loss) or decreased in accordance with improvement in credit quality (and a corresponding decrease in risk and loss).

Credits rated special mention show clear signs of financial weaknesses or deterioration in credit worthiness, however, such concerns are not so pronounced that the Company generally expects to experience significant loss within the short-term. Such credits typically maintain the ability to perform within standard credit terms and credit exposure is not as prominent as credits rated more harshly.

Credits rated substandard are those in which the normal repayment of principal and interest may be, or has been, jeopardized by reason of adverse trends or developments of a financial, managerial, economic or political nature, or important weaknesses exist in collateral. A protracted workout on these credits is a distinct possibility. Prompt corrective action is therefore required to strengthen the Company’s position, and/or to reduce exposure and to assure that adequate remedial measures are taken by the borrower. Credit exposure becomes more likely in such credits and a serious evaluation of the secondary support to the credit is performed.

Credits rated doubtful are those in which full collection of principal appears highly questionable, and which some degree of loss is anticipated, even though the ultimate amount of loss may not yet be certain and/or other factors exist which could affect collection of debt. Based upon available information, positive action by the Company is required to avert or minimize loss. Credits rated doubtful are generally also placed on non-accrual.

The following summarizes the Company’s internal ratings of its loans held-for-investment by class of financing receivables and portfolio segments, which are the same, at September 30, 2017 and 2016, and December 31, 2016 (in thousands):

September 30, 2017	Pass		Special Mention		Substandard		Doubtful		Total
Commercial	$	632,693	$	7,997	$	34,257	$	—	$	674,947
Agricultural		79,227		841		2,937		—		83,005
Real Estate		2,224,970		26,231		46,355		—		2,297,556
Consumer		414,043		168		2,508		—		416,719
Total	$	3,350,933	$	35,237	$	86,057	$	—	$	3,472,227
September 30, 2016	Pass		Special Mention		Substandard		Doubtful		Total
Commercial	$	614,900	$	6,108	$	42,573	$	—	$	663,581
Agricultural		82,400		—		2,316		—		84,716
Real Estate		2,118,807		19,064		53,389		—		2,191,260
Consumer		395,086		316		2,832		2		398,236
Total	$	3,211,193	$	25,488	$	101,110	$	2	$	3,337,793
December 31, 2016	Pass		Special Mention		Substandard		Doubtful		Total
Commercial	$	629,756	$	5,769	$	38,885	$	—	$	674,410
Agricultural		81,620		715		1,686		—		84,021
Real Estate		2,111,947		18,091		59,806		—		2,189,844
Consumer		406,182		212		2,638		—		409,032
Total	$	3,229,505	$	24,787	$	103,015	$	—	$	3,357,307

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At September 30, 2017 and 2016, and December 31, 2016, the Company’s past due loans are as follows (in thousands):

September 30, 2017	15-59 Days Past Due*		60-89 Days Past Due		Greater Than 90 Days		Total Past Due		Current		Total Loans		90 Days Past Due Still Accruing
Commercial	$	3,288	$	585	$	1,495	$	5,368	$	669,579	$	674,947	$	212
Agricultural		322		—		—		322		82,683		83,005		—
Real Estate		12,636		984		2,293		15,913		2,281,643		2,297,556		—
Consumer		1,211		457		176		1,844		414,875		416,719		45
Total	$	17,457	$	2,026	$	3,964	$	23,447	$	3,448,780	$	3,472,227	$	257
September 30, 2016	15-59 Days Past Due*		60-89 Days Past Due		Greater Than 90 Days		Total Past Due		Current		Total Loans		90 Days Past Due Still Accruing
Commercial	$	4,707	$	841	$	6,950	$	12,498	$	651,083	$	663,581	$	61
Agricultural		523		63		—		586		84,130		84,716		—
Real Estate		13,444		1,496		3,376		18,316		2,172,944		2,191,260		34
Consumer		1,418		314		180		1,912		396,324		398,236		12
Total	$	20,092	$	2,714	$	10,506	$	33,312	$	3,304,481	$	3,337,793	$	107
December 31, 2016	15-59 Days Past Due*		60-89 Days Past Due		Greater Than 90 Days		Total Past Due		Total Current		Total Loans		Total 90 Days Past Due Still Accruing
Commercial	$	3,908	$	1,122	$	2,220	$	7,250	$	667,160	$	674,410	$	10
Agricultural		185		—		—		185		83,836		84,021		—
Real Estate		13,172		1,301		5,268		19,741		2,170,103		2,189,844		272
Consumer		1,845		368		122		2,335		406,697		409,032		2
Total	$	19,110	$	2,791	$	7,610	$	29,511	$	3,327,796	$	3,357,307	$	284

*The Company monitors commercial, agricultural and real estate loans after such loans are 15 days past due. Consumer loans are monitored after such loans are 30 days past due.

The following table details the allowance for loan losses at September 30, 2017 and 2016, and December 31, 2016, by portfolio segment (in thousands). There were no allowances for purchased credit impaired loans at September 30, 2017 and 2016, and December 31, 2016. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.

September 30, 2017	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	1,671	$	17	$	1,984	$	505	$	4,177
Loans collectively evaluated for impairment		10,201		1,284		26,484		5,776		43,745
Total	$	11,872	$	1,301	$	28,468	$	6,281	$	47,922
September 30, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	3,983	$	41	$	2,566	$	452	$	7,042
Loans collectively evaluated for impairment		9,733		1,027		23,655		3,841		38,256
Total	$	13,716	$	1,068	$	26,221	$	4,293	$	45,298

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December 31, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	2,128	$	25	$	2,428	$	431	$	5,012
Loans collectively evaluated for impairment		9,579		1,076		24,436		5,676		40,767
Total	$	11,707	$	1,101	$	26,864	$	6,107	$	45,779

Changes in the allowance for loan losses for the three and nine months ended September 30, 2017 and 2016, are summarized as follows by portfolio segment (in thousands):

Three months ended September 30, 2017	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	11,935		$	1,127		$	28,023		$	6,325		$	47,410
Provision for loan losses		557			157			424			277			1,415
Recoveries		119			17			50			91			277
Charge-offs		(739	)		—			(29	)		(412	)		(1,180	)
Ending balance	$	11,872		$	1,301		$	28,468		$	6,281		$	47,922
Three months ended September 30, 2016	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	14,026		$	1,451		$	25,644		$	3,939		$	45,060
Provision for loan losses		3,248			(358	)		296			647			3,833
Recoveries		298			4			367			108			777
Charge-offs		(3,856	)		(29	)		(86	)		(401	)		(4,372	)
Ending balance	$	13,716		$	1,068		$	26,221		$	4,293		$	45,298
Nine months ended September 30, 2017	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	11,707		$	1,101		$	26,864		$	6,107		$	45,779
Provision for loan losses		1,485			211			2,556			838			5,090
Recoveries		868			25			141			400			1,434
Charge-offs		(2,188	)		(36	)		(1,093	)		(1,064	)		(4,381	)
Ending balance	$	11,872		$	1,301		$	28,468		$	6,281		$	47,922
Nine months ended September 30, 2016	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	12,644		$	1,191		$	24,375		$	3,667		$	41,877
Provision for loan losses		6,239			41			367			1,572			8,219
Recoveries		839			20			1,957			427			3,243
Charge-offs		(6,006	)		(184	)		(478	)		(1,373	)		(8,041	)
Ending balance	$	13,716		$	1,068		$	26,221		$	4,293		$	45,298

The Company’s recorded investment in loans as of September 30, 2017 and 2016, and December 31, 2016 related to the balance in the allowance for loan losses on the basis of the Company’s impairment methodology was as follows (in thousands). Purchased credit impaired loans of $736,000, $1,853,000 and $1,256,000 at September 30, 2017 and 2016, and December 31, 2016, respectively, are included in loans individually evaluated for impairment.

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September 30, 2017	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	4,133	$	60	$	13,386	$	1,171	$	18,750
Loans collectively evaluated for impairment		670,814		82,945		2,284,170		415,548		3,453,477
Total	$	674,947	$	83,005	$	2,297,556	$	416,719	$	3,472,227
September 30, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	12,714	$	167	$	19,582	$	1,249	$	33,712
Loans collectively evaluated for impairment		650,867		84,549		2,171,678		396,987		3,304,081
Total	$	663,581	$	84,716	$	2,191,260	$	398,236	$	3,337,793
December 31, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	7,284	$	99	$	18,754	$	1,234	$	27,371
Loan collectively evaluated for impairment		667,126		83,922		2,171,090		407,798		3,329,936
Total	$	674,410	$	84,021	$	2,189,844	$	409,032	$	3,357,307

The Company’s loans that were modified in the three and nine months ended September 30, 2017 and 2016 and considered troubled debt restructurings are as follows (in thousands):

	Three Months Ended September 30, 2017						Nine Months Ended September 30, 2017
	Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment		Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment
Commercial		3	$	514	$	514		9	$	838	$	838
Agricultural		—		—		—		—		—		—
Real Estate		1		256		256		3		473		473
Consumer		—		—		—		1		25		25
Total		4	$	770	$	770		13	$	1,336	$	1,336
	Three Months Ended September 30, 2016						Nine Months Ended September 30, 2016
	Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment		Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment
Commercial		3	$	230	$	230		14	$	3,156	$	3,156
Agricultural		—		—		—		—		—		—
Real Estate		3		706		706		5		1,169		1,169
Consumer		1		44		44		5		162		162
Total		7	$	980	$	980		24	$	4,487	$	4,487

The balances below provide information as to how the loans were modified as troubled debt restructured loans during the three and nine months ended September 30, 2017 and 2016 (in thousands):

	Three Months Ended September 30, 2017						Nine Months Ended September 30, 2017
	Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity		Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity
Commercial	$	—	$	—	$	514		—	$	181	$	657
Agricultural		—		—		—		—		—		—
Real Estate		—		256		—		—		312		161
Consumer		—		—		—		—		25		—
Total	$	—	$	256	$	514		—	$	518	$	818

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	Three Months Ended September 30, 2016						Nine Months Ended September 30, 2016
	Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity		Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity
Commercial	$	—	$	112	$	118		—	$	2,561	$	595
Agricultural		—		—		—		—		—		—
Real Estate		—		185		521		—		298		871
Consumer		—		—		44		—		43		119
Total	$	—	$	297	$	683		—	$	2,902	$	1,585

During the three months ended September 30, 2017 and 2016, two loans and two loans, respectively, were modified as troubled debt restructured loan within the previous 12 months and for which there was a payment default. During the nine months ended September 30, 2017 and 2016, four loans and three loans, respectively, were modified as troubled debt restructured loan within the previous 12 months and for which there was a payment default. A default for purposes of this disclosure is a troubled debt restructured loan in which the borrower is 90 days past due or more or results in the foreclosure and repossession of the applicable collateral. The loans with payment default are as follows (dollars in thousands):

	Three Months Ended September 30, 2017				Nine Months Ended September 30, 2017
	Number		Balance		Number		Balance
Commercial		2	$	88		3	$	141
Agriculture		—		—		—		—
Real Estate		—		—		1		62
Consumer		—		—		—		—
Total		2	$	88		4	$	203
	Three Months Ended September 30, 2016				Nine Months Ended September 30, 2016
	Number		Balance		Number		Balance
Commercial		1	$	62		1	$	62
Agriculture		—		—		—		—
Real Estate		1		112		2		462
Consumer		—		—		—		—
Total		2	$	174		3	$	524

As of September 30, 2017, the Company has no commitments to lend additional funds to loan customers whose terms have been modified in troubled debt restructurings.

Our subsidiary bank has established a line of credit with the Federal Home Loan Bank of Dallas (FHLB) to provide liquidity and meet pledging requirements for those customers eligible to have securities pledged to secure certain uninsured deposits. At September 30, 2017, $2,140,557,000 in loans held by our bank subsidiary were subject to blanket liens as security for this line of credit. At September 30, 2017, there was no balance outstanding under this line of credit.

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Note 6 - Borrowings

Borrowings at September 30, 2017 and 2016, and December 31, 2016 consisted of the following (dollars in thousands):

	September 30,				December 31,
	2017		2016		2016
Securities sold under agreements with customers to repurchase	$	339,660	$	345,559	$	360,820
Federal funds purchased		11,775		8,200		9,950
Advances from Federal Home Loan Bank of Dallas		—		160,000		75,000
Total	$	351,435	$	513,759	$	445,770

Securities sold under repurchase agreements are generally with significant customers of the Company that require short-term liquidity for their funds for which the Company pledges certain securities that have a fair value equal to at least the amount of the borrowings. The agreements mature daily and therefore the risk arising from a decline in the fair value of the collateral pledged is minimal. The securities pledged are mortgage-backed securities. These agreements do not include “right of set-off” provisions and therefore the Company does not offset such agreements for financial reporting purposes.

Note 7 - Income Taxes

Income tax expense was $9,195,000 for the third quarter of 2017 as compared to $7,440,000 for the same period in 2016. The Company’s effective tax rates on pretax income were 23.84% and 22.52% for the third quarters of 2017 and 2016, respectively. Income tax expense was $25,300,000 for the nine months ended September 30, 2017 as compared to $23,544,000 for the same period in 2016. The Company’s effective tax rates on pretax income were 23.10% and 23.16% for the nine months ended September 2017 and 2016, respectively. The effective tax rates differ from the statutory federal tax rate of 35% primarily due to tax exempt interest income earned on certain investment securities and loans, the deductibility of dividends paid to our employee stock ownership plan and excess tax benefits related to our directors’ deferred compensation plan.

Note 8 - Stock Option Plan and Restricted Stock Plan

The Company grants incentive stock options for a fixed number of shares with an exercise price equal to the fair value of the shares at the date of grant to employees. In June 2017, the Company granted 452,450 incentive stock options with an exercise price of $42.35 per share. The fair value of the options was $9.90 per option and was estimated using the Black-Scholes options pricing model with the following weighted average assumptions: risk-free interest rate of 1.89%; expected dividend yield of 1.79%; expected life of 6.24 years; and expected volatility of 26.51%. No options were granted in 2016.

The Company recorded stock option expense totaling $750,000 and $221,000 for the three-month periods ended September 30, 2017 and 2016, respectively. The Company recorded stock option expense totaling $1,182,000 and $662,000 for the nine months ended September 30, 2017 and 2016, respectively. The additional disclosure requirements under authoritative accounting guidance have been omitted due to the amounts being insignificant.

On July 21, 2015, 7,070 restricted shares were granted to the ten non-employee directors. Total value of these restricted shares totaled $250,000 and was expensed over the period from grant date to April 26, 2016, the annual shareholders’ meeting at which these director’s term expired. On April 26, 2016, upon re-election of existing directors, 7,660 restricted shares with a total value of $250,000 were granted to the ten non-employee directors and was expensed over the period from grant day to April 25, 2017, the annual shareholders’ meeting at which these directors’ term expired. On April 25, 2017, upon re-election of existing directors, 14,650 restricted shares with a total value of $600,000 were granted to the ten non-employee directors and is being expensed over the period from the grant date to April 24, 2018, the Company’s next shareholders’ meeting at which the directors’ term expires.

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The Company recorded director expense related to these restricted share grants of $150,000 and $63,000 for the three-month periods ended September 30, 2017 and 2016, respectively. The Company recorded director expense related to these restricted share grants of $333,000 and $215,000 for the nine-month periods ended September 30, 2017 and 2016, respectively.

On October 27, 2015, the Company granted 31,273 restricted shares with a total value of $1,060,000 to certain officers that is being expensed over the vesting period of three years. On October 25, 2016, the Company granted 15,405 restricted shares with a total value of $560,000 to certain officers that is being expensed over the vesting period of three years. The Company recorded restricted stock expense for officers of $133,000 and $88,000, for the three-month periods ended September 30, 2017 and 2016, respectively. The Company recorded restricted share expense for officers of $399,000 and $262,000 for the nine-month periods ended September 30, 2017 and 2016, respectively.

On October 24, 2017, the Company granted 14,191 restricted shares with a total value of $655,000 to certain officers that will be expensed over the vesting period of one to three years.

Note 9 - Pension Plan

The Company’s defined benefit pension plan was frozen effective January 1, 2004, whereby no new participants will be added to the plan and no additional years of service will accrue to participants, unless the pension plan is reinstated at a future date. The pension plan covered substantially all of the Company’s employees at the time. The benefits for each employee were based on years of service and a percentage of the employee’s qualifying compensation during the final years of employment. The Company’s funding policy was and is to contribute annually the amount necessary to satisfy the Internal Revenue Service’s funding standards. Contributions to the pension plan, prior to freezing the plan, were intended to provide not only for benefits attributed to service to date but also for those expected to be earned in the future. As a result of the Pension Protection Act of 2006 (the “Protection Act”), the Company will be required to contribute amounts in future years to fund any shortfalls. The Company has evaluated the provisions of the Protection Act as well as the Internal Revenue Service’s funding standards to develop a plan for funding in future years. The Company made a contribution totaling $500,000 in 2016, and has made no contribution through September 30, 2017.

Net periodic benefit costs totaling $84,000 and $82,000 were recorded for the three months ended September 30, 2017 and 2016, respectively. Net periodic benefit costs totaling $253,000 and $247,000 were recorded for the nine months ended September 30, 2017 and 2016, respectively.

Note 10 - Fair Value Disclosures

The authoritative accounting guidance for fair value measurements defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. The price in the principal (or most advantageous) market used to measure the fair value of the asset or liability shall not be adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets and liabilities; it is not a forced transaction. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact, and (iv) willing to transact.

The authoritative accounting guidance requires the use of valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets and liabilities. The income approach uses valuation techniques to convert future amounts, such as cash flows

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or earnings, to a single present amount on a discounted basis. The cost approach is based on the amount that currently would be required to replace the service capacity of an asset (replacement costs). Valuation techniques should be consistently applied.    Inputs to valuation techniques refer to the assumptions that market participants would use in pricing the asset or liability. Inputs may be observable, meaning those that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from independent sources, or unobservable, meaning those that reflect the reporting entity’s own assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. In that regard, the authoritative guidance 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:

• Level 1 Inputs – Unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date.

• Level 2 Inputs – Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. These include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (for example, interest rates, volatilities, prepayment speeds, loss severities, credit risks and default rates) or inputs that are derived principally from or corroborated by observable market data by correlation or other means.

• Level 3 Inputs – Significant unobservable inputs that reflect an entity’s own assumptions that market participants would use in pricing the assets or liabilities.

A description of the valuation methodologies used for assets and liabilities measured at fair value, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below.

In general, fair value is based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon internally developed models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. While management believes the Company’s valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date.

Securities classified as available-for-sale and trading are reported at fair value utilizing Level 1 and Level 2 inputs. For these securities, the Company obtains fair value measurements from an independent pricing service. The fair value measurements consider observable data that may include market spreads, cash flows, the United States Treasury yield curve, live trading levels, trade execution data, dealer quotes, market consensus prepayments speeds, credit information and the security’s terms and conditions, among other items.

There were no transfers between Level 1 and Level 2 or Level 2 and Level 3 during the three and nine months ended September 30, 2017 and 2016, and the year ended December 31, 2016.

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The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of September 30, 2017 and 2016, and December 31, 2016, respectively, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (dollars in thousands):

September 30, 2017
	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Available-for-sale investment securities:
Obligations of U. S. government sponsored enterprises and agencies	$	—	$	73,588	$	—	$	73,588
Obligations of states and political subdivisions		—		1,434,194		—		1,434,194
Corporate bonds		—		15,099		—		15,099
Residential mortgage-backed securities		—		1,029,284		—		1,029,284
Commercial mortgage-backed securities		—		328,862		—		328,862
Other securities		4,456		—		—		4,456
Total	$	4,456	$	2,881,027	$	—	$	2,885,483
September 30, 2016
	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Available-for-sale investment securities:
U.S. Treasury securities	$	10,739	$	—	$	—	$	10,739
Obligations of U. S. government sponsored enterprises and agencies		—		115,720		—		115,720
Obligations of states and political subdivisions		—		1,502,716		—		1,502,716
Corporate bonds		—		65,037		—		65,037
Residential mortgage-backed securities		—		766,499		—		766,499
Commercial mortgage-backed securities		—		263,747		—		263,747
Other securities		4,572		—		—		4,572
Total	$	15,311	$	2,713,719	$	—	$	2,729,030
December 31, 2016
	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Available-for-sale investment securities:
U.S. Treasury securities	$	10,668	$	—	$	—	$	10,668
Obligations of U. S. government sponsored enterprises and agencies		—		113,703		—		113,703
Obligations of states and political subdivisions		—		1,564,276		—		1,564,276
Corporate bonds		—		47,965		—		47,965
Residential mortgage-backed securities		—		851,361		—		851,361
Commercial mortgage-backed securities		—		268,436		—		268,436
Other securities		4,428		—		—		4,428
Total	$	15,096	$	2,845,741	$	—	$	2,860,837

Certain financial assets and financial 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). Financial assets and financial liabilities measured at fair value on a non-recurring basis include the following at September 30, 2017:

Impaired Loans – Impaired loans are reported at the fair value of the underlying collateral if repayment is expected solely from the collateral less costs to sell. Collateral values are estimated using Level 2 inputs based on observable market data. At September 30, 2017, impaired loans with a carrying value of $14,129,000 were reduced by specific valuation reserves totaling $4,177,000 resulting in a net fair value of $9,952,000. The Company also had impaired loans of $4,621,000 with no specific valuation reserve at September 30, 2017, due to the loans carrying value generally being lower than the value of the collateral associated with the loan.

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Loans Held-for-Sale – Loans held-for-sale are reported at the lower of cost or fair value. In determining whether the fair value of loans held-for-sale is less than cost when quoted market prices are not available, the Company considers investor commitments/contracts. These loans are considered Level 2 of the fair value hierarchy. At September 30, 2017, the Company’s mortgage loans held-for-sale were recorded at cost as fair value exceeded cost.    

Certain non-financial assets and non-financial liabilities measured at fair value on a non-recurring basis include other real estate owned, goodwill and other intangible assets and other non-financial long-lived assets. Non-financial assets measured at fair value on a non-recurring basis during the three months and nine months ended September 30, 2017 and 2016 include other real estate owned which, subsequent to their initial transfer to other real estate owned from loans, were re-measured at fair value through a write-down included in gain (loss) on sale of foreclosed assets. During the reported periods, all fair value measurements for foreclosed assets utilized Level 2 inputs based on observable market data, generally third-party appraisals, or Level 3 inputs based on customized discounting criteria. These appraisals are evaluated individually and discounted as necessary due to the age of the appraisal, lack of comparable sales, expected holding periods of property or special use type of the property. Such discounts vary by appraisal based on the above factors but generally range from 5% to 25% of the appraised value. Re-evaluation of other real estate owned is performed at least annually as required by regulatory guidelines or more often if particular circumstances arise. The following table presents other real estate owned that were re-measured subsequent to their initial transfer to other real estate owned (dollars in thousands):

	Three Months Ended September 30,
	2017			2016
Carrying value of other real estate owned prior to re-measurement	$	937		$	—
Write-downs included in gain (loss) on sale of other real estate owned		(288	)		—
Fair value	$	649		$	—
	Nine Months Ended September 30,
	2017			2016
Carrying value of other real estate owned prior to re-measurement	$	1,025		$	—
Write-downs included in gain (loss) on sale of other real estate owned		(296	)		—
Fair value	$	729		$	—

At September 30, 2017 and 2016, and December 31, 2016, other real estate owned totaled $2,176,000, $241,000, and $413,000, respectively.

The Company is required under current authoritative accounting guidance to disclose the estimated fair value of their financial instrument assets and liabilities including those subject to the requirements discussed above. For the Company, as for most financial institutions, substantially all of its assets and liabilities are considered financial instruments. Many of the Company’s financial instruments, however, lack an available trading market as characterized by a willing buyer and willing seller engaging in an exchange transaction.

The estimated fair value amounts of financial instruments have been determined by the Company using available market information and appropriate valuation methodologies. However, considerable judgment is required to interpret data to develop the estimates of fair value. Accordingly, the estimates presented herein are not necessarily indicative of the amounts the Company could realize in a current market exchange. The use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts.

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In addition, reasonable comparability between financial institutions may not be likely due to the wide range of permitted valuation techniques and numerous estimates that must be made given the absence of active secondary markets for many of the financial instruments. This lack of uniform valuation methodologies also introduces a greater degree of subjectivity to these estimated fair values.

Cash and due from banks, federal funds sold, interest-bearing deposits and time deposits in banks and accrued interest receivable and payable are liquid in nature and considered Levels 1 or 2 of the fair value hierarchy.

Financial instruments with stated maturities have been valued using a present value discounted cash flow with a discount rate approximating current market for similar assets and liabilities and are considered Levels 2 and 3 of the fair value hierarchy. Financial instrument liabilities with no stated maturities have an estimated fair value equal to both the amount payable on demand and the carrying value and are considered Level 1 of the fair value hierarchy.

The carrying value and the estimated fair value of the Company’s contractual off-balance-sheet unfunded lines of credit, loan commitments and letters of credit, which are generally priced at market at the time of funding, are not material.

The estimated fair values and carrying values of all financial instruments under current authoritative guidance at September 30, 2017 and 2016, and December 31, 2016, were as follows (in thousands):

	September 30,								December 31,
	2017				2016				2016
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value		Fair Value Hierarchy
Cash and due from banks	$	177,615	$	177,615	$	166,981	$	166,981	$	204,782	$	204,782	Level 1
Federal funds sold		—		—		3,400		3,400		3,130		3,130	Level 1
Interest-bearing deposits in banks		166,820		166,820		117,334		117,334		48,574		48,574	Level 1
Interest-bearing time deposits in banks		1,458		1,458		1,707		1,709		1,707		1,709	Level 2
Available-for-sale Securities		2,885,483		2,885,483		2,729,030		2,729,030		2,860,837		2,860,837	Levels 1 and 2
Held-to-maturity securities		—		—		129		133		121		124	Level 2
Loans		3,443,424		3,458,603		3,324,086		3,334,965		3,338,426		3,361,735	Level 3
Accrued interest receivable		26,321		26,321		26,209		26,209		36,469		36,469	Level 2
Deposits with stated maturities		464,782		465,655		535,793		537,167		508,996		510,304	Level 2
Deposits with no stated maturities		5,232,678		5,232,678		4,699,671		4,699,671		4,969,543		4,969,543	Level 1
Borrowings		351,435		351,435		513,759		513,759		445,770		445,770	Level 2
Accrued interest Payable		179		179		230		230		225		225	Level 2

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Note 11 - Recently Issued Authoritative Accounting Guidance

Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers.” ASU 2014-09 implements a comprehensive new revenue recognition standard that will supersede substantially all existing revenue recognition guidance. The new standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. To achieve that core principle, an entity should apply the following steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract and (v) recognize revenue when (or as) the entity satisfies a performance obligation. ASU 2015-4 “Revenue from Contracts with Customers – Deferral of the Effective Date” deferred the effective date of ASU 2014-09 by one year and as a result, the new standard will be effective the first quarter of 2018. The Company’s revenue is comprised of net interest income on financial assets and financial liabilities, which is explicitly excluded from the scope of ASU 2014-09, and non-interest income. Based on the Company’s analysis of the effect of the new standard on its recurring revenue streams, the Company does not expect these changes to have a significant impact on the Company’s financial statement. Upon adoption in the first quarter of 2018, no significant adjustment to opening retained earnings is expected.

ASU 2014-15, “Presentation of Financial Statements – Going Concern.” ASU 2014-15 requires management to evaluate an entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Management must evaluate whether conditions and events raise substantial doubt about an entity’s ability to continue as a going concern and then whether its plans alleviate that doubt. ASU 2014-15 was effective in 2016 and management has performed and continues to perform such required evaluation and has concluded there are no such conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern.

ASU 2015-01, “Income Statement – Extraordinary and Unusual Items.” ASU 2015-01 eliminated from U.S. GAAP the concept of extraordinary items, which, among other things, required an entity to show the item separately in the income statement, net of tax, after income from continuing operations. The new guidance became effective for the Company beginning January 1, 2016 and did not have a significant impact on the Company’s financial statements.

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ASU 2015-05, “Intangibles – Goodwill and Other – Internal-Use Software – Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement.” ASU 2015-05 addresses accounting for fees paid by a customer in cloud computing arrangements such as (i) software as a service, (ii) platform as a service, (iii) infrastructure as a service and (iv) other similar hosting arrangements. ASU 2015-05 provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. ASU 2015-05 became effective on January 1, 2016 and did not have a significant impact on the Company’s financial statements.

ASU 2015-16, “Business Combinations – Simplifying the Accounting Measurement Period Adjustments.” ASU 2015-16 amended business combination guidance to require that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The acquirer must record, in the same period’s financial statements, the effect of earnings on changes in depreciation, amortization, or other income effects, if any, as a result of the changes to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. Additionally, the entity is required to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the provisional amounts had been recognized as of the acquisition date. The amended guidance became effective for the Company on January 1, 2016 and did not have a significant impact on the Company’s financial statements.

ASU 2016-1, “Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-1, among other things, (i) requires equity investments, with certain exceptions, to be measured at fair value with changes in fair value recognized in net income, (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, (iii) eliminates the requirement for public business entities to disclose the methods and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet, (iv) requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes, (v) requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments, (vi) requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements and (vii) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities. ASU 2016-1 will be effective for the Company on January 1, 2018 and is not expected to have a significant impact on the Company’s financial statements.

ASU 2016-02, “Leases.” ASU 2016-02 will amend current lease accounting to require lessees to recognize (i) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis, and (ii) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. ASU 2016-02 does not significantly change lease accounting requirements applicable to lessors; however, certain changes were made to align, where necessary, lessor accounting with the lessee accounting model. The amended guidance will be effective in the first quarter of 2019 and will require transition using a modified retrospective approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The Company continues to evaluate the provision of the new lease standard but, due to the small number and dollar amount of lease agreements presently in effect for the Company, has concluded the new guidance will not have a significant impact on the Company’s financial statements.

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ASU 2016-09, “Compensation – Stock Compensation: Improvements to Employee Share-Based Payment Accounting.” ASU 2016-09 amends current guidance such that all excess tax benefits and tax deficiencies related to share-based payment awards will be recognized as income tax expense or benefit in the income statement during the period in which they occur. Previously, such amounts were recorded in capital surplus. Additionally, excess tax benefits will be classified along with other income tax cash flows as an operating activity rather than a financing activity, as was previously the case. ASU 2016-09 also provides that any entity can make an entity-wide accounting policy election to either estimate the number of awards that are expected to vest, which is the current requirement, or account for forfeitures when they occur. ASU 2016-09 became effective January 1, 2017 and did not have a significant impact on the Company’s financial statements.

ASU 2016-13, “Financial Instruments – Credit Losses.” ASU 2016-13 implements a comprehensive change in estimating the allowances for loan losses from the current model of losses inherent in the loan portfolio to a current expected credit loss model that generally is expected to result in earlier recognition of allowances for losses. Additionally, purchase accounting rules have been modified as well as credit losses on held-to-maturity debt securities. ASU 2016-13 will be effective in the first quarter of 2020. While the Company generally expects that the implementation of ASU 2016-13 will increase their allowance for loan losses balance, the Company is continuing to evaluate the potential impact on the Company’s financial statements.

ASU 2017-04, “Intangibles – Goodwill and Other.” ASU 2017-04 will amend and simplify current goodwill impairment testing to eliminate Step 2 from the current provisions. Under the new guidance, an entity should perform the goodwill impairment test by comparing the fair value of a reporting unit with its carrying value and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. An entity still has the option to perform the quantitative assessment for a reporting unit to determine if a quantitative impairment test is necessary. ASU 2017-04 will be effective for the Company on January 1, 2020 and is not expected to have a significant impact on the Company’s financial statements.

ASU 2017-07, “Compensation – Retirement Benefits, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Post-Retirement Benefit Cost.” ASU 2017-17 will require employers that sponsor defined benefit pension plans to present the service cost component of net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. Other components of the net periodic benefit cost will be presented separately from the service cost component. ASU 2017-17 will be effective in 2018 and, as the Company froze its defined benefit pension plan in 2004, there is no service cost component of its net periodic benefit cost and therefore will not have an impact on the Company’s financial statements.

ASU 2017-08, “Receivables – Nonrefundable Fees and Other Costs: Premium Amortization on Purchased Callable Debt Securities.” ASU 2017-08 addresses the amortization method for all callable bonds purchased at a premium to par. Under the revised guidance, entities will be required to amortize premiums on callable bonds to the earliest call date. ASU 2017-08 is effective in 2019 although early adoption is permitted. The Company elected to early adopt ASU 2017-08 in the first quarter of 2017. The adoption of this guidance did not have a material impact on the Company’s financial statements.

Note 12 - Acquisition Definitive Agreement Signed

On October 12, 2017, the Company announced that it has entered into a definitive agreement to acquire Commercial Bancshares, Inc. and its wholly owned bank subsidiary, Commercial State Bank, El Campo, Texas pursuant to an Agreement and Plan of Reorganization (the “Reorganization Agreement”) dated October 12, 2017, by and among the Company, Kingwood Merger Sub, Inc., a wholly owned subsidiary of the company, and Commercial Bancshares, Inc. for consideration to be paid in shares of Common Stock with an aggregate value of approximately $59,400,000. In addition, Commercial Bancshares, Inc. will make a $15,600,000 special dividend to its shareholders prior to closing of the transaction, which may be increased or decreased for the amount by which Commercial Bancshares, Inc.’s consolidated shareholders’ equity as of the closing date exceeds or is less than $42,400,000, after certain adjustments described in the Reorganization Agreement. At September 30, 2017 Commercial State Bank, Kingwood, Texas had gross loans totaling $263,800,000, total deposits of $322,100,000 and total assets of $366,800,000. Pending regulatory and shareholder approval, the acquisition is expected to close in the first quarter of 2018.

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Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Forward-Looking Statements

This Form 10-Q contains certain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. When used in this Form 10-Q, words such as “anticipate,” “believe,” “estimate,” “expect,” “intend,” “predict,” “project,” and similar expressions, as they relate to us or management, identify forward-looking statements. These forward-looking statements are based on information currently available to our management. Actual results could differ materially from those contemplated by the forward-looking statements as a result of certain factors, including, but not limited, to those listed in “Item 1A- Risk Factors” in our Annual Report on Form 10-K and the following:

• general economic conditions, including our local, state and national real estate markets and employment trends;

• effect of severe weather conditions, including hurricanes, tornadoes, flooding and drought;

• volatility and disruption in national and international financial and commodity markets;

• government intervention in the U.S. financial system including the effects of recent legislative, tax, accounting and regulatory actions and reforms, including the Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Dodd-Frank Act”), the Jumpstart Our Business Startups Act, the Consumer Financial Protection Bureau and the capital ratios of Basel III as adopted by the federal banking authorities;

• political instability;

• the ability of the Federal government to address the national economy;

• changes in our competitive environment from other financial institutions and financial service providers;

• the effects of and changes in trade, monetary and fiscal policies and laws, including interest rate policies of the Board of Governors of the Federal Reserve System (the “Federal Reserve Board”);

• 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;

• the effect of changes in laws and regulations (including laws and regulations concerning taxes, banking, securities and insurance) with which we and our subsidiaries must comply;

• changes in the demand for loans;

• fluctuations in the value of collateral securing our loan portfolio and in the level of the allowance for loan losses;

• the accuracy of our estimates of future loan losses;

• the accuracy of our estimates and assumptions regarding the performance of our securities portfolio;

• soundness of other financial institutions with which we have transactions;

• inflation, interest rate, market and monetary fluctuations;

• changes in consumer spending, borrowing and savings habits;

• changes in commodity prices (e.g., oil and gas, cattle and wind energy);

• our ability to attract deposits and increase market share;

• changes in our liquidity position;

• changes in the reliability of our vendors, internal control system or information systems;

• cyber attacks on our technology information systems, including fraud from our customers and external third party vendors;

• our ability to attract and retain qualified employees;

• acquisitions and integration of acquired businesses;

• the possible impairment of goodwill associated with our acquisitions;

• consequences of continued bank mergers and acquisitions in our market area, resulting in fewer but much larger and stronger competitors;

• expansion of operations, including branch openings, new product offerings and expansion into new markets;

• changes in compensation and benefit plans; and

• acts of God or of war or terrorism.

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Such forward-looking statements reflect the current views of our management with respect to future events and are subject to these and other risks, uncertainties and assumptions relating to our operations, results of operations, growth strategy and liquidity. All subsequent written and oral forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by this paragraph. We undertake no obligation to publicly update or otherwise revise any forward-looking statements, whether as a result of new information, future events or otherwise (except as required by law).

Introduction

As a financial holding company, we generate most of our revenue from interest on loans and investments, trust fees, and service charges. Our primary source of funding for our loans and investments are deposits held by our subsidiary, First Financial Bank, National Association, Abilene, Texas. Our largest expense is salaries and related employee benefits. We usually measure our performance by calculating our return on average assets, return on average equity, our regulatory leverage and risk based capital ratios and our efficiency ratio, which is calculated by dividing noninterest expense by the sum of net interest income on a tax equivalent basis and noninterest income.

The following discussion and analysis of operations and financial condition should be read in conjunction with the financial statements and accompanying footnotes included in Item 1 of this Form 10-Q as well as those included in the Company’s 2016 Annual Report on Form 10-K.

Critical Accounting Policies

We prepare consolidated financial statements based on GAAP and customary practices in the banking industry. These policies, in certain areas, require us to make significant estimates and assumptions.

We deem a policy critical if (1) the accounting estimate required us to make assumptions about matters that are highly uncertain at the time we make the accounting estimate; and (2) different estimates that reasonably could have been used in the current period, or changes in the accounting estimate that are reasonably likely to occur from period to period, would have a material impact on the financial statements.

We deem our most critical accounting policies to be (1) our allowance for loan losses and our provision for loan losses and (2) our valuation of securities. We have other significant accounting policies and continue to evaluate the materiality of their impact on our consolidated financial statements, but we believe these other policies either do not generally require us to make estimates and judgments that are difficult or subjective, or it is less likely they would have a material impact on our reported results for a given period. A discussion of (1) our allowance for loan losses and our provision for loan losses and (2) our valuation of securities is included in note 5 and note 4, respectively, to our notes to consolidated financial statements (unaudited) which begins on page 9.

Recent Development

Houston and surrounding areas around the Gulf Coast were significantly affected by Hurricane Harvey beginning in late August 2017 and continuing into September 2017. Our Company has regional locations (i) north of Houston in Conroe, Willis, Tomball, Huntsville, Montgomery, Magnolia and Cut and Shoot and (ii) in Southeast Texas in Orange, Beaumont, Vidor, Newton, Mauriceville and Port Arthur. We continue to evaluate the effect of the hurricane on our branch facilities and our loan and investment portfolios. Our initial assessment of our physical buildings and equipment indicates damage primarily at our Mauriceville branch, and amounts not covered by insurance do not appear to be significant. At September 30, 2017, we have loans totaling $448.82 million in our Conroe region and $397.63 million in the Southeast Texas/Orange region. We are evaluating these loans and the related collateral and business operations underlying such loans. At September 30, 2017, we provided additional allowance for loan and lease losses as deemed appropriate based on this analysis. We continue to evaluate these loans and expect some changes, plus or minus, as we learn more information about to the damage caused by the hurricane. Our tax exempt municipal bonds in the counties of Texas effected by the hurricane have been evaluated, including insurance on the bonds. At September 30, 2017, our municipal bonds in these counties totaled $254.48 million but only $9.13 million does not have bond insurance. Based on analysis of these bonds and the related municipality, at September 30, 2017, we do not believe we have any credit related losses other than temporary impairment.

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Results of Operations

Performance Summary. Net earnings for the third quarter of 2017 were $29.37 million compared to $25.60 million for the same quarter in 2016, or a 14.73% increase.

Basic earnings per share for the third quarter of 2017 were $0.44 compared to $0.39 for the same quarter last year. The return on average assets was 1.65% for the third quarter of 2017, as compared to 1.54% for the third quarter of 2016. The return on average equity was 12.95% for the third quarter of 2017 as compared to 11.72% for the third quarter of 2016.

Net earnings for the nine-month period ended September 30, 2017 were $84.23 million compared to $78.11 million for the same period in 2016, or a 7.83% increase.

Basic earnings per share for the first nine months of 2017 were $1.27 compared to $1.18 for the same period in 2016. The return on average assets was 1.62% for the first nine months of 2017 as compared to 1.59% for the same period in 2016. The return on average equity was 12.88% for the first nine months of 2017, as compared to 12.33% a year ago.

Net Interest Income. Net interest income is the difference between interest income on earning assets and interest expense on liabilities incurred to fund those assets. Our earning assets consist primarily of loans and investment securities. Our liabilities to fund those assets consist primarily of noninterest-bearing and interest-bearing deposits.

Tax-equivalent net interest income was $66.00 million for the third quarter of 2017, as compared to $63.00 million for the same period last year. The increase in 2017 compared to 2016 was largely attributable to the increase in interest earning assets, particularly loans and taxable securities. Average earning assets increased $431.96 million for the third quarter of 2017 over the same period in 2016. Average loans and taxable securities increased $119.07 million and $187.14 million, respectively, for the third quarter of 2017 over the same quarter of 2016. Average interest-bearing liabilities increased $222.71 million for the third quarter of 2017, as compared to the same period in 2016. The yield on earning assets decreased one basis points and the rate paid on interest-bearing liabilities increased fourteen basis points for the third quarter of 2017 compared to the third quarter of 2016.

Tax-equivalent net interest income was $195.16 million for the first nine months of 2017, as compared to $188.86 million for the same period last year. The increase in 2017 compared to 2016 was largely attributable to the increase in volume of interest earning assets. Average earning assets increased $363.44 million for the first nine months of 2017 over the same period in 2016. Average loans and taxable securities increased $99.77 million and $125.78 million, respectively, for the first nine months of 2017 over the same period of 2016. Average interest-bearing liabilities increased $223.70 million for the first nine months of 2017, as compared to the same period in 2016. The yield on earning assets decreased five basis points and the rate paid on interest-bearing liabilities increased eight basis points for the first nine months of 2017 over the first nine months of 2016.

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Table 1 allocates the change in tax-equivalent net interest income between the amount of change attributable to volume and to rate.

Table 1 - Changes in Interest Income and Interest Expense (in thousands):

	Three Months Ended September 30, 2017 Compared to Three Months Ended September 30, 2016							Nine Months Ended September 30, 2017 Compared to Nine Months Ended September 30, 2016
	Change Attributable to					Total Change		Change Attributable to						Total Change
	Volume			Rate				Volume			Rate
Short-term investments	$	175		$	364	$	539	$	312		$	503		$	815
Taxable investment securities		971			328		1,299		2,008			673			2,681
Tax-exempt investment securities (1)		(13	)		356		343		2,139			407			2,546
Loans (1) (2)		1,456			866		2,322		3,672			(687	)		2,985
Interest income		2,589			1,914		4,503		8,131			896			9,027
Interest-bearing deposits		86			1,031		1,117		325			2,226			2,551
Short-term borrowings		(20	)		404		384		(176	)		343			167
Interest expense		66			1,435		1,501		149			2,569			2,718
Net interest income	$	2,523		$	479	$	3,002	$	7,982		$	(1,673	)	$	6,309

(1) Computed on a tax-equivalent basis assuming a marginal tax rate of 35%.

(2) Non-accrual loans are included in loans.

The net interest margin for the third quarter of 2017 was 3.94%, a decrease of ten basis points from the same period in 2016. The continued decrease in our net interest margin in 2017 and 2016 was largely the result of the extended period of historically low levels of short-term interest rates. We have been able to somewhat mitigate the impact of lower short-term interest rates by establishing minimum interest rates on certain of our loans, improving the pricing for loan risk, and minimizing rates paid on interest bearing liabilities.

The net interest margin for the nine months ending September 30, 2017 was 4.01%, a decrease of nine basis points from the same period in 2016. The continued decrease in our net interest margin in 2017 and 2016 was largely the result of the extended period of historically low levels of short-term interest rates. We have been able to somewhat mitigate the impact of lower short-term interest rates by establishing minimum interest rates on certain of our loans, improving the pricing for loan risk, and minimizing rates paid on interest bearing liabilities.

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The net interest margin, which measures tax-equivalent net interest income as a percentage of average earning assets, is illustrated in Table 2.

Table 2 - Average Balances and Average Yields and Rates (in thousands, except percentages):

	Three Months Ended September 30,
	2017								2016
	Average Balance			Income/ Expense		Yield/ Rate			Average Balance			Income/ Expense		Yield/ Rate
Assets
Short-term investments (1)	$	200,789		$	638		1.26	%	$	73,881		$	99		0.53	%
Taxable investment securities (2)		1,492,246			8,074		2.16			1,305,103			6,775		2.08
Tax-exempt investment securities (2)(3)		1,477,559			16,884		4.57			1,478,719			16,541		4.47
Loans (3)(4)		3,468,524			43,270		4.95			3,349,458			40,948		4.86
Total earning assets		6,639,118		$	68,866		4.12	%		6,207,161		$	64,363		4.13	%
Cash and due from banks		157,983								152,080
Bank premises and equipment, net		123,550								122,944
Other assets		55,428								55,358
Goodwill and other intangible assets, net		141,776								143,854
Allowance for loan losses		(47,667	)							(45,997	)
Total assets	$	7,070,188							$	6,635,400
Liabilities and Shareholders’ Equity
Interest-bearing deposits	$	3,728,442		$	2,228		0.24	%	$	3,460,208		$	1,111		0.13	%
Short-term borrowings		524,357			638		0.48			569,883			254		0.18
Total interest-bearing liabilities		4,252,799		$	2,866		0.27	%		4,030,091		$	1,365		0.13	%
Noninterest-bearing deposits		1,864,144								1,663,460
Other liabilities		53,537								72,611
Total liabilities		6,170,480								5,766,162
Shareholders’ equity		899,708								869,238
Total liabilities and shareholders’ equity	$	7,070,188							$	6,635,400
Net interest income				$	66,000							$	62,998
Rate Analysis:
Interest income/earning assets							4.12	%							4.13	%
Interest expense/earning assets							0.18								0.09
Net yield on earning assets							3.94	%							4.04	%

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	Nine Months Ended September 30,
	2017								2016
	Average Balance			Income/ Expense		Yield/ Rate			Average Balance			Income/ Expense		Yield/ Rate
Assets
Short-term investments (1)	$	129,945		$	1,036		1.07	%	$	54,908		$	221		0.54	%
Taxable investment securities (2)		1,451,712			23,848		2.19			1,325,935			21,167		2.13
Tax-exempt investment securities (2)(3)		1,511,786			51,859		4.57			1,448,933			49,313		4.54
Loans (3)(4)		3,419,105			125,147		4.89			3,319,337			122,162		4.92
Total earning assets		6,512,548		$	201,890		4.14	%		6,149,113		$	192,863		4.19	%
Cash and due from banks		159,202								151,485
Bank premises and equipment, net		123,110								119,664
Other assets		57,191								55,094
Goodwill and other intangible assets, net		142,885								144,091
Allowance for loan losses		(47,021	)							(44,487	)
Total assets	$	6,947,915							$	6,574,960
Liabilities and Shareholders’ Equity
Interest-bearing deposits	$	3,779,967		$	5,748		0.20	%	$	3,431,572		$	3,197		0.12	%
Short-term borrowings		448,773			978		0.29			573,464			811		0.19
Total interest-bearing liabilities		4,228,740		$	6,726		0.21	%		4,005,036		$	4,008		0.13	%
Noninterest-bearing deposits		1,797,174								1,656,935
Other liabilities		47,720								66,855
Total liabilities		6,073,634								5,728,826
Shareholders’ equity		874,281								846,134
Total liabilities and shareholders’ equity	$	6,947,915							$	6,574,960
Net interest income				$	195,164							$	188,855
Rate Analysis:
Interest income/earning assets							4.14	%							4.19	%
Interest expense/earning assets							0.13								0.09
Net yield on earning assets							4.01	%							4.10	%

(1) Short-term investments are comprised of Fed Funds sold, interest-bearing deposits in banks and interest-bearing time deposits in banks.

(2) Average balances include unrealized gains and losses on available-for-sale securities.

(3) Computed on a tax-equivalent basis assuming a marginal tax rate of 35%.

(4) Non-accrual loans are included in loans.

Noninterest Income. Noninterest income for the third quarter of 2017 was $24.26 million, an increase of $2.11 million compared to the same period in 2016. Trust fees increased 19.23 percent to $6.04 million in the third quarter of 2017 compared with $5.07 million in the same quarter last year, due to continued growth in the fair value of trust assets managed to $4.92 billion from $4.22 billion a year ago and an increase in Trust fees. Service charges on deposit accounts increased 5.98 percent to $5.08 million compared with $4.80 million in the same quarter last year due to continued growth in net new accounts. ATM, interchange and credit card fees increased 5.67 percent to $6.34 million compared with $6.00 million in the same quarter last year due to continued growth in debit cards. Also included in noninterest income during the third quarter of 2017 were gains on the sale of securities of $1.08 million, an increase of $836 thousand when compared to the same quarter in 2016, and an increase of $629 thousand in other noninterest income when compared to the same period a year ago which largely resulted from a $505 thousand litigation settlement in the third quarter of 2017. Real estate mortgage fees decreased in the third quarter of 2017 to $3.89 million compared with $4.70 million in the same quarter a year ago and interest on loan recoveries decreased $304 thousand in the third quarter of 2017 compared to the same period in 2016.

Noninterest income for the nine-month period ended September 30, 2017 was $68.72 million, an increase of $5.31 million compared to the same period in 2016. Trust fees increased 23.25 percent to $17.80 million in the first nine months of 2017 compared with $14.45 million in the same period in 2016 due primarily to continued growth in the fair value of trust assets managed to $4.92 billion from $4.22 billion a year ago and an increase in Trust fees. Service charges on deposits increased 6.63 percent to $14.52

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million compared with $13.61 million in the same period last year due primarily to the continued growth in net new accounts. ATM, interchange and credit card fees increased 9.02 percent to $19.10 million compared with $17.52 million in the same period last year due to continued growth in debit cards. Also included in noninterest income for the nine-month period ended September 30, 2017 were gains on the sale of securities of $1.83 million, an increase of $672 thousand when compared to the same period in 2016, and an increase of $524 thousand in other noninterest income when compared to the same period a year ago which largely resulted from a $505 thousand litigation settlement in the third quarter of 2017. Real estate mortgage fees and interest on loan recoveries decreased $353 thousand and $1.07 million, respectively for the nine-month period ending September 30, 2017 when compared to the same period a year ago.

ATM and interchange fees are charges that merchants pay to us and other card-issuing banks for processing electronic payment transactions. ATM and interchange fees consist of income from debit card usage, point of sale income for debit card transactions and ATM service fees. Federal Reserve rules applicable to financial institutions that have assets of $10 billion or more provide that the maximum permissible interchange fee for an electronic debit transaction is the sum of 21 cents per transaction and 5 basis points multiplied by the value of the transaction. While we currently have assets under $10 billion, we are monitoring the effect of this reduction in per transaction fee income as we approach the $10 billion asset level.

Table 3 - Noninterest Income (in thousands):

	Three Months Ended September 30,									Nine Months Ended September 30,
	2017			Increase (Decrease)			2016			2017			Increase (Decrease)			2016
Trust fees	$	6,040		$	974		$	5,066		$	17,804		$	3,358		$	14,446
Service charges on deposit accounts		5,083			287			4,796			14,517			903			13,614
ATM, interchange and credit card fees		6,340			340			6,000			19,102			1,581			17,521
Real estate mortgage operations		3,891			(806	)		4,697			11,496			(353	)		11,849
Net gain on sale of available-for-sale securities		1,075			836			239			1,825			672			1,153
Net gain (loss) on sale of foreclosed assets		(11	)		(1	)		(10	)		(42	)		(385	)		343
Net gain (loss) on sale of assets		(15	)		153			(168	)		(211	)		(482	)		271
Interest on loan recoveries		405			(304	)		709			896			(1,074	)		1,970
Other:
Check printing fees		40			(11	)		51			121			(16	)		137
Safe deposit rental fees		108			(7	)		115			424			(2	)		426
Credit life fees		156			(83	)		239			439			(29	)		468
Brokerage commissions		323			276			47			908			608			300
Miscellaneous income		825			454			371			1,436			524			912
Total other		1,452			629			823			3,328			1,085			2,243
Total Noninterest Income	$	24,260		$	2,108		$	22,152		$	68,715		$	5,305		$	63,410

Noninterest Expense. Total noninterest expense for the third quarter of 2017 was $43.96 million, an increase of $1.96 million compared to $42.00 million in the same period of 2016. An important measure in determining whether a financial institution effectively manages noninterest expense is the efficiency ratio, which is calculated by dividing noninterest expense by the sum of net interest income on a tax-equivalent basis and noninterest income. Lower ratios indicate better efficiency since more income is generated with a lower noninterest expense total. Our efficiency ratio for the third quarter of 2017 was 48.71%, compared to 49.33% for the same period in 2016.

Salaries and employee benefits for the third quarter of 2017 totaled $24.14 million, an increase of $1.21 million compared to the same period in 2016. The increase was primarily driven by (i) annual merit pay increases that were effective March 1, 2017 (ii) an increase in our profit sharing expenses of $353 thousand over the same quarter in 2016 and (iii) an increase in stock option and stock grant expense of $574 thousand due to the stock option grant in June 2017.

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All other categories of noninterest expense for the third quarter of 2017 totaled $19.82 million, an increase of $749 thousand compared to the same quarter in 2016. This increase primarily resulted from increases in operational and other losses of $548 thousand due to fraud and weather related losses and software amortization and expense of $252 thousand from the write-off of software costs as compared to the same period in 2016.

Total noninterest expense for the first nine months of 2017 was $129.89 million, an increase of $6.05 million, compared to $123.84 million in the same period of 2016. Our efficiency ratio for the first nine months of 2017 was 49.22%, compared to 49.09% from the same period in 2016.

Salaries and employee benefits for the first nine months of 2017 totaled $70.87 million, an increase of $3.20 million compared to the same period in 2016. The increase was primarily driven by (i) annual pay increases that were effective March 1, 2017 (ii) an increase in our profit sharing expense over the same period in 2016 and (iii) an increase in stock option and stock grant expense of $657 thousand due to the stock option grant in June 2017.

All other categories of noninterest expense for the first nine months of 2017 totaled $59.02 million, an increase of approximately $2.85 million, as compared to the same period in 2016. The increase primarily resulted from increases in operational and other losses of $1.19 million due to fraud and weather related losses, professional and services fees of $779 thousand and software amortization and expense of $756 thousand from the write-off of software costs as compared to the same period in 2016.

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Table 4 - Noninterest Expense (in thousands):                

	Three Months Ended September 30,							Nine Months Ended September 30,
	2017		Increase (Decrease)			2016		2017		Increase (Decrease)			2016
Salaries	$	18,166	$	320		$	17,846	$	54,022	$	1,439		$	52,583
Medical		2,125		(97	)		2,222		6,201		(248	)		6,449
Profit sharing		1,091		353			738		3,074		1,181			1,893
Pension		84		2			82		253		6			247
401(k) match expense		603		12			591		1,829		35			1,794
Payroll taxes		1,191		48			1,143		3,907		129			3,778
Stock option and stock grant expense		883		574			309		1,581		657			924
Total salaries and employee benefits		24,143		1,212			22,931		70,867		3,199			67,668
Net occupancy expense		2,711		39			2,672		8,081		195			7,886
Equipment expense		3,294		(126	)		3,420		10,397		211			10,186
FDIC assessment fees		561		48			513		1,657		(498	)		2,155
ATM, interchange and credit card expense		2,001		142			1,859		5,517		165			5,352
Professional and service fees		2,036		153			1,883		5,878		779			5,099
Printing, stationery and supplies		449		(87	)		536		1,423		(81	)		1,504
Operational and other losses		1,081		548			533		2,639		1,187			1,452
Amortization of intangible assets		143		(29	)		172		477		(93	)		570
Other:
Data processing fees		349		230			119		896		563			333
Postage		399		(7	)		406		1,232		9			1,223
Advertising		894		(30	)		924		2,649		(6	)		2,655
Correspondent bank service charges		215		(25	)		240		662		(64	)		726
Telephone		737		(146	)		883		2,303		(185	)		2,488
Public relations and business development		633		(172	)		805		1,997		(58	)		2,055
Directors’ fees		387		86			301		1,125		125			1,000
Audit and accounting fees		385		(55	)		440		1,246		(94	)		1,340
Legal fees		331		(148	)		479		1,429		(103	)		1,532
Regulatory exam fees		296		15			281		880		32			848
Software amortization and expense		742		252			490		2,237		756			1,481
Travel		276		(56	)		332		892		(46	)		938
Courier expense		237		15			222		657		32			625
Other real estate		14		(20	)		34		102		(74	)		176
Other miscellaneous expense		1,650		122			1,528		4,648		100			4,548
Total other		7,545		61			7,484		22,955		987			21,968
Total Noninterest Expense	$	43,964	$	1,961		$	42,003	$	129,891	$	6,051		$	123,840

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Balance Sheet Review

Loans. Our portfolio is comprised of loans made to businesses, professionals, individuals, and farm and ranch operations located in the primary trade areas served by our subsidiary bank. Real estate loans represent loans primarily for 1-4 family residences and commercial real estate. The structure of loans in the real estate mortgage area generally provides re-pricing intervals to minimize the interest rate risk inherent in long-term fixed rate loans. As of September 30, 2017, total loans held for investment were $3.47 billion, an increase of $114.92 million, as compared to December 31, 2016 balances. As compared to December 31, 2016, commercial loans increased $537 thousand, agricultural loans decreased $1.02 million, real estate loans increased $107.71 million, and consumer loans increased $7.69 million. Loans averaged $3.47 billion during the third quarter of 2017, an increase of $119.07 million from the prior year third quarter average balances. Loans averaged $3.42 billion during the nine-month period ended September 30, 2017, an increase of $99.77 million from the prior year nine-month average balances.

Table 5 - Composition of Loans (in thousands):

	September 30,				December 31,
	2017		2016		2016
Commercial	$	674,947	$	663,581	$	674,410
Agricultural		83,005		84,716		84,021
Real estate		2,297,556		2,191,260		2,189,844
Consumer		416,719		398,236		409,032
Total loans held-for-investment	$	3,472,227	$	3,337,793	$	3,357,307

At September 30, 2017, our real estate loans represent approximately 66.17% of our loan portfolio and are comprised of (i) 1-4 family residence loans of 45.83%, (ii) commercial real estate loans of 23.91%, generally owner occupied, (iii) other loans, which includes ranches, hospitals and universities, of 16.09%, (iv) residential development and construction loans of 7.88%, which includes our custom and speculation home construction loans and (v) commercial development and construction loans of 6.29%.

Loans held for sale, consisting of secondary market mortgage loans, totaled $19.12 million, $31.59 million, and $26.90 million at September 30, 2017 and 2016, and December 31, 2016 respectively, which are valued using the lower of cost or market method.

Asset Quality. Our loan portfolio is subject to periodic reviews by our centralized independent loan review group as well as periodic examinations by bank regulatory agencies. Loans are placed on nonaccrual status when, in the judgment of management, the collectability of principal or interest under the original terms becomes doubtful. Nonaccrual, past due 90 days or more and still accruing, and restructured loans plus foreclosed assets were $22.08 million at September 30, 2017, as compared to $34.94 million at September 30, 2016 and $29.00 million at December 31, 2016. As a percent of loans and foreclosed assets, these assets were 0.63% at September 30, 2017, as compared to 1.04% at September 30, 2016 and 0.86% at December 31, 2016. As a percent of total assets, these assets were 0.31% at September 30, 2017, as compared to 0.52% at September 30, 2016 and 0.43% at December 31, 2016. We believe the level of these assets to be manageable and are not aware of any material classified credits not properly disclosed as nonperforming at September 30, 2017.

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Supplemental Oil and Gas Information. As of September 30, 2017, the Company’s exposure to the oil and gas industry totaled 1.99% of gross loans, or $69.43 million, down $9.05 million from December 31, 2016 year-end levels, and consisted (based on collateral supporting the loan) of (i) development and production loans of 2.65%, (ii) oil and gas field servicing loans of 6.91%, (iii) real estate loans of 40.77%, (iv) accounts receivable and inventory of 24.40% and (v) other of 25.27%. While the overall state of the Company’s oil and gas portfolio has improved, price fluctuations from the upper $40 to lower $50 continue to cause stress on several of our credits. The Company instituted additional monitoring procedures for these loans and classified, downgraded and charged-off loans as appropriate. The following oil and gas information is as of and for the quarters ended September 30, 2017 and 2016, and December 31, 2016:

	September 30,						December 31,
	2017			2016			2016
Oil and gas related loans	$	69,433		$	86,785		$	78,483
Oil and gas related loans as a % of total loans		1.99	%		2.58	%		2.32	%
Classified oil and gas related loans		21,817		$	31,541		$	32,518
Nonaccrual oil and gas related loans		1,569			5,140			4,092
Net charge-offs for oil and gas related loans for quarter/year then ended		—			104			1,145
Allowance for oil and gas related loans as a % of oil and gas loans		6.03	%		5.60	%		6.28	%

Table 6 - Non-accrual, Past Due 90 Days or More and Still Accruing, Restructured Loans and Foreclosed Assets (in thousands, except percentages):

	September 30,						December 31,
	2017			2016			2016
Non-accrual loans*	$	18,750		$	33,712		$	27,371
Loans still accruing and past due 90 days or more		257			107			284
Troubled debt restructured loans**		668			750			701
Nonperforming Loans		19,675			34,569			28,356
Foreclosed assets		2,401			369			644
Total nonperforming assets	$	22,076		$	34,938		$	29,000
As a % of loans and foreclosed assets		0.63	%		1.04	%		0.86	%
As a % of total assets		0.31	%		0.52	%		0.43	%

* Includes $736 thousand, $1.85 million and $1.26 million of purchased credit impaired loans as of September 30, 2017 and 2016, and December 31, 2016, respectively.

** Other troubled debt restructured loans of $5.28 million, $7.51 million and $6.86 million, whose interest collection, after considering economic and business conditions and collection efforts, is doubtful are included in non-accrual loans at September 30, 2017 and 2016, and December 31, 2016, respectively.

We record interest payments received on non-accrual loans as reductions of principal. Prior to the loans being placed on non-accrual, we recognized interest income on impaired loans of approximately $790 thousand for the year ended December 31, 2016. If interest on these impaired loans had been recognized on a full accrual basis during the year ended December 31, 2016, such income would have approximated $2.90 million. Such amounts for the 2017 and 2016 interim periods were not significant.

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Provision and Allowance for Loan Losses. The allowance for loan losses is the amount we determine as of a specific date to be appropriate to absorb probable losses on existing loans in which full collectability is unlikely based on our review and evaluation of the loan portfolio. For a discussion of our methodology, see note 5 to our notes to the consolidated financial statements (unaudited). The provision for loan losses was $1.42 million for the third quarter of 2017, as compared to $3.83 million for the third quarter of 2016. The provision for loan losses was $5.09 million for the nine-month period ended 2017 as compared to $8.22 million for the same period in 2016. The continued provision for loan losses in 2017 and 2016 reflects the growth in the loan portfolio, the continued levels of gross charge-offs and the effects related to Hurricane Harvey on the loan portfolio. As a percent of average loans, net loan charge-offs were 0.10% for the third quarter of 2017, as compared to 0.43% for the third quarter of 2016. As a percent of average loans, net loan charge-offs were 0.12% for the first nine months of 2017, as compared to 0.19% for the first nine months of 2016. The allowance for loan losses as a percent of loans was 1.37% as of September 30, 2017, as compared to 1.34% as of September 30, 2016 and 1.35% as of December 31, 2016. Included in Table 7 is further analysis of our allowance for loan losses.

Table 7 - Loan Loss Experience and Allowance for Loan Losses (in thousands, except percentages):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
Allowance for loan losses at period-end	$	47,922		$	45,298		$	47,922		$	45,298
Loans held for investment at period-end		3,472,227			3,337,793			3,472,227			3,337,793
Average loans for period	$	3,468,524		$	3,349,458		$	3,419,105		$	3,319,337
Net charge-offs/average loans (annualized)		0.10	%		0.43	%		0.12	%		0.19	%
Allowance for loan losses/period-end loans		1.37	%		1.34	%		1.37	%		1.34	%
Allowance for loan losses/non-accrual loans, past due 90 days still accruing and restructured loans		243.57	%		131.04	%		243.57	%		131.04	%

Interest-Bearing Deposits in Banks. At September 30, 2017, our interest-bearing deposits in banks were $168.28 million compared to $119.04 million at September 30, 2016 and $50.28 million at December 31, 2016, respectively. At September 30, 2017, interest-bearing deposits in banks included $1.46 million invested in FDIC-insured certificates of deposit, $166.26 million maintained at the Federal Reserve Bank of Dallas and $556 thousand on deposit with the Federal Home Loan Bank of Dallas (“FHLB”).

Available-for-Sale and Held-to-Maturity Securities. At September 30, 2017, securities with a fair value of $2.89 billion were classified as securities available-for-sale. As compared to December 31, 2016, the available-for-sale portfolio at September 30, 2017 reflected (i) a decrease of $10.67 million in U.S. Treasury securities (ii) a decrease of $40.12 million in obligations of U.S. government sponsored enterprises and agencies, (iii) a decrease of $130.08 million in obligations of states and political subdivisions, (iv) a decrease of $32.84 million in corporate bonds and other, and (v) an increase of $238.35 million in mortgage-backed securities. Our mortgage related securities are backed by GNMA, FNMA or FHLMC or are collateralized by securities backed by these agencies.

See note 4 to the consolidated financial statements (unaudited) for additional disclosures relating to the investment portfolio at September 30, 2017 and 2016, and December 31, 2016.

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Table 8 - Maturities and Yields of Available-for-Sale Securities Held at September 30, 2017 (in thousands, except percentages):

	Maturing
	One Year or Less					After One Year Through Five Years					After Five Years Through Ten Years					After Ten Years					Total
Available-for-Sale:	Amount		Yield			Amount		Yield			Amount		Yield			Amount		Yield			Amount		Yield
Obligations of U.S. government sponsored enterprises and agencies	$	33,038		1.16	%	$	40,550		1.47	%	$	—		—	%	$	—		—	%	$	73,588		1.33	%
Obligations of states and political subdivisions		136,783		5.02			638,745		5.14			656,623		4.73			2,043		6.86			1,434,194		4.94
Corporate bonds and other securities		19,315		2.72			240		1.15			—		—			—		—			19,555		2.70
Mortgage-backed securities		18,469		2.31			1,062,189		2.24			227,721		2.64			49,767		2.80			1,358,146		2.33
Total	$	207,605		3.95	%	$	1,741,724		3.28	%	$	884,344		4.19	%	$	51,810		2.96	%	$	2,885,483		3.60	%

Amounts for held-to-maturity securities are not included herein due to insignificance.

All yields are computed on a tax-equivalent basis assuming a marginal tax rate of 35%. Yields on available-for-sale securities are based on amortized cost. Maturities of mortgage-backed securities are based on contractual maturities and could differ due to prepayments of underlying mortgages. Maturities of other securities are reported at the earlier of maturity date or call date.

As of September 30, 2017, the investment portfolio had an overall tax equivalent yield of 3.60%, a weighted average life of 4.18 years and modified duration of 3.74 years.

Deposits. Deposits held by our subsidiary bank represent our primary source of funding. Total deposits were $5.70 billion as of September 30, 2017, as compared to $5.24 billion as of September 30, 2016 and $5.48 billion as of December 31, 2016. Table 9 provides a breakdown of average deposits and rates paid for the three and nine months periods ended September 30, 2017 and 2016.

Table 9 - Composition of Average Deposits (in thousands, except percentages):

	Three Months Ended September 30,
	2017					2016
	Average Balance		Average Rate			Average Balance		Average Rate
Noninterest-bearing deposits	$	1,864,144		—	%	$	1,663,460		—	%
Interest-bearing deposits:
Interest-bearing checking		1,878,400		0.31			1,688,540		0.11
Savings and money market accounts		1,378,258		0.14			1,230,111		0.09
Time deposits under $100,000		208,848		0.17			233,443		0.18
Time deposits of $100,000 or more		262,936		0.32			308,114		0.32
Total interest-bearing deposits		3,728,442		0.24	%		3,460,208		0.13	%
Total average deposits	$	5,592,586				$	5,123,668

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	Nine Months Ended September 30,
	2017					2016
	Average Balance		Average Rate			Average Balance		Average Rate
Noninterest-bearing deposits	$	1,797,174		—	%	$	1,656,935		—	%
Interest-bearing deposits:
Interest-bearing checking		1,882,295		0.25			1,712,095		0.11
Savings and money market accounts		1,410,824		0.13			1,146,368		0.07
Time deposits under $100,000		214,653		0.17			241,031		0.18
Time deposits of $100,000 or more		272,195		0.32			332,078		0.31
Total interest-bearing deposits		3,779,967		0.20			3,431,572		0.12	%
Total average deposits	$	5,577,141				$	5,088,507

Borrowings. Included in borrowings were federal funds purchased, securities sold under repurchase agreements and advances from the FHLB of $351.44 million, $513.76 million and $445.77 million at September 30, 2017 and 2016 and December 31, 2016, respectively. Securities sold under repurchase agreements are generally with significant customers of the Company that require short-term liquidity for their funds for which we pledge certain securities that have a fair value equal to at least the amount of the borrowings. The average balance of federal funds purchased, securities sold under repurchase agreements and advances from the FHLB were $524.36 million and $569.88 million in the third quarter of 2017 and 2016, respectively. The weighted average interest rates paid on these borrowings were 0.48% and 0.18% for the third quarters of 2017 and 2016, respectively. The average balances of federal funds purchased, securities sold under repurchase agreements and advances from the FHLB was $448.77 million and $573.46 million for the nine-month periods ended September 30, 2017 and 2016, respectively. The weighted average interest rate paid on these short-term borrowings was 0.29% and 0.19% for the first nine months of 2017 and 2016, respectively.

Capital Resources

We evaluate capital resources by our ability to maintain adequate regulatory capital ratios to do business in the banking industry. Issues related to capital resources arise primarily when we are growing at an accelerated rate but not retaining a significant amount of our profits or when we experience significant asset quality deterioration.

Total shareholders’ equity was $906.56 million, or 12.93% of total assets at September 30, 2017, as compared to $867.94 million, or 12.98% of total assets at September 30, 2016 and $837.89 million, or 12.30% of total assets at December 31, 2016. Included in shareholders’ equity at September 30, 2017 and 2016 and December 31, 2016, were $38.95 million, $68.31 million and $21.49 million, respectively, in unrealized gains on investment securities available-for-sale, net of related income taxes. For the third quarter of 2017, total shareholders’ equity averaged $899.71 million, or 12.73% of average assets, as compared to $869.24 million, or 13.10% of average assets, during the same period in 2016. For the nine months ended September 30, 2017, total shareholders’ equity averaged $874.28 million, or 12.58%, as compared to $846.13 million or 12.87% of total assets during the same period in 2016.

Banking regulators measure capital adequacy by means of the risk-based capital ratios and the leverage ratio under the Basel III regulatory capital framework and prompt corrective action regulations. The risk-based capital rules provide for the weighting of assets and off-balance-sheet commitments and contingencies according to prescribed risk categories. Regulatory capital is then divided by risk-weighted assets to determine the risk-adjusted capital ratios. The leverage ratio is computed by dividing shareholders’ equity less intangible assets by quarter-to-date average assets less intangible assets.

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Beginning in January 2016, under the Basel III regulatory capital framework, the implementation of the capital conservation buffer was effective for the Company starting at the 0.625% level and increasing 0.625% each year thereafter, until it reaches 2.5% on January 1, 2019. The capital conservation buffer is designed to absorb losses during periods of economic stress and requires increased capital levels for the purpose of capital distributions and other payments. Failure to meet the amount of the buffer will result in restrictions on the Company’s ability to make capital distributions, including dividend payments and stock repurchases, and to pay discretionary bonuses to executive officers.

As of September 30, 2017 and 2016, and December 31, 2016, we had a total capital to risk-weighted assets ratio of 19.54%, 18.28% and 18.45%, a Tier 1 capital to risk-weighted assets ratio of 18.35%, 17.12% and 17.30%; a common equity Tier 1 to risk-weighted assets ratio of 18.35%, 17.12% and 17.30% and a leverage ratio of 10.84%, 10.60% and 10.71%, respectively. The regulatory capital ratios as of September 30, 2017 and 2016, and December 31, 2016 were calculated under Basel III rules. There is no threshold for well-capitalized status for bank holding companies.

As of September 30, 2017 and 2016, and December 31, 2016, the regulatory capital ratios of the Company and Bank under the Basel III regulatory capital framework are as follows:    

	Actual					Minimum Capital Required Under Basel III Phase-In					Minimum Capital Required-Basel III Fully Phased-In					Required to be Considered Well- Capitalized
As of September 30, 2017:	Amount		Ratio			Amount		Ratio			Amount		Ratio			Amount		Ratio
Total Capital to Risk-Weighted Assets:
Consolidated	$	794,388		19.54	%	$	376,053		9.25	%	$	426,872		10.50	%		—		N/A
First Financial Bank, N.A	$	693,155		17.10	%	$	375,032		9.25	%	$	425,712		10.50	%	$	405,440		10.00	%
Tier 1 Capital to Risk-Weighted Assets:
Consolidated	$	745,856		18.35	%	$	294,745		7.25	%	$	345,563		8.50	%		—		N/A
First Financial Bank, N.A	$	644,623		15.90	%	$	293,944		7.25	%	$	344,624		8.50	%	$	324,352		8.00	%
Common Equity Tier 1 Capital to Risk-Weighted Assets:
Consolidated	$	745,856		18.35	%	$	233,763		5.75	%	$	284,581		7.00	%		—		N/A
First Financial Bank, N.A	$	644,623		15.90	%	$	233,128		5.75	%	$	283,808		7.00	%	$	263,536		6.50	%
Leverage Ratio:
Consolidated	$	745,856		10.84	%	$	275,265		4.00	%	$	275,265		4.00	%		—		N/A
First Financial Bank, N.A	$	644,623		9.40	%	$	274,314		4.00	%	$	274,314		4.00	%	$	342,893		5.00	%

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	Actual					Minimum Capital Required Under Basel III Phase-In					Minimum Capital Required-Basel III Fully Phased-In					Required to be Considered Well- Capitalized
As of September 30, 2016:	Amount		Ratio			Amount		Ratio			Amount		Ratio			Amount		Ratio
Total Capital to Risk-Weighted Assets
Consolidated	$	723,248		18.28	%	$	341,309		8.625	%	$	415,506		10.50	%		—		N/A
First Financial Bank, N.A	$	629,168		15.94	%	$	340,429		8.625	%	$	414,436		10.50	%	$	394,701		10.00	%
Tier 1 Capital to Risk-Weighted Assets
Consolidated	$	677,289		17.12	%	$	262,165		6.625	%	$	336,362		8.50	%		—		N/A
First Financial Bank, N.A	$	583,209		14.78	%	$	261,489		6.625	%	$	335,496		8.50	%	$	315,760		8.00	%
Common Equity Tier 1 Capital to Risk-Weighted Assets
Consolidated	$	677,289		17.12	%	$	202,807		5.125	%	$	277,004		7.00	%		—		N/A
First Financial Bank, N.A	$	583,209		14.78	%	$	202,284		5.125	%	$	276,290		7.00	%	$	256,555		6.50	%
Leverage Ratio
Consolidated	$	677,289		10.60	%	$	255,659		4.00	%	$	255,659		4.00	%		—		N/A
First Financial Bank, N.A	$	583,209		9.16	%	$	254,799		4.00	%	$	254,799		4.00	%	$	318,499		5.00	%
As of December 31, 2016:
Total Capital to Risk-Weighted Assets:
Consolidated	$	739,959		18.45	%	$	345,827		8.625	%	$	421,007		10.50	%		—		N/A
First Financial Bank, N.A	$	633,403		15.84	%	$	344,930		8.625	%	$	419,915		10.50	%	$	399,919		10.00	%
Tier 1 Capital to Risk-Weighted Assets:
Consolidated	$	693,584		17.30	%	$	265,635		6.625	%	$	340,815		8.50	%		—		N/A
First Financial Bank, N.A	$	587,028		14.68	%	$	264,946		6.625	%	$	339,931		8.50	%	$	319,935		8.00	%
Common Equity Tier 1 Capital to Risk-Weighted Assets:
Consolidated	$	693,584		17.30	%	$	205,491		5.125	%	$	280,671		7.00	%		—		N/A
First Financial Bank, N.A	$	587,028		14.68	%	$	204,959		5.125	%	$	279,943		7.00	%	$	259,947		6.50	%
Leverage Ratio:
Consolidated	$	693,584		10.71	%	$	258,978		4.00	%	$	258,978		4.00	%		—		N/A
First Financial Bank, N.A	$	587,028		9.10	%	$	257,941		4.00	%	$	257,941		4.00	%	$	322,426		5.00	%

We have performed a preliminary assessment using the regulatory capital estimation tool made available by the OCC and believe the Company and Bank are prepared to meet the new requirements upon full adoption of Basel III that will be effective December 31, 2019.

In connection with the adoption of the Basel III regulatory capital framework, our subsidiary bank made the election to continue to exclude most accumulated other comprehensive income (“AOCI”) from capital in connection with its quarterly financial filing and, in effect, to retain the AOCI treatment under the prior capital rules.

Interest Rate Risk

Interest rate risk results when the maturity or repricing intervals of interest-earning assets and interest-bearing liabilities are different. Our exposure to interest rate risk is managed primarily through our strategy of selecting the types and terms of interest-earning assets and interest-bearing liabilities that generate favorable earnings while limiting the potential negative effects of changes in market interest rates. We use no off-balance sheet financial instruments to manage interest rate risk.

Our subsidiary bank has an asset liability management committee that monitors interest rate risk and compliance with investment policies. The subsidiary bank utilizes an earnings simulation model as the

48

primary quantitative tool in measuring the amount of interest rate risk associated with changing market rates. The model quantifies the effects of various interest rate scenarios on projected net interest income and net income over the next twelve months. The model measures the impact on net interest income relative to a base case scenario of hypothetical fluctuations in interest rates over the next twelve months. These simulations incorporate assumptions regarding balance sheet growth and mix, pricing and the re-pricing and maturity characteristics of the existing and projected balance sheet.

As of September 30, 2017, the model simulations projected that 100 and 200 basis point increases in interest rates would result in negative variances in net interest income of 0.80% and 2.33%, respectively, relative to the current financial statement structure over the next twelve months, while a decrease in interest rates of 100 basis points would result in a negative variance in net interest income of 3.89% relative to the current financial statement structure over the next twelve months. We consider the likelihood of a decrease in interest rates beyond 100 basis points as of September 30, 2017 remote given the Federal Reserves proposed rate increase. Our model simulation as of September 30, 2017 indicates that our balance sheet is more liability sensitive in the short-term categories. These are good faith estimates and assume that the composition of our interest sensitive assets and liabilities existing at each year-end will remain constant over the relevant twelve-month measurement period and that changes in market interest rates are instantaneous and sustained across the yield curve regardless of duration of pricing characteristics on specific assets or liabilities. Also, this analysis does not contemplate any actions that we might undertake in response to changes in market interest rates. We believe these estimates are not necessarily indicative of what actually could occur in the event of immediate interest rate increases or decreases of this magnitude. As interest-bearing assets and liabilities re-price in different time frames and proportions to market interest rate movements, various assumptions must be made based on historical relationships of these variables in reaching any conclusion. Since these correlations are based on competitive and market conditions, we anticipate that our future results will likely be different from the foregoing estimates, and such differences could be material.

Should we be unable to maintain a reasonable balance of maturities and repricing of our interest-earning assets and our interest-bearing liabilities, we could be required to dispose of our assets in an unfavorable manner or pay a higher than market rate to fund our activities. Our asset liability committee oversees and monitors this risk.

Liquidity

Liquidity is our ability to meet cash demands as they arise. Such needs can develop from loan demand, deposit withdrawals or acquisition opportunities. Potential obligations resulting from the issuance of standby letters of credit and commitments to fund future borrowings to our loan customers are other factors affecting our liquidity needs. Many of these obligations and commitments are expected to expire without being drawn upon; therefore the total commitment amounts do not necessarily represent future cash requirements affecting our liquidity position. The potential need for liquidity arising from these types of financial instruments is represented by the contractual notional amount of the instrument. Asset liquidity is provided by cash and assets which are readily marketable or which will mature in the near future. Liquid assets include cash, federal funds sold, and short-term investments in time deposits in banks. Liquidity is also provided by access to funding sources, which include core depositors and correspondent banks that maintain accounts with and sell federal funds to our subsidiary bank. Other sources of funds include our ability to borrow from short-term sources, such as purchasing federal funds from correspondent banks, sales of securities under agreements to repurchase and advances from the FHLB (see below) and an unfunded $25.00 million revolving line of credit established with Frost Bank, a nonaffiliated bank, which matures in June 2019 (see next paragraph). Our subsidiary bank also has federal funds purchased lines of credit with two non-affiliated banks totaling $130.00 million. At September 30, 2017, no amounts were drawn on these lines of credit. Our subsidiary bank also has available a line of credit with the FHLB totaling $1.18 billion, at September 30, 2017, secured by portions of our loan portfolio and certain investment securities. At September 30, 2017, the Company did not have any balances outstanding under this line of credit.

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The Company renewed its loan agreement, effective June 30, 2017, with Frost Bank. Under the loan agreement, as renewed and amended, we are permitted to draw up to $25.00 million on a revolving line of credit. Prior to June 30, 2019, interest is paid quarterly at The Wall Street Journal Prime Rate and the line of credit matures June 30, 2019. If a balance exists at June 30, 2019, the principal balance converts to a term facility payable quarterly over five years and interest is paid quarterly at our election at The Wall Street Journal Prime Rate plus 50 basis points or LIBOR plus 250 basis points. The line of credit is unsecured. Among other provisions in the credit agreement, we must satisfy certain financial covenants during the term of the loan agreement, including, without limitation, covenants that require us to maintain certain capital, tangible net worth, loan loss reserve, non-performing asset and cash flow coverage ratios. In addition, the credit agreement contains certain operational covenants, which among others, restricts the payment of dividends above 55% of consolidated net income, limits the incurrence of debt (excluding any amounts acquired in an acquisition) and prohibits the disposal of assets except in the ordinary course of business. Since 1995, we have historically declared dividends as a percentage of our consolidated net income in a range of 37% (low) in 1995 to 53% (high) in 2003 and 2006. The Company was in compliance with the financial and operational covenants at September 30, 2017. There was no outstanding balance under the line of credit as of September 30, 2017 or December 31, 2016.

In addition, we anticipate that future acquisitions of financial institutions, expansion of branch locations or offerings of new products could also place a demand on our cash resources. Available cash and cash equivalents at our parent company which totaled $72.19 million at September 30, 2017, investment securities which totaled $8.58 million at September 30, 2017 and mature over 6 to 13 years, available dividends from our subsidiaries which totaled $170.03 million at September 30, 2017, utilization of available lines of credit, and future debt or equity offerings are expected to be the source of funding for these potential acquisitions or expansions.

Our liquidity position is continuously monitored and adjustments are made to the balance between sources and uses of funds as deemed appropriate. Liquidity risk management is an important element in our asset/liability management process. We regularly model liquidity stress scenarios to assess potential liquidity outflows or funding problems resulting from economic disruptions, volatility in the financial markets, unexpected credit events or other significant occurrences deemed potentially problematic by management. These scenarios are incorporated into our contingency funding plan, which provides the basis for the identification of our liquidity needs. As of September 30, 2017, management is not aware of any events that are reasonably likely to have a material adverse effect on our liquidity, capital resources or operations. Given the strong core deposit base and relatively low loan to deposit ratios maintained at our subsidiary bank, we consider our current liquidity position to be adequate to meet our short-term and long-term liquidity needs. In addition, management is not aware of any regulatory recommendations regarding liquidity that would have a material adverse effect on us.

Off-Balance Sheet Arrangements. We are a party to financial instruments with off-balance-sheet risk in the normal course of business to meet the financing needs of our customers. These financial instruments include unfunded lines of credit, commitments to extend credit and federal funds sold to correspondent banks and standby letters of credit. Those instruments involve, to varying degrees, elements of credit and interest rate risk in excess of the amount recognized in our consolidated balance sheets.

Our exposure to credit loss in the event of nonperformance by the counterparty to the financial instrument for unfunded lines of credit, commitments to extend credit and standby letters of credit is represented by the contractual notional amount of these instruments. We generally use the same credit policies in making commitments and conditional obligations as we do for on-balance-sheet instruments.

Unfunded lines of credit and commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. These commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. We evaluate each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, as we deem necessary upon extension of credit, is based on our credit evaluation of the counterparty. Collateral held varies but may include accounts receivable, inventory, property, plant, and equipment and income-producing commercial properties.

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Standby letters of credit are conditional commitments we issue to guarantee the performance of a customer to a third party. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. The average collateral value held on letters of credit usually exceeds the contract amount.

Table 10 - Commitments as of September 30, 2017 (in thousands):

	Total Notional Amounts Committed
Unfunded lines of credit	$	519,764
Unfunded commitments to extend credit		267,856
Standby letters of credit		32,649
Total commercial commitments	$	820,269

We believe we have no other off-balance sheet arrangements or transactions with unconsolidated, special purpose entities that would expose us to liability that is not reflected on the face of the financial statements.

Parent Company Funding. Our ability to fund various operating expenses, dividends, and cash acquisitions is generally dependent on our own earnings (without giving effect to our subsidiaries), cash reserves and funds derived from our subsidiaries. These funds historically have been produced by intercompany dividends and management fees that are limited to reimbursement of actual expenses. We anticipate that our recurring cash sources will continue to include dividends and management fees from our subsidiaries. At September 30, 2017, approximately $170.03 million was available for the payment of intercompany dividends by our subsidiaries without the prior approval of regulatory agencies. Our subsidiaries paid aggregate dividends of $29.00 million and $25.60 million for the nine-month periods ended September 30, 2017 and 2016, respectively.

Dividends. Our long-term dividend policy is to pay cash dividends to our shareholders of approximately 40% of annual net earnings while maintaining adequate capital to support growth. We are also restricted by a loan covenant within our line of credit agreement with Frost Bank to dividend no greater than 55% of net income, as defined in such loan agreement. The cash dividend payout ratios have amounted to 43.99% and 43.98% of net earnings for the first nine months of 2017 and 2016, respectively. Given our current capital position and projected earnings and asset growth rates, we do not anticipate any significant change in our current dividend policy.

Our bank subsidiary, which is a national banking association and a member of the Federal Reserve System, is required by federal law to obtain the prior approval of the OCC to declare and pay dividends if the total of all dividends declared in any calendar year would exceed the total of (1) such bank’s net profits (as defined and interpreted by regulation) for that year plus (2) its retained net profits (as defined and interpreted by regulation) for the preceding two calendar years, less any required transfers to surplus.

To pay dividends, we and our subsidiary bank must maintain adequate capital above regulatory guidelines. In addition, if the applicable regulatory authority believes that a bank under its jurisdiction is engaged in or is about to engage in an unsafe or unsound practice (which, depending on the financial condition of the bank, could include the payment of dividends), the authority may require, after notice and hearing, that such bank cease and desist from the unsafe practice. The Federal Reserve, the FDIC and the OCC have each indicated that paying dividends that deplete a bank’s capital base to an inadequate level would be an unsafe and unsound banking practice. The Federal Reserve, the OCC and the FDIC have issued policy statements that recommend that bank holding companies and insured banks should generally only pay dividends out of current operating earnings.

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Item 3. Quantitative and Qualitative Disclosures About Market Risk

Management considers interest rate risk to be a significant market risk for the Company. See “Item 2 – Management’s Discussion and Analysis of Financial Condition and Results of Operations – Capital Resources – Interest Rate Risk” for disclosure regarding this market risk.

Item 4. Controls and Procedures

As of September 30, 2017, we carried out an evaluation, under the supervision and with the participation of our management, including our principal executive officer and principal financial officer, of the effectiveness of the design and operation of our disclosure controls and procedures (as defined in Rule 13a-15(e) or 15d-15(e) of the Securities Exchange Act of 1934). Our management, which includes our principal executive officer and our principal financial officer, does not expect that our disclosure controls and procedures will prevent all errors and all fraud.

A control system, no matter how well conceived and operated, can provide only reasonable, not absolute, assurance that the objectives of the control system are met. Further, the design of a control system must reflect the fact that there are resource constraints, and the benefits of controls must be considered relative to their costs. Because of the inherent limitations in all control systems, no evaluation of controls can provide absolute assurance that all control issues and instances of fraud, if any, within the Company have been detected. These inherent limitations include the realities that judgments in decision-making can be faulty and that breakdowns can occur because of simple error or mistake. Additionally, controls can be circumvented by the individual acts of some persons, by collusion of two or more people, or by management override of the control. The design of any system of controls also is based in part upon certain assumptions about the likelihood of future events, and there can be no assurance that any design will succeed in achieving its stated goals under all potential future conditions; over time, controls may become inadequate because of changes in conditions or the degree of compliance with the policies or procedures may deteriorate. Because of the inherent limitations in a cost-effective control system, misstatements due to error or fraud may occur and not be detected. Our principal executive officer and principal financial officer have concluded, based on our evaluation of our disclosure controls and procedures, that our disclosure controls and procedures were effective at the reasonable assurance level as of September 30, 2017.

Subsequent to our evaluation, there were no significant changes in internal controls over financial reporting or other factors that have materially affected, or are reasonably likely to materially affect, these internal controls.

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PART II

OTHER INFORMATION

Item 1. Legal Proceedings

From time to time we and our subsidiaries are parties to lawsuits arising in the ordinary course of our banking business. However, there are no material pending legal proceedings to which we, our subsidiaries, or any of their properties, are currently subject. Other than regular, routine examinations by state and federal banking authorities, there are no proceedings pending or known to be contemplated by any governmental authorities.

Item 1A. Risk Factors

There has been no material change in the risk factors previously disclosed under Item 1A. of the Company’s 2016 Annual Report on Form 10-K.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds

None

Item 3. Defaults Upon Senior Securities

Not Applicable

Item 4. Mine Safety Disclosures

Not Applicable

Item 5. Other Information

None

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Item 6. Exhibits

2.1	—	Agreement and Plan of Reorganization, dated October 12, 2017, by and among First Financial Bankshares, Inc., Kingwood Merger Sub, Inc., and Commercial Bancshares, Inc. (schedules have been omitted pursuant to Item 601 (b)(2) of Regulation S-K) ( incorporated by reference from Exhibit 2.1 to Registrant’s Form 8-K filed October 12, 2017).
3.1	—	Amended and Restated Certificate of Formation (incorporated by reference from Exhibit 3.1 of the Registrant’s Form 8-K filed April 28, 2015).
3.2	—	Amended and Restated Bylaws of the Registrant (incorporated by reference from Exhibit 99.1 of the Registrant’s Form 8-K filed January 24, 2012).
4.1	—	Specimen certificate of First Financial Common Stock (incorporated by reference from Exhibit 3 of the Registrant’s Amendment No. 1 to Form 8-A filed on Form 8-A/A No. 1 on January 7, 1994).
10.1	—	2002 Incentive Stock Option Plan (incorporated by reference from Exhibit 10.3 of the Registrant’s Form 10-Q filed May 4, 2010)++
10.2	—	2012 Incentive Stock Option Plan (incorporated by reference from Appendix  A of the Registrant’s Definitive Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 filed March 1, 2012).++
10.3	—	Loan agreement dated June  30, 2013, between First Financial Bankshares, Inc. and Frost Bank (incorporated by reference from Exhibit 10.1 of the Registrant’s Form 8-K filed July 1, 2013).
10.4	—	First Amendment to Loan Agreement, dated June  30, 2015, between First Financial Bankshares, Inc. and Frost Bank (incorporated by reference from Exhibit 10.1 of the Registrant’s Form 8-K filed June 30, 2015).
10.5	—	2015 Restricted Stock Plan (incorporated by reference from Appendix  A of the Registrant’s Definitive Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 filed March 2, 2015).++
10.6	—	Form of Executive Recognition Agreement (incorporated by reference from Exhibit 10.1 of the Registrant’s Form 8-K filed August 26, 2016).++
10.7	—	Second Amendment to Loan Agreement, dated June  30, 2017, between First Financial Bankshares, Inc. and Frost Bank (incorporated by reference from Exhibit 10.1 of the Registrant’s Form 8-K filed June 30, 2017).
31.1	—	Rule 13a-14(a) / 15(d)-14(a) Certification of Chief Executive Officer of First Financial Bankshares, Inc.*
31.2	—	Rule 13a-14(a) / 15(d)-14(a) Certification of Chief Financial Officer of First Financial Bankshares, Inc.*
32.1	—	Section 1350 Certification of Chief Executive Officer of First Financial Bankshares, Inc.+
32.2	—	Section 1350 Certification of Chief Financial Officer of First Financial Bankshares, Inc.+
101.INS	—	XBRL Instance Document.*
101.SCH	—	XBRL Taxonomy Extension Schema Document.*
101.CAL	—	XBRL Taxonomy Extension Calculation Linkbase Document.*
101.DEF	—	XBRL Taxonomy Extension Definition Linkbase Document.*
101.LAB	—	XBRL Taxonomy Extension Label Linkbase Document.*
101.PRE	—	XBRL Taxonomy Extension Presentation Linkbase Document.*

* Filed herewith

+ Furnished herewith. This Exhibit shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, or otherwise subject to the liability of that section, and shall not be deemed to be incorporated into any filing under the Securities Act of 1933 or the Securities Exchange Act of 1934.

++ Management contract or compensatory plan on arrangement.

54

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.

	FIRST FINANCIAL BANKSHARES, INC.
Date: October 31, 2017	By:	/s/ F. Scott Dueser
		F. Scott Dueser
		President and Chief Executive Officer
Date: October 31, 2017	By:	/s/ J. Bruce Hildebrand
		J. Bruce Hildebrand
		Executive Vice President and
		Chief Financial Officer

55

EX-31.1

Exhibit 31.1

Certification of

Chief Executive Officer

of First Financial Bankshares, Inc.

I, F. Scott Dueser, President and Chief Executive Officer of First Financial Bankshares, Inc., certify that:

1. I have reviewed this Form 10-Q of First Financial Bankshares, Inc.;

2. Based on my knowledge, this quarterly 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 quarterly 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 officer 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 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: October 31, 2017

By:	/s/ F. SCOTT DUESER
	F. Scott Dueser
	President and Chief Executive Officer

EX-31.2

Exhibit 31.2

Certification of

Chief Financial Officer

of First Financial Bankshares, Inc.

I, J. Bruce Hildebrand, Executive Vice President and Chief Financial Officer of First Financial Bankshares, Inc., certify that:

1. I have reviewed this Form 10-Q of First Financial Bankshares, Inc.;

2. Based on my knowledge, this quarterly 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 quarterly 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 officer 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 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: October 31, 2017

By:	/s/ J. Bruce Hildebrand
	J. Bruce Hildebrand
	Executive Vice President and Chief
	Financial Officer

EX-32.1

Exhibit 32.1

Certification of

Chief Executive Officer

of First Financial Bankshares, Inc.

This certification is provided pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (subsections (a) and (b) of Section 1350, Chapter 63 of Title 18, United States Code) and accompanies the quarterly report on Form 10-Q (the “Form 10-Q”) for the quarter ended September 30, 2017 of First Financial Bankshares, Inc. (the “Company”).

I, F. Scott Dueser, the President and Chief Executive Officer of the Company, certify that:

1. the Form 10-Q fully complies with the requirements of section 13(a) or section 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m(a) or 78o(d)); and

2. the information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Company.

Dated: October 31, 2017
	By:	/s/ F. SCOTT DUESER
		F. Scott Dueser
		Chief Executive Officer

Subscribed and sworn to before me this 31^st day of October, 2017.

/s/ Melissa A. Lomax

Melissa A. Lomax

Notary Public

My commission expires: October 11, 2020

EX-32.2

Exhibit 32.2

Certification of

Chief Financial Officer

of First Financial Bankshares, Inc.

This certification is provided pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (subsections (a) and (b) of Section 1350, Chapter 63 of Title 18, United States Code) and accompanies the quarterly report on Form 10-Q (the “Form 10-Q”) for the quarter ended September 30, 2017 of First Financial Bankshares, Inc. (the “Company”).

I, J. Bruce Hildebrand, the Executive Vice President and Chief Financial Officer of the Company, certify that:

1. the Form 10-Q fully complies with the requirements of section 13(a) or section 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m(a) or 78o(d)); and

2. the information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Company.

Dated: October 31, 2017
	By:	/s/ J. Bruce Hildebrand
		J. Bruce Hildebrand
		Chief Financial Officer

Subscribed and sworn to before me this 31^st day of October, 2017.

/s/ Melissa A. Lomax

Melissa A. Lomax

Notary Public

My commission expires: October 11, 2020

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Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Trading Symbol	FFIN
Entity Registrant Name	FIRST FINANCIAL BANKSHARES INC
Entity Central Index Key	0000036029
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		66,226,057

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Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
ASSETS
CASH AND DUE FROM BANKS	$ 177,615	$ 204,782	$ 166,981
FEDERAL FUNDS SOLD		3,130	3,400
INTEREST-BEARING DEPOSITS IN BANKS	166,820	48,574	117,334
Total cash and cash equivalents	344,435	256,486	287,715
INTEREST-BEARING TIME DEPOSITS IN BANKS	1,458	1,707	1,707
SECURITIES AVAILABLE-FOR-SALE, at fair value	2,885,483	2,860,837	2,729,030
SECURITIES HELD-TO-MATURITY (fair value of $133 and $124 at September 30, 2016, and December 31, 2016, respectively)	0	121	129
LOANS:
Held for investment	3,472,227	3,357,307	3,337,793
Less - allowance for loan losses	(47,922)	(45,779)	(45,298)
Net loans held for investment	3,424,305	3,311,528	3,292,495
Held for sale	19,119	26,898	31,591
Net loans	3,443,424	3,338,426	3,324,086
BANK PREMISES AND EQUIPMENT, net	125,668	122,685	122,725
INTANGIBLE ASSETS	141,355	143,603	143,729
OTHER ASSETS	67,341	86,066	77,615
Total assets	7,009,164	6,809,931	6,686,736
LIABILITIES AND SHAREHOLDERS' EQUITY
NONINTEREST-BEARING DEPOSITS	1,949,174	1,717,722	1,702,993
INTEREST-BEARING DEPOSITS	3,748,286	3,760,817	3,532,471
Total deposits	5,697,460	5,478,539	5,235,464
DIVIDENDS PAYABLE	12,580	11,897	11,891
BORROWINGS	351,435	445,770	513,759
OTHER LIABILITIES	41,133	35,840	57,678
Total liabilities	6,102,608	5,972,046	5,818,792
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS' EQUITY:
Common stock - ($0.01 par value, authorized 120,000,000 shares; 66,223,957, 66,063,285, and 66,094,695 shares issued at September 30, 2017 and 2016, and December 31, 2016, respectively)	662	661	661
Capital surplus	376,286	372,245	371,170
Retained earnings	493,706	446,534	431,765
Treasury stock (shares at cost: 498,459, 510,955, and 507,409 at September 30, 2017 and 2016, and December 31, 2016, respectively)	(7,028)	(6,671)	(6,566)
Deferred compensation	7,028	6,671	6,566
Accumulated other comprehensive earnings	35,902	18,445	64,348
Total shareholders' equity	906,556	837,885	867,944
Total liabilities and shareholders' equity	$ 7,009,164	$ 6,809,931	$ 6,686,736

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Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Statement of Financial Position [Abstract]
SECURITIES HELD-TO-MATURITY, fair value		$ 124	$ 133
Common stock, par value	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized	120,000,000	120,000,000	120,000,000
Common stock, shares issued	66,223,957	66,094,695	66,063,285
Treasury stock, shares	498,459	507,409	510,955

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Consolidated Statements of Earnings (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
INTEREST INCOME:
Interest and fees on loans	$ 42,749	$ 40,411	$ 123,643	$ 120,700
Interest on investment securities:
Taxable	8,074	6,775	23,848	21,167
Exempt from federal income tax	11,091	10,808	33,991	32,220
Interest on federal funds sold and interest-bearing deposits in banks	640	99	1,037	222
Total interest income	62,554	58,093	182,519	174,309
INTEREST EXPENSE:
Interest on deposits	2,228	1,112	5,748	3,197
Other	638	254	978	811
Total interest expense	2,866	1,366	6,726	4,008
Net interest income	59,688	56,727	175,793	170,301
PROVISION FOR LOAN LOSSES	1,415	3,833	5,090	8,219
Net interest income after provision for loan losses	58,273	52,894	170,703	162,082
NONINTEREST INCOME:
Trust fees	6,040	5,066	17,804	14,446
Service charges on deposit accounts	5,083	4,796	14,517	13,614
ATM, interchange and credit card fees	6,340	6,000	19,102	17,521
Real estate mortgage operations	3,891	4,697	11,496	11,849
Net gain on sale of available-for-sale securities (includes $1,075 and $239 for the three months ended September 30, 2017 and 2016, respectively, and $1,825 and $1,153 for the nine months ended September 30, 2017 and 2016, respectively, related to accumulated other comprehensive earnings reclassifications)	1,075	239	1,825	1,153
Net gain (loss) on sale of foreclosed assets	(11)	(10)	(42)	343
Net gain (loss) on sale of assets	(15)	(168)	(211)	271
Interest on loan recoveries	405	709	896	1,970
Other	1,452	823	3,328	2,243
Total noninterest income	24,260	22,152	68,715	63,410
NONINTEREST EXPENSE:
Salaries and employee benefits	24,143	22,931	70,867	67,668
Net occupancy expense	2,711	2,672	8,081	7,886
Equipment expense	3,294	3,420	10,397	10,186
FDIC insurance premiums	561	513	1,657	2,155
ATM, interchange and credit card expenses	2,001	1,859	5,517	5,352
Professional and service fees	2,036	1,883	5,878	5,099
Printing, stationery and supplies	449	536	1,423	1,504
Operational and other losses	1,081	533	2,639	1,452
Amortization of intangible assets	143	172	477	570
Other	7,545	7,484	22,955	21,968
Total noninterest expense	43,964	42,003	129,891	123,840
EARNINGS BEFORE INCOME TAXES	38,569	33,043	109,527	101,652
INCOME TAX EXPENSE (includes $376 and $84 for the three months ended September 30, 2017 and 2016, respectively, and $639 and $404 for the nine months ended September 30, 2017 and 2016, respectively, related to income tax expense from reclassification items)	9,195	7,440	25,300	23,544
NET EARNINGS	$ 29,374	$ 25,603	$ 84,227	$ 78,108
EARNINGS PER SHARE, BASIC	$ 0.44	$ 0.39	$ 1.27	$ 1.18
EARNINGS PER SHARE, ASSUMING DILUTION	0.44	0.39	1.27	1.18
DIVIDENDS PER SHARE	$ 0.19	$ 0.18	$ 0.56	$ 0.52

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Consolidated Statements of Earnings (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Reclassifications adjustment for realized gains on investment securities included in net earnings (loss), before income tax	$ 1,075	$ 239	$ 1,825	$ 1,153
Income tax expense from reclassification items	$ 376	$ 84	$ 639	$ 404

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Consolidated Statements of Comprehensive Earnings (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
NET EARNINGS	$ 29,374	$ 25,603	$ 84,227	$ 78,108
OTHER ITEMS OF COMPREHENSIVE EARNINGS (LOSS):
Change in unrealized gain on investment securities available-for-sale, before income taxes	1,729	(18,984)	28,682	27,235
Reclassification adjustment for realized gains on investment securities included in net earnings, before income tax	(1,075)	(239)	(1,825)	(1,153)
Total other items of comprehensive earnings	654	(19,223)	26,857	26,082
Income tax benefit (expense) related to other items of comprehensive earnings	(229)	6,728	(9,400)	(9,129)
COMPREHENSIVE EARNINGS	$ 29,799	$ 13,108	$ 101,684	$ 95,061

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Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Deferred Compensation [Member]	Accumulated Other Comprehensive Earnings [Member]
Beginning Balance at Dec. 31, 2015	$ 804,986	$ 660	$ 368,925	$ 388,006	$ (6,296)	$ 6,296	$ 47,395
Beginning Balance, Shares at Dec. 31, 2015		65,990,234
Treasury Stock, Beginning Balance, Shares at Dec. 31, 2015					(520,651)
Net earnings (unaudited)	78,108			78,108
Stock option exercises (unaudited)	989	$ 1	988
Stock option exercises, Shares (Unaudited)		66,866
Restricted stock grant (unaudited)	250		250
Restricted stock grant, Shares (unaudited)		6,185
Cash dividends declared (Unaudited)	(34,349)			(34,349)
Change in unrealized gain in investment securities available-for-sale, net of related income taxes (unaudited)	16,953						16,953
Additional tax benefit related to directors' deferred compensation plan (unaudited)	345		345
Shares purchased in connection with directors' deferred compensation plan, net (unaudited)					$ (270)	270
Shares purchased in connection with directors' deferred compensation plan, net, Shares (Unaudited)					9,696
Stock option expense (unaudited)	662		662
Ending Balance at Sep. 30, 2016	$ 867,944	$ 661	371,170	431,765	$ (6,566)	6,566	64,348
Ending Balance, Shares at Sep. 30, 2016		66,063,285
Treasury Stock, Ending Balance, Shares at Sep. 30, 2016	(510,955)				(510,955)
Beginning Balance at Dec. 31, 2016	$ 837,885	$ 661	372,245	446,534	$ (6,671)	6,671	18,445
Beginning Balance, Shares at Dec. 31, 2016		66,094,695
Treasury Stock, Beginning Balance, Shares at Dec. 31, 2016	(507,409)				(507,409)
Net earnings (unaudited)	$ 84,227			84,227
Stock option exercises (unaudited)	2,260	$ 1	2,259
Stock option exercises, Shares (Unaudited)		114,612
Restricted stock grant (unaudited)	600		600
Restricted stock grant, Shares (unaudited)		14,650
Cash dividends declared (Unaudited)	(37,055)			(37,055)
Change in unrealized gain in investment securities available-for-sale, net of related income taxes (unaudited)	17,457						17,457
Shares purchased in connection with directors' deferred compensation plan, net (unaudited)					$ (357)	357
Shares purchased in connection with directors' deferred compensation plan, net, Shares (Unaudited)					8,950
Stock option expense (unaudited)	1,182		1,182
Ending Balance at Sep. 30, 2017	$ 906,556	$ 662	$ 376,286	$ 493,706	$ (7,028)	$ 7,028	$ 35,902
Ending Balance, Shares at Sep. 30, 2017		66,223,957
Treasury Stock, Ending Balance, Shares at Sep. 30, 2017	(498,459)				(498,459)

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Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash dividend per share (Unaudited)	$ 0.56	$ 0.52
Retained Earnings [Member]
Cash dividend per share (Unaudited)	$ 0.56	$ 0.52

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Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
NET EARNINGS	$ 84,227	$ 78,108
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	9,447	8,627
PROVISION FOR LOAN LOSSES	5,090	8,219
Securities premium amortization (discount accretion), net	23,009	21,275
Gain on sale of assets, net	(1,572)	(1,767)
Deferred federal income tax benefit	1,290	825
Change in loans held-for-sale	7,779	1,952
Change in other assets	18,703	10,059
Change in other liabilities	7,172	530
Total adjustments	70,918	49,720
Net cash provided by operating activities	155,145	127,828
CASH FLOWS FROM INVESTING ACTIVITIES:
Net decrease in interest-bearing time deposits in banks	249	1,788
Activity in available-for-sale securities:
Sales	120,576	20,792
Maturities	4,299,781	2,830,522
Purchases	(4,450,719)	(2,835,964)
Activity in held-to-maturity securities - maturities	124	148
Net increase in loans	(119,911)	(27,446)
Purchases of bank premises and equipment and other assets	(12,626)	(17,151)
Proceeds from sale of other assets	4,857	2,960
Net cash used in investing activities	(157,669)	(24,351)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase (decrease) in noninterest-bearing deposits	231,452	(42,959)
Net increase (decrease) in interest-bearing deposits	(12,531)	88,254
Net decrease in borrowings	(94,335)	(101,916)
Common stock transactions:
Proceeds from stock issuances	2,260	989
Dividends paid	(36,373)	(33,016)
Net cash provided by (used in) financing activities	90,473	(88,648)
NET DECREASE IN CASH AND CASH EQUIVALENTS	87,949	14,829
CASH AND CASH EQUIVALENTS, beginning of period	256,486	272,886
CASH AND CASH EQUIVALENTS, end of period	344,435	287,715
SUPPLEMENTAL INFORMATION AND NONCASH TRANSACTIONS:
Interest paid	6,772	4,018
Federal income tax paid	21,896	21,631
Transfer of loans and bank premises to other real estate owned	2,044	1,905
Investment securities purchased but not settled	993	4,521
Restricted stock grant to officers and directors	$ 600	$ 250

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Basis of Presentation

9 Months Ended

Sep. 30, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

Note 1 - Basis of Presentation

The unaudited interim consolidated financial statements include the accounts of the Company, a Texas corporation and a financial holding company registered under the Bank Holding Company Act of 1956, as amended, or BHCA, and its wholly-owned subsidiaries: First Financial Bank, National Association, Abilene, Texas; First Technology Services, Inc.; First Financial Trust & Asset Management Company, National Association; First Financial Investments, Inc.; and First Financial Insurance Agency, Inc.

Through our subsidiary bank, we conduct a full-service commercial banking business. Our banking centers are located primarily in Central, North Central, Southeast and West Texas. As of September 30, 2017, we had 69 financial centers across Texas, with eleven locations in Abilene, three locations in San Angelo and Weatherford, two locations in Cleburne, Conroe, Stephenville and Granbury, and one location each in Acton, Albany, Aledo, Alvarado, Beaumont, Boyd, Bridgeport, Brock, Burleson, Cisco, Clyde, Cut and Shoot, Decatur, Eastland, Fort Worth, Glen Rose, Grapevine, Hereford, Huntsville, Keller, Magnolia, Mauriceville, Merkel, Midlothian, Mineral Wells, Montgomery, Moran, New Waverly, Newton, Odessa, Orange, Port Arthur, Ranger, Rising Star, Roby, Southlake, Sweetwater, Tomball, Trent, Trophy Club, Vidor, Waxahachie, Willis and Willow Park, all in Texas. Our trust subsidiary has seven locations which are located in Abilene, Fort Worth, Odessa, Beaumont, San Angelo, Stephenville and Sweetwater.

In the opinion of management, the unaudited interim consolidated financial statements reflect all adjustments necessary for a fair presentation of the Company’s financial position and unaudited results of operations and should be read in conjunction with the Company’s audited consolidated financial statements, and notes thereto in the Company’s Annual Report on Form 10-K, for the year ended December 31, 2016. All adjustments were of a normal recurring nature. However, the results of operations for the three and nine months ended September 30, 2017, are not necessarily indicative of the results to be expected for the year ending December 31, 2017, due to seasonality, changes in economic conditions and loan credit quality, interest rate fluctuations, regulatory and legislative changes and other factors. The preparation of financial statements in conformity with United States generally accepted accounting principles (“GAAP”) require management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the financial statement date. Actual results could vary. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted under U.S. Securities and Exchange Commission (“SEC”) rules and regulations. The Company evaluated subsequent events for potential recognition and/or disclosure through the date the consolidated financial statements were issued.

Goodwill and other intangible assets are evaluated annually for impairment as of the end of the second quarter. No such impairment has been noted in connection with the current or any prior evaluations.

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Stock Repurchase

9 Months Ended

Sep. 30, 2017

Equity [Abstract]

Stock Repurchase

Note 2 - Stock Repurchase

On July 25, 2017, the Company’s Board of Directors authorized the repurchase of up to 2,000,000 common shares through September 30, 2020. Previously, the Board had authorized the repurchase of up to 1,500,000 common shares through September 30, 2017. The shares buyback plan authorizes management to repurchase the shares at such time as repurchases are considered beneficial to shareholders. Any repurchase of shares will be made through the open market, block trades or in privately negotiated transactions in accordance with applicable laws and regulations. Under the repurchase plan, there is no minimum number of shares that the Company is required to repurchase. Through October 27, 2017, no shares were repurchased under this authorization or the previous authorization.

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Earnings Per Share

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Earnings Per Share

Note 3 - Earnings Per Share

Basic earnings per common share is computed by dividing net income available to common shareholders by the weighted average number of shares outstanding during the periods presented. In computing diluted earnings per common share for the three months and nine months ended September 30, 2017 and 2016, the Company assumes that all dilutive outstanding options to purchase common shares have been exercised at the beginning of the period (or the time of issuance, if later). The dilutive effect of the outstanding options and the restricted shares is reflected by application of the treasury stock method, whereby the proceeds from exercised options and restricted shares are assumed to be used to purchase common stock at the average market price during the respective periods. The weighted average common shares outstanding used in computing basic earnings per common share for the three months ended September 30, 2017 and 2016 were 66,140,518 and 66,023,069 shares, respectively. The weighted average common shares outstanding used in computing basic earnings per common share for the nine months ended September 30, 2017 and 2016 were 66,104,914 and 66,004,797 shares, respectively. The weighted average common shares outstanding used in computing fully diluted earnings per common share for the three months ended September 30, 2017 and 2016 were 66,417,281 and 66,147,202 shares, respectively. The weighted average common shares outstanding used in computing fully diluted earnings per common share for the nine months ended September 30, 2017 and 2016 were 66,392,210 and 66,135,918 shares, respectively.

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Interest-bearing Time Deposits in Banks and Securities

9 Months Ended

Sep. 30, 2017

Cash and Cash Equivalents [Abstract]

Interest-bearing Time Deposits in Banks and Securities

Note 4 - Interest-bearing Time Deposits in Banks and Securities

Interest-bearing time deposits in banks totaled $1,458,000, $1,707,000 and $1,707,000 at September 30, 2017 and 2016 and December 31, 2016, respectively, and have original maturities generally ranging from one to two years.

Management classifies debt and equity securities as held-to-maturity, available-for-sale, or trading based on its intent. Debt securities that management has the positive intent and ability to hold to maturity are classified as held-to-maturity and recorded at cost, adjusted for amortization of premiums and accretion of discounts, which are recognized as adjustments to interest income using the interest method. Securities not classified as held-to-maturity or trading are classified as available-for-sale and recorded at fair value, with all unrealized gains and unrealized losses judged to be temporary, net of deferred income taxes, excluded from earnings and reported in the consolidated statements of comprehensive earnings. Available-for-sale securities that have unrealized losses that are judged other-than-temporary are included in gain (loss) on sale of securities and a new cost basis is established. Securities classified as trading are recorded at fair value with unrealized gains and losses included in earnings.

The Company records its available-for-sale and trading securities portfolio at fair value. Fair values of these securities are determined based on methodologies in accordance with current authoritative accounting guidance. Fair values are volatile and may be influenced by a number of factors, including market interest rates, prepayment speeds, discount rates, credit ratings and yield curves. Fair values for investment securities are based on quoted market prices, where available. If quoted market prices are not available, fair values are based on the quoted prices of similar instruments or an estimate of fair value by using a range of fair value estimates in the market place as a result of the illiquid market specific to the type of security.

When the fair value of a security is below its amortized cost, and depending on the length of time the condition exists and the extent the fair value is below amortized cost, additional analysis is performed to determine whether an other-than-temporary impairment condition exists. Available-for-sale and held-to-maturity securities are analyzed quarterly for possible other-than-temporary impairment. The analysis considers (i) whether we have the intent to sell our securities prior to recovery and/or maturity, (ii) whether it is more likely than not that we will have to sell our securities prior to recovery and/or maturity, (iii) the length of time and extent to which the fair value has been less than amortized cost, and (iv) the financial condition of the issuer. Often, the information available to conduct these assessments is limited and rapidly changing, making estimates of fair value subject to judgment. If actual information or conditions are different than estimated, the extent of the impairment of the security may be different than previously estimated, which could have a material effect on the Company’s results of operations and financial condition.

The Company’s investment portfolio consists of U.S. Treasury securities, obligations of U.S. government sponsored enterprises and agencies, obligations of states and political subdivisions, mortgage pass-through securities, corporate bonds and general obligation or revenue based municipal bonds. Pricing for such securities is generally readily available and transparent in the market. The Company utilizes independent third-party pricing services to value its investment securities, which the Company reviews as well as the underlying pricing methodologies for reasonableness and to ensure such prices are aligned with pricing matrices. The Company validates quarterly, on a sample basis, prices supplied by the independent pricing services by comparison to prices obtained from other third-party sources.

A summary of the Company’s available-for-sale securities follows (in thousands):

	September 30, 2017
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Obligations of U.S. government sponsored enterprises and agencies	$	73,583	$	35	$	(30	)	$	73,588
Obligations of states and political subdivisions		1,379,117		56,671		(1,594	)		1,434,194
Corporate bonds and other		19,439		118		(2	)		19,555
Residential mortgage-backed securities		1,024,615		8,466		(3,797	)		1,029,284
Commercial mortgage-backed securities		328,806		945		(889	)		328,862
Total securities available-for-sale	$	2,825,560	$	66,235	$	(6,312	)	$	2,885,483

	September 30, 2016
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
U.S. Treasury securities	$	10,685	$	54	$	—		$	10,739
Obligations of U.S. government sponsored enterprises and agencies		114,918		802		—			115,720
Obligations of states and political subdivisions		1,419,737		83,694		(715	)		1,502,716
Corporate bonds and other		68,285		1,325		(1	)		69,609
Residential mortgage-backed securities		750,673		17,125		(1,299	)		766,499
Commercial mortgage-backed securities		259,636		4,200		(89	)		263,747
Total securities available-for-sale	$	2,623,934	$	107,200	$	(2,104	)	$	2,729,030

	December 31, 2016
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
U.S. Treasury securities	$	10,649	$	19	$	—		$	10,668
Obligations of U.S. government sponsored enterprises and agencies		113,450		253		—			113,703
Obligations of states and political subdivisions		1,534,095		40,194		(10,013	)		1,564,276
Corporate bonds and other		51,920		476		(3	)		52,393
Residential mortgage-backed securities		848,614		8,260		(5,513	)		851,361
Commercial mortgage-backed securities		269,044		622		(1,230	)		268,436
Total securities available-for-sale	$	2,827,772	$	49,824	$	(16,759	)	$	2,860,837

Disclosures related to the Company’s held-to-maturity securities, which totaled $129,000 and $121,000 at September 30, 2016, and December 31, 2016, respectively, have not been presented due to insignificance. There were no held-to-maturity securities owned by the Company at September 30, 2017.

The Company invests in mortgage-backed securities that have expected maturities that differ from their contractual maturities. These differences arise because borrowers may have the right to call or prepay obligations with or without a prepayment penalty. These securities include collateralized mortgage obligations (CMOs) and other asset backed securities. The expected maturities of these securities at September 30, 2017 were computed by using scheduled amortization of balances and historical prepayment rates. At September 30, 2017 and 2016, and December 31, 2016, the Company did not hold CMOs that entail higher risks than standard mortgage-backed securities.

The amortized cost and estimated fair value of available-for-sale securities at September 30, 2017, by contractual and expected maturity, are shown below (in thousands):

	Amortized Cost Basis		Estimated Fair Value
Due within one year	$	187,370	$	189,136
Due after one year through five years		650,523		679,535
Due after five years through ten years		632,562		656,623
Due after ten years		1,684		2,043
Mortgage-backed securities		1,353,421		1,358,146
Total	$	2,825,560	$	2,885,483

The following tables disclose, as of September 30, 2017 and 2016, and December 31, 2016, the Company’s investment securities that have been in a continuous unrealized-loss position for less than 12 months and for 12 or more months (in thousands):

	Less than 12 Months				12 Months or Longer				Total
September 30, 2017	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of U.S.government sponsored enterprises and agencies	$	45,050	$	30	$	—	$	—	$	45,050	$	30
Obligations of states and political subdivisions		54,983		309		45,217		1,285		100,200		1,594
Corporate bonds and other		—		—		240		2		240		2
Residential mortgage-backed securities		225,369		1,531		131,849		2,266		357,218		3,797
Commercial mortgage-backed securities		170,146		751		21,001		138		191,147		889
Total	$	495,548	$	2,621	$	198,307	$	3,691	$	693,855	$	6,312
	Less than 12 Months				12 Months or Longer				Total
September 30, 2016	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of states and political subdivisions	$	82,131	$	711	$	741	$	4	$	82,872	$	715
Corporate bonds and other		12,257		1		—		—		12,257		1
Residential mortgage-backed securities		80,015		267		57,334		1,032		137,349		1,299
Commercial mortgage-backed securities		10,213		25		13,692		64		23,905		89
Total	$	184,616	$	1,004	$	71,767	$	1,100	$	256,383	$	2,104
	Less than 12 Months				12 Months or Longer				Total
December 31, 2016	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of state and political subdivisions	$	446,052	$	9,997	$	1,209	$	16	$	447,261	$	10,013
Corporate bonds and other		244		3		—		—		244		3
Residential mortgage-backed securities		372,331		4,532		33,227		981		405,558		5,513
Commercial mortgage-backed securities		193,495		1,180		13,263		50		206,758		1,230
Total	$	1,012,122	$	15,712	$	47,699	$	1,047	$	1,059,821	$	16,759

The number of investments in an unrealized loss position totaled 179 at September 30, 2017. We do not believe these unrealized losses are “other-than-temporary” as (i) we do not have the intent to sell our securities prior to recovery and/or maturity and (ii) it is more likely than not that we will not have to sell our securities prior to recovery and/or maturity. In making this determination, we also consider the length of time and extent to which fair value has been less than cost and the financial condition of the issuer. The unrealized losses noted are interest rate related due to the level of interest rates at September 30, 2017 compared to the time of purchase. We have reviewed the ratings of the issuers and have not identified any issues related to the ultimate repayment of principal as a result of credit concerns on these securities. Our mortgage related securities are backed by GNMA, FNMA and FHLMC or are collateralized by securities backed by these agencies. At September 30, 2017, 82.70% of our available-for-sale securities that are obligations of states and political subdivisions were issued within the State of Texas, of which 31.16% are guaranteed by the Texas Permanent School Fund.

At September 30, 2017, $1,787,958,000 of the Company’s securities were pledged as collateral for public or trust fund deposits, repurchase agreements and for other purposes required or permitted by law.

During the quarters ended September 30, 2017 and 2016, sales of investment securities that were classified as available-for-sale totaled $83,605,000 and $7,410,000, respectively. Gross realized gains from security sales during the third quarter of 2017 and 2016 totaled $1,750,000 and $239,000, respectively. Gross realized losses from security sales during the third quarter of 2017 totaled $675,000. There were no gross realized losses during the third quarter of 2016.

During the nine months ended September 30, 2017 and 2016, sale of investment securities were classified as available-for-sale totaled $120,576,000 and $20,792,000, respectively. Gross realized gains from security sales during the nine-month period ended September 30, 2017 and 2016 totaled $2,550,000 and $1,158,000, respectively. Gross realized losses from security sales during the nine-month periods ended September 30, 2017 and 2016 totaled $725,000 and $5,000, respectively.

The specific identification method was used to determine cost in order to compute the realized gains and losses.

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Loans and Allowance for Loan Losses

9 Months Ended

Sep. 30, 2017

Receivables [Abstract]

Loans and Allowance for Loan Losses

Note 5 - Loans and Allowance for Loan Losses

Loans held for investment are stated at the amount of unpaid principal, reduced by unearned income and an allowance for loan losses. Interest on loans is calculated by using the simple interest method on daily balances of the principal amounts outstanding. The Company defers and amortizes net loan origination fees and costs as an adjustment to yield. The allowance for loan losses is established through a provision for loan losses charged to expense. Loans are charged against the allowance for loan losses when management believes the collectability of the principal is unlikely.

The Company has certain lending policies and procedures in place that are designed to maximize loan income with an acceptable level of risk. Management reviews and approves these policies and procedures on an annual basis and makes changes as appropriate. Management receives and reviews monthly reports related to loan originations, quality, concentrations, delinquencies, nonperforming and potential problem loans. Diversification in the loan portfolio is a means of managing risk associated with fluctuations in economic conditions, both by type of loan and geographic location.

Commercial loans are underwritten after evaluating and understanding the borrower’s ability to operate profitably and effectively. Underwriting standards are designed to determine whether the borrower possesses sound business ethics and practices and to evaluate current and projected cash flows to determine the ability of the borrower to repay their obligations as agreed. Commercial loans are primarily made based on the identified cash flows of the borrower and, secondarily, on the underlying collateral provided by the borrower. Most commercial loans are secured by the assets being financed or other business assets, such as accounts receivable or inventory, and include personal guarantees.

Agricultural loans are subject to underwriting standards and processes similar to commercial loans. These agricultural loans are based primarily on the identified cash flows of the borrower and secondarily on the underlying collateral provided by the borrower. Most agricultural loans are secured by the agriculture related assets being financed, such as farm land, cattle or equipment, and include personal guarantees.

Real estate loans are also subject to underwriting standards and processes similar to commercial and agricultural loans. These loans are underwritten primarily based on projected cash flows and, secondarily, as loans secured by real estate. The repayment of real estate loans is generally largely dependent on the successful operation of the property securing the loans or the business conducted on the property securing the loan. Real estate loans may be more adversely affected by conditions in the real estate markets or in the general economy. The properties securing the Company’s real estate portfolio are generally diverse in terms of type and geographic location within Texas. This diversity helps reduce the exposure to adverse economic events that affect any single market or industry. Generally, real estate loans are owner occupied which further reduces the Company’s risk.

Consumer loan underwriting utilizes methodical credit standards and analysis to supplement the Company’s underwriting policies and procedures. The Company’s loan policy addresses types of consumer loans that may be originated and the collateral, if secured, which must be perfected. The relatively smaller individual dollar amounts of consumer loans that are spread over numerous individual borrowers also minimize the Company’s risk.

The allowance for loan losses is an amount which represents management’s best estimate of probable losses that are inherent in the Company’s loan portfolio as of the balance sheet date. The allowance for loan losses is comprised of three elements: (i) specific reserves determined based on probable losses on specific classified loans; (ii) a historical valuation reserve component that considers historical loss rates; and (iii) qualitative reserves based upon general economic conditions and other qualitative risk factors both internal and external to the Company. The allowance for loan losses is increased by charges to income and decreased by charge-offs (net of recoveries). Management’s periodic evaluation of the appropriateness of the allowance is based on general economic conditions, the financial condition of borrowers, the value and liquidity of collateral, delinquency, prior loan loss experience, and the results of periodic reviews of the portfolio. For purposes of determining our historical valuation reserve, the loan portfolio, less cash secured loans, government guaranteed loans and classified loans, is multiplied by the Company’s historical loss rate. Specific allocations are increased or decreased in accordance with deterioration or improvement in credit quality and a corresponding increase or decrease in risk of loss on a particular loan. In addition, we adjust our allowance for qualitative factors such as current local economic conditions and trends, including, without limitations, unemployment, oil and gas prices, flood and drought conditions, changes in lending staff, policies and procedures, changes in credit concentrations, changes in the trends and severity of problem loans and changes in trends in volume and terms of loans. This qualitative reserve serves to estimate for additional areas of losses inherent in our portfolio that are not reflected in our historic loss factors.

Although we believe we use the best information available to make loan loss allowance determinations, future adjustments could be necessary if circumstances or economic conditions differ substantially from the assumptions used in making our initial determinations. A decline in the economy and employment rates could result in increased levels of non-performing assets and charge-offs, increased loan provisions and reductions in income. Additionally, bank regulatory agencies periodically review our allowance for loan losses and methodology and could require, in accordance with generally accepted accounting principles, additional provisions to the allowance for loan losses based on their judgment of information available to them at the time of their examination as well as changes to our methodology.

Accrual of interest is discontinued on a loan and payments are applied to principal when management believes, after considering economic and business conditions and collection efforts, the borrower’s financial condition is such that collection of interest is doubtful. Except consumer loans, generally all loans past due greater than 90 days, based on contractual terms, are placed on non-accrual. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured. Consumer loans are generally charged-off when a loan becomes past due 90 days. For other loans in the portfolio, facts and circumstances are evaluated in making charge-off decisions.

Loans are considered impaired when, based on current information and events, management determines that it is probable we will be unable to collect all amounts due in accordance with the loan agreement, including scheduled principal and interest payments. If a loan is impaired, a specific valuation allowance is allocated, if necessary. Interest payments on impaired loans are typically applied to principal unless collectability of the principal amount is reasonably assured, in which case interest is recognized on a cash basis. Impaired loans, or portions thereof, are charged off when deemed uncollectable.

The Company’s policy requires measurement of the allowance for an impaired, collateral dependent loan based on the fair value of the collateral. Other loan impairments for non-collateral dependent loans are measured based on the present value of expected future cash flows or the loan’s observable market price. At September 30, 2017 and 2016, and December 31, 2016, all significant impaired loans have been determined to be collateral dependent and the allowance for loss has been measured utilizing the estimated fair value of the collateral less costs to sell.

From time to time, the Company modifies its loan agreement with a borrower. A modified loan is considered a troubled debt restructuring when two conditions are met: (i) the borrower is experiencing financial difficulty and (ii) concessions are made by the Company that would not otherwise be considered for a borrower with similar credit risk characteristics. Modifications to loan terms may include a lower interest rate, a reduction of principal, or a longer term to maturity. For all impaired loans, including the Company’s troubled debt restructurings, the Company performs a periodic, well-documented credit evaluation of the borrower’s financial condition and prospects for repayment to assess the likelihood that all principal and interest payments required under the terms of the agreement will be collected in full. When doubt exists about the ultimate collectability of principal and interest, the troubled debt restructuring remains on non-accrual status and payments received are applied to reduce principal to the extent necessary to eliminate such doubt. This determination of accrual status is judgmental and is based on facts and circumstances related to each troubled debt restructuring. Each of these loans is individually evaluated for impairment and a specific reserve is recorded based on probable losses, taking into consideration the related collateral, modified loan terms and cash flow. As of September 30, 2017 and 2016, and December 31, 2016, substantially all of the Company’s troubled debt restructured loans are included in the non-accrual totals.

The Company originates certain mortgage loans for sale in the secondary market. Accordingly, these loans are classified as held-for-sale and are carried at the lower of cost or fair value on an aggregate basis. The mortgage loan sales contracts contain indemnification clauses should the loans default, generally in the first three to nine months, or if documentation is determined not to be in compliance with regulations. The Company’s historic losses as a result of these indemnities have been insignificant.

Loans acquired, including loans acquired in a business combination, are initially recorded at fair value with no valuation allowance. Acquired loans are segregated between those considered to be credit impaired and those deemed performing. To make this determination, management considers such factors as past due status, non-accrual status and credit risk ratings. The fair value of acquired performing loans is determined by discounting expected cash flows, both principal and interest, at prevailing market interest rates. The difference between the fair value and principal balances at acquisition date, the fair value discount, is accreted into interest income over the estimated life of the acquired loan portfolio.

Purchased credit impaired loans are those loans that showed evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all amounts contractually owed. Their acquisition fair value, which includes a credit component at the acquisition date, was based on the estimate of cash flows, both principal and interest, expected to be collected or estimated collateral values if cash flows are not estimable, discounted at prevailing market rates of interest. The difference between the discounted cash flows expected at acquisition and the investment in the loan is recognized as interest income on a level-yield method over the life of the loan, unless management was unable to reasonably forecast cash flows in which case the loans were placed on nonaccrual. Contractually required payments for interest and principal that exceed the cash flows expected at acquisition are not recognized as a yield adjustment. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows subsequent to acquisition are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition. The carrying amount of purchased credit impaired loans at September 30, 2017 and 2016, and December 31, 2016, was $736,000, $1,853,000 and $1,256,000, respectively, compared to a contractual balance of $932,000, $2,528,000, and $1,865,000, respectively. Other purchased credit impaired loan disclosures were omitted due to immateriality.

Loans held-for-investment by class of financing receivables are as follows (in thousands):    

	September 30,				December 31,
	2017		2016		2016
Commercial	$	674,947	$	663,581	$	674,410
Agricultural		83,005		84,716		84,021
Real estate		2,297,556		2,191,260		2,189,844
Consumer		416,719		398,236		409,032
Total loans held-for-investment	$	3,472,227	$	3,337,793	$	3,357,307

Loans held for sale totaled $19,119,000, $31,591,000 and $26,898,000 at September 30, 2017 and 2016, and December 31, 2016, respectively, which are valued using the lower of cost or fair value.

The Company’s non-accrual loans, loans still accruing and past due 90 days or more and restructured loans are as follows (in thousands):

	September 30,				December 31,
	2017		2016		2016
Non-accrual loans*	$	18,750	$	33,712	$	27,371
Loans still accruing and past due 90 days or more		257		107		284
Troubled debt restructured loans**		668		750		701
Total	$	19,675	$	34,569	$	28,356

*Includes $736,000, $1,853,000 and $1,256,000 of purchased credit impaired loans as of September 30, 2017 and 2016, and December 31, 2016, respectively.

**Troubled debt restructured loans of $5,277,000, $7,513,000 and $6,863,000, whose interest collection, after considering economic and business conditions and collection efforts, is doubtful are included in non-accrual loans at September 30, 2017 and 2016, and December 31, 2016, respectively.

The Company’s recorded investment in impaired loans and the related valuation allowance are as follows (in thousands):

September 30, 2017		September 30, 2016		December 31, 2016
Recorded Investment	Valuation Allowance	Recorded Investment	Valuation Allowance	Recorded Investment	Valuation Allowance
$18,750	$4,177	$33,712	$7,042	$27,371	$5,012

The Company had $22,076,000, $34,938,000 and $29,000,000 in non-accrual, past due 90 days or more and still accruing, restructured loans and foreclosed assets at September 30, 2017 and 2016, and December 31, 2016, respectively. Non-accrual loans at September 30, 2017 and 2016, and December 31, 2016, consisted of the following by class of financing receivables (in thousands):

	September 30,				December 31,
	2017		2016		2016
Commercial	$	4,133	$	12,714	$	7,284
Agricultural		60		167		99
Real estate		13,386		19,582		18,754
Consumer		1,171		1,249		1,234
Total	$	18,750	$	33,712	$	27,371

No significant additional funds are committed to be advanced in connection with impaired loans as of September 30, 2017.

The Company’s impaired loans and related allowance as of September 30, 2017 and 2016, and December 31, 2016, are summarized in the following tables by class of financing receivables (in thousands). No interest income was recognized on impaired loans subsequent to their classification as impaired.

September 30, 2017	Unpaid Contractual Principal Balance		Recorded Investment With No Allowance*		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance		Year-to- Date Average Recorded Investment		Three- Month Average Recorded Investment
Commercial	$	10,989	$	617	$	3,516	$	4,133	$	1,671	$	7,313	$	5,866
Agricultural		66		—		60		60		17		66		60
Real Estate		17,306		3,742		9,644		13,386		1,984		14,279		13,829
Consumer		1,388		262		909		1,171		505		1,341		1,238
Total	$	29,749	$	4,621	$	14,129	$	18,750	$	4,177	$	22,999	$	20,993

*Includes $736,000 of purchased credit impaired loans.

September 30, 2016	Unpaid Contractual Principal Balance		Recorded Investment With No Allowance*		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance		Year-to- Date Average Recorded Investment		Three- Month Average Recorded Investment
Commercial	$	21,696	$	1,067	$	11,647	$	12,714	$	3,983	$	8,421	$	14,238
Agricultural		168		—		167		167		41		83		84
Real Estate		24,130		5,626		13,956		19,582		2,566		17,021		19,436
Consumer		1,479		324		925		1,249		452		989		1,166
Total	$	47,473	$	7,017	$	26,695	$	33,712	$	7,042	$	26,514	$	34,924

*Includes $1,853,000 of purchased credit impaired loans.

December 31, 2016	Unpaid Contractual Principal Balance		Recorded Investment With No Allowance*		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance		Year Average Recorded Investment
Commercial	$	13,389	$	1,148	$	6,136	$	7,284	$	2,128	$	4,921
Agricultural		103		—		99		99		25		50
Real Estate		23,466		6,229		12,525		18,754		2,428		16,170
Consumer		1,421		280		954		1,234		431		914
Total	$	38,379	$	7,657	$	19,714	$	27,371	$	5,012	$	22,055

*Includes $1,256,000 of purchased credit impaired loans.

The Company recognized interest income on impaired loans prior to being recognized as impaired of approximately $829,000 during the year ended December 31, 2016. Such amounts for the three-month and nine-month periods ended September 30, 2017 and 2016 were not significant.

From a credit risk standpoint, the Company rates its loans in one of four categories: (i) pass, (ii) special mention, (iii) substandard or (iv) doubtful. Loans rated as loss are charged-off.

The ratings of loans reflect a judgment about the risks of default and loss associated with the loan. The Company reviews the ratings on our credits as part of our on-going monitoring of the credit quality of our loan portfolio. Ratings are adjusted to reflect the degree of risk and loss that are felt to be inherent in each credit as of each reporting period. Our methodology is structured so that specific allocations are increased in accordance with deterioration in credit quality (and a corresponding increase in risk and loss) or decreased in accordance with improvement in credit quality (and a corresponding decrease in risk and loss).

Credits rated special mention show clear signs of financial weaknesses or deterioration in credit worthiness, however, such concerns are not so pronounced that the Company generally expects to experience significant loss within the short-term. Such credits typically maintain the ability to perform within standard credit terms and credit exposure is not as prominent as credits rated more harshly.

Credits rated substandard are those in which the normal repayment of principal and interest may be, or has been, jeopardized by reason of adverse trends or developments of a financial, managerial, economic or political nature, or important weaknesses exist in collateral. A protracted workout on these credits is a distinct possibility. Prompt corrective action is therefore required to strengthen the Company’s position, and/or to reduce exposure and to assure that adequate remedial measures are taken by the borrower. Credit exposure becomes more likely in such credits and a serious evaluation of the secondary support to the credit is performed.

Credits rated doubtful are those in which full collection of principal appears highly questionable, and which some degree of loss is anticipated, even though the ultimate amount of loss may not yet be certain and/or other factors exist which could affect collection of debt. Based upon available information, positive action by the Company is required to avert or minimize loss. Credits rated doubtful are generally also placed on non-accrual.

The following summarizes the Company’s internal ratings of its loans held-for-investment by class of financing receivables and portfolio segments, which are the same, at September 30, 2017 and 2016, and December 31, 2016 (in thousands):

September 30, 2017	Pass		Special Mention		Substandard		Doubtful		Total
Commercial	$	632,693	$	7,997	$	34,257	$	—	$	674,947
Agricultural		79,227		841		2,937		—		83,005
Real Estate		2,224,970		26,231		46,355		—		2,297,556
Consumer		414,043		168		2,508		—		416,719
Total	$	3,350,933	$	35,237	$	86,057	$	—	$	3,472,227
September 30, 2016	Pass		Special Mention		Substandard		Doubtful		Total
Commercial	$	614,900	$	6,108	$	42,573	$	—	$	663,581
Agricultural		82,400		—		2,316		—		84,716
Real Estate		2,118,807		19,064		53,389		—		2,191,260
Consumer		395,086		316		2,832		2		398,236
Total	$	3,211,193	$	25,488	$	101,110	$	2	$	3,337,793
December 31, 2016	Pass		Special Mention		Substandard		Doubtful		Total
Commercial	$	629,756	$	5,769	$	38,885	$	—	$	674,410
Agricultural		81,620		715		1,686		—		84,021
Real Estate		2,111,947		18,091		59,806		—		2,189,844
Consumer		406,182		212		2,638		—		409,032
Total	$	3,229,505	$	24,787	$	103,015	$	—	$	3,357,307

At September 30, 2017 and 2016, and December 31, 2016, the Company’s past due loans are as follows (in thousands):

September 30, 2017	15-59 Days Past Due*		60-89 Days Past Due		Greater Than 90 Days		Total Past Due		Current		Total Loans		90 Days Past Due Still Accruing
Commercial	$	3,288	$	585	$	1,495	$	5,368	$	669,579	$	674,947	$	212
Agricultural		322		—		—		322		82,683		83,005		—
Real Estate		12,636		984		2,293		15,913		2,281,643		2,297,556		—
Consumer		1,211		457		176		1,844		414,875		416,719		45
Total	$	17,457	$	2,026	$	3,964	$	23,447	$	3,448,780	$	3,472,227	$	257
September 30, 2016	15-59 Days Past Due*		60-89 Days Past Due		Greater Than 90 Days		Total Past Due		Current		Total Loans		90 Days Past Due Still Accruing
Commercial	$	4,707	$	841	$	6,950	$	12,498	$	651,083	$	663,581	$	61
Agricultural		523		63		—		586		84,130		84,716		—
Real Estate		13,444		1,496		3,376		18,316		2,172,944		2,191,260		34
Consumer		1,418		314		180		1,912		396,324		398,236		12
Total	$	20,092	$	2,714	$	10,506	$	33,312	$	3,304,481	$	3,337,793	$	107
December 31, 2016	15-59 Days Past Due*		60-89 Days Past Due		Greater Than 90 Days		Total Past Due		Total Current		Total Loans		Total 90 Days Past Due Still Accruing
Commercial	$	3,908	$	1,122	$	2,220	$	7,250	$	667,160	$	674,410	$	10
Agricultural		185		—		—		185		83,836		84,021		—
Real Estate		13,172		1,301		5,268		19,741		2,170,103		2,189,844		272
Consumer		1,845		368		122		2,335		406,697		409,032		2
Total	$	19,110	$	2,791	$	7,610	$	29,511	$	3,327,796	$	3,357,307	$	284

*The Company monitors commercial, agricultural and real estate loans after such loans are 15 days past due. Consumer loans are monitored after such loans are 30 days past due.

The following table details the allowance for loan losses at September 30, 2017 and 2016, and December 31, 2016, by portfolio segment (in thousands). There were no allowances for purchased credit impaired loans at September 30, 2017 and 2016, and December 31, 2016. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.

September 30, 2017	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	1,671	$	17	$	1,984	$	505	$	4,177
Loans collectively evaluated for impairment		10,201		1,284		26,484		5,776		43,745
Total	$	11,872	$	1,301	$	28,468	$	6,281	$	47,922
September 30, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	3,983	$	41	$	2,566	$	452	$	7,042
Loans collectively evaluated for impairment		9,733		1,027		23,655		3,841		38,256
Total	$	13,716	$	1,068	$	26,221	$	4,293	$	45,298

December 31, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	2,128	$	25	$	2,428	$	431	$	5,012
Loans collectively evaluated for impairment		9,579		1,076		24,436		5,676		40,767
Total	$	11,707	$	1,101	$	26,864	$	6,107	$	45,779

Changes in the allowance for loan losses for the three and nine months ended September 30, 2017 and 2016, are summarized as follows by portfolio segment (in thousands):

Three months ended September 30, 2017	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	11,935		$	1,127		$	28,023		$	6,325		$	47,410
Provision for loan losses		557			157			424			277			1,415
Recoveries		119			17			50			91			277
Charge-offs		(739	)		—			(29	)		(412	)		(1,180	)
Ending balance	$	11,872		$	1,301		$	28,468		$	6,281		$	47,922
Three months ended September 30, 2016	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	14,026		$	1,451		$	25,644		$	3,939		$	45,060
Provision for loan losses		3,248			(358	)		296			647			3,833
Recoveries		298			4			367			108			777
Charge-offs		(3,856	)		(29	)		(86	)		(401	)		(4,372	)
Ending balance	$	13,716		$	1,068		$	26,221		$	4,293		$	45,298
Nine months ended September 30, 2017	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	11,707		$	1,101		$	26,864		$	6,107		$	45,779
Provision for loan losses		1,485			211			2,556			838			5,090
Recoveries		868			25			141			400			1,434
Charge-offs		(2,188	)		(36	)		(1,093	)		(1,064	)		(4,381	)
Ending balance	$	11,872		$	1,301		$	28,468		$	6,281		$	47,922
Nine months ended September 30, 2016	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	12,644		$	1,191		$	24,375		$	3,667		$	41,877
Provision for loan losses		6,239			41			367			1,572			8,219
Recoveries		839			20			1,957			427			3,243
Charge-offs		(6,006	)		(184	)		(478	)		(1,373	)		(8,041	)
Ending balance	$	13,716		$	1,068		$	26,221		$	4,293		$	45,298

The Company’s recorded investment in loans as of September 30, 2017 and 2016, and December 31, 2016 related to the balance in the allowance for loan losses on the basis of the Company’s impairment methodology was as follows (in thousands). Purchased credit impaired loans of $736,000, $1,853,000 and $1,256,000 at September 30, 2017 and 2016, and December 31, 2016, respectively, are included in loans individually evaluated for impairment.

September 30, 2017	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	4,133	$	60	$	13,386	$	1,171	$	18,750
Loans collectively evaluated for impairment		670,814		82,945		2,284,170		415,548		3,453,477
Total	$	674,947	$	83,005	$	2,297,556	$	416,719	$	3,472,227
September 30, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	12,714	$	167	$	19,582	$	1,249	$	33,712
Loans collectively evaluated for impairment		650,867		84,549		2,171,678		396,987		3,304,081
Total	$	663,581	$	84,716	$	2,191,260	$	398,236	$	3,337,793
December 31, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	7,284	$	99	$	18,754	$	1,234	$	27,371
Loan collectively evaluated for impairment		667,126		83,922		2,171,090		407,798		3,329,936
Total	$	674,410	$	84,021	$	2,189,844	$	409,032	$	3,357,307

The Company’s loans that were modified in the three and nine months ended September 30, 2017 and 2016 and considered troubled debt restructurings are as follows (in thousands):

	Three Months Ended September 30, 2017						Nine Months Ended September 30, 2017
	Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment		Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment
Commercial		3	$	514	$	514		9	$	838	$	838
Agricultural		—		—		—		—		—		—
Real Estate		1		256		256		3		473		473
Consumer		—		—		—		1		25		25
Total		4	$	770	$	770		13	$	1,336	$	1,336
	Three Months Ended September 30, 2016						Nine Months Ended September 30, 2016
	Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment		Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment
Commercial		3	$	230	$	230		14	$	3,156	$	3,156
Agricultural		—		—		—		—		—		—
Real Estate		3		706		706		5		1,169		1,169
Consumer		1		44		44		5		162		162
Total		7	$	980	$	980		24	$	4,487	$	4,487

The balances below provide information as to how the loans were modified as troubled debt restructured loans during the three and nine months ended September 30, 2017 and 2016 (in thousands):

	Three Months Ended September 30, 2017						Nine Months Ended September 30, 2017
	Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity		Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity
Commercial	$	—	$	—	$	514		—	$	181	$	657
Agricultural		—		—		—		—		—		—
Real Estate		—		256		—		—		312		161
Consumer		—		—		—		—		25		—
Total	$	—	$	256	$	514		—	$	518	$	818
	Three Months Ended September 30, 2016						Nine Months Ended September 30, 2016
	Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity		Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity
Commercial	$	—	$	112	$	118		—	$	2,561	$	595
Agricultural		—		—		—		—		—		—
Real Estate		—		185		521		—		298		871
Consumer		—		—		44		—		43		119
Total	$	—	$	297	$	683		—	$	2,902	$	1,585

During the three months ended September 30, 2017 and 2016, two loans and two loans, respectively, were modified as troubled debt restructured loan within the previous 12 months and for which there was a payment default. During the nine months ended September 30, 2017 and 2016, four loans and three loans, respectively, were modified as troubled debt restructured loan within the previous 12 months and for which there was a payment default. A default for purposes of this disclosure is a troubled debt restructured loan in which the borrower is 90 days past due or more or results in the foreclosure and repossession of the applicable collateral. The loans with payment default are as follows (dollars in thousands):

	Three Months Ended September 30, 2017				Nine Months Ended September 30, 2017
	Number		Balance		Number		Balance
Commercial		2	$	88		3	$	141
Agriculture		—		—		—		—
Real Estate		—		—		1		62
Consumer		—		—		—		—
Total		2	$	88		4	$	203
	Three Months Ended September 30, 2016				Nine Months Ended September 30, 2016
	Number		Balance		Number		Balance
Commercial		1	$	62		1	$	62
Agriculture		—		—		—		—
Real Estate		1		112		2		462
Consumer		—		—		—		—
Total		2	$	174		3	$	524

As of September 30, 2017, the Company has no commitments to lend additional funds to loan customers whose terms have been modified in troubled debt restructurings.

Our subsidiary bank has established a line of credit with the Federal Home Loan Bank of Dallas (FHLB) to provide liquidity and meet pledging requirements for those customers eligible to have securities pledged to secure certain uninsured deposits. At September 30, 2017, $2,140,557,000 in loans held by our bank subsidiary were subject to blanket liens as security for this line of credit. At September 30, 2017, there was no balance outstanding under this line of credit.

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Borrowings

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Borrowings

Note 6 - Borrowings

Borrowings at September 30, 2017 and 2016, and December 31, 2016 consisted of the following (dollars in thousands):

	September 30,				December 31,
	2017		2016		2016
Securities sold under agreements with customers to repurchase	$	339,660	$	345,559	$	360,820
Federal funds purchased		11,775		8,200		9,950
Advances from Federal Home Loan Bank of Dallas		—		160,000		75,000
Total	$	351,435	$	513,759	$	445,770

Securities sold under repurchase agreements are generally with significant customers of the Company that require short-term liquidity for their funds for which the Company pledges certain securities that have a fair value equal to at least the amount of the borrowings. The agreements mature daily and therefore the risk arising from a decline in the fair value of the collateral pledged is minimal. The securities pledged are mortgage-backed securities. These agreements do not include “right of set-off” provisions and therefore the Company does not offset such agreements for financial reporting purposes.

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Income Taxes

9 Months Ended

Sep. 30, 2017

Income Tax Disclosure [Abstract]

Income Taxes

Note 7 - Income Taxes

Income tax expense was $9,195,000 for the third quarter of 2017 as compared to $7,440,000 for the same period in 2016. The Company’s effective tax rates on pretax income were 23.84% and 22.52% for the third quarters of 2017 and 2016, respectively. Income tax expense was $25,300,000 for the nine months ended September 30, 2017 as compared to $23,544,000 for the same period in 2016. The Company’s effective tax rates on pretax income were 23.10% and 23.16% for the nine months ended September 2017 and 2016, respectively. The effective tax rates differ from the statutory federal tax rate of 35% primarily due to tax exempt interest income earned on certain investment securities and loans, the deductibility of dividends paid to our employee stock ownership plan and excess tax benefits related to our directors’ deferred compensation plan.

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Stock Option Plan and Restricted Stock Plan

9 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock Option Plan and Restricted Stock Plan

Note 8 - Stock Option Plan and Restricted Stock Plan

The Company grants incentive stock options for a fixed number of shares with an exercise price equal to the fair value of the shares at the date of grant to employees. In June 2017, the Company granted 452,450 incentive stock options with an exercise price of $42.35 per share. The fair value of the options was $9.90 per option and was estimated using the Black-Scholes options pricing model with the following weighted average assumptions: risk-free interest rate of 1.89%; expected dividend yield of 1.79%; expected life of 6.24 years; and expected volatility of 26.51%. No options were granted in 2016.

The Company recorded stock option expense totaling $750,000 and $221,000 for the three-month periods ended September 30, 2017 and 2016, respectively. The Company recorded stock option expense totaling $1,182,000 and $662,000 for the nine months ended September 30, 2017 and 2016, respectively. The additional disclosure requirements under authoritative accounting guidance have been omitted due to the amounts being insignificant.

On July 21, 2015, 7,070 restricted shares were granted to the ten non-employee directors. Total value of these restricted shares totaled $250,000 and was expensed over the period from grant date to April 26, 2016, the annual shareholders’ meeting at which these director’s term expired. On April 26, 2016, upon re-election of existing directors, 7,660 restricted shares with a total value of $250,000 were granted to the ten non-employee directors and was expensed over the period from grant day to April 25, 2017, the annual shareholders’ meeting at which these directors’ term expired. On April 25, 2017, upon re-election of existing directors, 14,650 restricted shares with a total value of $600,000 were granted to the ten non-employee directors and is being expensed over the period from the grant date to April 24, 2018, the Company’s next shareholders’ meeting at which the directors’ term expires.

The Company recorded director expense related to these restricted share grants of $150,000 and $63,000 for the three-month periods ended September 30, 2017 and 2016, respectively. The Company recorded director expense related to these restricted share grants of $333,000 and $215,000 for the nine-month periods ended September 30, 2017 and 2016, respectively.

On October 27, 2015, the Company granted 31,273 restricted shares with a total value of $1,060,000 to certain officers that is being expensed over the vesting period of three years. On October 25, 2016, the Company granted 15,405 restricted shares with a total value of $560,000 to certain officers that is being expensed over the vesting period of three years. The Company recorded restricted stock expense for officers of $133,000 and $88,000, for the three-month periods ended September 30, 2017 and 2016, respectively. The Company recorded restricted share expense for officers of $399,000 and $262,000 for the nine-month periods ended September 30, 2017 and 2016, respectively.

On October 24, 2017, the Company granted 14,191 restricted shares with a total value of $655,000 to certain officers that will be expensed over the vesting period of one to three years.

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Pension Plan

9 Months Ended

Sep. 30, 2017

Retirement Benefits [Abstract]

Pension Plan

Note 9 - Pension Plan

The Company’s defined benefit pension plan was frozen effective January 1, 2004, whereby no new participants will be added to the plan and no additional years of service will accrue to participants, unless the pension plan is reinstated at a future date. The pension plan covered substantially all of the Company’s employees at the time. The benefits for each employee were based on years of service and a percentage of the employee’s qualifying compensation during the final years of employment. The Company’s funding policy was and is to contribute annually the amount necessary to satisfy the Internal Revenue Service’s funding standards. Contributions to the pension plan, prior to freezing the plan, were intended to provide not only for benefits attributed to service to date but also for those expected to be earned in the future. As a result of the Pension Protection Act of 2006 (the “Protection Act”), the Company will be required to contribute amounts in future years to fund any shortfalls. The Company has evaluated the provisions of the Protection Act as well as the Internal Revenue Service’s funding standards to develop a plan for funding in future years. The Company made a contribution totaling $500,000 in 2016, and has made no contribution through September 30, 2017.

Net periodic benefit costs totaling $84,000 and $82,000 were recorded for the three months ended September 30, 2017 and 2016, respectively. Net periodic benefit costs totaling $253,000 and $247,000 were recorded for the nine months ended September 30, 2017 and 2016, respectively.

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Fair Value Disclosures

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value Disclosures

Note 10 - Fair Value Disclosures

The authoritative accounting guidance for fair value measurements defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. The price in the principal (or most advantageous) market used to measure the fair value of the asset or liability shall not be adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets and liabilities; it is not a forced transaction. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact, and (iv) willing to transact.

The authoritative accounting guidance requires the use of valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets and liabilities. The income approach uses valuation techniques to convert future amounts, such as cash flows or earnings, to a single present amount on a discounted basis. The cost approach is based on the amount that currently would be required to replace the service capacity of an asset (replacement costs). Valuation techniques should be consistently applied.    Inputs to valuation techniques refer to the assumptions that market participants would use in pricing the asset or liability. Inputs may be observable, meaning those that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from independent sources, or unobservable, meaning those that reflect the reporting entity’s own assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. In that regard, the authoritative guidance 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:

• Level 1 Inputs – Unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date.

• Level 2 Inputs – Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. These include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (for example, interest rates, volatilities, prepayment speeds, loss severities, credit risks and default rates) or inputs that are derived principally from or corroborated by observable market data by correlation or other means.

• Level 3 Inputs – Significant unobservable inputs that reflect an entity’s own assumptions that market participants would use in pricing the assets or liabilities.

A description of the valuation methodologies used for assets and liabilities measured at fair value, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below.

In general, fair value is based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon internally developed models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. While management believes the Company’s valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date.

Securities classified as available-for-sale and trading are reported at fair value utilizing Level 1 and Level 2 inputs. For these securities, the Company obtains fair value measurements from an independent pricing service. The fair value measurements consider observable data that may include market spreads, cash flows, the United States Treasury yield curve, live trading levels, trade execution data, dealer quotes, market consensus prepayments speeds, credit information and the security’s terms and conditions, among other items.

There were no transfers between Level 1 and Level 2 or Level 2 and Level 3 during the three and nine months ended September 30, 2017 and 2016, and the year ended December 31, 2016.

The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of September 30, 2017 and 2016, and December 31, 2016, respectively, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (dollars in thousands):

September 30, 2017
	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Available-for-sale investment securities:
Obligations of U. S. government sponsored enterprises and agencies	$	—	$	73,588	$	—	$	73,588
Obligations of states and political subdivisions		—		1,434,194		—		1,434,194
Corporate bonds		—		15,099		—		15,099
Residential mortgage-backed securities		—		1,029,284		—		1,029,284
Commercial mortgage-backed securities		—		328,862		—		328,862
Other securities		4,456		—		—		4,456
Total	$	4,456	$	2,881,027	$	—	$	2,885,483
September 30, 2016
	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Available-for-sale investment securities:
U.S. Treasury securities	$	10,739	$	—	$	—	$	10,739
Obligations of U. S. government sponsored enterprises and agencies		—		115,720		—		115,720
Obligations of states and political subdivisions		—		1,502,716		—		1,502,716
Corporate bonds		—		65,037		—		65,037
Residential mortgage-backed securities		—		766,499		—		766,499
Commercial mortgage-backed securities		—		263,747		—		263,747
Other securities		4,572		—		—		4,572
Total	$	15,311	$	2,713,719	$	—	$	2,729,030
December 31, 2016
	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Available-for-sale investment securities:
U.S. Treasury securities	$	10,668	$	—	$	—	$	10,668
Obligations of U. S. government sponsored enterprises and agencies		—		113,703		—		113,703
Obligations of states and political subdivisions		—		1,564,276		—		1,564,276
Corporate bonds		—		47,965		—		47,965
Residential mortgage-backed securities		—		851,361		—		851,361
Commercial mortgage-backed securities		—		268,436		—		268,436
Other securities		4,428		—		—		4,428
Total	$	15,096	$	2,845,741	$	—	$	2,860,837

Certain financial assets and financial 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). Financial assets and financial liabilities measured at fair value on a non-recurring basis include the following at September 30, 2017:

Impaired Loans – Impaired loans are reported at the fair value of the underlying collateral if repayment is expected solely from the collateral less costs to sell. Collateral values are estimated using Level 2 inputs based on observable market data. At September 30, 2017, impaired loans with a carrying value of $14,129,000 were reduced by specific valuation reserves totaling $4,177,000 resulting in a net fair value of $9,952,000. The Company also had impaired loans of $4,621,000 with no specific valuation reserve at September 30, 2017, due to the loans carrying value generally being lower than the value of the collateral associated with the loan.

Loans Held-for-Sale – Loans held-for-sale are reported at the lower of cost or fair value. In determining whether the fair value of loans held-for-sale is less than cost when quoted market prices are not available, the Company considers investor commitments/contracts. These loans are considered Level 2 of the fair value hierarchy. At September 30, 2017, the Company’s mortgage loans held-for-sale were recorded at cost as fair value exceeded cost.    

Certain non-financial assets and non-financial liabilities measured at fair value on a non-recurring basis include other real estate owned, goodwill and other intangible assets and other non-financial long-lived assets. Non-financial assets measured at fair value on a non-recurring basis during the three months and nine months ended September 30, 2017 and 2016 include other real estate owned which, subsequent to their initial transfer to other real estate owned from loans, were re-measured at fair value through a write-down included in gain (loss) on sale of foreclosed assets. During the reported periods, all fair value measurements for foreclosed assets utilized Level 2 inputs based on observable market data, generally third-party appraisals, or Level 3 inputs based on customized discounting criteria. These appraisals are evaluated individually and discounted as necessary due to the age of the appraisal, lack of comparable sales, expected holding periods of property or special use type of the property. Such discounts vary by appraisal based on the above factors but generally range from 5% to 25% of the appraised value. Re-evaluation of other real estate owned is performed at least annually as required by regulatory guidelines or more often if particular circumstances arise. The following table presents other real estate owned that were re-measured subsequent to their initial transfer to other real estate owned (dollars in thousands):

	Three Months Ended September 30,
	2017			2016
Carrying value of other real estate owned prior to re-measurement	$	937		$	—
Write-downs included in gain (loss) on sale of other real estate owned		(288	)		—
Fair value	$	649		$	—
	Nine Months Ended September 30,
	2017			2016
Carrying value of other real estate owned prior to re-measurement	$	1,025		$	—
Write-downs included in gain (loss) on sale of other real estate owned		(296	)		—
Fair value	$	729		$	—

At September 30, 2017 and 2016, and December 31, 2016, other real estate owned totaled $2,176,000, $241,000, and $413,000, respectively.

The Company is required under current authoritative accounting guidance to disclose the estimated fair value of their financial instrument assets and liabilities including those subject to the requirements discussed above. For the Company, as for most financial institutions, substantially all of its assets and liabilities are considered financial instruments. Many of the Company’s financial instruments, however, lack an available trading market as characterized by a willing buyer and willing seller engaging in an exchange transaction.

The estimated fair value amounts of financial instruments have been determined by the Company using available market information and appropriate valuation methodologies. However, considerable judgment is required to interpret data to develop the estimates of fair value. Accordingly, the estimates presented herein are not necessarily indicative of the amounts the Company could realize in a current market exchange. The use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts.

In addition, reasonable comparability between financial institutions may not be likely due to the wide range of permitted valuation techniques and numerous estimates that must be made given the absence of active secondary markets for many of the financial instruments. This lack of uniform valuation methodologies also introduces a greater degree of subjectivity to these estimated fair values.

Cash and due from banks, federal funds sold, interest-bearing deposits and time deposits in banks and accrued interest receivable and payable are liquid in nature and considered Levels 1 or 2 of the fair value hierarchy.

Financial instruments with stated maturities have been valued using a present value discounted cash flow with a discount rate approximating current market for similar assets and liabilities and are considered Levels 2 and 3 of the fair value hierarchy. Financial instrument liabilities with no stated maturities have an estimated fair value equal to both the amount payable on demand and the carrying value and are considered Level 1 of the fair value hierarchy.

The carrying value and the estimated fair value of the Company’s contractual off-balance-sheet unfunded lines of credit, loan commitments and letters of credit, which are generally priced at market at the time of funding, are not material.

The estimated fair values and carrying values of all financial instruments under current authoritative guidance at September 30, 2017 and 2016, and December 31, 2016, were as follows (in thousands):

	September 30,								December 31,
	2017				2016				2016
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value		Fair Value Hierarchy
Cash and due from banks	$	177,615	$	177,615	$	166,981	$	166,981	$	204,782	$	204,782	Level 1
Federal funds sold		—		—		3,400		3,400		3,130		3,130	Level 1
Interest-bearing deposits in banks		166,820		166,820		117,334		117,334		48,574		48,574	Level 1
Interest-bearing time deposits in banks		1,458		1,458		1,707		1,709		1,707		1,709	Level 2
Available-for-sale Securities		2,885,483		2,885,483		2,729,030		2,729,030		2,860,837		2,860,837	Levels 1 and 2
Held-to-maturity securities		—		—		129		133		121		124	Level 2
Loans		3,443,424		3,458,603		3,324,086		3,334,965		3,338,426		3,361,735	Level 3
Accrued interest receivable		26,321		26,321		26,209		26,209		36,469		36,469	Level 2
Deposits with stated maturities		464,782		465,655		535,793		537,167		508,996		510,304	Level 2
Deposits with no stated maturities		5,232,678		5,232,678		4,699,671		4,699,671		4,969,543		4,969,543	Level 1
Borrowings		351,435		351,435		513,759		513,759		445,770		445,770	Level 2
Accrued interest Payable		179		179		230		230		225		225	Level 2

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Recently Issued Authoritative Accounting Guidance

9 Months Ended

Sep. 30, 2017

Accounting Changes and Error Corrections [Abstract]

Recently Issued Authoritative Accounting Guidance

Note 11 - Recently Issued Authoritative Accounting Guidance

Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers.” ASU 2014-09 implements a comprehensive new revenue recognition standard that will supersede substantially all existing revenue recognition guidance. The new standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. To achieve that core principle, an entity should apply the following steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract and (v) recognize revenue when (or as) the entity satisfies a performance obligation. ASU 2015-4 “Revenue from Contracts with Customers – Deferral of the Effective Date” deferred the effective date of ASU 2014-09 by one year and as a result, the new standard will be effective the first quarter of 2018. The Company’s revenue is comprised of net interest income on financial assets and financial liabilities, which is explicitly excluded from the scope of ASU 2014-09, and non-interest income. Based on the Company’s analysis of the effect of the new standard on its recurring revenue streams, the Company does not expect these changes to have a significant impact on the Company’s financial statement. Upon adoption in the first quarter of 2018, no significant adjustment to opening retained earnings is expected.

ASU 2014-15, “Presentation of Financial Statements – Going Concern.” ASU 2014-15 requires management to evaluate an entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Management must evaluate whether conditions and events raise substantial doubt about an entity’s ability to continue as a going concern and then whether its plans alleviate that doubt. ASU 2014-15 was effective in 2016 and management has performed and continues to perform such required evaluation and has concluded there are no such conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern.

ASU 2015-01, “Income Statement – Extraordinary and Unusual Items.” ASU 2015-01 eliminated from U.S. GAAP the concept of extraordinary items, which, among other things, required an entity to show the item separately in the income statement, net of tax, after income from continuing operations. The new guidance became effective for the Company beginning January 1, 2016 and did not have a significant impact on the Company’s financial statements.

ASU 2015-05, “Intangibles – Goodwill and Other – Internal-Use Software – Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement.” ASU 2015-05 addresses accounting for fees paid by a customer in cloud computing arrangements such as (i) software as a service, (ii) platform as a service, (iii) infrastructure as a service and (iv) other similar hosting arrangements. ASU 2015-05 provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. ASU 2015-05 became effective on January 1, 2016 and did not have a significant impact on the Company’s financial statements.

ASU 2015-16, “Business Combinations – Simplifying the Accounting Measurement Period Adjustments.” ASU 2015-16 amended business combination guidance to require that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The acquirer must record, in the same period’s financial statements, the effect of earnings on changes in depreciation, amortization, or other income effects, if any, as a result of the changes to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. Additionally, the entity is required to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the provisional amounts had been recognized as of the acquisition date. The amended guidance became effective for the Company on January 1, 2016 and did not have a significant impact on the Company’s financial statements.

ASU 2016-1, “Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-1, among other things, (i) requires equity investments, with certain exceptions, to be measured at fair value with changes in fair value recognized in net income, (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, (iii) eliminates the requirement for public business entities to disclose the methods and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet, (iv) requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes, (v) requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments, (vi) requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements and (vii) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities. ASU 2016-1 will be effective for the Company on January 1, 2018 and is not expected to have a significant impact on the Company’s financial statements.

ASU 2016-02, “Leases.” ASU 2016-02 will amend current lease accounting to require lessees to recognize (i) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis, and (ii) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. ASU 2016-02 does not significantly change lease accounting requirements applicable to lessors; however, certain changes were made to align, where necessary, lessor accounting with the lessee accounting model. The amended guidance will be effective in the first quarter of 2019 and will require transition using a modified retrospective approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The Company continues to evaluate the provision of the new lease standard but, due to the small number and dollar amount of lease agreements presently in effect for the Company, has concluded the new guidance will not have a significant impact on the Company’s financial statements.

ASU 2016-09, “Compensation – Stock Compensation: Improvements to Employee Share-Based Payment Accounting.” ASU 2016-09 amends current guidance such that all excess tax benefits and tax deficiencies related to share-based payment awards will be recognized as income tax expense or benefit in the income statement during the period in which they occur. Previously, such amounts were recorded in capital surplus. Additionally, excess tax benefits will be classified along with other income tax cash flows as an operating activity rather than a financing activity, as was previously the case. ASU 2016-09 also provides that any entity can make an entity-wide accounting policy election to either estimate the number of awards that are expected to vest, which is the current requirement, or account for forfeitures when they occur. ASU 2016-09 became effective January 1, 2017 and did not have a significant impact on the Company’s financial statements.

ASU 2016-13, “Financial Instruments – Credit Losses.” ASU 2016-13 implements a comprehensive change in estimating the allowances for loan losses from the current model of losses inherent in the loan portfolio to a current expected credit loss model that generally is expected to result in earlier recognition of allowances for losses. Additionally, purchase accounting rules have been modified as well as credit losses on held-to-maturity debt securities. ASU 2016-13 will be effective in the first quarter of 2020. While the Company generally expects that the implementation of ASU 2016-13 will increase their allowance for loan losses balance, the Company is continuing to evaluate the potential impact on the Company’s financial statements.

ASU 2017-04, “Intangibles – Goodwill and Other.” ASU 2017-04 will amend and simplify current goodwill impairment testing to eliminate Step 2 from the current provisions. Under the new guidance, an entity should perform the goodwill impairment test by comparing the fair value of a reporting unit with its carrying value and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. An entity still has the option to perform the quantitative assessment for a reporting unit to determine if a quantitative impairment test is necessary. ASU 2017-04 will be effective for the Company on January 1, 2020 and is not expected to have a significant impact on the Company’s financial statements.

ASU 2017-07, “Compensation – Retirement Benefits, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Post-Retirement Benefit Cost.” ASU 2017-17 will require employers that sponsor defined benefit pension plans to present the service cost component of net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. Other components of the net periodic benefit cost will be presented separately from the service cost component. ASU 2017-17 will be effective in 2018 and, as the Company froze its defined benefit pension plan in 2004, there is no service cost component of its net periodic benefit cost and therefore will not have an impact on the Company’s financial statements.

ASU 2017-08, “Receivables – Nonrefundable Fees and Other Costs: Premium Amortization on Purchased Callable Debt Securities.” ASU 2017-08 addresses the amortization method for all callable bonds purchased at a premium to par. Under the revised guidance, entities will be required to amortize premiums on callable bonds to the earliest call date. ASU 2017-08 is effective in 2019 although early adoption is permitted. The Company elected to early adopt ASU 2017-08 in the first quarter of 2017. The adoption of this guidance did not have a material impact on the Company’s financial statements.

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Acquisition Definitive Agreement Signed

9 Months Ended

Sep. 30, 2017

Business Combinations [Abstract]

Acquisition Definitive Agreement Signed

Note 12 - Acquisition Definitive Agreement Signed

On October 12, 2017, the Company announced that it has entered into a definitive agreement to acquire Commercial Bancshares, Inc. and its wholly owned bank subsidiary, Commercial State Bank, El Campo, Texas pursuant to an Agreement and Plan of Reorganization (the “Reorganization Agreement”) dated October 12, 2017, by and among the Company, Kingwood Merger Sub, Inc., a wholly owned subsidiary of the company, and Commercial Bancshares, Inc. for consideration to be paid in shares of Common Stock with an aggregate value of approximately $59,400,000. In addition, Commercial Bancshares, Inc. will make a $15,600,000 special dividend to its shareholders prior to closing of the transaction, which may be increased or decreased for the amount by which Commercial Bancshares, Inc.’s consolidated shareholders’ equity as of the closing date exceeds or is less than $42,400,000, after certain adjustments described in the Reorganization Agreement. At September 30, 2017 Commercial State Bank, Kingwood, Texas had gross loans totaling $263,800,000, total deposits of $322,100,000 and total assets of $366,800,000. Pending regulatory and shareholder approval, the acquisition is expected to close in the first quarter of 2018.

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Basis of Presentation (Policies)

9 Months Ended

Sep. 30, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Loans and Allowance for Loan Losses

Loans held for investment are stated at the amount of unpaid principal, reduced by unearned income and an allowance for loan losses. Interest on loans is calculated by using the simple interest method on daily balances of the principal amounts outstanding. The Company defers and amortizes net loan origination fees and costs as an adjustment to yield. The allowance for loan losses is established through a provision for loan losses charged to expense. Loans are charged against the allowance for loan losses when management believes the collectability of the principal is unlikely.

The Company has certain lending policies and procedures in place that are designed to maximize loan income with an acceptable level of risk. Management reviews and approves these policies and procedures on an annual basis and makes changes as appropriate. Management receives and reviews monthly reports related to loan originations, quality, concentrations, delinquencies, nonperforming and potential problem loans. Diversification in the loan portfolio is a means of managing risk associated with fluctuations in economic conditions, both by type of loan and geographic location.

Commercial loans are underwritten after evaluating and understanding the borrower’s ability to operate profitably and effectively. Underwriting standards are designed to determine whether the borrower possesses sound business ethics and practices and to evaluate current and projected cash flows to determine the ability of the borrower to repay their obligations as agreed. Commercial loans are primarily made based on the identified cash flows of the borrower and, secondarily, on the underlying collateral provided by the borrower. Most commercial loans are secured by the assets being financed or other business assets, such as accounts receivable or inventory, and include personal guarantees.

Agricultural loans are subject to underwriting standards and processes similar to commercial loans. These agricultural loans are based primarily on the identified cash flows of the borrower and secondarily on the underlying collateral provided by the borrower. Most agricultural loans are secured by the agriculture related assets being financed, such as farm land, cattle or equipment, and include personal guarantees.

Real estate loans are also subject to underwriting standards and processes similar to commercial and agricultural loans. These loans are underwritten primarily based on projected cash flows and, secondarily, as loans secured by real estate. The repayment of real estate loans is generally largely dependent on the successful operation of the property securing the loans or the business conducted on the property securing the loan. Real estate loans may be more adversely affected by conditions in the real estate markets or in the general economy. The properties securing the Company’s real estate portfolio are generally diverse in terms of type and geographic location within Texas. This diversity helps reduce the exposure to adverse economic events that affect any single market or industry. Generally, real estate loans are owner occupied which further reduces the Company’s risk.

Consumer loan underwriting utilizes methodical credit standards and analysis to supplement the Company’s underwriting policies and procedures. The Company’s loan policy addresses types of consumer loans that may be originated and the collateral, if secured, which must be perfected. The relatively smaller individual dollar amounts of consumer loans that are spread over numerous individual borrowers also minimize the Company’s risk.

The allowance for loan losses is an amount which represents management’s best estimate of probable losses that are inherent in the Company’s loan portfolio as of the balance sheet date. The allowance for loan losses is comprised of three elements: (i) specific reserves determined based on probable losses on specific classified loans; (ii) a historical valuation reserve component that considers historical loss rates; and (iii) qualitative reserves based upon general economic conditions and other qualitative risk factors both internal and external to the Company. The allowance for loan losses is increased by charges to income and decreased by charge-offs (net of recoveries). Management’s periodic evaluation of the appropriateness of the allowance is based on general economic conditions, the financial condition of borrowers, the value and liquidity of collateral, delinquency, prior loan loss experience, and the results of periodic reviews of the portfolio. For purposes of determining our historical valuation reserve, the loan portfolio, less cash secured loans, government guaranteed loans and classified loans, is multiplied by the Company’s historical loss rate. Specific allocations are increased or decreased in accordance with deterioration or improvement in credit quality and a corresponding increase or decrease in risk of loss on a particular loan. In addition, we adjust our allowance for qualitative factors such as current local economic conditions and trends, including, without limitations, unemployment, oil and gas prices, flood and drought conditions, changes in lending staff, policies and procedures, changes in credit concentrations, changes in the trends and severity of problem loans and changes in trends in volume and terms of loans. This qualitative reserve serves to estimate for additional areas of losses inherent in our portfolio that are not reflected in our historic loss factors.

Although we believe we use the best information available to make loan loss allowance determinations, future adjustments could be necessary if circumstances or economic conditions differ substantially from the assumptions used in making our initial determinations. A decline in the economy and employment rates could result in increased levels of non-performing assets and charge-offs, increased loan provisions and reductions in income. Additionally, bank regulatory agencies periodically review our allowance for loan losses and methodology and could require, in accordance with generally accepted accounting principles, additional provisions to the allowance for loan losses based on their judgment of information available to them at the time of their examination as well as changes to our methodology.

Accrual of interest is discontinued on a loan and payments are applied to principal when management believes, after considering economic and business conditions and collection efforts, the borrower’s financial condition is such that collection of interest is doubtful. Except consumer loans, generally all loans past due greater than 90 days, based on contractual terms, are placed on non-accrual. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured. Consumer loans are generally charged-off when a loan becomes past due 90 days. For other loans in the portfolio, facts and circumstances are evaluated in making charge-off decisions.

Loans are considered impaired when, based on current information and events, management determines that it is probable we will be unable to collect all amounts due in accordance with the loan agreement, including scheduled principal and interest payments. If a loan is impaired, a specific valuation allowance is allocated, if necessary. Interest payments on impaired loans are typically applied to principal unless collectability of the principal amount is reasonably assured, in which case interest is recognized on a cash basis. Impaired loans, or portions thereof, are charged off when deemed uncollectable.

The Company’s policy requires measurement of the allowance for an impaired, collateral dependent loan based on the fair value of the collateral. Other loan impairments for non-collateral dependent loans are measured based on the present value of expected future cash flows or the loan’s observable market price. At September 30, 2017 and 2016, and December 31, 2016, all significant impaired loans have been determined to be collateral dependent and the allowance for loss has been measured utilizing the estimated fair value of the collateral less costs to sell.

From time to time, the Company modifies its loan agreement with a borrower. A modified loan is considered a troubled debt restructuring when two conditions are met: (i) the borrower is experiencing financial difficulty and (ii) concessions are made by the Company that would not otherwise be considered for a borrower with similar credit risk characteristics. Modifications to loan terms may include a lower interest rate, a reduction of principal, or a longer term to maturity. For all impaired loans, including the Company’s troubled debt restructurings, the Company performs a periodic, well-documented credit evaluation of the borrower’s financial condition and prospects for repayment to assess the likelihood that all principal and interest payments required under the terms of the agreement will be collected in full. When doubt exists about the ultimate collectability of principal and interest, the troubled debt restructuring remains on non-accrual status and payments received are applied to reduce principal to the extent necessary to eliminate such doubt. This determination of accrual status is judgmental and is based on facts and circumstances related to each troubled debt restructuring. Each of these loans is individually evaluated for impairment and a specific reserve is recorded based on probable losses, taking into consideration the related collateral, modified loan terms and cash flow. As of September 30, 2017 and 2016, and December 31, 2016, substantially all of the Company’s troubled debt restructured loans are included in the non-accrual totals.

The Company originates certain mortgage loans for sale in the secondary market. Accordingly, these loans are classified as held-for-sale and are carried at the lower of cost or fair value on an aggregate basis. The mortgage loan sales contracts contain indemnification clauses should the loans default, generally in the first three to nine months, or if documentation is determined not to be in compliance with regulations. The Company’s historic losses as a result of these indemnities have been insignificant.

Loans acquired, including loans acquired in a business combination, are initially recorded at fair value with no valuation allowance. Acquired loans are segregated between those considered to be credit impaired and those deemed performing. To make this determination, management considers such factors as past due status, non-accrual status and credit risk ratings. The fair value of acquired performing loans is determined by discounting expected cash flows, both principal and interest, at prevailing market interest rates. The difference between the fair value and principal balances at acquisition date, the fair value discount, is accreted into interest income over the estimated life of the acquired loan portfolio.

Purchased credit impaired loans are those loans that showed evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all amounts contractually owed. Their acquisition fair value, which includes a credit component at the acquisition date, was based on the estimate of cash flows, both principal and interest, expected to be collected or estimated collateral values if cash flows are not estimable, discounted at prevailing market rates of interest. The difference between the discounted cash flows expected at acquisition and the investment in the loan is recognized as interest income on a level-yield method over the life of the loan, unless management was unable to reasonably forecast cash flows in which case the loans were placed on nonaccrual. Contractually required payments for interest and principal that exceed the cash flows expected at acquisition are not recognized as a yield adjustment. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows subsequent to acquisition are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition. The carrying amount of purchased credit impaired loans at September 30, 2017 and 2016, and December 31, 2016, was $633,000, $1,853,000 and $1,256,000, respectively, compared to a contractual balance of $812,000, $2,528,000, and $1,865,000, respectively. Other purchased credit impaired loan disclosures were omitted due to immateriality.

Recently Issued Authoritative Accounting Guidance

Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers.” ASU 2014-09 implements a comprehensive new revenue recognition standard that will supersede substantially all existing revenue recognition guidance. The new standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. To achieve that core principle, an entity should apply the following steps: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract and (v) recognize revenue when (or as) the entity satisfies a performance obligation. ASU 2015-4 “Revenue from Contracts with Customers – Deferral of the Effective Date” deferred the effective date of ASU 2014-09 by one year and as a result, the new standard will be effective the first quarter of 2018. The Company’s revenue is comprised of net interest income on financial assets and financial liabilities, which is explicitly excluded from the scope of ASU 2014-09, and non-interest income. Based on the Company’s analysis of the effect of the new standard on its recurring revenue streams, the Company does not expect these changes to have a significant impact on the Company’s financial statement. Upon adoption in the first quarter of 2018, no significant adjustment to opening retained earnings is expected.

ASU 2014-15, “Presentation of Financial Statements – Going Concern.” ASU 2014-15 requires management to evaluate an entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Management must evaluate whether conditions and events raise substantial doubt about an entity’s ability to continue as a going concern and then whether its plans alleviate that doubt. ASU 2014-15 was effective in 2016 and management has performed and continues to perform such required evaluation and has concluded there are no such conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern.

ASU 2015-01, “Income Statement – Extraordinary and Unusual Items.” ASU 2015-01 eliminated from U.S. GAAP the concept of extraordinary items, which, among other things, required an entity to show the item separately in the income statement, net of tax, after income from continuing operations. The new guidance became effective for the Company beginning January 1, 2016 and did not have a significant impact on the Company’s financial statements.

ASU 2015-05, “Intangibles – Goodwill and Other – Internal-Use Software – Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement.” ASU 2015-05 addresses accounting for fees paid by a customer in cloud computing arrangements such as (i) software as a service, (ii) platform as a service, (iii) infrastructure as a service and (iv) other similar hosting arrangements. ASU 2015-05 provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. ASU 2015-05 became effective on January 1, 2016 and did not have a significant impact on the Company’s financial statements.

ASU 2015-16, “Business Combinations – Simplifying the Accounting Measurement Period Adjustments.” ASU 2015-16 amended business combination guidance to require that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The acquirer must record, in the same period’s financial statements, the effect of earnings on changes in depreciation, amortization, or other income effects, if any, as a result of the changes to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. Additionally, the entity is required to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the provisional amounts had been recognized as of the acquisition date. The amended guidance became effective for the Company on January 1, 2016 and did not have a significant impact on the Company’s financial statements.

ASU 2016-1, “Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-1, among other things, (i) requires equity investments, with certain exceptions, to be measured at fair value with changes in fair value recognized in net income, (ii) simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment, (iii) eliminates the requirement for public business entities to disclose the methods and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet, (iv) requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes, (v) requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments, (vi) requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset on the balance sheet or the accompanying notes to the financial statements and (vii) clarifies that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities. ASU 2016-1 will be effective for the Company on January 1, 2018 and is not expected to have a significant impact on the Company’s financial statements.

ASU 2016-02, “Leases.” ASU 2016-02 will amend current lease accounting to require lessees to recognize (i) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis, and (ii) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. ASU 2016-02 does not significantly change lease accounting requirements applicable to lessors; however, certain changes were made to align, where necessary, lessor accounting with the lessee accounting model. The amended guidance will be effective in the first quarter of 2019 and will require transition using a modified retrospective approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The Company continues to evaluate the provision of the new lease standard but, due to the small number and dollar amount of lease agreements presently in effect for the Company, has concluded the new guidance will not have a significant impact on the Company’s financial statements.

ASU 2016-09, “Compensation – Stock Compensation: Improvements to Employee Share-Based Payment Accounting.” ASU 2016-09 amends current guidance such that all excess tax benefits and tax deficiencies related to share-based payment awards will be recognized as income tax expense or benefit in the income statement during the period in which they occur. Previously, such amounts were recorded in capital surplus. Additionally, excess tax benefits will be classified along with other income tax cash flows as an operating activity rather than a financing activity, as was previously the case. ASU 2016-09 also provides that any entity can make an entity-wide accounting policy election to either estimate the number of awards that are expected to vest, which is the current requirement, or account for forfeitures when they occur. ASU 2016-09 became effective January 1, 2017 and did not have a significant impact on the Company’s financial statements.

ASU 2016-13, “Financial Instruments – Credit Losses.” ASU 2016-13 implements a comprehensive change in estimating the allowances for loan losses from the current model of losses inherent in the loan portfolio to a current expected credit loss model that generally is expected to result in earlier recognition of allowances for losses. Additionally, purchase accounting rules have been modified as well as credit losses on held-to-maturity debt securities. ASU 2016-13 will be effective in the first quarter of 2020. While the Company generally expects that the implementation of ASU 2016-13 will increase their allowance for loan losses balance, the Company is continuing to evaluate the potential impact on the Company’s financial statements.

ASU 2017-04, “Intangibles – Goodwill and Other.” ASU 2017-04 will amend and simplify current goodwill impairment testing to eliminate Step 2 from the current provisions. Under the new guidance, an entity should perform the goodwill impairment test by comparing the fair value of a reporting unit with its carrying value and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. An entity still has the option to perform the quantitative assessment for a reporting unit to determine if a quantitative impairment test is necessary. ASU 2017-04 will be effective for the Company on January 1, 2020 and is not expected to have a significant impact on the Company’s financial statements.

ASU 2017-07, “Compensation – Retirement Benefits, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Post-Retirement Benefit Cost.” ASU 2017-17 will require employers that sponsor defined benefit pension plans to present the service cost component of net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. Other components of the net periodic benefit cost will be presented separately from the service cost component. ASU 2017-17 will be effective in 2018 and, as the Company froze its defined benefit pension plan in 2004, there is no service cost component of its net periodic benefit cost and therefore will not have an impact on the Company’s financial statements.

ASU 2017-08, “Receivables – Nonrefundable Fees and Other Costs: Premium Amortization on Purchased Callable Debt Securities.” ASU 2017-08 addresses the amortization method for all callable bonds purchased at a premium to par. Under the revised guidance, entities will be required to amortize premiums on callable bonds to the earliest call date. ASU 2017-08 is effective in 2019 although early adoption is permitted. The Company elected to early adopt ASU 2017-08 in the first quarter of 2017. The adoption of this guidance did not have a material impact on the Company’s financial statements.

Fair Value Disclosures

The authoritative accounting guidance for fair value measurements defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. The price in the principal (or most advantageous) market used to measure the fair value of the asset or liability shall not be adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets and liabilities; it is not a forced transaction. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact, and (iv) willing to transact.

The authoritative accounting guidance requires the use of valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets and liabilities. The income approach uses valuation techniques to convert future amounts, such as cash flows or earnings, to a single present amount on a discounted basis. The cost approach is based on the amount that currently would be required to replace the service capacity of an asset (replacement costs). Valuation techniques should be consistently applied.    Inputs to valuation techniques refer to the assumptions that market participants would use in pricing the asset or liability. Inputs may be observable, meaning those that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from independent sources, or unobservable, meaning those that reflect the reporting entity’s own assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. In that regard, the authoritative guidance 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:

• Level 1 Inputs – Unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date.

• Level 2 Inputs – Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. These include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (for example, interest rates, volatilities, prepayment speeds, loss severities, credit risks and default rates) or inputs that are derived principally from or corroborated by observable market data by correlation or other means.

• Level 3 Inputs – Significant unobservable inputs that reflect an entity’s own assumptions that market participants would use in pricing the assets or liabilities.

A description of the valuation methodologies used for assets and liabilities measured at fair value, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below.

In general, fair value is based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon internally developed models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. While management believes the Company’s valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date.

Securities classified as available-for-sale and trading are reported at fair value utilizing Level 1 and Level 2 inputs. For these securities, the Company obtains fair value measurements from an independent pricing service. The fair value measurements consider observable data that may include market spreads, cash flows, the United States Treasury yield curve, live trading levels, trade execution data, dealer quotes, market consensus prepayments speeds, credit information and the security’s terms and conditions, among other items.

Investment Securities

Management classifies debt and equity securities as held-to-maturity, available-for-sale, or trading based on its intent. Debt securities that management has the positive intent and ability to hold to maturity are classified as held-to-maturity and recorded at cost, adjusted for amortization of premiums and accretion of discounts, which are recognized as adjustments to interest income using the interest method. Securities not classified as held-to-maturity or trading are classified as available-for-sale and recorded at fair value, with all unrealized gains and unrealized losses judged to be temporary, net of deferred income taxes, excluded from earnings and reported in the consolidated statements of comprehensive earnings. Available-for-sale securities that have unrealized losses that are judged other-than-temporary are included in gain (loss) on sale of securities and a new cost basis is established. Securities classified as trading are recorded at fair value with unrealized gains and losses included in earnings.

The Company records its available-for-sale and trading securities portfolio at fair value. Fair values of these securities are determined based on methodologies in accordance with current authoritative accounting guidance. Fair values are volatile and may be influenced by a number of factors, including market interest rates, prepayment speeds, discount rates, credit ratings and yield curves. Fair values for investment securities are based on quoted market prices, where available. If quoted market prices are not available, fair values are based on the quoted prices of similar instruments or an estimate of fair value by using a range of fair value estimates in the market place as a result of the illiquid market specific to the type of security.

When the fair value of a security is below its amortized cost, and depending on the length of time the condition exists and the extent the fair value is below amortized cost, additional analysis is performed to determine whether an other-than-temporary impairment condition exists. Available-for-sale and held-to-maturity securities are analyzed quarterly for possible other-than-temporary impairment. The analysis considers (i) whether we have the intent to sell our securities prior to recovery and/or maturity, (ii) whether it is more likely than not that we will have to sell our securities prior to recovery and/or maturity, (iii) the length of time and extent to which the fair value has been less than amortized cost, and (iv) the financial condition of the issuer. Often, the information available to conduct these assessments is limited and rapidly changing, making estimates of fair value subject to judgment. If actual information or conditions are different than estimated, the extent of the impairment of the security may be different than previously estimated, which could have a material effect on the Company’s results of operations and financial condition.

The Company’s investment portfolio consists of U.S. Treasury securities, obligations of U.S. government sponsored enterprises and agencies, obligations of states and political subdivisions, mortgage pass-through securities, corporate bonds and general obligation or revenue based municipal bonds. Pricing for such securities is generally readily available and transparent in the market. The Company utilizes independent third-party pricing services to value its investment securities, which the Company reviews as well as the underlying pricing methodologies for reasonableness and to ensure such prices are aligned with pricing matrices. The Company validates quarterly, on a sample basis, prices supplied by the independent pricing services by comparison to prices obtained from other third-party sources.

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Interest-bearing Time Deposits in Banks and Securities (Tables)

9 Months Ended

Sep. 30, 2017

Cash and Cash Equivalents [Abstract]

Summary of Available-for-Sale Securities

A summary of the Company’s available-for-sale securities follows (in thousands):

	September 30, 2017
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Obligations of U.S. government sponsored enterprises and agencies	$	73,583	$	35	$	(30	)	$	73,588
Obligations of states and political subdivisions		1,379,117		56,671		(1,594	)		1,434,194
Corporate bonds and other		19,439		118		(2	)		19,555
Residential mortgage-backed securities		1,024,615		8,466		(3,797	)		1,029,284
Commercial mortgage-backed securities		328,806		945		(889	)		328,862
Total securities available-for-sale	$	2,825,560	$	66,235	$	(6,312	)	$	2,885,483

	September 30, 2016
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
U.S. Treasury securities	$	10,685	$	54	$	—		$	10,739
Obligations of U.S. government sponsored enterprises and agencies		114,918		802		—			115,720
Obligations of states and political subdivisions		1,419,737		83,694		(715	)		1,502,716
Corporate bonds and other		68,285		1,325		(1	)		69,609
Residential mortgage-backed securities		750,673		17,125		(1,299	)		766,499
Commercial mortgage-backed securities		259,636		4,200		(89	)		263,747
Total securities available-for-sale	$	2,623,934	$	107,200	$	(2,104	)	$	2,729,030

	December 31, 2016
	Amortized Cost Basis		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
U.S. Treasury securities	$	10,649	$	19	$	—		$	10,668
Obligations of U.S. government sponsored enterprises and agencies		113,450		253		—			113,703
Obligations of states and political subdivisions		1,534,095		40,194		(10,013	)		1,564,276
Corporate bonds and other		51,920		476		(3	)		52,393
Residential mortgage-backed securities		848,614		8,260		(5,513	)		851,361
Commercial mortgage-backed securities		269,044		622		(1,230	)		268,436
Total securities available-for-sale	$	2,827,772	$	49,824	$	(16,759	)	$	2,860,837

Amortized Cost and Estimated Fair Value of Available-for-Sale Securities

The amortized cost and estimated fair value of available-for-sale securities at September 30, 2017, by contractual and expected maturity, are shown below (in thousands):

	Amortized Cost Basis		Estimated Fair Value
Due within one year	$	187,370	$	189,136
Due after one year through five years		650,523		679,535
Due after five years through ten years		632,562		656,623
Due after ten years		1,684		2,043
Mortgage-backed securities		1,353,421		1,358,146
Total	$	2,825,560	$	2,885,483

Continuous Unrealized-Loss Position of Available-for-Sale Securities

The following tables disclose, as of September 30, 2017 and 2016, and December 31, 2016, the Company’s investment securities that have been in a continuous unrealized-loss position for less than 12 months and for 12 or more months (in thousands):

	Less than 12 Months				12 Months or Longer				Total
September 30, 2017	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of U.S.government sponsored enterprises and agencies	$	45,050	$	30	$	—	$	—	$	45,050	$	30
Obligations of states and political subdivisions		54,983		309		45,217		1,285		100,200		1,594
Corporate bonds and other		—		—		240		2		240		2
Residential mortgage-backed securities		225,369		1,531		131,849		2,266		357,218		3,797
Commercial mortgage-backed securities		170,146		751		21,001		138		191,147		889
Total	$	495,548	$	2,621	$	198,307	$	3,691	$	693,855	$	6,312
	Less than 12 Months				12 Months or Longer				Total
September 30, 2016	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of states and political subdivisions	$	82,131	$	711	$	741	$	4	$	82,872	$	715
Corporate bonds and other		12,257		1		—		—		12,257		1
Residential mortgage-backed securities		80,015		267		57,334		1,032		137,349		1,299
Commercial mortgage-backed securities		10,213		25		13,692		64		23,905		89
Total	$	184,616	$	1,004	$	71,767	$	1,100	$	256,383	$	2,104
	Less than 12 Months				12 Months or Longer				Total
December 31, 2016	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Obligations of state and political subdivisions	$	446,052	$	9,997	$	1,209	$	16	$	447,261	$	10,013
Corporate bonds and other		244		3		—		—		244		3
Residential mortgage-backed securities		372,331		4,532		33,227		981		405,558		5,513
Commercial mortgage-backed securities		193,495		1,180		13,263		50		206,758		1,230
Total	$	1,012,122	$	15,712	$	47,699	$	1,047	$	1,059,821	$	16,759

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Loans and Allowance for Loan Losses (Tables)

9 Months Ended

Sep. 30, 2017

Receivables [Abstract]

Loans Held-for-Investment by Class of Financing Receivables

Loans held-for-investment by class of financing receivables are as follows (in thousands):    

	September 30,				December 31,
	2017		2016		2016
Commercial	$	674,947	$	663,581	$	674,410
Agricultural		83,005		84,716		84,021
Real estate		2,297,556		2,191,260		2,189,844
Consumer		416,719		398,236		409,032
Total loans held-for-investment	$	3,472,227	$	3,337,793	$	3,357,307

Non-Accrual Loans, Loans Still Accruing and Past Due 90 Days or More and Restructured Loans

The Company’s non-accrual loans, loans still accruing and past due 90 days or more and restructured loans are as follows (in thousands):

	September 30,				December 31,
	2017		2016		2016
Non-accrual loans*	$	18,750	$	33,712	$	27,371
Loans still accruing and past due 90 days or more		257		107		284
Troubled debt restructured loans**		668		750		701
Total	$	19,675	$	34,569	$	28,356

*Includes $736,000, $1,853,000 and $1,256,000 of purchased credit impaired loans as of September 30, 2017 and 2016, and December 31, 2016, respectively.

**Troubled debt restructured loans of $5,277,000, $7,513,000 and $6,863,000, whose interest collection, after considering economic and business conditions and collection efforts, is doubtful are included in non-accrual loans at September 30, 2017 and 2016, and December 31, 2016, respectively.

Recorded Investment in Impaired Loans and Related Valuation Allowance

The Company’s recorded investment in impaired loans and the related valuation allowance are as follows (in thousands):

September 30, 2017		September 30, 2016		December 31, 2016
Recorded Investment	Valuation Allowance	Recorded Investment	Valuation Allowance	Recorded Investment	Valuation Allowance
$18,750	$4,177	$33,712	$7,042	$27,371	$5,012

Schedule of Non-Accrual Loans

Non-accrual loans at September 30, 2017 and 2016, and December 31, 2016, consisted of the following by class of financing receivables (in thousands):

	September 30,				December 31,
	2017		2016		2016
Commercial	$	4,133	$	12,714	$	7,284
Agricultural		60		167		99
Real estate		13,386		19,582		18,754
Consumer		1,171		1,249		1,234
Total	$	18,750	$	33,712	$	27,371

Schedule of Impaired Loans and Related Allowance

The Company’s impaired loans and related allowance as of September 30, 2017 and 2016, and December 31, 2016, are summarized in the following tables by class of financing receivables (in thousands). No interest income was recognized on impaired loans subsequent to their classification as impaired.

September 30, 2017	Unpaid Contractual Principal Balance		Recorded Investment With No Allowance*		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance		Year-to- Date Average Recorded Investment		Three- Month Average Recorded Investment
Commercial	$	10,989	$	617	$	3,516	$	4,133	$	1,671	$	7,313	$	5,866
Agricultural		66		—		60		60		17		66		60
Real Estate		17,306		3,742		9,644		13,386		1,984		14,279		13,829
Consumer		1,388		262		909		1,171		505		1,341		1,238
Total	$	29,749	$	4,621	$	14,129	$	18,750	$	4,177	$	22,999	$	20,993

*Includes $736,000 of purchased credit impaired loans.

September 30, 2016	Unpaid Contractual Principal Balance		Recorded Investment With No Allowance*		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance		Year-to- Date Average Recorded Investment		Three- Month Average Recorded Investment
Commercial	$	21,696	$	1,067	$	11,647	$	12,714	$	3,983	$	8,421	$	14,238
Agricultural		168		—		167		167		41		83		84
Real Estate		24,130		5,626		13,956		19,582		2,566		17,021		19,436
Consumer		1,479		324		925		1,249		452		989		1,166
Total	$	47,473	$	7,017	$	26,695	$	33,712	$	7,042	$	26,514	$	34,924

*Includes $1,853,000 of purchased credit impaired loans.

December 31, 2016	Unpaid Contractual Principal Balance		Recorded Investment With No Allowance*		Recorded Investment With Allowance		Total Recorded Investment		Related Allowance		Year Average Recorded Investment
Commercial	$	13,389	$	1,148	$	6,136	$	7,284	$	2,128	$	4,921
Agricultural		103		—		99		99		25		50
Real Estate		23,466		6,229		12,525		18,754		2,428		16,170
Consumer		1,421		280		954		1,234		431		914
Total	$	38,379	$	7,657	$	19,714	$	27,371	$	5,012	$	22,055

*Includes $1,256,000 of purchased credit impaired loans.

Schedule of Internal Ratings of Loans

The following summarizes the Company’s internal ratings of its loans held-for-investment by class of financing receivables and portfolio segments, which are the same, at September 30, 2017 and 2016, and December 31, 2016 (in thousands):

September 30, 2017	Pass		Special Mention		Substandard		Doubtful		Total
Commercial	$	632,693	$	7,997	$	34,257	$	—	$	674,947
Agricultural		79,227		841		2,937		—		83,005
Real Estate		2,224,970		26,231		46,355		—		2,297,556
Consumer		414,043		168		2,508		—		416,719
Total	$	3,350,933	$	35,237	$	86,057	$	—	$	3,472,227
September 30, 2016	Pass		Special Mention		Substandard		Doubtful		Total
Commercial	$	614,900	$	6,108	$	42,573	$	—	$	663,581
Agricultural		82,400		—		2,316		—		84,716
Real Estate		2,118,807		19,064		53,389		—		2,191,260
Consumer		395,086		316		2,832		2		398,236
Total	$	3,211,193	$	25,488	$	101,110	$	2	$	3,337,793
December 31, 2016	Pass		Special Mention		Substandard		Doubtful		Total
Commercial	$	629,756	$	5,769	$	38,885	$	—	$	674,410
Agricultural		81,620		715		1,686		—		84,021
Real Estate		2,111,947		18,091		59,806		—		2,189,844
Consumer		406,182		212		2,638		—		409,032
Total	$	3,229,505	$	24,787	$	103,015	$	—	$	3,357,307

Schedule of Past Due Loans

At September 30, 2017 and 2016, and December 31, 2016, the Company’s past due loans are as follows (in thousands):

September 30, 2017	15-59 Days Past Due*		60-89 Days Past Due		Greater Than 90 Days		Total Past Due		Current		Total Loans		90 Days Past Due Still Accruing
Commercial	$	3,288	$	585	$	1,495	$	5,368	$	669,579	$	674,947	$	212
Agricultural		322		—		—		322		82,683		83,005		—
Real Estate		12,636		984		2,293		15,913		2,281,643		2,297,556		—
Consumer		1,211		457		176		1,844		414,875		416,719		45
Total	$	17,457	$	2,026	$	3,964	$	23,447	$	3,448,780	$	3,472,227	$	257
September 30, 2016	15-59 Days Past Due*		60-89 Days Past Due		Greater Than 90 Days		Total Past Due		Current		Total Loans		90 Days Past Due Still Accruing
Commercial	$	4,707	$	841	$	6,950	$	12,498	$	651,083	$	663,581	$	61
Agricultural		523		63		—		586		84,130		84,716		—
Real Estate		13,444		1,496		3,376		18,316		2,172,944		2,191,260		34
Consumer		1,418		314		180		1,912		396,324		398,236		12
Total	$	20,092	$	2,714	$	10,506	$	33,312	$	3,304,481	$	3,337,793	$	107
December 31, 2016	15-59 Days Past Due*		60-89 Days Past Due		Greater Than 90 Days		Total Past Due		Total Current		Total Loans		Total 90 Days Past Due Still Accruing
Commercial	$	3,908	$	1,122	$	2,220	$	7,250	$	667,160	$	674,410	$	10
Agricultural		185		—		—		185		83,836		84,021		—
Real Estate		13,172		1,301		5,268		19,741		2,170,103		2,189,844		272
Consumer		1,845		368		122		2,335		406,697		409,032		2
Total	$	19,110	$	2,791	$	7,610	$	29,511	$	3,327,796	$	3,357,307	$	284

*The Company monitors commercial, agricultural and real estate loans after such loans are 15 days past due. Consumer loans are monitored after such loans are 30 days past due.

Schedule of Allowance for Loan Losses by Portfolio Segment

The following table details the allowance for loan losses at September 30, 2017 and 2016, and December 31, 2016, by portfolio segment (in thousands). There were no allowances for purchased credit impaired loans at September 30, 2017 and 2016, and December 31, 2016. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.

September 30, 2017	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	1,671	$	17	$	1,984	$	505	$	4,177
Loans collectively evaluated for impairment		10,201		1,284		26,484		5,776		43,745
Total	$	11,872	$	1,301	$	28,468	$	6,281	$	47,922
September 30, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	3,983	$	41	$	2,566	$	452	$	7,042
Loans collectively evaluated for impairment		9,733		1,027		23,655		3,841		38,256
Total	$	13,716	$	1,068	$	26,221	$	4,293	$	45,298

December 31, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	2,128	$	25	$	2,428	$	431	$	5,012
Loans collectively evaluated for impairment		9,579		1,076		24,436		5,676		40,767
Total	$	11,707	$	1,101	$	26,864	$	6,107	$	45,779

Changes in Allowance for Loan Losses

Changes in the allowance for loan losses for the three and nine months ended September 30, 2017 and 2016, are summarized as follows by portfolio segment (in thousands):

Three months ended September 30, 2017	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	11,935		$	1,127		$	28,023		$	6,325		$	47,410
Provision for loan losses		557			157			424			277			1,415
Recoveries		119			17			50			91			277
Charge-offs		(739	)		—			(29	)		(412	)		(1,180	)
Ending balance	$	11,872		$	1,301		$	28,468		$	6,281		$	47,922
Three months ended September 30, 2016	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	14,026		$	1,451		$	25,644		$	3,939		$	45,060
Provision for loan losses		3,248			(358	)		296			647			3,833
Recoveries		298			4			367			108			777
Charge-offs		(3,856	)		(29	)		(86	)		(401	)		(4,372	)
Ending balance	$	13,716		$	1,068		$	26,221		$	4,293		$	45,298
Nine months ended September 30, 2017	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	11,707		$	1,101		$	26,864		$	6,107		$	45,779
Provision for loan losses		1,485			211			2,556			838			5,090
Recoveries		868			25			141			400			1,434
Charge-offs		(2,188	)		(36	)		(1,093	)		(1,064	)		(4,381	)
Ending balance	$	11,872		$	1,301		$	28,468		$	6,281		$	47,922
Nine months ended September 30, 2016	Commercial			Agricultural			Real Estate			Consumer			Total
Beginning balance	$	12,644		$	1,191		$	24,375		$	3,667		$	41,877
Provision for loan losses		6,239			41			367			1,572			8,219
Recoveries		839			20			1,957			427			3,243
Charge-offs		(6,006	)		(184	)		(478	)		(1,373	)		(8,041	)
Ending balance	$	13,716		$	1,068		$	26,221		$	4,293		$	45,298

Schedule of Investment in Loans Related to Balance in Allowance for Loan Losses on Basis of Company's Impairment Methodology

The Company’s recorded investment in loans as of September 30, 2017 and 2016, and December 31, 2016 related to the balance in the allowance for loan losses on the basis of the Company’s impairment methodology was as follows (in thousands). Purchased credit impaired loans of $736,000, $1,853,000 and $1,256,000 at September 30, 2017 and 2016, and December 31, 2016, respectively, are included in loans individually evaluated for impairment.

September 30, 2017	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	4,133	$	60	$	13,386	$	1,171	$	18,750
Loans collectively evaluated for impairment		670,814		82,945		2,284,170		415,548		3,453,477
Total	$	674,947	$	83,005	$	2,297,556	$	416,719	$	3,472,227
September 30, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	12,714	$	167	$	19,582	$	1,249	$	33,712
Loans collectively evaluated for impairment		650,867		84,549		2,171,678		396,987		3,304,081
Total	$	663,581	$	84,716	$	2,191,260	$	398,236	$	3,337,793
December 31, 2016	Commercial		Agricultural		Real Estate		Consumer		Total
Loans individually evaluated for impairment	$	7,284	$	99	$	18,754	$	1,234	$	27,371
Loan collectively evaluated for impairment		667,126		83,922		2,171,090		407,798		3,329,936
Total	$	674,410	$	84,021	$	2,189,844	$	409,032	$	3,357,307

Schedule of Loans Modified and Considered Troubled Debt Restructurings

The Company’s loans that were modified in the three and nine months ended September 30, 2017 and 2016 and considered troubled debt restructurings are as follows (in thousands):

	Three Months Ended September 30, 2017						Nine Months Ended September 30, 2017
	Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment		Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment
Commercial		3	$	514	$	514		9	$	838	$	838
Agricultural		—		—		—		—		—		—
Real Estate		1		256		256		3		473		473
Consumer		—		—		—		1		25		25
Total		4	$	770	$	770		13	$	1,336	$	1,336
	Three Months Ended September 30, 2016						Nine Months Ended September 30, 2016
	Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment		Number		Pre- Modification Recorded Investment		Post- Modification Recorded Investment
Commercial		3	$	230	$	230		14	$	3,156	$	3,156
Agricultural		—		—		—		—		—		—
Real Estate		3		706		706		5		1,169		1,169
Consumer		1		44		44		5		162		162
Total		7	$	980	$	980		24	$	4,487	$	4,487

Schedule of How Loans Were Modified as Troubled Debt Restructured Loans

The balances below provide information as to how the loans were modified as troubled debt restructured loans during the three and nine months ended September 30, 2017 and 2016 (in thousands):

	Three Months Ended September 30, 2017						Nine Months Ended September 30, 2017
	Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity		Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity
Commercial	$	—	$	—	$	514		—	$	181	$	657
Agricultural		—		—		—		—		—		—
Real Estate		—		256		—		—		312		161
Consumer		—		—		—		—		25		—
Total	$	—	$	256	$	514		—	$	518	$	818
	Three Months Ended September 30, 2016						Nine Months Ended September 30, 2016
	Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity		Adjusted Interest Rate		Extended Maturity		Combined Rate and Maturity
Commercial	$	—	$	112	$	118		—	$	2,561	$	595
Agricultural		—		—		—		—		—		—
Real Estate		—		185		521		—		298		871
Consumer		—		—		44		—		43		119
Total	$	—	$	297	$	683		—	$	2,902	$	1,585

Schedule of Troubled Debt Restructurings

The loans with payment default are as follows (dollars in thousands):

	Three Months Ended September 30, 2017				Nine Months Ended September 30, 2017
	Number		Balance		Number		Balance
Commercial		2	$	88		3	$	141
Agriculture		—		—		—		—
Real Estate		—		—		1		62
Consumer		—		—		—		—
Total		2	$	88		4	$	203
	Three Months Ended September 30, 2016				Nine Months Ended September 30, 2016
	Number		Balance		Number		Balance
Commercial		1	$	62		1	$	62
Agriculture		—		—		—		—
Real Estate		1		112		2		462
Consumer		—		—		—		—
Total		2	$	174		3	$	524

XML

Borrowings (Tables)

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Schedule of Borrowings

Borrowings at September 30, 2017 and 2016, and December 31, 2016 consisted of the following (dollars in thousands):

	September 30,				December 31,
	2017		2016		2016
Securities sold under agreements with customers to repurchase	$	339,660	$	345,559	$	360,820
Federal funds purchased		11,775		8,200		9,950
Advances from Federal Home Loan Bank of Dallas		—		160,000		75,000
Total	$	351,435	$	513,759	$	445,770

XML

Fair Value Disclosures (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis

The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of September 30, 2017 and 2016, and December 31, 2016, respectively, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (dollars in thousands):

September 30, 2017
	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Available-for-sale investment securities:
Obligations of U. S. government sponsored enterprises and agencies	$	—	$	73,588	$	—	$	73,588
Obligations of states and political subdivisions		—		1,434,194		—		1,434,194
Corporate bonds		—		15,099		—		15,099
Residential mortgage-backed securities		—		1,029,284		—		1,029,284
Commercial mortgage-backed securities		—		328,862		—		328,862
Other securities		4,456		—		—		4,456
Total	$	4,456	$	2,881,027	$	—	$	2,885,483
September 30, 2016
	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Available-for-sale investment securities:
U.S. Treasury securities	$	10,739	$	—	$	—	$	10,739
Obligations of U. S. government sponsored enterprises and agencies		—		115,720		—		115,720
Obligations of states and political subdivisions		—		1,502,716		—		1,502,716
Corporate bonds		—		65,037		—		65,037
Residential mortgage-backed securities		—		766,499		—		766,499
Commercial mortgage-backed securities		—		263,747		—		263,747
Other securities		4,572		—		—		4,572
Total	$	15,311	$	2,713,719	$	—	$	2,729,030
December 31, 2016
	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Available-for-sale investment securities:
U.S. Treasury securities	$	10,668	$	—	$	—	$	10,668
Obligations of U. S. government sponsored enterprises and agencies		—		113,703		—		113,703
Obligations of states and political subdivisions		—		1,564,276		—		1,564,276
Corporate bonds		—		47,965		—		47,965
Residential mortgage-backed securities		—		851,361		—		851,361
Commercial mortgage-backed securities		—		268,436		—		268,436
Other securities		4,428		—		—		4,428
Total	$	15,096	$	2,845,741	$	—	$	2,860,837

Other Real Estate Owned

The following table presents other real estate owned that were re-measured subsequent to their initial transfer to other real estate owned (dollars in thousands):

	Three Months Ended September 30,
	2017			2016
Carrying value of other real estate owned prior to re-measurement	$	937		$	—
Write-downs included in gain (loss) on sale of other real estate owned		(288	)		—
Fair value	$	649		$	—
	Nine Months Ended September 30,
	2017			2016
Carrying value of other real estate owned prior to re-measurement	$	1,025		$	—
Write-downs included in gain (loss) on sale of other real estate owned		(296	)		—
Fair value	$	729		$	—

Schedule of Estimated Fair Values and Carrying Values of All Financial Instruments

The estimated fair values and carrying values of all financial instruments under current authoritative guidance at September 30, 2017 and 2016, and December 31, 2016, were as follows (in thousands):

	September 30,								December 31,
	2017				2016				2016
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value		Fair Value Hierarchy
Cash and due from banks	$	177,615	$	177,615	$	166,981	$	166,981	$	204,782	$	204,782	Level 1
Federal funds sold		—		—		3,400		3,400		3,130		3,130	Level 1
Interest-bearing deposits in banks		166,820		166,820		117,334		117,334		48,574		48,574	Level 1
Interest-bearing time deposits in banks		1,458		1,458		1,707		1,709		1,707		1,709	Level 2
Available-for-sale Securities		2,885,483		2,885,483		2,729,030		2,729,030		2,860,837		2,860,837	Levels 1 and 2
Held-to-maturity securities		—		—		129		133		121		124	Level 2
Loans		3,443,424		3,458,603		3,324,086		3,334,965		3,338,426		3,361,735	Level 3
Accrued interest receivable		26,321		26,321		26,209		26,209		36,469		36,469	Level 2
Deposits with stated maturities		464,782		465,655		535,793		537,167		508,996		510,304	Level 2
Deposits with no stated maturities		5,232,678		5,232,678		4,699,671		4,699,671		4,969,543		4,969,543	Level 1
Borrowings		351,435		351,435		513,759		513,759		445,770		445,770	Level 2
Accrued interest Payable		179		179		230		230		225		225	Level 2

XML

Basis of Presentation - Additional Information (Detail)	Sep. 30, 2017 Location
Basis Of Presentation [Line Items]
Number of locations	69
Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of locations	7
Abilene [Member]
Basis Of Presentation [Line Items]
Number of locations	11
Abilene [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of locations	1
San Angelo [Member]
Basis Of Presentation [Line Items]
Number of locations	3
San Angelo [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Weatherford [Member]
Basis Of Presentation [Line Items]
Number of locations	3
Cleburne [Member]
Basis Of Presentation [Line Items]
Number of locations	2
Stephenville [Member]
Basis Of Presentation [Line Items]
Number of locations	2
Stephenville [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Granbury [Member]
Basis Of Presentation [Line Items]
Number of locations	2
Conroe [Member]
Basis Of Presentation [Line Items]
Number of locations	2
Acton [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Albany [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Aledo [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Alvarado [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Beaumont [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Beaumont [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Boyd [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Bridgeport [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Brock [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Burleson [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Cisco [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Clyde [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Cut and Shoot [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Decatur [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Eastland [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Fort Worth [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Fort Worth [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Glen Rose [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Grapevine [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Hereford [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Huntsville [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Keller [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Magnolia [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Mauriceville [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Merkel [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Midlothian [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Mineral Wells [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Montgomery [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Moran [Member]
Basis Of Presentation [Line Items]
Number of locations	1
New Waverly [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Newton [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Odessa [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Odessa [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Orange [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Port Arthur [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Ranger [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Rising Star [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Roby [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Southlake [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Sweetwater [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Sweetwater [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Tomball [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Trent [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Trophy Club [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Vidor [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Waxahachie [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Willis [Member]
Basis Of Presentation [Line Items]
Number of locations	1
Willow Park [Member]
Basis Of Presentation [Line Items]
Number of locations	1

XML

Stock Repurchase - Additional Information (Detail) - shares		3 Months Ended	9 Months Ended
	Oct. 27, 2017	Mar. 31, 2017	Sep. 30, 2017	Jul. 25, 2017
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program expiration date		Sep. 30, 2017	Sep. 30, 2020
Minimum number of shares that company is required to repurchase			0
Maximum [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, number of shares authorized to be repurchased			1,500,000	2,000,000
Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchased under authorization	0

XML

Earnings Per Share - Additional Information (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Weighted average common shares outstanding, basic	66,140,518	66,023,069	66,104,914	66,004,797
Weighted average common shares outstanding, diluted	66,417,281	66,147,202	66,392,210	66,135,918

XML

Interest-bearing Time Deposits in Banks and Securities - Additional Information (Detail) $ in Thousands		3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) Investment	Sep. 30, 2017 USD ($) Investment	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Investment	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Interest Bearing Time Deposits In Banks And Securities [Line Items]
INTEREST-BEARING TIME DEPOSITS IN BANKS	$ 1,458	$ 1,458	$ 1,707	$ 1,458	$ 1,707	$ 1,707
Held-to-maturity securities	$ 0	$ 0	129	$ 0	129	$ 121
Number of investment positions | Investment	179	179		179
Securities pledged as collateral	$ 1,787,958	$ 1,787,958		$ 1,787,958
Sales of investment securities available-for-sale		83,605	7,410	120,576	20,792
Gross realized gains from security sales		1,750	239	2,550	1,158
Gross realized losses from security sales or calls		$ 675	$ 0	$ 725	$ 5
Obligations of States and Political Subdivisions [Member] | Texas [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Percentage of securities guaranteed by Texas Permanent School Fund	31.16%
Obligations of States and Political Subdivisions [Member] | Texas [Member] | Available-for-Sale Securities [Member] | Geographic Concentration Risk [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Concentration risk, percentage	82.70%
Minimum [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Interest-bearing time deposits, maturity period, years				1 year
Maximum [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Interest-bearing time deposits, maturity period, years				2 years

XML

Interest-bearing Time Deposits in Banks and Securities - Summary of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	$ 2,825,560	$ 2,827,772	$ 2,623,934
Securities available-for-sale, Gross Unrealized Holding Gains	66,235	49,824	107,200
Securities available-for-sale, Gross Unrealized Holding Losses	(6,312)	(16,759)	(2,104)
Securities available-for-sale, Estimated Fair Value	2,885,483	2,860,837	2,729,030
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total		10,649	10,685
Securities available-for-sale, Gross Unrealized Holding Gains		19	54
Securities available-for-sale, Estimated Fair Value		10,668	10,739
Obligations of U.S. Government Sponsored Enterprises and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	73,583	113,450	114,918
Securities available-for-sale, Gross Unrealized Holding Gains	35	253	802
Securities available-for-sale, Gross Unrealized Holding Losses	(30)
Securities available-for-sale, Estimated Fair Value	73,588	113,703	115,720
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	1,379,117	1,534,095	1,419,737
Securities available-for-sale, Gross Unrealized Holding Gains	56,671	40,194	83,694
Securities available-for-sale, Gross Unrealized Holding Losses	(1,594)	(10,013)	(715)
Securities available-for-sale, Estimated Fair Value	1,434,194	1,564,276	1,502,716
Corporate Bonds and Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	19,439	51,920	68,285
Securities available-for-sale, Gross Unrealized Holding Gains	118	476	1,325
Securities available-for-sale, Gross Unrealized Holding Losses	(2)	(3)	(1)
Securities available-for-sale, Estimated Fair Value	19,555	52,393	69,609
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	1,024,615	848,614	750,673
Securities available-for-sale, Gross Unrealized Holding Gains	8,466	8,260	17,125
Securities available-for-sale, Gross Unrealized Holding Losses	(3,797)	(5,513)	(1,299)
Securities available-for-sale, Estimated Fair Value	1,029,284	851,361	766,499
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	328,806	269,044	259,636
Securities available-for-sale, Gross Unrealized Holding Gains	945	622	4,200
Securities available-for-sale, Gross Unrealized Holding Losses	(889)	(1,230)	(89)
Securities available-for-sale, Estimated Fair Value	$ 328,862	$ 268,436	$ 263,747

XML

Interest-bearing Time Deposits in Banks and Securities - Amortized Cost and Estimated Fair Value of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Available-for-Sale, Amortized Cost Basis, Due within one year	$ 187,370
Available-for-Sale, Amortized Cost Basis, Due after one year through five years	650,523
Available-for-Sale, Amortized Cost Basis, Due after five years through ten years	632,562
Available-for-Sale, Amortized Cost Basis, Due after ten years	1,684
Available-for-Sale, Amortized Cost Basis, Mortgage-backed securities	1,353,421
Available-for-Sale, Amortized Cost Basis, Total	2,825,560	$ 2,827,772	$ 2,623,934
Available-for-Sale, Estimated Fair Value, Due within one year	189,136
Available-for-Sale, Estimated Fair Value, Due after one year through five years	679,535
Available-for-Sale, Estimated Fair Value, Due after five years through ten years	656,623
Available-for-Sale, Estimated Fair Value, Due after ten years	2,043
Available-for-Sale, Estimated Fair Value, Mortgage-backed securities	1,358,146
Securities available-for-sale, Estimated Fair Value, Total	$ 2,885,483	$ 2,860,837	$ 2,729,030

XML

Interest-bearing Time Deposits in Banks and Securities - Continuous Unrealized-Loss Position of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value	$ 495,548	$ 1,012,122	$ 184,616
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	2,621	15,712	1,004
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Fair Value	198,307	47,699	71,767
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss	3,691	1,047	1,100
Available-for-sale securities, continuous unrealized loss position, Fair Value	693,855	1,059,821	256,383
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss	6,312	16,759	2,104
Obligations of U.S. Government Sponsored Enterprises and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value	45,050
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	30
Available-for-sale securities, continuous unrealized loss position, Fair Value	45,050
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss	30
Obligations of States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value	54,983	446,052	82,131
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	309	9,997	711
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Fair Value	45,217	1,209	741
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss	1,285	16	4
Available-for-sale securities, continuous unrealized loss position, Fair Value	100,200	447,261	82,872
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss	1,594	10,013	715
Corporate Bonds and Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value		244	12,257
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss		3	1
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Fair Value	240
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss	2
Available-for-sale securities, continuous unrealized loss position, Fair Value	240	244	12,257
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss	2	3	1
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value	225,369	372,331	80,015
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	1,531	4,532	267
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Fair Value	131,849	33,227	57,334
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss	2,266	981	1,032
Available-for-sale securities, continuous unrealized loss position, Fair Value	357,218	405,558	137,349
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss	3,797	5,513	1,299
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value	170,146	193,495	10,213
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	751	1,180	25
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Fair Value	21,001	13,263	13,692
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss	138	50	64
Available-for-sale securities, continuous unrealized loss position, Fair Value	191,147	206,758	23,905
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss	$ 889	$ 1,230	$ 89

XML

Loans and Allowance for Loan Losses - Additional Information (Detail)				3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Contract	Sep. 30, 2016 USD ($) Contract	Sep. 30, 2017 USD ($) Contract	Sep. 30, 2016 USD ($) Contract	Dec. 31, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum number of days to consider the loans as non-accrual						90 days
Loans individually evaluated for impairment	$ 18,750,000	$ 27,371,000	$ 33,712,000	$ 18,750,000	$ 33,712,000	$ 18,750,000	$ 33,712,000	$ 27,371,000
Contractual balance	29,749,000	38,379,000	47,473,000	29,749,000	47,473,000	29,749,000	47,473,000	38,379,000
Loans held for sale	19,119,000	26,898,000	31,591,000	19,119,000	31,591,000	19,119,000	31,591,000	26,898,000
Nonaccrual, past due 90 days or more and still accruing, restructured loans and foreclosed assets	22,076,000	29,000,000	34,938,000	22,076,000	34,938,000	22,076,000	34,938,000	29,000,000
Additional funds advanced in connection with impaired loans	0			0		0
Interest income recognized on impaired loans	0	0	0
Interest income recognized on impaired loans				0	0	0	0	829,000
Allowance for loan losses	47,922,000	45,779,000	45,298,000	$ 47,922,000	$ 45,298,000	$ 47,922,000	$ 45,298,000	45,779,000	$ 47,410,000	$ 45,060,000	$ 41,877,000
Default for purposes of this disclosure is a troubled debt restructured loan						90 days	90 days
Number of loans modified | Contract				2	2	4	3
Commitments to lend additional funds to borrowers with loan that have been modified as TDRs	0			$ 0		$ 0
Loans held by subsidiaries subject to blanket liens	2,140,557,000			2,140,557,000		2,140,557,000
Advances from Federal Home Loan Bank of Dallas	0	75,000,000	160,000,000	0	$ 160,000,000	0	$ 160,000,000	75,000,000
Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans individually evaluated for impairment	736,000	1,256,000	1,853,000	736,000	1,853,000	736,000	1,853,000	1,256,000
Contractual balance	932,000	1,865,000	2,528,000	932,000	2,528,000	932,000	2,528,000	1,865,000
Allowance for loan losses	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0

XML

Loans and Allowance for Loan Losses - Loans Held-for-Investment by Class of Financing Receivables (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Loans and Leases Receivable Disclosure [Line Items]
Total	$ 3,472,227	$ 3,357,307	$ 3,337,793
Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total	674,947	674,410	663,581
Agriculture [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total	83,005	84,021	84,716
Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total	2,297,556	2,189,844	2,191,260
Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total	$ 416,719	$ 409,032	$ 398,236

XML

Loans and Allowance for Loan Losses - Non-Accrual Loans, Loans Still Accruing and Past Due 90 Days or More and Restructured Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Receivables [Abstract]
Non-accrual loans	$ 18,750	$ 27,371	$ 33,712
Loans still accruing and past due 90 days or more	257	284	107
Troubled debt restructured loans	668	701	750
Total	$ 19,675	$ 28,356	$ 34,569

XML

Loans and Allowance for Loan Losses - Non-Accrual Loans, Loans Still Accruing and Past Due 90 Days or More and Restructured Loans (Parenthetical) (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	$ 18,750	$ 27,371	$ 33,712
Troubled debt restructured loans	668	701	750
Purchased Credit Impaired Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	736	1,256	1,853
Doubtful [Member]
Loans and Leases Receivable Disclosure [Line Items]
Troubled debt restructured loans	$ 5,277	$ 6,863	$ 7,513

XML

Loans and Allowance for Loan Losses - Recorded Investment in Impaired Loans and Related Valuation Allowance (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Receivables [Abstract]
Recorded Investment	$ 18,750	$ 27,371	$ 33,712
Valuation Allowance	$ 4,177	$ 5,012	$ 7,042

XML

Loans and Allowance for Loan Losses - Schedule of Non-Accrual Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	$ 18,750	$ 27,371	$ 33,712
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	4,133	7,284	12,714
Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	60	99	167
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	13,386	18,754	19,582
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	$ 1,171	$ 1,234	$ 1,249

XML

Loans and Allowance for Loan Losses - Schedule of Impaired Loans and Related Allowance (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	$ 29,749	$ 47,473	$ 29,749	$ 47,473	$ 38,379
Recorded Investment With No Allowance	4,621	7,017	4,621	7,017	7,657
Recorded Investment With Allowance	14,129	26,695	14,129	26,695	19,714
Total Recorded Investment	18,750	33,712	18,750	33,712	27,371
Related Allowance	4,177	7,042	4,177	7,042	5,012
Average Recorded Investment	20,993	34,924	22,999	26,514	22,055
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	10,989	21,696	10,989	21,696	13,389
Recorded Investment With No Allowance	617	1,067	617	1,067	1,148
Recorded Investment With Allowance	3,516	11,647	3,516	11,647	6,136
Total Recorded Investment	4,133	12,714	4,133	12,714	7,284
Related Allowance	1,671	3,983	1,671	3,983	2,128
Average Recorded Investment	5,866	14,238	7,313	8,421	4,921
Agriculture [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	66	168	66	168	103
Recorded Investment With Allowance	60	167	60	167	99
Total Recorded Investment	60	167	60	167	99
Related Allowance	17	41	17	41	25
Average Recorded Investment	60	84	66	83	50
Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	17,306	24,130	17,306	24,130	23,466
Recorded Investment With No Allowance	3,742	5,626	3,742	5,626	6,229
Recorded Investment With Allowance	9,644	13,956	9,644	13,956	12,525
Total Recorded Investment	13,386	19,582	13,386	19,582	18,754
Related Allowance	1,984	2,566	1,984	2,566	2,428
Average Recorded Investment	13,829	19,436	14,279	17,021	16,170
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	1,388	1,479	1,388	1,479	1,421
Recorded Investment With No Allowance	262	324	262	324	280
Recorded Investment With Allowance	909	925	909	925	954
Total Recorded Investment	1,171	1,249	1,171	1,249	1,234
Related Allowance	505	452	505	452	431
Average Recorded Investment	$ 1,238	$ 1,166	$ 1,341	$ 989	$ 914

XML

Loans and Allowance for Loan Losses - Schedule of Impaired Loans and Related Allowance (Parenthetical) (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	$ 4,621	$ 7,657	$ 7,017
Purchased Credit Impaired Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	$ 736	$ 1,256	$ 1,853

XML

Loans and Allowance for Loan Losses - Schedule of Internal Ratings of Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	$ 3,472,227	$ 3,357,307	$ 3,337,793
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	674,947	674,410	663,581
Agriculture [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	83,005	84,021	84,716
Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	2,297,556	2,189,844	2,191,260
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	416,719	409,032	398,236
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	3,350,933	3,229,505	3,211,193
Pass [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	632,693	629,756	614,900
Pass [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	79,227	81,620	82,400
Pass [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	2,224,970	2,111,947	2,118,807
Pass [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	414,043	406,182	395,086
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	35,237	24,787	25,488
Special Mention [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	7,997	5,769	6,108
Special Mention [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	841	715
Special Mention [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	26,231	18,091	19,064
Special Mention [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	168	212	316
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	86,057	103,015	101,110
Substandard [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	34,257	38,885	42,573
Substandard [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	2,937	1,686	2,316
Substandard [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	46,355	59,806	53,389
Substandard [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	$ 2,508	$ 2,638	2,832
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan			2
Doubtful [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan			$ 2

XML

Loans and Allowance for Loan Losses - Schedule of Past Due Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 23,447	$ 29,511	$ 33,312
Total Current	3,448,780	3,327,796	3,304,481
Total Loans	3,472,227	3,357,307	3,337,793
Total 90 Days Past Due Still Accruing	257	284	107
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,368	7,250	12,498
Total Current	669,579	667,160	651,083
Total Loans	674,947	674,410	663,581
Total 90 Days Past Due Still Accruing	212	10	61
Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	322	185	586
Total Current	82,683	83,836	84,130
Total Loans	83,005	84,021	84,716
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	15,913	19,741	18,316
Total Current	2,281,643	2,170,103	2,172,944
Total Loans	2,297,556	2,189,844	2,191,260
Total 90 Days Past Due Still Accruing		272	34
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,844	2,335	1,912
Total Current	414,875	406,697	396,324
Total Loans	416,719	409,032	398,236
Total 90 Days Past Due Still Accruing	45	2	12
15-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	17,457	19,110	20,092
15-59 Days Past Due [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,288	3,908	4,707
15-59 Days Past Due [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	322	185	523
15-59 Days Past Due [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	12,636	13,172	13,444
15-59 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,211	1,845	1,418
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,026	2,791	2,714
60-89 Days Past Due [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	585	1,122	841
60-89 Days Past Due [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due			63
60-89 Days Past Due [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	984	1,301	1,496
60-89 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	457	368	314
Greater than 90 Days [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,964	7,610	10,506
Greater than 90 Days [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,495	2,220	6,950
Greater than 90 Days [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,293	5,268	3,376
Greater than 90 Days [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 176	$ 122	$ 180

XML

Loans and Allowance for Loan Losses - Schedule of Allowance for Loan Losses by Portfolio Segment (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	$ 4,177		$ 5,012	$ 7,042
Loans collectively evaluated for impairment	43,745		40,767	38,256
Total allowance for loan losses	47,922	$ 47,410	45,779	45,298	$ 45,060	$ 41,877
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	1,671		2,128	3,983
Loans collectively evaluated for impairment	10,201		9,579	9,733
Total allowance for loan losses	11,872	11,935	11,707	13,716	14,026	12,644
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	17		25	41
Loans collectively evaluated for impairment	1,284		1,076	1,027
Total allowance for loan losses	1,301	1,127	1,101	1,068	1,451	1,191
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	1,984		2,428	2,566
Loans collectively evaluated for impairment	26,484		24,436	23,655
Total allowance for loan losses	28,468	28,023	26,864	26,221	25,644	24,375
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	505		431	452
Loans collectively evaluated for impairment	5,776		5,676	3,841
Total allowance for loan losses	$ 6,281	$ 6,325	$ 6,107	$ 4,293	$ 3,939	$ 3,667

XML

Loans and Allowance for Loan Losses - Changes in Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 47,410	$ 45,060	$ 45,779	$ 41,877
Provision for loan losses	1,415	3,833	5,090	8,219
Recoveries	277	777	1,434	3,243
Charge-offs	(1,180)	(4,372)	(4,381)	(8,041)
Ending balance	47,922	45,298	47,922	45,298
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	11,935	14,026	11,707	12,644
Provision for loan losses	557	3,248	1,485	6,239
Recoveries	119	298	868	839
Charge-offs	(739)	(3,856)	(2,188)	(6,006)
Ending balance	11,872	13,716	11,872	13,716
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,127	1,451	1,101	1,191
Provision for loan losses	157	(358)	211	41
Recoveries	17	4	25	20
Charge-offs		(29)	(36)	(184)
Ending balance	1,301	1,068	1,301	1,068
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	28,023	25,644	26,864	24,375
Provision for loan losses	424	296	2,556	367
Recoveries	50	367	141	1,957
Charge-offs	(29)	(86)	(1,093)	(478)
Ending balance	28,468	26,221	28,468	26,221
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	6,325	3,939	6,107	3,667
Provision for loan losses	277	647	838	1,572
Recoveries	91	108	400	427
Charge-offs	(412)	(401)	(1,064)	(1,373)
Ending balance	$ 6,281	$ 4,293	$ 6,281	$ 4,293

XML

Loans and Allowance for Loan Losses - Schedule of Investment in Loans Related to Balance in Allowance for Loan Losses on Basis of Company's Impairment Methodology (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	$ 18,750	$ 27,371	$ 33,712
Loan collectively evaluated for impairment	3,453,477	3,329,936	3,304,081
Total	3,472,227	3,357,307	3,337,793
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	4,133	7,284	12,714
Loan collectively evaluated for impairment	670,814	667,126	650,867
Total	674,947	674,410	663,581
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	60	99	167
Loan collectively evaluated for impairment	82,945	83,922	84,549
Total	83,005	84,021	84,716
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	13,386	18,754	19,582
Loan collectively evaluated for impairment	2,284,170	2,171,090	2,171,678
Total	2,297,556	2,189,844	2,191,260
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	1,171	1,234	1,249
Loan collectively evaluated for impairment	415,548	407,798	396,987
Total	$ 416,719	$ 409,032	$ 398,236

XML

Loans and Allowance for Loan Losses - Schedule of Loans Modified and Considered Troubled Debt Restructurings (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) SecurityLoan	Sep. 30, 2016 USD ($) SecurityLoan	Sep. 30, 2017 USD ($) SecurityLoan	Sep. 30, 2016 USD ($) SecurityLoan
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	4	7	13	24
Pre-Modification Recorded Investment	$ 770	$ 980	$ 1,336	$ 4,487
Post-Modification Recorded Investment	$ 770	$ 980	$ 1,336	$ 4,487
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	3	3	9	14
Pre-Modification Recorded Investment	$ 514	$ 230	$ 838	$ 3,156
Post-Modification Recorded Investment	$ 514	$ 230	$ 838	$ 3,156
Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	1	3	3	5
Pre-Modification Recorded Investment	$ 256	$ 706	$ 473	$ 1,169
Post-Modification Recorded Investment	$ 256	$ 706	$ 473	$ 1,169
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan		1	1	5
Pre-Modification Recorded Investment		$ 44	$ 25	$ 162
Post-Modification Recorded Investment		$ 44	$ 25	$ 162

XML

Loans and Allowance for Loan Losses - Schedule of How Loans Were Modified as Troubled Debt Restructured Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	$ 770	$ 980	$ 1,336	$ 4,487
Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	256	297	518	2,902
Combined Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	514	683	818	1,585
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	514	230	838	3,156
Commercial [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		112	181	2,561
Commercial [Member] | Combined Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	514	118	657	595
Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	256	706	473	1,169
Real Estate [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	$ 256	185	312	298
Real Estate [Member] | Combined Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		521	161	871
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		44	25	162
Consumer [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans			$ 25	43
Consumer [Member] | Combined Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		$ 44		$ 119

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Loans and Allowance for Loan Losses - Schedule of Troubled Debt Restructurings (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) Contract	Sep. 30, 2016 USD ($) Contract	Sep. 30, 2017 USD ($) Contract	Sep. 30, 2016 USD ($) Contract
Financing Receivable, Modifications [Line Items]
Number | Contract	2	2	4	3
Balance | $	$ 88	$ 174	$ 203	$ 524
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number | Contract	2	1	3	1
Balance | $	$ 88	$ 62	$ 141	$ 62
Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number | Contract		1	1	2
Balance | $		$ 112	$ 62	$ 462

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Borrowings - Schedule of Borrowings (Detail) - USD ($)	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Debt Disclosure [Abstract]
Securities sold under agreements with customers to repurchase	$ 339,660,000	$ 360,820,000	$ 345,559,000
Federal funds purchased	11,775,000	9,950,000	8,200,000
Advances from Federal Home Loan Bank of Dallas	0	75,000,000	160,000,000
Total	$ 351,435,000	$ 445,770,000	$ 513,759,000

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Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income tax expense	$ 9,195	$ 7,440	$ 25,300	$ 23,544
Effective tax rates on pre-tax income	23.84%	22.52%	23.10%	23.16%
Statutory federal tax rate			35.00%

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Stock Option Plan and Restricted Stock Plan - Additional Information (Detail)							1 Months Ended	3 Months Ended		6 Months Ended	9 Months Ended
	Oct. 24, 2017 USD ($) shares	Apr. 25, 2017 USD ($) Non_Employee_Directors shares	Oct. 25, 2016 USD ($) shares	Apr. 26, 2016 USD ($) Non_Employee_Directors shares	Oct. 27, 2015 USD ($) shares	Jul. 21, 2015 USD ($) Non_Employee_Directors shares	Jun. 30, 2017 $ / shares shares	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 shares	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted | shares							452,450			0
Exercise price of stock option | $ / shares							$ 42.35
Fair value assumptions method used							Black-Scholes options pricing model
Fair value of the options | $ / shares							$ 9.90
Risk-free interest rate							1.89%
Expected dividend yield							1.79%
Expected life							6 years 2 months 27 days
Expected volatility							26.51%
Stock compensation expense								$ 750,000	$ 221,000		$ 1,182,000	$ 662,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of non employee directors | Non_Employee_Directors		10		10		10
Restricted Stock [Member] | Non-Employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares granted | shares		14,650		7,660		7,070
Restricted shares value		$ 600,000		$ 250,000		$ 250,000
Restricted Stock [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense								150,000	63,000		333,000	215,000
Restricted Stock [Member] | Officers [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense								$ 133,000	$ 88,000		$ 399,000	$ 262,000
Restricted shares granted | shares			15,405		31,273
Restricted shares value			$ 560,000		$ 1,060,000
Restricted shares vesting period			3 years		3 years
Restricted Stock [Member] | Officers [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares granted | shares	14,191
Restricted shares value	$ 655,000
Restricted Stock [Member] | Officers [Member] | Minimum [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares vesting period	1 year
Restricted Stock [Member] | Officers [Member] | Maximum [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares vesting period	3 years

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Pension Plan - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Retirement Benefits [Abstract]
Contributions to the plan			$ 0		$ 500,000
Net periodic benefit costs, total	$ 84,000	$ 82,000	$ 253,000	$ 247,000

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Fair Value Disclosures - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets transfer between Level 1 and Level 2	$ 0	$ 0	$ 0	$ 0	$ 0
Assets transfer between Level 2 and Level 3	0	0	0	0	0
Impaired loans carrying value	14,129,000	26,695,000	14,129,000	26,695,000	19,714,000
Impaired loans valuation reserves	4,177,000	7,042,000	4,177,000	7,042,000	5,012,000
Impaired loans net fair value	9,952,000		9,952,000
Recorded Investment With No Allowance	4,621,000	7,017,000	4,621,000	7,017,000	7,657,000
Other real estate owned, total	$ 2,176,000	$ 241,000	$ 2,176,000	$ 241,000	$ 413,000
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt discounts, percentage			5.00%
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt discounts, percentage			25.00%

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Fair Value Disclosures - Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	$ 2,885,483	$ 2,860,837	$ 2,729,030
U.S. Treasury Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value		10,668	10,739
Obligations of U.S. Government Sponsored Enterprises and Agencies [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	73,588	113,703	115,720
Obligations of States and Political Subdivisions [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	1,434,194	1,564,276	1,502,716
Residential Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	1,029,284	851,361	766,499
Commercial Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	328,862	268,436	263,747
Fair Value, Measurements, Recurring [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	2,885,483	2,860,837	2,729,030
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	15,099	47,965	65,037
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value		10,668	10,739
Fair Value, Measurements, Recurring [Member] | Obligations of U.S. Government Sponsored Enterprises and Agencies [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	73,588	113,703	115,720
Fair Value, Measurements, Recurring [Member] | Obligations of States and Political Subdivisions [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	1,434,194	1,564,276	1,502,716
Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	1,029,284	851,361	766,499
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	328,862	268,436	263,747
Fair Value, Measurements, Recurring [Member] | Other Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	4,456	4,428	4,572
Fair Value, Measurements, Recurring [Member] | Level 1 Inputs [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	4,456	15,096	15,311
Fair Value, Measurements, Recurring [Member] | Level 1 Inputs [Member] | U.S. Treasury Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value		10,668	10,739
Fair Value, Measurements, Recurring [Member] | Level 1 Inputs [Member] | Other Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	4,456	4,428	4,572
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	2,881,027	2,845,741	2,713,719
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member] | Corporate Bonds [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	15,099	47,965	65,037
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member] | Obligations of U.S. Government Sponsored Enterprises and Agencies [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	73,588	113,703	115,720
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member] | Obligations of States and Political Subdivisions [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	1,434,194	1,564,276	1,502,716
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member] | Residential Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	1,029,284	851,361	766,499
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member] | Commercial Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	$ 328,862	$ 268,436	$ 263,747

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Fair Value Disclosures - Other Real Estate Owned (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Carrying value of other real estate owned prior to re-measurement	$ 937	$ 1,025
Write-downs included in gain (loss) on sale of other real estate owned	(288)	(296)
Other real estate owned, fair value	$ 649	$ 729

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Fair Value Disclosures - Schedule of Estimated Fair Values and Carrying Values of All Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CASH AND DUE FROM BANKS	$ 177,615	$ 204,782	$ 166,981
FEDERAL FUNDS SOLD		3,130	3,400
INTEREST-BEARING DEPOSITS IN BANKS	166,820	48,574	117,334
INTEREST-BEARING TIME DEPOSITS IN BANKS	1,458	1,707	1,707
Available-for-sale Securities	2,885,483	2,860,837	2,729,030
Held-to-maturity securities	0	121	129
Loans	3,443,424	3,338,426	3,324,086
BORROWINGS	351,435	445,770	513,759
Carrying Value [Member] | Level 1 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CASH AND DUE FROM BANKS	177,615	204,782	166,981
FEDERAL FUNDS SOLD		3,130	3,400
INTEREST-BEARING DEPOSITS IN BANKS	166,820	48,574	117,334
Deposits with no stated maturities	5,232,678	4,969,543	4,699,671
Carrying Value [Member] | Level 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
INTEREST-BEARING TIME DEPOSITS IN BANKS	1,458	1,707	1,707
Held-to-maturity securities		121	129
Accrued interest receivable	26,321	36,469	26,209
Deposits with stated maturities	464,782	508,996	535,793
BORROWINGS	351,435	445,770	513,759
Accrued interest Payable	179	225	230
Carrying Value [Member] | Levels 1 and 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities	2,885,483	2,860,837	2,729,030
Carrying Value [Member] | Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	3,443,424	3,338,426	3,324,086
Estimated Fair Value [Member] | Level 1 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CASH AND DUE FROM BANKS	177,615	204,782	166,981
FEDERAL FUNDS SOLD		3,130	3,400
INTEREST-BEARING DEPOSITS IN BANKS	166,820	48,574	117,334
Deposits with no stated maturities	5,232,678	4,969,543	4,699,671
Estimated Fair Value [Member] | Level 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
INTEREST-BEARING TIME DEPOSITS IN BANKS	1,458	1,709	1,709
Held-to-maturity securities		124	133
Accrued interest receivable	26,321	36,469	26,209
Deposits with stated maturities	465,655	510,304	537,167
BORROWINGS	351,435	445,770	513,759
Accrued interest Payable	179	225	230
Estimated Fair Value [Member] | Levels 1 and 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities	2,885,483	2,860,837	2,729,030
Estimated Fair Value [Member] | Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	$ 3,458,603	$ 3,361,735	$ 3,334,965

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Acquisitions Definitive Agreement Signed - Additional Information (Detail) - USD ($)	Oct. 12, 2017	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Business Acquisition [Line Items]
Gross loans		$ 3,472,227,000	$ 3,357,307,000	$ 3,337,793,000
Total deposits		5,697,460,000	5,478,539,000	5,235,464,000
Total assets		7,009,164,000	$ 6,809,931,000	$ 6,686,736,000
Commercial State Bank [Member]
Business Acquisition [Line Items]
Gross loans		263,800,000
Total deposits		322,100,000
Total assets		$ 366,800,000
Subsequent Event [Member] | Commercial Bancshares, Inc [Member]
Business Acquisition [Line Items]
Business acquisition, agreement date	Oct. 12, 2017
Business acquisition, expected stock purchase price	$ 59,400,000
Business acquisition, special dividend	15,600,000
Increase decrease in business acquisition, special dividend	$ 42,400,000