10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

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

FOR THE QUARTERLY PERIOD ENDED SEPTEMBER 30, 2012

OR

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

FOR THE TRANSITION PERIOD FROM             TO            

COMMISSION FILE NUMBER: 001-35388

PROSPERITY BANCSHARES, INC.^®

(Exact name of registrant as specified in its charter)

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

Prosperity Bank Plaza

4295 San Felipe

Houston, Texas 77027

(Address of principal executive offices, including zip code)

(713) 693-9300

(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  x    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 Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  x    No  ¨

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

Large Accelerated Filer	x	Accelerated Filer	¨
Non-accelerated Filer	¨  (Do not check if a smaller reporting company)	Smaller Reporting Company	¨

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

As of November 5, 2012, there were 56,430,192 outstanding shares of the registrant’s Common Stock, par value $1.00 per share.

PROSPERITY BANCSHARES, INC. ^® AND SUBSIDIARIES

INDEX TO FORM 10-Q

		Page
PART I—FINANCIAL INFORMATION
Item 1.	Financial Statements		3
	Consolidated Balance Sheets as of September 30, 2012 and December 31, 2011 (unaudited)		3
	Consolidated Statements of Income for the Three and Nine Months Ended September 30, 2012 and  2011 (unaudited)		4
	Consolidated Statements of Comprehensive Income for the Three and Nine Months Ended September 30, 2012 and 2011 (unaudited)		5
	Consolidated Statements of Changes in Shareholders’ Equity for the Nine Months Ended September 30, 2012 and 2011 (unaudited)		6
	Consolidated Statements of Cash Flows for the Nine Months Ended September  30, 2012 and 2011 (unaudited)		7
	Notes to Interim Consolidated Financial Statements (unaudited)		9
Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations		35
Item 3.	Quantitative and Qualitative Disclosures about Market Risk		50
Item 4.	Controls and Procedures		50
PART II—OTHER INFORMATION
Item 1.	Legal Proceedings		51
Item 1A.	Risk Factors		51
Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds		51
Item 3.	Defaults upon Senior Securities		51
Item 4.	Mine Safety Disclosures		51
Item 5.	Other Information		51
Item 6.	Exhibits		51
Signatures			52

2

PART I—FINANCIAL INFORMATION

ITEM 1. FINANCIAL STATEMENTS

PROSPERITY BANCSHARES, INC^®. AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

(UNAUDITED)

	September 30, 2012			December 31, 2011
	(In thousands, except share data)
ASSETS
Cash and due from banks	$	207,401		$	212,800
Federal funds sold		302			642
Total cash and cash equivalents		207,703			213,442
Interest-bearing time deposits in other financial institutions		249			—
Securities available for sale, at fair value (amortized cost of $233,396 and $301,589, respectively)		250,387			322,316
Securities held to maturity, at cost (fair value of $6,772,151 and $4,492,988, respectively)		6,549,126			4,336,620
Loans held for investment		5,074,771			3,765,906
Loans held for sale		4,332			—
Allowance for credit losses		(50,927	)		(51,594	)
Loans, net		5,028,176			3,714,312
Accrued interest receivable		39,661			29,405
Goodwill		1,200,098			924,537
Core deposit intangibles, net of accumulated amortization of $63,455 and $58,158, respectively		28,092			20,996
Bank premises and equipment, net		201,445			159,656
Other real estate owned		8,846			8,328
Bank Owned Life Insurance (BOLI)		107,859			50,029
Federal Home Loan Bank stock		42,417			11,601
Other assets		48,060			31,429
TOTAL ASSETS	$	13,712,119		$	9,822,671
LIABILITIES AND SHAREHOLDERS’ EQUITY
LIABILITIES:
Deposits:
Noninterest-bearing	$	2,827,748		$	1,972,226
Interest-bearing		8,126,849			6,088,028
Total deposits		10,954,597			8,060,254
Other borrowings		112,017			12,790
Securities sold under repurchase agreements		443,856			54,883
Accrued interest payable		2,089			2,803
Other liabilities		76,329			39,621
Junior subordinated debentures		85,055			85,055
Total liabilities		11,673,943			8,255,406
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS’ EQUITY:
Preferred stock, $1 par value; 20,000,000 shares authorized; none issued or outstanding		—			—
Common stock, $1 par value; 200,000,000 shares authorized; 56,095,248 and 46,947,415 shares issued at September 30, 2012 and December 31, 2011, respectively; 56,058,160 and 46,910,327 shares outstanding at September 30, 2012 and December 31, 2011, respectively		56,095			46,947
Capital surplus		1,257,541			883,575
Retained earnings		714,103			623,878
Accumulated other comprehensive income—net unrealized gain on available for sale securities, net of tax of $5,947 and $7,254, respectively		11,044			13,472
Less treasury stock, at cost, 37,088 shares		(607	)		(607	)
Total shareholders’ equity		2,038,176			1,567,265
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY	$	13,712,119		$	9,822,671

See notes to interim consolidated financial statements.

3

PROSPERITY BANCSHARES, INC. ^® AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF INCOME

(UNAUDITED)

	Three Months Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
	(Dollars in thousands, except per share data)
INTEREST INCOME:
Loans, including fees	$	80,587	$	54,471	$	188,597	$	160,374
Securities		37,025		38,714		113,418		121,861
Federal funds sold		21		4		108		15
Total interest income		117,633		93,189		302,123		282,250
INTEREST EXPENSE:
Deposits		9,395		9,717		26,269		32,293
Junior subordinated debentures		651		607		1,962		2,352
Federal funds purchased and other borrowings		379		200		1,076		718
Securities sold under repurchase agreements		315		127		411		306
Total interest expense		10,740		10,651		29,718		35,669
NET INTEREST INCOME		106,893		82,538		272,405		246,581
PROVISION FOR CREDIT LOSSES		1,800		950		2,550		4,050
NET INTEREST INCOME AFTER PROVISION FOR CREDIT LOSSES		105,093		81,588		269,855		242,531
NONINTEREST INCOME:
Customer service fees		18,873		12,662		42,430		37,250
Other		4,955		1,919		8,999		4,728
Total noninterest income		23,828		14,581		51,429		41,978
NONINTEREST EXPENSE:
Salaries and employee benefits		36,701		23,601		83,525		70,799
Net occupancy		4,614		3,784		11,663		10,979
Debit card, data processing and software amortization		2,901		1,954		6,339		5,406
Core deposit intangible amortization		2,007		1,924		5,297		5,901
Depreciation		2,369		2,041		6,432		6,099
Other		11,650		7,847		28,233		26,176
Total noninterest expense		60,242		41,151		141,489		125,360
INCOME BEFORE INCOME TAXES		68,679		55,018		179,795		159,149
PROVISION FOR INCOME TAXES		22,503		18,645		60,160		53,806
NET INCOME AVAILABLE TO COMMON SHAREHOLDERS	$	46,176	$	36,373	$	119,635	$	105,343
EARNINGS PER SHARE
Basic	$	0.83	$	0.78	$	2.38	$	2.25
Diluted	$	0.82	$	0.77	$	2.37	$	2.24
DIVIDENDS PAID PER SHARE	$	0.195	$	0.175	$	0.585	$	0.525

See notes to interim consolidated financial statements.

4

PROSPERITY BANCSHARES, INC. ^® AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(UNAUDITED)

	Three Months Ended September 30,						Nine Months Ended September 30,
	2012			2011			2012			2011
	(In thousands)
Net income	$	46,176		$	36,373		$	119,635		$	105,343
Other comprehensive (loss) income, before tax:
Securities available for sale:
Change in unrealized (loss) gain during period		(718	)		632			(3,736	)		2,272
Total other comprehensive (loss) income		(718	)		632			(3,736	)		2,272
Deferred tax benefit (expense) related to other comprehensive income		251			(222	)		1,308			(795	)
Other comprehensive (loss) income, net of tax		(467	)		410			(2,428	)		1,477
Comprehensive income	$	45,709		$	36,783		$	117,207		$	106,820

See notes to interim consolidated financial statements.

5

PROSPERITY BANCSHARES, INC. ^® AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS’ EQUITY

(UNAUDITED)

	Common Stock				Capital		Retained			Accumulated Other Comprehensive			Treasury			Total Shareholders’
	Shares		Amount		Surplus		Earnings			Income (Loss)			Stock			Equity
	(Amounts in thousands, except share and per share data)
BALANCE AT JANUARY 1, 2012		46,947,415	$	46,947	$	883,575	$	623,878		$	13,472		$	(607	)	$	1,567,265
Net income								119,635									119,635
Other comprehensive loss											(2,428	)					(2,428	)
Common stock issued in connection with the exercise of stock options and restricted stock awards		172,698		173		2,518											2,691
Common stock issued in connection with the acquisition of Texas Bankers, Inc.		314,953		315		12,393											12,708
Common stock issued in connection with the acquisition of The Bank Arlington		135,347		135		6,063											6,198
Common stock issued in connection with the acquisition of American State Financial Corporation		8,524,835		8,525		349,774											358,299
Stock based compensation expense						3,218											3,218
Cash dividends declared, $0.585 per share								(29,410	)								(29,410	)
BALANCE AT SEPTEMBER 30, 2012		56,095,248	$	56,095	$	1,257,541	$	714,103		$	11,044		$	(607	)	$	2,038,176
BALANCE AT JANUARY 1, 2011		46,721,114	$	46,721	$	876,050	$	515,871		$	14,304		$	(607	)	$	1,452,339
Net income								105,343									105,343
Other comprehensive income											1,477						1,477
Common stock issued in connection with the exercise of stock options and restricted stock awards		208,918		209		3,966											4,175
Stock based compensation expense						2,604											2,604
Cash dividends declared, $0.525 per share								(24,599	)								(24,599	)
BALANCE AT SEPTEMBER 30, 2011		46,930,032	$	46,930	$	882,620	$	596,615		$	15,781		$	(607	)	$	1,541,339

See notes to interim consolidated financial statements.

6

PROSPERITY BANCSHARES, INC.^® AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS

(UNAUDITED)

	Nine Months Ended September 30,
	2012			2011
	(In thousands)
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$	119,635		$	105,343
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		11,729			12,000
Stock based compensation expense		3,218			2,604
Net proceeds from the sale of held for sale loans		9,438			—
Net accretion of discount on loans and deposits		(11,988	)		(27	)
Provision for credit losses		2,550			4,050
Net amortization of premium on investments		42,897			19,686
Net loss on sale of other real estate		344			431
Net gain on sale of premises and equipment		(13	)		(377	)
Net (increase) decrease in accrued interest receivable and other assets		(19,623	)		19,352
Net increase in accrued interest payable and other liabilities		42,510			19,314
Net cash provided by operating activities		200,697			182,376
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities and principal paydowns of securities held to maturity		1,238,538			875,900
Purchase of securities held to maturity		(2,499,561	)		(781,977	)
Proceeds from maturities, sales and principal paydowns of securities available for sale		1,703,676			1,075,249
Purchase of securities available for sale		(1,109,999	)		(1,000,000	)
Net increase in loans held for investment		(128,225	)		(263,587	)
Purchase of bank premises and equipment		(7,924	)		(7,621	)
Net proceeds from sale of bank premises, equipment and other real estate		12,004			10,699
Net cash and cash equivalents acquired in the purchase of Texas Bankers, Inc.		44,550			—
Net cash and cash equivalents acquired in the purchase of The Bank Arlington		12,037			—
Net cash and cash equivalents acquired in the purchase of American State
Financial Corporation		123,022			—
Net cash used in investing activities		(611,882	)		(91,337	)

7

PROSPERITY BANCSHARES, INC.^® AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS

(UNAUDITED)

	Nine Months Ended September 30,
	2012			2011
	(In thousands)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in noninterest-bearing deposits		193,360		$	188,717
Net increase in interest-bearing deposits		101,866			155,408
Net proceeds from (repayments of) short-term debt		100,000			(360,000	)
Net repayments of long-term debt		(772	)		(850	)
Redemption of junior subordinated debentures		—			(7,210	)
Net increase in securities sold under repurchase agreements		37,711			5,507
Proceeds from exercise of stock options		2,691			4,175
Payments of cash dividends		(29,410	)		(24,599	)
Net cash provided by (used in) financing activities		405,446			(38,852	)
NET DECREASE IN CASH AND CASH EQUIVALENTS	$	(5,739	)	$	52,187
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD		213,442			159,368
CASH AND CASH EQUIVALENTS, END OF PERIOD	$	207,703		$	211,555
NONCASH ACTIVITIES:
Stock issued in connection with the Texas Bankers, Inc. acquisition	$	12,708			—
Stock issued in connection with The Bank Arlington acquisition		6,198			—
Stock issued in connection with the American State Financial Corporation acquisition		358,299			—
SUPPLEMENTAL DISCLOSURES:
Cash paid for income taxes	$	53,737		$	51,438
Cash paid for interest		30,434			36,616
Noncash investing and financing activities – acquisition of real estate through foreclosure of collateral		11,354			9,414

See notes to interim consolidated financial statements.

8

PROSPERITY BANCSHARES, INC.^® AND SUBSIDIARIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS

SEPTEMBER 30, 2012

(UNAUDITED)

1. BASIS OF PRESENTATION

The interim consolidated financial statements include the accounts of Prosperity Bancshares, Inc.^® (the “Company”) and its wholly-owned subsidiaries, Prosperity Bank ^®(the “Bank”) and Prosperity Holdings of Delaware, L.L.C. All intercompany transactions and balances have been eliminated.

The accompanying unaudited interim consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, the statements reflect all adjustments necessary for a fair presentation of the financial position, results of operations and cash flows of the Company on a consolidated basis, and all such adjustments are of a normal recurring nature. These financial statements and the notes thereto should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2011. Operating results for the nine month period ended September 30, 2012 are not necessarily indicative of the results that may be expected for the year ending December 31, 2012 or any other period.

2. EARNINGS PER SHARE

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

	Three Months Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
	(In thousands, except per share amounts)
Net income available to common shareholders	$	46,176	$	36,373	$	119,635	$	105,343
Weighted average common shares outstanding		55,958		46,890		50,239		46,830
Potential dilutive common shares		135		143		154		183
Weighted average common shares and equivalents outstanding		56,093		47,033		50,393		47,013
Basic earnings per common share	$	0.83	$	0.78	$	2.38	$	2.25
Diluted earnings per common share	$	0.82	$	0.77	$	2.37	$	2.24

Basic earnings per share is computed by dividing net income by the weighted average number of shares outstanding during the applicable period using the two-class method. Diluted earnings per share is computed using the weighted-average number of shares determined for the basic computation plus the dilutive effect of stock options and non-vested restricted stock granted using the treasury stock method. There were no stock options exercisable at September 30, 2012 and 2011 that would have had an anti-dilutive effect on the above computation.

3. NEW ACCOUNTING STANDARDS

Accounting Standards Updates

ASU 2011-03, “Transfers and Servicing (Topic 860)—Reconsideration of Effective Control for Repurchase Agreements.” ASU 2011-03 is intended to improve financial reporting of repurchase agreements and other agreements that both entitle and obligate a transferor to repurchase or redeem financial assets before their maturity. ASU 2011-03 removes from the assessment of effective control (i) the criterion requiring the transferor to have the ability to repurchase or redeem the financial assets on substantially the agreed terms, even in the event of default by the transferee, and (ii) the collateral maintenance guidance related to that criterion. ASU 2011-03 became effective for the Company on January 1, 2012 and did not have a significant impact on the Company’s financial statements.

9

PROSPERITY BANCSHARES, INC.^® AND SUBSIDIARIES

NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS

SEPTEMBER 30, 2012

(UNAUDITED)

ASU 2011-04, “Fair Value Measurement (Topic 820)—Amendments to Achieve Common Fair Value Measurements and Disclosure Requirements in U.S. GAAP and IFRSs.” ASU 2011-04 amends Topic 820, “Fair Value Measurements and Disclosures,” to converge the fair value measurement guidance in U.S. generally accepted accounting principles and International Financial Reporting Standards. ASU 2011-04 clarifies the application of existing fair value measurement requirements, changes certain principles in Topic 820 and requires additional fair value disclosures. ASU 2011-04 became effective for the Company on January 1, 2012 and did not have a significant impact on the Company’s financial statements (see Note 5-Fair Value).

ASU 2011-05, “Comprehensive Income (Topic 220)—Presentation of Comprehensive Income.” ASU 2011-05 amends Topic 220, “Comprehensive Income,” to require that all non-owner changes in stockholders’ equity be presented in either a single continuous statement of comprehensive income or in two separate but consecutive statements. Additionally, ASU 2011-05 requires entities to present, on the face of the financial statements, reclassification adjustments for items that are reclassified from other comprehensive income to net income in the statement or statements where the components of net income and the components of other comprehensive income are presented. The option to present components of other comprehensive income as part of the statement of changes in stockholders’ equity was eliminated. ASU 2011-05 became effective for the Company on January 1, 2012; however, certain provisions related to the presentation of reclassification adjustments have been deferred by ASU 2011-12 “Comprehensive Income (Topic 220)—Deferral of the Effective Date for Amendments to the Presentation of Reclassifications of Items Out of Accumulated Other Comprehensive Income in Accounting Standards Update No. 2011-05,” as further discussed below. In connection with the application of ASU 2011-05, the Company’s financial statements now include a separate statement of comprehensive income.

ASU 2011-08, “Intangibles—Goodwill and Other (Topic 350)—Testing Goodwill for Impairment.” ASU 2011-08 amends Topic 350, “Intangibles—Goodwill and Other,” to give entities the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the totality of events or circumstances, an entity determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then performing the two-step impairment test is unnecessary. However, if an entity concludes otherwise, then it is required to perform the first step of the two-step impairment test by calculating the fair value of the reporting unit and comparing the fair value with the carrying amount of the reporting unit. ASU 2011-08 became effective for the Company on January 1, 2012 and its adoption did not have a significant impact on its financial statements.

ASU 2011-11, “Balance Sheet (Topic 210)—“Disclosures about Offsetting Assets and Liabilities.” ASU 2011-11 amends Topic 210, “Balance Sheet,” to require an entity to disclose both gross and net information about financial instruments, such as sales and repurchase agreements and reverse sale and repurchase agreements and securities borrowing/lending arrangements, and derivative instruments that are eligible for offset in the statement of financial position and/or subject to a master netting arrangement or similar agreement. ASU 2011-11 is effective for annual and interim periods beginning on January 1, 2013, and is not expected to have a significant impact on the Company’s financial statements.

ASU 2011-12 “Comprehensive Income (Topic 220)—Deferral of the Effective Date for Amendments to the Presentation of Reclassifications of Items Out of Accumulated Other Comprehensive Income in Accounting Standards Update No. 2011-05.” ASU 2011-12 defers changes in ASU 2011-05 that relate to the presentation of reclassification adjustments to allow the FASB time to redeliberate whether to require presentation of such adjustments on the face of the financial statements to show the effects of reclassifications out of accumulated other comprehensive income on the components of net income and other comprehensive income. ASU 2011-12 allows entities to continue to report reclassifications out of accumulated other comprehensive income consistent with the presentation requirements in effect before ASU 2011-05. All other requirements in ASU 2011-05 are not affected by ASU 2011-12. ASU 2011-12 became effective for the Company on January 1, 2012. In connection with the application of ASU 2011-05, the Company’s financial statements now include a separate statement of comprehensive income.

ASU 2012-02 “Intangibles—Goodwill and Other (Topic 350)—Testing Indefinite-Lived Intangible Assets for Impairment.” ASU 2012-02 give entities the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that an indefinite-lived intangible asset is impaired. If, after assessing the totality of events or circumstances, an entity determines it is more likely than not that an indefinite-lived intangible asset is impaired, then the entity must perform the quantitative impairment test. If, under the quantitative impairment test, the carrying amount of the intangible asset exceeds its fair value, an entity should recognize an impairment loss in the amount of that excess. Permitting an entity to assess qualitative factors when testing indefinite-lived intangible assets for impairment results in guidance that is similar to the goodwill impairment testing guidance in ASU 2011-08. ASU 2012-02 is effective for the Company beginning January 1, 2013 (early adoption permitted) and is not expected to have a significant impact on the Company’s financial statements.

10

ASU 2012-03 “Technical Amendments and Corrections to SEC Sections—Amendments to SEC Paragraphs Pursuant to SEC Staff Bulletin No. 114, Technical Amendments Pursuant to SEC Release No. 33-9250, and Corrections Related to FASB Accounting Standards Update 2010-22.” ASU 2012-03 amends a number of SEC sections in the ASC as a result of (1) the issuance of SAB 114, (2) the issuance of SEC Final Rule 33-9250, and (3) necessary corrections related to ASU 2010-22. ASU 2012-03 is effective for the Company beginning January 1, 2013 and is not expected to have a significant impact on the Company’s financial statements.

ASU 2012-04 “Technical Corrections and Improvements.” ASU 2012-04 makes certain technical corrections and “conforming fair value amendments” to the FASB Accounting Standards Codification (the “Codification”). The amendments cover a wide range of Topics in the Codification, related to technical corrections and improvements and conforming amendments related to fair value measurements. The amendments represent changes to clarify the Codification, correct unintended application of guidance, or make minor improvements to the Codification that are not expected to have a significant effect on current accounting practice. The amendments apply to all reporting entities within the scope of those topics. ASU 2012-04 is effective for the Company beginning January 1, 2013 and is not expected to have a significant impact on the Company’s financial statements.

4. LOANS AND ALLOWANCE FOR CREDIT LOSSES

Total loans were $5.08 billion at September 30, 2012, an increase of $1.31 billion or 34.9% compared with $3.77 billion at December 31, 2011. Loan growth was impacted by the acquisition of Texas Bankers, Inc., The Bank Arlington and American State Financial Corporation (“ASB”). The fair value of loans attributed to these acquisitions totaled $24.2 million, $21.8 million and $1.13 billion at September 30, 2012, respectively. The Company recorded a preliminary discount on loans of $104.9 million, of which $27.1 million related to purchased credit impaired loans accounted for under ASC Topic 310-30 (formerly SOP 03-03) and $77.8 million related to loans accounted for under ASC Topic 310-20 (formerly SFAS No. 91). Acquired loans included in the tables below are reported at fair value. See Note 11-Acquisitions for more information on acquired loans and purchased credit impaired loans.

The loan portfolio consists of various types of loans made principally to borrowers located in Bryan/College Station, Central Texas, Dallas/Fort Worth, East Texas, Houston, South Texas and West Texas and is classified by major type as follows:

	September 30, 2012		December 31, 2011
	(Dollars in thousands)
Commercial and industrial	$	756,342	$	406,433
Real estate:
Construction and land development		496,417		482,140
1-4 family residential(1)		1,213,873		1,007,266
Home equity		183,844		146,999
Commercial mortgage		1,837,224		1,351,986
Agriculture real estate		205,333		136,008
Multi-family residential		138,888		89,240
Agriculture		98,801		34,226
Consumer (net of unearned discount)		112,476		78,187
Other		35,905		33,421
Total	$	5,079,103	$	3,765,906

(1) Includes $4.3 million in loans held for sale carried at the lower of cost or market.

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

(ii) Commercial Mortgages. The Company makes commercial mortgage loans collateralized by owner-occupied and non-owner-occupied real estate to finance the purchase of real estate. The Company’s commercial mortgage loans are collateralized by first liens on real estate, typically have variable interest rates (or five year or less fixed rates) and amortize over a 15 to 20 year period. Payments on loans secured by such properties are often dependent on the successful operation or management of the properties.

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Accordingly, repayment of these loans may be subject to adverse conditions in the real estate market or the economy to a greater extent than other types of loans. The Company seeks to minimize these risks in a variety of ways, including giving careful consideration to the property’s operating history, future operating projections, current and projected occupancy, location and physical condition in connection with underwriting these loans. The underwriting analysis also includes credit verification, analysis of global cash flow, appraisals and a review of the financial condition of the borrower. At September 30, 2012, approximately 43.3% of the outstanding principal balance of the Company’s commercial real estate loans was secured by owner-occupied properties. At September 30, 2012, the Company had commercial real estate loans totaling $2.47 billion which include the categories of construction and land development loans, commercial mortgage loans and multi-family residential loans.

(iii) 1-4 Family Residential Loans. The Company originates 1-4 family residential mortgage loans collateralized by owner-occupied residential properties located in the Company’s market areas. The Company offers a variety of mortgage loan products which generally are amortized over five to 25 years. Loans collateralized by 1-4 family residential real estate generally have been originated in amounts of no more than 89% of appraised value or have mortgage insurance. The Company requires mortgage title insurance and hazard insurance. The Company has elected to keep all 1-4 family residential loans for its own account rather than selling such loans into the secondary market. By doing so, the Company is able to realize a higher yield on these loans; however, the Company also incurs interest rate risk as well as the risks associated with nonpayments on such loans.

(iv) Construction and Land Development Loans. The Company makes loans to finance the construction of residential and, to a lesser extent, nonresidential properties. Construction loans generally are collateralized by first liens on real estate and have floating interest rates. The Company conducts periodic inspections, either directly or through an agent, prior to approval of periodic draws on these loans. Underwriting guidelines similar to those described above are also used in the Company’s construction lending activities. Construction loans involve additional risks attributable to the fact that loan funds are advanced upon the security of a project under construction, and the project is of uncertain value prior to its completion. Because of uncertainties inherent in estimating construction costs, the market value of the completed project and the effects of governmental regulation on real property, it can be difficult to accurately evaluate the total funds required to complete a project and the related loan to value ratio. As a result of these uncertainties, construction lending often involves the disbursement of substantial funds with repayment dependent, in part, on the success of the ultimate project rather than the ability of a borrower or guarantor to repay the loan. If the Company is forced to foreclose on a project prior to completion, there is no assurance that the Company will be able to recover all of the unpaid portion of the loan. In addition, the Company may be required to fund additional amounts to complete a project and may have to hold the property for an indeterminate period of time. While the Company has underwriting procedures designed to identify what it believes to be acceptable levels of risks in construction lending, no assurance can be given that these procedures will prevent losses from the risks described above.

(v) Agriculture Loans and Farmland. The Company provides agriculture loans for short-term crop production, including rice, cotton, milo and corn, farm equipment financing and agriculture real estate financing. The Company evaluates agriculture borrowers primarily based on their historical profitability, level of experience in their particular agriculture industry, overall financial capacity and the availability of secondary collateral to withstand economic and natural variations common to the industry. Because agriculture loans present a higher level of risk associated with events caused by nature, the Company routinely makes on-site visits and inspections in order to identify and monitor such risks. The Company’s farmland loans are collateralized by first liens on real estate and typically have five to 15 year fixed rates.

(vi) Consumer Loans. Consumer loans made by the Company include direct credit automobile loans, recreational vehicle loans, boat loans, home improvement loans, home equity loans, personal loans (collateralized and uncollateralized) and deposit account collateralized loans. The terms of these loans typically range from 12 to 120 months and vary based upon the nature of collateral and size of loan. Generally, consumer loans present greater risk than do real estate secured loans, particularly in the case of consumer loans that are unsecured or collateralized by rapidly depreciating assets such as automobiles. In such cases, any repossessed collateral for a defaulted consumer loan may not provide an adequate source of repayment for the outstanding loan balance. The remaining deficiency often does not warrant further substantial collection efforts against the borrower beyond obtaining a deficiency judgment. In addition, consumer loan collections are dependent on the borrower’s continuing financial stability, and thus are more likely to be adversely affected by job loss, divorce, illness or personal bankruptcy. Furthermore, the application of various federal and state laws may limit the amount which can be recovered on such loans.

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

Concentrations of Credit. Most of the Company’s lending activity occurs within the State of Texas, including the four largest metropolitan areas of Austin, Dallas/Ft. Worth, Houston and San Antonio. The majority of the Company’s loan portfolio consists of commercial real estate loans, 1-4 family residential loans and commercial and industrial loans. As of September 30, 2012 and December 31, 2011, there were no concentrations of loans related to any single industry in excess of 10% of total loans.

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Foreign Loans. The Company has U.S. dollar denominated loans and commitments to borrowers in Mexico. The outstanding balance of these loans and the unfunded amounts available under these commitments were not significant at September 30, 2012 or December 31, 2011.

Related Party Loans. As of September 30, 2012 and December 31, 2011, loans outstanding to directors, officers and their affiliates totaled $6.7 million and $9.8 million, respectively. All transactions entered into between the Company and such related parties are done in the ordinary course of business, made on the same terms and conditions as similar transactions with unaffiliated persons.

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

	For the Nine Months Ended September  30, 2012			For the Year Ended December 31, 2011
	(Dollars in thousands)
Beginning balance	$	9,809		$	12,783
New loans and reclassified related loans		736			4,168
Repayments		(3,851	)		(7,142	)
Ending balance	$	6,694		$	9,809

Nonaccrual and Past Due Loans. The Company has several procedures in place to assist it in maintaining the overall quality of its loan portfolio. The Company has established underwriting guidelines to be followed by its officers and the Company also monitors its delinquency levels for any negative or adverse trends. There can be no assurance, however, that the Company’s loan portfolio will not become subject to increasing pressures from deteriorating borrower credit due to general economic conditions.

The Company generally places a loan on nonaccrual status and ceases accruing interest when the payment of principal or interest is delinquent for 90 days, or earlier in some cases, unless the loan is in the process of collection and the underlying collateral fully supports the carrying value of the loan.

The Company requires appraisals on loans collateralized by real estate. With respect to potential problem loans, an evaluation of the borrower’s overall financial condition is made to determine the need, if any, for possible writedowns or appropriate additions to the allowance for credit losses.

As of the dates indicated, nonaccrual loans, segregated by class of loans, were as follows:

	September 30, 2012		December 31, 2011
	(Dollars in thousands)
Construction and land development	$	86	$	1,175
Agriculture and agriculture real estate		410		49
1-4 family (includes home equity)		1,694		923
Commercial real estate (commercial mortgage and multi-family residential)		1,292		790
Commercial and industrial		1,557		633
Consumer and other		24		8
Total	$	5,063	$	3,578

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An age analysis of past due loans, segregated by class of loans, as of the dates indicated, was as follows:

	As of September 30, 2012
	Loans 30-89  Days Past Due		Loans 90 or  More Days Past Due		Total Past Due  Loans		Current Loans		Accruing Loans 90  or More Days Past Due
	(Dollars in thousands)
Construction and land development	$	5,157	$	86	$	5,243	$	491,174	$	—
Agriculture and agriculture real estate		1,772		362		2,134		302,000		—
1-4 family (includes home equity)		1,756		1,413		3,169		1,394,548		—
Commercial real estate (commercial mortgage and multi-family residential)		9,965		—		9,965		1,966,147		—
Commercial and industrial		4,211		426		4,637		751,705		132
Consumer and other		1,104		20		1,124		147,257		—
Total	$	23,965	$	2,307	$	26,272	$	5,052,831	$	132

	As of December 31, 2011
	Loans 30-89  Days Past Due		Loans 90 or  More Days Past Due		Total Past Due  Loans		Current Loans		Accruing Loans 90  or More Days Past Due
	(Dollars in thousands)
Construction and land development	$	1,281	$	111	$	1,392	$	480,748	$	—
Agriculture and agriculture real estate		365		9		374		169,860		—
1-4 family (includes home equity)		1,527		314		1,841		1,152,424		—
Commercial real estate (commercial mortgage and multi-family residential)		5,630		390		6,020		1,435,206		—
Commercial and industrial		1,544		394		1,938		404,495		—
Consumer and other		89		—		89		111,519		—
Total	$	10,436	$	1,218	$	11,654	$	3,754,252	$	—

The following table presents information regarding past due loans and nonperforming assets at the dates indicated:

	September 30, 2012			December 31, 2011
	(Dollars in thousands)
Nonaccrual loans	$	5,063		$	3,578
Accruing loans 90 or more days past due		132			—
Total nonperforming loans		5,195			3,578
Repossessed assets		10			146
Other real estate		8,846			8,328
Total nonperforming assets	$	14,051		$	12,052
Nonperforming assets to total loans and other real estate		0.28	%		0.32	%

The Company had $14.1 million in nonperforming assets at September 30, 2012 compared with $12.1 million at December 31, 2011. If interest on nonaccrual loans had been accrued under the original loan terms, approximately $252,000 and $156,000 would have been recorded as income for the nine months ended September 30, 2012 and 2011, respectively.

Impaired Loans. Loans are considered impaired when, based on current information and events, it is probable the Company will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreement, including scheduled principal and interest payments. Impairment is evaluated in total for smaller-balance loans of a similar nature and on an individual loan basis for other loans. If a loan is impaired, a specific valuation allowance is allocated, if necessary, so that the loan is reported net, at the present value of estimated future cash flows using the loan’s existing rate or at the fair value of collateral if repayment is expected solely from the collateral. 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 uncollectible.

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Impaired loans as of September 30, 2012 are set forth in the following table. No interest income was recognized on impaired loans subsequent to their classification as impaired.

	September 30, 2012
	Recorded Investment		Unpaid Principal Balance		Related Allowance		Average Recorded Investment  Quarter to Date		Average Recorded Investment  Year to Date
	(Dollars in thousands)
With no related allowance recorded:
Construction and land development	$	60	$	61	$	—	$	143	$	168
Agriculture and agriculture real estate		77		77		—		41		23
1-4 family (includes home equity)		362		407		—		379		353
Commercial real estate (commercial mortgage and multi-family residential)		396		421		—		379		733
Commercial and industrial		157		158		—		80		69
Consumer and other		—		—		—		—		—
With an allowance recorded:
Construction and land development		26		26		26		64		564
Agriculture and agriculture real estate		66		72		61		52		47
1-4 family (includes home equity)		1,086		1,103		336		660		650
Commercial real estate (commercial mortgage and multi-family residential)		2,774		2,786		567		2,766		2,794
Commercial and industrial		1,238		1,547		1,180		869		717
Consumer and other		20		34		20		13		10
Total:
Construction and land development		86		87		26		207		732
Agriculture and agriculture real estate		143		149		61		93		70
1-4 family (includes home equity)		1,448		1,510		336		1,039		1,003
Commercial real estate (commercial mortgage and multi-family residential)		3,170		3,207		567		3,145		3,527
Commercial and industrial		1,395		1,705		1,180		949		786
Consumer and other		20		34		20		13		10

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Impaired loans as of December 31, 2011 are set forth in the following table. No interest income was recognized on impaired loans subsequent to their classification as impaired. The average recorded investment is reported on a year-to-date basis.

	December 31, 2011
	Recorded Investment		Unpaid  Principal Balance		Related Allowance		Average  Recorded Investment
	(Dollars in thousands)
With no related allowance recorded:
Construction and land development	$	111	$	111	$	—	$	58
Agriculture and agriculture real estate		6		6		—		5
1-4 family (includes home equity)		313		344		—		291
Commercial real estate (commercial mortgage and multi-family residential)		668		705		—		637
Commercial and industrial		112		1,513		—		253
Consumer and other		—		—		—		3
With an allowance recorded:
Construction and land development		1,064		1,064		312		584
Agriculture and agriculture real estate		43		46		39		21
1-4 family (includes home equity)		677		731		362		663
Commercial real estate (commercial mortgage and multi-family residential)		483		485		165		309
Commercial and industrial		521		535		300		642
Consumer and other		8		20		8		18
Total:
Construction and land development		1,175		1,175		312		642
Agriculture and agriculture real estate		49		52		39		26
1-4 family (includes home equity)		990		1,075		362		954
Commercial real estate (commercial mortgage and multi-family residential)		1,151		1,190		165		946
Commercial and industrial		633		2,048		300		895
Consumer and other		8		20		8		21

Credit Quality Indicators. As part of the ongoing monitoring of the credit quality of the Company’s loan portfolio and methodology for calculating the allowance for credit losses, management assigns and tracks loan risk grades to be used as credit quality indicators. The following is a general description of the loan risk grades used (1-7):

Grade 1—Credits in this category are of the highest standards of credit quality with virtually no risk of loss. These borrowers would represent top rated companies and individuals with unquestionable financial standing with excellent global cash flow coverage, net worth, liquidity and collateral coverage and/or secured by CD/savings accounts.

Grade 2—Credits in this category are not immune from risk but are well-protected by the collateral and paying capacity of the borrower. These loans may exhibit a minor unfavorable credit factor, but the overall credit is sufficiently strong to minimize the possibility of loss.

Grade 3—Credits graded 3 constitute an undue and unwarranted credit risk, however the factors do not rise to a level of substandard. These credits have potential weaknesses and/or declining trends that, if not corrected, could expose the Bank to risk at a future date. Credits graded 3 are monitored on the Bank’s internally generated watch list and evaluated on a quarterly basis.

Grade 4—Credits in this category are deemed “substandard” loans in accordance with regulatory guidelines. Loans in this category have well-defined weakness that, if not corrected, could make default of principal and interest possible, but it is not yet certain. Loans in this category are still accruing interest and may be dependent upon secondary sources of repayment and/or collateral liquidation.

Grade 5—Credits in this category are deemed “substandard” and “impaired” pursuant to regulatory guidelines. As such, the Bank has determined that it is probable that less than 100% of the principal and interest will be collected. Loans graded 5 are individually evaluated for a specific reserve valuation and will typically have the accrual of interest stopped.

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Grade 6—Credits in this category include “doubtful” loans in accordance with regulatory guidance. Such loans are on nonaccrual and factors have indicated a loss is imminent. These loans are also deemed “impaired.” While a specific reserve may be in place while the loan and collateral is being evaluated these loans are typically charged down to an amount the Bank deems can be collected.

Grade 7—Credits in this category are deemed a “loss” in accordance with regulatory guidelines and charged off or charged down. The Bank may continue collection efforts and may have partial recovery in the future.

The following table presents loan risk grades and classified loans by class of loan at September 30, 2012. Classified loans include loans in risk grades 5, 6 and 7.

	Construction and Land Development		Agriculture and Agriculture Real Estate		1-4 Family (Includes Home Equity)		Commercial Real Estate (Commercial Mortgage and Multi- Family)		Commercial and Industrial		Consumer and Other		Total
	(Dollars in thousands)
Grade 1	$	—	$	2,601	$	—	$	—	$	45,371	$	28,269	$	76,241
Grade 2		482,385		297,231		1,384,513		1,930,565		695,762		119,392		4,909,848
Grade 3		8,351		2,128		6,617		9,163		8,206		—		34,465
Grade 4		5,595		2,031		5,139		33,214		5,608		700		52,287
Grade 5		86		143		1,435		3,170		1,393		20		6,247
Grade 6		—		—		13		—		2		—		15
Grade 7		—		—		—		—		—		—		—
Total	$	496,417	$	304,134	$	1,397,717	$	1,976,112	$	756,342	$	148,381	$	5,079,103

The following table presents risk grades and classified loans by class of loan at December 31, 2011. Classified loans include loans in risk grades 5, 6 and 7.

	Construction and Land Development		Agriculture and Agriculture Real Estate		1-4 Family (Includes Home Equity)		Commercial Real Estate (Commercial Mortgage and Multi- Family)		Commercial and Industrial		Consumer and Other		Total
	(Dollars in thousands)
Grade 1	$	—	$	3,319	$	—	$	—	$	45,218	$	31,602	$	80,139
Grade 2		465,572		166,656		1,140,210		1,399,915		355,862		79,996		3,608,211
Grade 3		1,757		210		9,131		14,335		4,189		—		29,622
Grade 4		13,636		—		3,934		25,825		531		2		43,928
Grade 5		1,175		49		970		1,151		532		8		3,885
Grade 6		—		—		20		—		101		—		121
Grade 7		—		—		—		—		—		—		—
Total	$	482,140	$	170,234	$	1,154,265	$	1,441,226	$	406,433	$	111,608	$	3,765,906

Net charge-offs/recoveries, segregated by class of loans, for the three and nine months ended September 30, 2012 and 2011 were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2012			2011			2012			2011
Construction and land development	$	(155	)	$	197		$	(1,356	)	$	(955	)
1-4 family (includes home equity)		(251	)		(134	)		(392	)		(517	)
Commercial real estate and agriculture (includes multi-family)		(770	)		(271	)		(1,080	)		(768	)
Commercial and industrial		511			(7	)		345			(492	)
Consumer and other		(590	)		(153	)		(734	)		(389	)
Total	$	(1,255	)	$	(368	)	$	(3,217	)	$	(3,121	)

Allowance for Credit Losses. The allowance for credit losses is a valuation established through charges to earnings in the form of a provision for credit losses. Management has established an allowance for credit losses which it believes is adequate for estimated losses in the Company’s loan portfolio. The amount of the allowance for credit losses is affected by the following: (i) charge-offs of loans that occur when loans are deemed uncollectible and decrease the allowance, (ii) recoveries on loans previously charged off that

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increase the allowance and (iii) provisions for credit losses charged to earnings that increase the allowance. Based on an evaluation of the loan portfolio and consideration of the factors listed below, management presents a quarterly review of the allowance for credit losses to the Bank’s Board of Directors, indicating any change in the allowance since the last review and any recommendations as to adjustments in the allowance.

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

In setting the specific valuation allowance, the Company follows a loan review program to evaluate the credit risk in the loan portfolio. Through this loan review process, the Company maintains an internal list of impaired loans which, along with the delinquency list of loans, helps management assess the overall quality of the loan portfolio and the adequacy of the allowance for credit losses. All loans that have been identified as impaired are reviewed on a quarterly basis in order to determine whether a specific reserve is required. For each impaired loan, the Company allocates a specific loan loss reserve primarily based on the value of the collateral securing the impaired loan in accordance with ASC Topic 310, Receivables. The specific reserves are determined on an individual loan basis. Loans for which specific reserves are provided are excluded from the general valuation allowance described below.

In determining the amount of the general valuation allowance, management considers factors such as historical loan loss experience, industry diversification of the Company’s commercial loan portfolio, concentration risk of specific loan types, the volume, growth and composition of the Company’s loan portfolio, current economic conditions that may affect the borrower’s ability to pay and the value of collateral, the evaluation of the Company’s loan portfolio through its internal loan review process, general economic conditions and other qualitative risk factors both internal and external to the Company and other relevant factors in accordance with ASC Topic 450, Contingencies. Based on a review of these factors for each loan type, the Company applies an estimated percentage to the outstanding balance of each loan type, excluding any loan that has a specific reserve allocated to it. The Company uses this information to establish the amount of the general valuation allowance.

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

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

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

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

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

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

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

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

At September 30, 2012, the allowance for credit losses totaled $50.9 million or 1.00% of total loans. At December 31, 2011, the allowance aggregated $51.6 million or 1.37% of total loans.

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The following table details the recorded investment in loans and activity in the allowance for credit losses by portfolio segment for the nine months ended September 30, 2012. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.

	Construction and Land Development			Agriculture and Agriculture Real Estate		1-4 Family (includes Home Equity)			Commercial Real Estate (Commercial Mortgage and Multi-Family)			Commercial and Industrial			Consumer and Other			Total
	(Dollars in thousands)
Allowance for credit losses:
Beginning balance	$	12,094		$	511	$	12,645		$	21,460		$	3,826		$	1,058		$	51,594
Provision for credit losses		(469	)		226		1,121			(250	)		1,237			685			2,550
Charge-offs		(1,368	)		—		(478	)		(1,278	)		(376	)		(2,101	)		(5,601	)
Recoveries		12			33		86			165			721			1,367			2,384
Net charge-offs		(1,356	)		33		(392	)		(1,113	)		345			(734	)		(3,217	)
Ending balance		10,269			770		13,374			20,097			5,408			1,009			50,927
Ending balance: individually evaluated for impairment		26			61		336			567			1,180			20			2,190
Ending balance: collectively evaluated for impairment	$	10,243		$	709	$	13,038		$	19,530		$	4,228		$	989		$	48,737
Loans:
Ending balance: individually evaluated for impairment		86			143		1,448			3,170			1,395			20			6,262
Ending balance: collectively evaluated for impairment		496,331			303,991		1,396,269			1,972,942			754,947			148,361			5,072,841
Ending balance	$	496,417		$	304,134	$	1,397,717		$	1,976,112		$	756,342		$	148,381		$	5,079,103

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The following table details the recorded investment in loans and activity in the allowance for credit losses by portfolio segment for the year ended December 31, 2011. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.

	Construction and Land Development			Agriculture and Agriculture Real Estate		1-4 Family (includes Home Equity)			Commercial Real Estate (Commercial Mortgage and Multi-Family)			Commercial and Industrial			Consumer and Other			Total
	(Dollars in thousands)
Allowance for credit losses:
Beginning balance	$	12,994		$	271	$	12,837		$	20,436		$	3,891		$	1,155		$	51,584
Provision for credit losses		209			239		1,168			2,011			1,103			470			5,200
Charge-offs		(1,509	)		—		(1,392	)		(1,027	)		(1,694	)		(1,228	)		(6,850	)
Recoveries		400			1		32			40			526			661			1,660
Net charge-offs		(1,109	)		1		(1,360	)		(987	)		(1,168	)		(567	)		(5,190	)
Ending balance		12,094			511		12,645			21,460			3,826			1,058			51,594
Ending balance: individually evaluated for impairment		312			39		362			165			300			8			1,186
Ending balance: collectively evaluated for impairment	$	11,782		$	472	$	12,283		$	21,295		$	3,526		$	1,050		$	50,408
Loans:
Ending balance: individually evaluated for impairment		1,175			49		990			1,151			633			8			4,006
Ending balance: collectively evaluated for impairment		480,965			170,185		1,153,275			1,440,075			405,800			111,600			3,761,900
Ending balance	$	482,140		$	170,234	$	1,154,265		$	1,441,226		$	406,433		$	111,608		$	3,765,906

Troubled Debt Restructurings. The restructuring of a loan is considered a “troubled debt restructuring” if both (i) the borrower is experiencing financial difficulties and (ii) the creditor has granted a concession. Concessions may include interest rate reductions or below market interest rates, principal forgiveness, restructuring amortization schedules and other actions intended to minimize potential losses. Effective July 1, 2011, the Company adopted the provisions of ASU No. 2011-02, “Receivables (Topic 310)—A Creditor’s Determination of Whether a Restructuring Is a Troubled Debt Restructuring.” As such, the Company reassessed all loan modifications occurring since January 1, 2011 for identification as troubled debt restructurings.

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The Company had the following troubled debt restructurings outstanding as of the dates indicated:

	As of September 30, 2012						As of December 31, 2011
	Number of Contracts		Pre- Modification Outstanding Recorded Investment		Post- Modification Outstanding Recorded Investment		Number of Contracts		Pre- Modification Outstanding Recorded Investment		Post- Modification Outstanding Recorded Investment
	(Dollars in thousands)
Troubled Debt Restructurings
Construction and land development		—	$	—	$	—		—	$	—	$	—
Agriculture and agriculture real estate		—		—		—		—		—		—
1-4 family (includes home equity)		4		109		66		4		109		84
Commercial real estate (commercial mortgage and multi-family)		1		2,560		2,469		2		5,264		5,171
Commercial and industrial		7		1,086		1,061		3		114		93
Consumer and other		—		—		—		—		—		—
Total		12	$	3,755	$	3,596		9	$	5,487	$	5,348

As of September 30, 2012, there have been no defaults on any loans that were modified as troubled debt restructurings during the preceding twelve months. Default is determined at 90 or more days past due. The modifications primarily related to extending the amortization periods of the loans, which may include loans modified during bankruptcy. The Company did not grant principal reductions on any restructured loan. Loans restructured during the nine months ended September 30, 2012 on non-accrual status as of September 30, 2012 totaled $972,000. The remaining restructured loans are performing and accruing loans. These modifications did not have a material impact on the Company’s determination of the allowance for credit losses.

5. FAIR VALUE DISCLOSURES

Effective January 1, 2008, the Company adopted FASB ASC Topic 820, Fair Value Measurement and Disclosures. ASC Topic 820, which defines fair value, addresses aspects of the expanding application of fair value accounting and establishes a consistent framework for measuring fair value. Fair value represents the estimated price that would be received from selling an asset or paid to transfer a liability, otherwise known as an “exit price”.

Fair Value Hierarchy

ASC Topic 820 specifies a hierarchy of valuation techniques based on whether the inputs to those valuation techniques are observable or unobservable. In accordance with ASC Topic 820, these inputs are summarized in the three broad levels listed below:

• Level 1—Quoted prices in active markets for identical assets or liabilities. Level 1 assets include U.S. Treasury securities that are highly liquid and are actively traded in over-the-counter markets and CRA funds.

• Level 2—Other significant observable inputs (including quoted prices in active markets for similar assets or liabilities) or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company’s Level 2 assets include U.S. government and agency mortgage-backed debt securities, corporate securities and municipal bonds.

• Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair values requires significant management judgment or estimation.

In determining the appropriate levels, the Company performs a detailed analysis of the assets and liabilities that are subject to ASC Topic 820.

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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, 2012 and December 31, 2011, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value:

	September 30, 2012
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Available for sale securities (at fair value):
States and political subdivisions	$	—	$	37,188	$	—	$	37,188
Corporate debt securities and other		7,747		1,553		—		9,300
Collateralized mortgage obligations		—		638		—		638
Mortgage-backed securities		—		203,261		—		203,261
Total	$	7,747	$	242,640	$	—	$	250,387
	December 31, 2011
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Available for sale securities (at fair value):
States and political subdivisions	$	—	$	39,076	$	—	$	39,076
Corporate debt securities and other		7,656		1,613		—		9,269
Collateralized mortgage obligations		—		765		—		765
Mortgage-backed securities		—		273,206		—		273,206
Total	$	7,656	$	314,660	$	—	$	322,316

Certain assets and liabilities are measured at fair value on a non-recurring 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 measured at fair value on a non-recurring basis during the reported periods include certain impaired loans reported at the fair value of the underlying collateral if repayment is expected solely from the collateral. Collateral values are estimated using Level 2 inputs based on observable market data, typically in the case of real estate collateral. For the nine months ended September 30, 2012, the Company had additions to impaired loans of $8.2 million, of which $4.3 million were outstanding at September 30, 2012.

Assets measured at fair value on a non-recurring basis during the reported periods also include other real estate owned and repossessed assets. For the nine months ended September 30, 2012, the Company had additions to other real estate owned of $10.9 million, of which $5.2 million were outstanding at September 30, 2012. The remaining assets and liabilities measured at fair value on a non-recurring basis that were recorded in 2012 and remained outstanding at September 30, 2012 were not significant. During the reported periods, all fair value measurements for assets and liabilities measured at fair value on a non-recurring basis utilized Level 2 inputs based on observable market data. There were no transfers between Level 1 and Level 2 assets during the nine months ended September 30, 2012.

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

The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate that value:

Cash and Cash Equivalents—For these short-term instruments, the carrying amount is a reasonable estimate of fair value.

Federal Funds Sold—For these short-term instruments, the carrying amount is a reasonable estimate of fair value.

Securities —For securities held as investments, fair value equals quoted market price, if available. If a quoted market price is not available, fair value is estimated using quoted market prices for similar securities.

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Loans Held for Investment—For fixed rate loans and certain homogeneous categories of loans (such as some residential mortgages and other consumer loans), fair value is estimated by discounting the future cash flows using the risk-free Treasury rate for the applicable maturity, adjusted for servicing and credit risk. An overall valuation adjustment is made for specific credit risks as well as general portfolio credit risk. The carrying value of variable rate loans approximates fair value because the loans reprice frequently to current market rates.

Loans Held for Sale—Loans held for sale are recorded at the lower of cost or fair value. Loans held for sale may be carried at fair value on a nonrecurring basis when fair value is less than cost. The fair value is based on what secondary markets are currently offering for portfolios with similar characteristics. As such, the Company classifies both loans held for sale subjected to nonrecurring fair value adjustments and the estimated fair value of loans held for sale as Level 2.

Deposits—The fair value of demand deposits, savings accounts and certain money market deposits is the amount payable on demand at the reporting date. The fair value of fixed-maturity certificates of deposit is estimated using the rates currently offered for deposits of similar remaining maturities.

Junior Subordinated Debentures—The fair value of the junior subordinated debentures is calculated using the quoted market prices, if available. If quoted market prices are not available, fair value is estimated using quoted market prices for similar subordinated debentures.

Other Borrowings—Rates currently available to the Company for debt with similar terms and remaining maturities are used to estimate the fair value of existing debt using a discounted cash flows methodology.

Securities Sold Under Repurchase Agreements—The fair value of securities sold under repurchase agreements is the amount payable on demand at the reporting date.

Off-Balance Sheet Financial Instruments—The fair value of commitments to extend credit and standby letters of credit is estimated using the fees currently charged to enter into similar agreements, taking into account the remaining terms of the agreement and the present creditworthiness of the counterparties. The Company’s off-balance sheet commitments are funded at current market rates at the date they are drawn upon. It is management’s opinion that the fair value of these commitments would approximate their carrying value, if drawn upon.

FASB ASC Topic 825, Financial Instruments, requires disclosure of the fair value of financial assets and financial liabilities, including those financial assets and financial liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis. The Company provides fair value estimates for loans not recorded at fair value. During the reported periods, fair value measurements for loans utilized Level 3 inputs. The estimated fair value is determined based on characteristics such as loan category, repricing features and remaining maturity, and includes prepayment and credit loss estimates. The model used to estimate fair value of loans employs a discount rate that reflects the Company’s current pricing for loans with similar characteristics and remaining maturity, adjusted by an amount for estimated credit losses inherent in the portfolio and liquidity risk, at the balance sheet date. The adjustment approximates 25 basis points for the reported periods. The rates take into account the expected yield curve, as well as an adjustment for prepayment risk, when applicable. The Company utilizes a third party to assist with its fair value measurements. Inputs used in the pricing model are validated by management.

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All fair value measurements for remaining financial assets and financial liabilities utilized Level 2 inputs based on observable market data. The carrying amount and estimated fair value of the Company’s financial instruments, as of the dates indicated, are as follows:

	September 30, 2012				December 31, 2011
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
	(Dollars in thousands)
Financial Assets:
Cash and due from banks	$	207,401	$	207,401	$	212,800	$	212,800
Federal funds sold		302		302		642		642
Interest-bearing time deposits in other financial institutions		249		249		—		—
Held to maturity securities		6,549,126		6,772,151		4,336,620		4,492,988
Available for sale securities		250,387		250,387		322,316		322,316
Loans held for sale		4,332		4,332		—		—
Loans held for investment, net of allowance for credit losses		5,023,844		5,098,007		3,714,312		3,814,858
Total	$	12,035,641	$	12,332,829	$	8,586,690	$	8,843,604
Financial liabilities:
Deposits	$	10,954,597	$	10,971,925	$	8,060,254	$	8,074,093
Junior subordinated debentures		85,055		72,242		85,055		71,001
Other borrowings		112,017		114,170		12,790		14,974
Securities sold under repurchase agreements		443,856		443,976		54,883		54,883
Total	$	11,595,525	$	11,602,313	$	8,212,982	$	8,214,951

The Company’s off-balance sheet commitments, which total $911.5 million at September 30, 2012, are funded at current market rates at the date they are drawn upon. It is management’s opinion that the fair value of these commitments would approximate their carrying value, if drawn upon.

The fair value estimates presented herein are based on pertinent information available to management at September 30, 2012. Although management is not aware of any factors that would significantly affect the estimated fair value amounts, such amounts have not been comprehensively revalued for purposes of these financial statements since those dates and, therefore, current estimates of fair value may differ significantly from the amounts presented herein.

Under ASC Topic 825, entities may choose to measure eligible financial instruments at fair value at specified election dates. The fair value measurement option (i) may be applied instrument by instrument, with certain exceptions, (ii) is generally irrevocable and (iii) is applied only to entire instruments and not to portions of instruments. Unrealized gains and losses on items for which the fair value measurement option has been elected must be reported in earnings at each subsequent reporting date. During the reported periods, the Company had no financial instruments measured at fair value under the fair value measurement option.

6. GOODWILL AND CORE DEPOSIT INTANGIBLES

Changes in the carrying amount of the Company’s goodwill and core deposit intangibles (CDI) for nine months ended September 30, 2012 were as follows:

	Goodwill		Core Deposit Intangibles
	(Dollars in thousands)
Balance as of December 31, 2011	$	924,537	$	20,996
Amortization		—		(5,297	)
Acquisition of Texas Bankers, Inc.		5,869		—
Acquisition of The Bank Arlington		3,013		—
Acquisition of American State Financial Corp.		266,679		12,393
Balance as of September 30, 2012	$	1,200,098	$	28,092

Goodwill is recorded on the acquisition date of each entity. The Company may record subsequent adjustments to goodwill for amounts undeterminable at acquisition date, such as deferred taxes and real estate valuations, and therefore the goodwill amounts reflected in the table above may change accordingly. The Company initially records the total premium paid on acquisitions as goodwill. After finalizing the valuation, core deposit intangibles are identified and reclassified from goodwill to core deposit intangibles on the balance sheet. This reclassification has no effect on total assets or liabilities. Management performs an evaluation annually, and more frequently if a triggering event occurs, of whether any impairment of the goodwill and other intangibles has occurred. If any such impairment is determined, a write down is recorded. As of September 30, 2012, there were no impairments recorded on goodwill or other intangibles.

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Although the Company completed the Texas Bankers, Inc. acquisition in January 2012, The Bank Arlington acquisition in April 2012 and the American State Financial Corporation acquisition in July 2012, the Company has not yet completed the allocation of the purchase price and therefore fair values for certain acquired assets and assumed liabilities are still being finalized (see Note 11-Acquisitions).

Core deposit intangibles are amortized on an accelerated basis over their estimated lives, which the Company believes is between 8 and 10 years. Gross core deposit intangibles outstanding were $91.5 million at September 30, 2012 and $79.2 million at December 31, 2011. Net core deposit intangibles outstanding were $28.1 million and $21.0 million at the same dates, respectively. Amortization expense related to intangible assets totaled $2.0 million and $1.9 million for the three months ended September 30, 2012 and 2011, respectively, and $5.3 million and $5.9 million for the nine months ended September 30, 2012 and 2011, respectively.

The estimated aggregate future amortization expense for intangible assets remaining as of September 30, 2012 is as follows (dollars in thousands):

Remaining 2012	$	1,933
2013		6,186
2014		4,866
2015		4,219
2016		3,781
Thereafter		7,107
Total	$	28,092

7. STOCK BASED COMPENSATION

At September 30, 2012, the Company had four stock-based employee compensation plans and one stock option plan assumed in connection with an acquisition under which no additional options will be granted. Two of the four plans adopted by the Company have expired and therefore no additional awards may be issued under those plans. The Company accounts for stock-based employee compensation plans using the fair value-based method of accounting in accordance with ASC Topic 718. ASC Topic 718 was effective for companies in 2006; however, the Company has been recognizing compensation expense since January 1, 2003. The Company recognized $1.1 million and $961,000 in stock-based compensation expense for the three months ended September 30, 2012 and 2011, respectively, and $3.2 million and $2.6 million in stock-based compensation expense for the nine months ended September 30, 2012 and 2011, respectively. There was approximately $364,000 and $322,000 of income tax benefit recorded for the stock-based compensation expense for the three months ended September 30, 2012 and 2011, respectively, and $1.1 million and $870,000 of income tax benefit recorded for the stock-based compensation expense for the nine months ended September 30, 2012 and 2011, respectively.

On February 22, 2012, the Company’s Board of Directors adopted the Prosperity Bancshares, Inc. 2012 Stock Incentive Plan (the “2012 Plan”), subject to approval by the Company’s shareholders. The Company’s shareholders approved the 2012 Plan at the annual meeting of shareholders on April 17, 2012. The 2012 Plan authorizes the issuance of up to 1,250,000 shares of common stock upon the exercise of options granted under the 2012 Plan or pursuant to the grant or exercise, as the case may be, of other awards granted under the 2012 Plan, including restricted stock, stock appreciation rights, phantom stock awards and performance awards. As of September 30, 2012, no options or other awards have been granted under the 2012 Plan.

During 2004, the Company’s Board of Directors adopted the Prosperity Bancshares, Inc. 2004 Stock Incentive Plan (the “2004 Plan”) which authorizes the issuance of up to 1,250,000 shares of common stock pursuant to the exercise or grant, as the case may be, of awards under such plan and the shareholders approved the 2004 Plan in 2005. The Company has granted shares with forfeiture restrictions (“restricted stock”) to certain directors, officers and associates under the 2004 Plan. The awardee is not entitled to the shares until they vest, which is generally over a one to five year period, but the awardee is entitled to receive dividends on and vote the shares prior to vesting. The shares granted do not have a cost to the awardee and the only requirement of vesting is continued service to the Company. Compensation cost related to restricted stock is calculated based on the fair value of the shares at the date of grant. If the awardee leaves the Company before the shares vest, the unvested shares are forfeited. Options to purchase a total of 162,250 shares of common stock of the Company granted under the 2004 Plan were outstanding at September 30, 2012, of which 98,375 were exercisable. As of September 30, 2012, there were 446,146 shares of restricted stock outstanding with a weighted average grant date fair value of $38.06 per share. Remaining shares available for grant under the 2004 Plan totaled 477,625 at September 30, 2012.

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Stock options are issued at the current market price on the date of the grant, subject to a pre-determined vesting period with a contractual term of 10 years. Options assumed in connection with acquisitions have contractual terms as established in the original option grant agreements entered into prior to acquisition. The fair value of stock options granted is estimated at the date of grant using the Black-Scholes option-pricing model. Stock-based compensation expense is recognized ratably over the requisite service period for all awards.

The fair value of options was estimated using an option-pricing model with the following weighted average assumptions:

	September 30,
	2012			2011
Expected life in years		5.26			5.30
Risk free interest rate		3.67	%		3.67	%
Volatility		20.84	%		20.98	%
Dividend yield		1.26	%		1.25	%

A summary of changes in outstanding vested and unvested options during the nine months ended September 30, 2012 is set forth below:

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
	(In thousands)					(In years)		(In thousands)
Options outstanding, beginning of period		525		$	28.18
Options granted		—			—
Options forfeited		(6	)		31.63
Options exercised		(99	)		27.03
Options outstanding, end of period		420		$	28.36		3.36	$	5,982
Options vested or expected to vest		407		$	27.98		3.32	$	5,956
Options exercisable, end of period		280		$	27.62		2.83	$	4,198

No options were granted during the nine months ended September 30, 2012 and 2011. The total intrinsic value of the options exercised during the nine month periods ended September 30, 2012 and 2011 was $1.8 million and $1.4 million, respectively. The total fair value of options vested during the nine month periods ended September 30, 2012 and 2011 was $234,000 and $368,000, respectively.

A summary of changes in unvested options is set forth below:

	Nine Months Ended September 30,
	2012					2011
	Number of Options			Weighted Average Grant Date Fair Value		Number of Options			Weighted Average Grant Date Fair Value
	(In thousands)					(In thousands)
Unvested options outstanding, beginning of period		177		$	6.96		313		$	6.89
Options granted		—			—		—			—
Unvested options forfeited		(4	)		6.76		—			—
Options vested		(33	)		7.07		(59	)		6.31
Unvested options outstanding, end of period		140		$	6.92		254		$	6.96

The Company received $2.7 million and $4.2 million in cash from the exercise of stock options during the nine month periods ended September 30, 2012 and 2011, respectively. There was no tax benefit realized from option exercises of the stock-based compensation arrangements during the nine month periods ended September 30, 2012 and 2011.

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As of September 30, 2012, there was $8.9 million of total unrecognized compensation expense related to unvested stock-based compensation arrangements. That cost is expected to be recognized over a weighted average period of 2.6 years.

8. SECURITIES

The carrying cost of securities totaled $6.80 billion at September 30, 2012 compared with $4.66 billion at December 31, 2011, an increase of $2.14 billion or 45.9%. The increase is due to securities acquired from ASB. At September 30, 2012, securities represented 49.6% of total assets compared with 47.4% of total assets at December 31, 2011.

The amortized cost and fair value of investment securities as of September 30, 2012 are as follows:

	September 30, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	35,262	$	1,937	$	(11	)	$	37,188
Collateralized mortgage obligations		651		—		(13	)		638
Mortgage-backed securities		188,699		14,618		(56	)		203,261
Corporate debt securities and other		8,784		516		—			9,300
Total	$	233,396	$	17,071	$	(80	)	$	250,387
Held to Maturity
U.S. Treasury securities and obligations of U.S. government agencies	$	10,597	$	213	$	—		$	10,810
States and political subdivisions (including QSCB)		387,246		9,355		(151	)		396,450
Corporate debt securities		1,500		53		—			1,553
Collateralized mortgage obligations		160,478		2,994		(215	)		163,257
Mortgage-backed securities		5,989,305		211,153		(377	)		6,200,081
Total	$	6,549,126	$	223,768	$	(743	)	$	6,772,151

The amortized cost and fair value of investment securities as of December 31, 2011 are as follows:

	December 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	37,060	$	2,022	$	(6	)	$	39,076
Collateralized mortgage obligations		786		—		(21	)		765
Mortgage-backed securities		254,965		18,307		(66	)		273,206
Corporate debt securities and other		8,778		491		—			9,269
Total	$	301,589	$	20,820	$	(93	)	$	322,316
Held to Maturity
U.S. Treasury securities and obligations of U.S. government agencies	$	8,696	$	455	$	—		$	9,151
States and political subdivisions (including QSCB)		50,814		3,324		(284	)		53,854
Corporate debt securities		1,500		114		—			1,614
Collateralized mortgage obligations		281,778		5,009		(150	)		286,637
Mortgage-backed securities		3,993,832		147,991		(91	)		4,141,732
Total	$	4,336,620	$	156,893	$	(525	)	$	4,492,988

Management evaluates securities for other-than-temporary impairment at least on a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. The investment securities portfolio is evaluated for OTTI by segregating the portfolio into two general segments and applying the appropriate OTTI model. Investment securities classified as available for sale or held-to-maturity are evaluated for OTTI under FASB ASC Topic 320, “Investments—Debt and Equity Securities.” Certain purchased beneficial interests, including non-agency mortgage-backed securities, asset-backed securities, and collateralized debt obligations, that had credit ratings at the time of purchase of below AA are evaluated using the model outlined in ASC Topic 325, “Investments—Other.” The Company currently does not own any securities that are accounted for under ASC Topic 325.

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In determining OTTI under ASC Topic 320, management considers many factors, including: (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer, (3) whether the market decline was affected by macroeconomic conditions, and (4) whether the entity has the intent to sell the debt security or more likely than not will be required to sell the debt security before its anticipated recovery. The assessment of whether an other-than-temporary decline exists involves a high degree of subjectivity and judgment and is based on the information available to management at a point in time. If applicable, the second segment of the portfolio uses the OTTI guidance provided by ASC Topic 325 that is specific to purchased beneficial interests that, on the purchase date, were rated below AA. Under the ASC Topic 325 model, an impairment is considered other than temporary if, based on the Company’s best estimate of cash flows that a market participant would use in determining the current fair value of the beneficial interest, there has been an adverse change in those estimated cash flows.

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

As of September 30, 2012, the Company does not intend to sell any debt securities and management believes that the Company more likely than not will not be required to sell any debt securities before their anticipated recovery, at which time the Company will receive full value for the securities. Furthermore, as of September 30, 2012, management does not have the intent to sell any of its securities and believes that it is more likely than not that the Company will not have to sell any such securities before a recovery of cost. The unrealized losses are largely due to increases in market interest rates over the yields available at the time the underlying securities were purchased. The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline. Management does not believe any of the securities are impaired due to reasons of credit quality. Accordingly, as of September 30, 2012, management believes any impairment in the Company’s securities are temporary and no impairment loss has been realized in the Company’s consolidated statements of income.

Securities with unrealized losses segregated by length of time such securities have been in a continuous loss position at September 30, 2012 were as follows:

	Less than 12 Months					More than 12 Months					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	—	$	—		$	503	$	(11	)	$	503	$	(11	)
Collateralized mortgage obligations		—		—			638		(13	)		638		(13	)
Mortgage-backed securities		162		—			6,779		(56	)		6,941		(56	)
Total	$	162	$	—		$	7,920	$	(80	)	$	8,082	$	(80	)
Held to Maturity
States and political subdivisions	$	14,301	$	(131	)	$	1,140	$	(19	)	$	15,441	$	(150	)
Collateralized mortgage obligations		2,384		(215	)		—		—			2,384		(215	)
Mortgage-backed securities		16,551		(375	)		320		(3	)		16,871		(378	)
Total	$	33,236	$	(721	)	$	1,460	$	(22	)	$	34,696	$	(743	)

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The amortized cost and fair value of investment securities at September 30, 2012, by contractual maturity, are shown below. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations at any time with or without call or prepayment penalties.

	September 30, 2012
	Held to Maturity				Available for Sale
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
Due in one year or less	$	30,938	$	31,294	$	8,874	$	9,392
Due after one year through five years		118,902		120,003		2,942		3,116
Due after five years through ten years		148,003		150,818		23,562		24,862
Due after ten years		101,500		106,698		8,668		9,118
Subtotal		399,343		408,813		44,046		46,488
Mortgage-backed securities and collateralized mortgage obligations		6,149,783		6,363,338		189,350		203,899
Total	$	6,549,126	$	6,772,151	$	233,396	$	250,387

The Company had no gain or loss on sale of securities for the three months ended September 30, 2012 or 2011 and had no gain or loss on sale of securities for the nine months ended September 30, 2012 compared with a net loss of $581,000 for the nine months ended September 30, 2011. The Company sold two non-agency CMO’s with a total book value of $3.2 million due to a downgrade of the CMO’s to less than investment grade in the second quarter of 2011. As of September 30, 2012, the Company had eight non-agency CMO’s remaining with a total book value of $2.7 million and total market value of $2.5 million.

At September 30, 2012 and December 31, 2011, the Company did not own securities of any one issuer (other than the U.S. government and its agencies) for which aggregate adjusted cost exceeded 10% of the consolidated shareholders’ equity at such respective dates.

Securities with an amortized cost of $4.22 billion and $2.48 billion and a fair value of $4.37 billion and $2.57 billion at September 30, 2012 and December 31, 2011, respectively, were pledged to collateralize public deposits and for other purposes required or permitted by law.

9. CONTRACTUAL OBLIGATIONS AND OFF-BALANCE SHEET ITEMS

Contractual Obligations

The following table summarizes the Company’s contractual obligations and other commitments to make future payments as of September 30, 2012 (other than deposit obligations). The payments do not include pre-payment options that may be available to the Company. The Company’s future cash payments associated with its contractual obligations pursuant to its junior subordinated debentures, FHLB borrowings and operating leases as of September 30, 2012 are summarized below. Payments for junior subordinated debentures include interest of $52.0 million that will be paid over the future periods. The future interest payments were calculated using the current rate in effect at September 30, 2012. The current principal balance of the junior subordinated debentures at September 30, 2012 was $85.1 million. Payments for FHLB borrowings include interest of $3.0 million that will be paid over the future periods. Payments related to leases are based on actual payments specified in underlying contracts.

	Payments due in:
	Remaining Fiscal 2012		Fiscal 2013-2014		Fiscal 2015-2016		Thereafter		Total
	(Dollars in thousands)
Junior subordinated debentures	$	1,222	$	4,888	$	4,888	$	126,017	$	137,015
Federal Home Loan Bank borrowings		100,282		3,258		3,456		8,001		114,997
Operating leases		1,324		8,547		4,013		759		14,643
Total	$	102,828	$	16,693	$	12,357	$	134,777	$	266,655

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Off-Balance Sheet Items

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

The Company’s commitments associated with outstanding standby letters of credit and commitments to extend credit as of September 30, 2012 are summarized below. Since commitments associated with letters of credit and commitments to extend credit may expire unused, the amounts shown do not necessarily reflect the actual future cash funding requirements.

	Remaining Fiscal 2012		Fiscal 2013-2014		Fiscal 2015-2016		Thereafter		Total
	(Dollars in thousands)
Standby letters of credit	$	4,472	$	20,399	$	564	$	—	$	25,435
Commitments to extend credit		114,567		445,549		50,391		275,538		886,045
Total	$	119,039	$	465,948	$	50,955	$	275,538	$	911,480

10. OTHER COMPREHENSIVE (LOSS) INCOME

The tax effects allocated to each component of other comprehensive (loss) income were as follows (dollars in thousands):

	Three Months Ended September 30, 2012									Three Months Ended September 30, 2011
	Before Tax Amount			Tax Expense, (Benefit)			Net of Tax Amount			Before Tax Amount		Tax Expense, (Benefit)		Net of Tax Amount
Securities available for sale:
Change in net unrealized (loss) gain during the period	$	(718	)	$	(251	)	$	(467	)	$	632	$	222	$	410
Total other comprehensive (loss) income	$	(718	)	$	(251	)	$	(467	)	$	632	$	222	$	410
	Nine Months Ended September 30, 2012									Nine Months Ended September 30, 2011
	Before Tax Amount			Tax Expense, (Benefit)			Net of Tax Amount			Before Tax Amount		Tax Expense, (Benefit)		Net of Tax Amount
Securities available for sale:
Change in net unrealized (loss) gain during the period	$	(3,736	)	$	(1,308	)	$	(2,428	)	$	2,272	$	795	$	1,477
Total other comprehensive (loss) income	$	(3,736	)	$	(1,308	)	$	(2,428	)	$	2,272	$	795	$	1,477

Activity in accumulated other comprehensive income, net of tax, was as follows:

	Securities Available For Sale			Accumulated Other Comprehensive Income
	(Dollars in thousands)
Balance January 1, 2012	$	13,472		$	13,472
Other comprehensive (loss) income		(2,428	)		(2,428	)
Balance September 30, 2012	$	11,044		$	11,044
Balance as of January 1, 2011	$	14,304		$	14,304
Other comprehensive (loss) income		1,477			1,477
Balance September 30, 2011	$	15,781		$	15,781

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11. ACQUISITIONS

Acquisition of American State Financial Corporation—On July 1, 2012, the Company completed the previously announced acquisition of American State Financial Corporation and its wholly owned subsidiary American State Bank (collectively referred to as “ASB”). ASB operated thirty-seven (37) full service banking offices in eighteen (18) counties across West Texas.

As of June 30, 2012, ASB, on a consolidated basis, reported total assets of $3.16 billion, total loans of $1.24 billion and total deposits of $2.51 billion. Under the terms of the merger agreement, the Company issued 8,524,835 shares of Company common stock plus $178.5 million in cash for all outstanding shares of American State Financial Corporation capital stock, for total merger consideration of $536.8 million and an initial premium of $240.4 million.

The acquisition was accounted for under the acquisition method of accounting. Under this method of accounting, the identifiable assets acquired and assumed liabilities were recorded at their estimated fair value as of the date of the acquisition. Accordingly, the results of operations of the acquired company have been included in the Company’s results of operations since the date of acquisition.

FAIR VALUE: The measurement period for the Company to determine the fair values of acquired identifiable assets and assumed liabilities will end at the earlier of (i) twelve months from the date of the acquisition or (ii) as soon as the Company receives the information it was seeking about facts and circumstances that existed as of the acquisition date or learns that more information is not obtainable. The Company is currently in the process of obtaining fair values for certain acquired assets and assumed liabilities and therefore the following estimates are preliminary.

	As of July 1, 2012
	(In thousands)
Cash and due from banks	$	98,720
Federal funds sold		202,810
Total cash and cash equivalents		301,530
Securities available for sale		524,959
Securities held to maturity		994,873
Loans held for sale		13,770
Loans held for investment		1,133,867
Bank premises and equipment		36,502
Other real estate owned		1,232
Goodwill		266,679
Core deposit intangibles		12,393
Federal Home Loan Bank stock		2,355
Other assets		91,242
Total assets acquired	$	3,379,402
Deposits		2,495,652
Other borrowings		318,692
Other liabilities		28,252
Total liabilities assumed		2,842,596
Common stock and capital surplus		536,806
Total liabilities assumed and shareholders’ equity	$	3,379,402

The Company recognized goodwill of $266.7 million which is calculated as the excess of both the consideration exchanged and liabilities assumed as compared to the fair value of identifiable assets acquired. Goodwill resulted from a combination of expected operational synergies, an enhanced branching network, and cross-selling opportunities. Goodwill is not expected to be deductible for tax purposes while the core deposit intangible is expected to be deductible over 10 years.

MERGER RELATED EXPENSES AND PRO FORMA INFORMATION: For the three and nine months ended September 30, 2012, the Company incurred $5.1 million and $5.4 million of pre-tax merger related expenses related to the ASB acquisition, respectively and estimates total merger related expenses will range from $5.4 to $6.0 million, pre-tax. The merger expenses are reflected on the Company’s income statement for the applicable periods and are reported primarily in the categories of salaries and benefits, data processing and professional fees.

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Operations of ASB have been included in the consolidated financial statements since July 1, 2012. The Company does not consider ASB a separate reporting segment and does not track the amount of revenue and net income attributable to ASB since acquisition. As such, it is impracticable to determine such amounts for the three and nine months ended September 30, 2012.

The following pro forma information presents the results of operations for the three and nine months ended September 30, 2012 and 2011, as if the ASB acquisition had occurred on January 1, 2011. The previously completed acquisitions of Texas Bankers, Inc. and The Bank Arlington are not deemed material in the aggregate and are therefore excluded from the pro forma information in the table below.

	Three Months Ended				Nine Months Ended
	September 30				September 30
	2012		2011		2012		2011
	(Dollars in thousands, except per share data)
Net interest income	$	106,893	$	113,858	$	336,249	$	337,096
Net income	$	49,479	$	48,081	$	163,333	$	149,425
Basic earnings per share	$	0.88	$	0.87	$	2.78	$	2.70
Diluted earnings per share	$	0.88	$	0.87	$	2.77	$	2.69

The above pro forma results are presented for illustrative purposes and are not intended to represent or be indicative of the actual results of operations of the merged companies that would have been achieved had the acquisition occurred at January 1, 2011, nor are they intended to represent or be indicative of future results of operations. These pro forma results require significant estimates and judgments particularly as it relates to accretion of income associated with acquired loans. Pro forma adjustments principally included:

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

• Reversing depreciation and amortization expense recorded by ASB and reporting depreciation and amortization based on estimated fair values and remaining lives of acquired premises, equipment, and leasehold improvements.

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

• Reporting acquisition-related charges and professional fees related to the acquisition as if they were incurred in 2011.

ACQUIRED LOANS AND PURCHASE CREDIT IMPAIRED LOANS: Acquired loans were preliminarily recorded at fair value based on a discounted cash flow valuation methodology that considers, among other things, projected default rates, loss given defaults and recovery rates. No allowance for credit losses was carried over from ASB.

The Company has identified certain loans which have experienced credit deterioration since origination (“purchased credit impaired loans” or “PCI loans”). PCI loan identification considers the following factors: payment history and past due status, debt service coverage, loan grading, collateral values and other factors that may indicate deterioration of credit quality since origination. Accretion of purchased discounts on PCI loans will be based on estimated future cash flows, regardless of contractual maturities. Accretion of purchased discounts on non-PCI loans will be recognized on a level-yield basis based on contractual maturity of individual loans per ASC Topic 310-30. See Note 4—Loans.

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The following table discloses the preliminary fair value and contractual value of loans acquired as of July 1, 2012:

	Purchased Credit Impaired Loans		Non-PCI Loans		Total Acquired Loans
	(Dollars in thousands)
Commercial and industrial	$	3,568	$	221,341	$	224,909
Real estate
Construction and land development		1,326		112,011		113,337
1-4 family residential		155		126,954		127,109
Home equity		—		24,851		24,851
Commercial mortgage		22,454		460,378		482,832
Agriculture real estate		—		53,979		53,979
Multi-family residential		—		48,423		48,423
Agriculture		78		—		78
Consumer		—		72,119		72,119
Other		—		—		—
Total fair value	$	27,581	$	1,120,056	$	1,147,637
Contractual principal balance	$	54,403	$	1,195,741	$	1,250,144

The following presents additional information on purchased credit impaired loans (dollars in thousands):

Contractually required principal and interest	$	60,167
Non-accretable difference		(24,429	)
Cash flows expected to be collected		35,738
Accretable difference		(8,157	)
Fair value of purchased credit impaired loans	$	27,581

The process for identifying, valuing and determining pools (if any) of the loans that were (or may be) considered PCI loans as of the acquisition date remains on-going. Income recognition on PCI loans is subject to the Company’s ability to reasonably estimate both the timing and amount of future cash flows. PCI loans for which the Company is accruing interest income are not considered non-performing or impaired. The non-accretable difference represents contractual principal and interest the Company does not expect to collect.

Acquisition of The Bank Arlington—On April 1, 2012, the Company completed the previously announced acquisition of The Bank Arlington. The Bank Arlington operated one banking office in Arlington, Texas, in the Dallas/Fort Worth CMSA. The Company acquired The Bank Arlington to increase its market share in the Dallas/Fort Worth area. The acquisition is not considered significant to the Company’s financial statements and therefore pro forma financial data and related disclosures are not included. The Company incurred approximately $163,000 in expense related to this acquisition which is primarily recorded in legal and professional fees and data processing.

As of March 31, 2012, The Bank Arlington reported total assets of $37.3 million, total loans of $22.8 million and total deposits of $33.2 million. Under the terms of the agreement, the Company issued 135,347 shares of Company common stock for all outstanding shares of The Bank Arlington capital stock, which resulted in an initial premium of $2.8 million.

Acquisition of Texas Bankers, Inc.—On January 1, 2012, the Company completed the previously announced acquisition of Texas Bankers, Inc. and its wholly-owned subsidiary, Bank of Texas, Austin, Texas. The three (3) Bank of Texas banking offices in the Austin, Texas CMSA consisted of a location in Rollingwood, which was consolidated with the Company’s Westlake location and remains in Bank of Texas’ Rollingwood banking office; one banking center in downtown Austin, which was consolidated into the Company’s downtown Austin location; and another banking center in Thorndale. The Company acquired Texas Bankers, Inc. to increase is its market share in the Central Texas area. The acquisition is not considered significant to the Company’s financial statements and therefore pro forma financial data and related disclosures are not included. The Company incurred approximately $352,000 in expense related to this acquisition which is primarily recorded in legal and professional fees and data processing.

Texas Bankers, Inc. on a consolidated basis, reported total assets of $77.0 million, total loans of $27.6 million and total deposits of $70.4 million as of December 31, 2011. Under the terms of the agreement, the Company issued 314,953 shares of Company common stock for all outstanding shares of Texas Bankers capital stock, which resulted in an initial premium of $5.2 million.

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12. SUBSEQUENT EVENTS

Acquisition of Community National Bank—On October 1, 2012, the Company completed the previously announced acquisition of Community National Bank, Bellaire, Texas. Community National Bank operated one (1) banking office in Bellaire, Texas, in the Houston Metropolitan Area. The acquisition is not considered significant to the Company’s financial statements and therefore pro forma financial data is not included. The Company incurred approximately $326,000 in expense related to this acquisition which is primarily recorded in legal and professional fees and data processing.

As of September 30, 2012, Community National Bank reported total assets of $183.0 million, total loans of $68.0 million and total deposits of $164.6 million. Under the terms of the acquisition agreement, the Company issued 372,282 shares of Company common stock plus $11.4 million in cash for all outstanding shares of Community National Bank capital stock which resulted in a premium of $10.6 million.

Pending Acquisition of East Texas Financial Services, Inc.—On December 9, 2011, the Company entered into a definitive agreement to acquire East Texas Financial Services, Inc. (OTC BB: FFBT) and its wholly-owned subsidiary, First Federal Bank Texas (“Firstbank”). Firstbank operates four banking offices in the Tyler MSA, including three locations in Tyler, Texas and one location in Gilmer, Texas.

As of September 30, 2012, Firstbank reported total assets of $191.1 million, total loans of $139.2 million and total deposits of $116.0 million. Under the terms of the definitive agreement, the Company will issue up to 531,000 shares of Company common stock for all outstanding shares of East Texas Financial Services capital stock, subject to certain conditions and potential adjustments. Pending the satisfaction of closing conditions, the closing is expected to occur in early 2013.

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

Special Cautionary Notice Regarding Forward-Looking Statements

Statements and financial discussion and analysis contained in this quarterly report on Form 10-Q that are not historical facts are forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements are based on assumptions and involve a number of risks and uncertainties, many of which are beyond the Company’s control. Many possible events or factors could affect the future financial results and performance of the Company and could cause such results or performance to differ materially from those expressed in the forward-looking statements. These possible events or factors include, without limitation:

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

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

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

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

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

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

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

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

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

• the failure of assumptions underlying the establishment of and provisions made to the allowance for credit losses;

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

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

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

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

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

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

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

• increases in FDIC deposit insurance assessments;

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

• other risks and uncertainties listed from time to time in the Company’s reports and documents filed with the Securities and Exchange Commission.

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

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Management’s Discussion and Analysis of Financial Condition and Results of Operations analyzes the major elements of the Company’s interim consolidated financial statements and accompanying notes. This section should be read in conjunction with the Company’s interim consolidated financial statements and accompanying notes included elsewhere in this report and with the consolidated financial statements and accompanying notes and other detailed information appearing in the Company’s Annual Report on Form 10-K for the year ended December 31, 2011.

OVERVIEW

The Company, a Texas corporation, was formed in 1983 as a vehicle to acquire the former Allied First Bank in Edna, Texas which was chartered in 1949 as The First National Bank of Edna. The Company is a registered financial holding company that derives substantially all of its revenues and income from the operation of its bank subsidiary, Prosperity Bank^® (“Prosperity Bank^®” or the “Bank”). The Bank provides a wide array of financial products and services to small and medium-sized businesses and consumers. As of September 30, 2012, the Bank operated two hundred thirteen (213) full-service banking locations; with ten (10) in the Bryan/College Station area, thirty-four (34) in the Central Texas area, thirty-five (35) in the Dallas/Fort Worth area, twenty-one (21) in East Texas, fifty-nine (59) in the Houston area, twenty (20) in the South Texas area including Corpus Christi and Victoria, and thirty-four (34) in the West Texas area. The Company’s headquarters are located at Prosperity Bank Plaza, 4295 San Felipe in Houston, Texas and its telephone number is (281) 269-7199. The Company’s website address is www.prosperitybanktx.com. Information contained on the Company’s website is not incorporated by reference into this quarterly report on Form 10-Q and is not part of this or any other report.

The Company generates the majority of its revenues from interest income on loans, service charges on customer accounts and income from investment in securities. The revenues are partially offset by interest expense paid on deposits and other borrowings and non-interest expenses such as administrative and occupancy expenses. Net interest income is the difference between interest income on earning assets such as loans and securities and interest expense on liabilities such as deposits and borrowings which are used to fund those assets. The level of interest rates and the volume and mix of earning assets and interest-bearing liabilities impact net interest income and margin.

Three principal components of the Company’s growth strategy are internal growth, stringent cost control practices and strategic merger transactions. The Company focuses on continual internal growth. Each banking center is operated as a separate profit center, maintaining separate data with respect to its net interest income, efficiency ratio, deposit growth, loan growth and overall profitability. Banking center presidents and managers are accountable for performance in these areas and compensated accordingly. The Company also focuses on maintaining stringent cost control practices and policies. The Company has invested significantly in the infrastructure required to centralize many of its critical operations, such as data processing and loan application processing. Management believes that this centralized infrastructure can accommodate substantial additional growth while enabling the Company to minimize operational costs through certain economies of scale. The Company also intends to continue to seek expansion opportunities. On January 1, 2012, the Company completed the acquisition of Texas Bankers, Inc. which added three banking centers, of which two were consolidated with nearby existing banking centers. On April 1, 2012, the Company completed the acquisition of The Bank Arlington which added one banking center. On July 1, 2012, the Company completed the acquisition of American State Financial Corporation (“ASB”), which added 37 banking centers. On October 1, 2012, the Company completed the acquisition of Community National Bank which added one banking center. In addition, the Company has previously announced the pending acquisition of East Texas Financial Services, Inc.

Total assets were $13.71 billion at September 30, 2012 compared with $9.82 billion at December 31, 2011, an increase of $3.89 billion or 39.6%. Total loans were $5.08 billion at September 30, 2012 compared with $3.77 billion at December 31, 2011, an increase of $1.31 billion or 34.9%. Total deposits were $10.95 billion at September 30, 2012 compared with $8.06 billion December 31, 2011, an increase of $2.89 billion or 35.9%. Total shareholders’ equity was $2.04 billion at September 30, 2012 compared with $1.57 billion at December 31, 2011, an increase of $470.9 million or 30.0%. The increases were primarily due to the acquisition of ASB on July 1, 2012.

RECENT AND PENDING ACQUISTIONS

Acquisition of American State Financial Corporation—On July 1, 2012, the Company completed the previously announced acquisition of American State Financial Corporation and its wholly owned subsidiary American State Bank (collectively referred to as “ASB”). ASB operated thirty-seven (37) full service banking offices in eighteen (18) counties across West Texas.

As of June 30, 2012, ASB, on a consolidated basis, reported total assets of $3.16 billion, total loans of $1.24 billion and total deposits of $2.51 billion. Under the terms of the merger agreement, the Company issued 8,524,835 shares of Company common stock plus $178.5 million in cash for all outstanding shares of American State Financial Corporation capital stock, for total merger consideration of $536.8 million and an initial premium of $240.4 million.

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Acquisition of Community National Bank—On October 1, 2012, the Company completed the previously announced acquisition of Community National Bank, Bellaire, Texas. Community National Bank operated one (1) banking office in Bellaire, Texas, in the Houston Metropolitan Area. The acquisition is not considered significant to the Company’s financial statements and therefore pro forma financial data is not included. The Company incurred approximately $326,000 in expense related to this acquisition which is primarily recorded in legal and professional fees and data processing.

As of September 30, 2012, Community National Bank reported total assets of $183.0 million, total loans of $68.0 million and total deposits of $164.6 million. Under the terms of the acquisition agreement, the Company issued 372,282 shares of Company common stock plus $11.4 million in cash for all outstanding shares of Community National Bank capital stock which resulted in a premium of $10.6 million.

Pending Acquisition of East Texas Financial Services, Inc.—On December 9, 2011, the Company entered into a definitive agreement to acquire East Texas Financial Services, Inc. (OTC BB: FFBT) and its wholly-owned subsidiary, First Federal Bank Texas (“Firstbank”). Firstbank operates four banking offices in the Tyler MSA, including three locations in Tyler, Texas and one location in Gilmer, Texas.

As of September 30, 2012, Firstbank reported total assets of $191.1 million, total loans of $139.2 million and total deposits of $116.0 million. Under the terms of the definitive agreement, the Company will issue up to 531,000 shares of Company common stock for all outstanding shares of East Texas Financial Services capital stock, subject to certain conditions and potential adjustments. Pending the satisfaction of closing conditions, the closing is expected to occur in early 2013.

CRITICAL ACCOUNTING POLICIES

The Company’s accounting policies are integral to understanding the financial results reported. Accounting policies are described in detail in Note 1 to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2011. The Company believes that of its significant accounting policies, the following may involve a higher degree of judgment and complexity:

Allowance for Credit Losses—The allowance for credit losses is established through charges to earnings in the form of a provision for credit losses. Management has established an allowance for credit losses which it believes is adequate for estimated losses in the Company’s loan portfolio. Based on an evaluation of the loan portfolio, management presents a monthly review of the allowance for credit losses to the Bank’s Board of Directors, indicating any change in the allowance since the last review and any recommendations as to adjustments in the allowance. In making its evaluation, management considers factors such as historical loan loss experience, industry diversification of the Company’s commercial loan portfolio, the amount of nonperforming assets and related collateral, the volume, growth and composition of the Company’s loan portfolio, current economic conditions that may affect the borrower’s ability to pay and the value of collateral, the evaluation of the Company’s loan portfolio through its internal loan review process and other relevant factors. Portions of the allowance may be allocated for specific credits; however, the entire allowance is available for any credit that, in management’s judgment, should be charged off. Charge-offs occur when loans are deemed to be uncollectible. The allowance for credit losses includes allowance allocations calculated in accordance with FASB ASC Topic 310, “Receivables,” and allowance allocations determined in accordance with FASB ASC Topic 450, “Contingencies.”

Goodwill and Intangible Assets—Goodwill and intangible assets that have indefinite useful lives are subject to an impairment test at least annually, or more often, if events or circumstances indicate that it is more likely than not that the fair value of Prosperity Bank, the Company’s only reporting unit with assigned goodwill, is below the carrying value of its equity. Goodwill is tested for impairment using a two-step process that begins with an estimation of the fair value of the Company’s reporting unit compared with its carrying value. If the carrying amount exceeds the fair value of the reporting unit, a second test is completed comparing the implied fair value of the reporting unit’s goodwill to its carrying value to measure the amount of impairment. The Company estimated the fair value of its reporting unit through several valuation techniques that consider, among other things, the historical and current financial position and results of operations of the Company, general economic and market conditions and exit prices for recent market transactions. The Company had no intangible assets with indefinite useful lives at September 30, 2012. Other identifiable intangible assets that are subject to amortization are amortized on an accelerated basis over the years expected to be benefited, which the Company believes is between eight and ten years. These amortizable intangible assets are reviewed for impairment if circumstances indicate their value may not be recoverable based on a comparison of fair value to carrying value. Based on the Company’s annual goodwill impairment test as of September 30, 2012, management does not believe any of its goodwill is impaired as of September 30, 2012 because the fair value of the Company’s equity exceeded its carrying value. While the Company believes no impairment existed at September 30, 2012, under accounting standards applicable at that date, different conditions or assumptions, or changes in cash flows or profitability, if significantly negative or unfavorable, could have a material adverse effect on the outcome of the Company’s impairment evaluation and financial condition or future results of operations.

Stock-Based Compensation—The Company accounts for stock-based employee compensation plans using the fair value-based method of accounting in accordance with FASB ASC Topic 718, Stock Compensation. ASC 718 was effective for companies in 2006; however, the Company had been recognizing compensation expense since January 1, 2003. The Company’s results of operations reflect compensation expense for all employee stock-based compensation, including the unvested portion of stock options granted

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prior to 2003. ASC 718 requires that management make assumptions including stock price volatility and employee turnover that are utilized to measure compensation expense. The fair value of stock options granted is estimated at the date of grant using the Black-Scholes option-pricing model. This model requires the input of subjective assumptions.

Other-Than-Temporarily Impaired Securities—The Company’s available for sale securities portfolio is reported at fair value. 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 market value is below amortized cost, additional analysis is performed to determine whether an impairment exists. Available for sale and held to maturity securities are analyzed quarterly for possible other-than-temporary impairment. The analysis considers (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, (iii) whether the market decline was affected by macroeconomic conditions, and (iv) whether the entity has the intent to sell the debt security or more likely than not will be required to sell the debt security before its anticipated recovery. 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.

RESULTS OF OPERATIONS

Net income available to common shareholders was $46.2 million ($0.82 per common share on a diluted basis) for the quarter ended September 30, 2012 compared with $36.4 million ($0.77 per common share on a diluted basis) for the quarter ended September 30, 2011, an increase in net income of $9.8 million, or 27.0%. The increase is primarily due to the acquisition of ASB. The Company posted returns on average common equity of 9.10% and 9.51%, returns on average assets of 1.32% and 1.52% and efficiency ratios of 46.07% and 42.38% for the quarters ended September 30, 2012 and 2011, respectively. The efficiency ratio is calculated by dividing total noninterest expense (excluding credit loss provisions) by net interest income plus noninterest income (excluding net gains and losses on the sale of assets). Additionally, taxes are not part of this calculation.

For the nine months ended September 30, 2012, net income available to common shareholders was $119.6 million ($2.37 per common share on a diluted basis) compared with $105.3 million ($2.24 per common share on a diluted basis) for the same period in 2011, an increase in net income of $14.3 million or 13.6%. The increase is primarily due to the acquisition of ASB. The Company posted returns on average common equity of 9.08% and 9.37%, returns on average assets of 1.35% and 1.46% and efficiency ratios of 43.69% and 43.41% for the nine months ended September 30, 2012 and 2011, respectively.

Net Interest Income

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

Net interest income was $106.9 million for the quarter ended September 30, 2012 compared with $82.5 million for the quarter ended September 30, 2011, an increase of $24.4 million, or 29.5%. Included in net interest income for the quarter ended September 30, 2012 is loan discount accretion of $11.2 million related to loans acquired in the 2012 acquisitions. Net interest income increased primarily as a result of an increase in average net interest-earning assets. Interest-earning assets increased to $12.33 billion for the quarter ended September 30, 2012 compared with $8.24 billion for the quarter ended September 30, 2011, an increase of $4.09 billion, or 49.7%. Additionally, the average yield on earning assets decreased 69 basis points from 4.49% for the quarter ended September 30, 2011 compared with 3.80% for the quarter ended September 30, 2012 while the average rate paid on interest-bearing liabilities decreased 22 basis points from 0.69% for the quarter ended September 30, 2011 compared with 0.47% for the quarter ended September 30, 2012. Average interest-bearing liabilities increased $2.99 billion or 48.7% for the same periods. The increases in volumes were due to the acquisition of ASB.

The net interest margin on a tax equivalent basis decreased 50 basis points to 3.52% for the quarter ended September 30, 2012 compared with 4.02% for the quarter ended September 30, 2011. The decrease in the net interest margin primarily resulted from the decrease in the overall yield on interest-earning assets not being matched by a corresponding decrease in the average cost of funds. The average cost of funds was 0.36% for the three months ended September 30, 2012.

Net interest income increased $25.8 million, or 10.5%, to $272.4 million for the nine months ended September 30, 2012 compared with $246.6 million for the same period in 2011. Included in net interest income for the nine months ended September 30, 2012 is loan discount accretion of $11.9 million related to loans acquired in the 2012 acquisitions. The increase in net interest income was mainly attributable to higher average net interest-earning assets for the same periods. The yield on average interest-earning assets decreased at a faster pace than the rates paid on average interest-bearing liabilities. The average yield on earning assets decreased 67 basis points from 4.57% for the nine months ended September 30, 2011 compared with 3.90% for the nine months ended September 30, 2012, while the average rate paid on interest-bearing liabilities decreased 25 basis points from 0.76% for the nine months ended September 30, 2011 compared with 0.51% for the same period in 2012. The net interest margin on a tax equivalent basis for the nine months ended September 30, 2012 decreased 47 basis points to 3.56% compared with 4.03% for the same period in 2011.

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The following tables set forth, for each category of interest-earning assets and interest-bearing liabilities, the average amounts outstanding, the interest earned or paid on such amounts, and the average rate earned or paid for the quarters ended September 30, 2012 and 2011 and the nine months ended September 30, 2012 and 2011. The tables also set forth the average rate paid on total interest-bearing liabilities, and the net interest margin on average total interest-earning assets for the same periods. Except as indicated in the footnotes, no tax-equivalent adjustments were made and all average balances are daily average balances. Any nonaccruing loans have been included in the table as loans carrying a zero yield.

	Three Months Ended September 30,
	2012								2011
	Average Outstanding Balance			Interest Earned/ Paid		Average Yield/ Rate (4)			Average Outstanding Balance			Interest Earned/ Paid		Average Yield/ Rate (4)
	(Dollars in thousands)
Assets
Interest-earning assets:
Loans	$	5,169,101		$	80,587		6.20	%	$	3,694,039		$	54,471		5.85	%
Securities (1)		7,106,871			37,025		2.08			4,524,213			38,714		3.42
Federal funds sold and other temporary investments		53,111			21		0.16			18,636			4		0.09
Total interest-earning assets		12,329,083			117,633		3.80	%		8,236,888			93,189		4.49	%
Less allowance for credit losses		(53,944	)							(52,208	)
Total interest-earning assets, net of allowance		12,275,139								8,184,680
Noninterest-earning assets		1,730,120								1,375,394
Total assets	$	14,005,259							$	9,560,074
Liabilities and shareholders’ equity
Interest-bearing liabilities:
Interest-bearing demand deposits	$	2,181,928		$	2,273		0.41	%	$	1,319,800		$	1,667		0.50	%
Savings and money market accounts		3,516,601			2,987		0.34			2,369,745			2,702		0.45
Certificates of deposit		2,387,279			4,135		0.69			2,134,082			5,348		0.99
Junior subordinated debentures		85,055			651		3.04			85,055			607		2.83
Securities sold under repurchase agreements		438,410			315		0.29			90,821			127		0.55
Federal funds purchased and other borrowings		512,739			379		0.29			135,336			200		0.59
Total interest-bearing liabilities		9,122,012			10,740		0.47	%		6,134,839			10,651		0.69	%
Noninterest-bearing liabilities:
Noninterest-bearing demand deposits		2,760,405								1,828,957
Other liabilities		92,873								66,560
Total liabilities		11,975,290								8,030,356
Shareholders’ equity		2,029,969								1,529,718
Total liabilities and shareholders’ equity	$	14,005,259							$	9,560,074
Net interest rate spread							3.33	%							3.80	%
Net interest income and margin (2)				$	106,893		3.45	%				$	82,538		3.98	%
Net interest income and margin (tax-equivalent basis) (3)				$	109,031		3.52	%				$	83,440		4.02	%

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

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

(3) In order to make pretax income and resultant yields on tax-exempt investments and loans comparable to those on taxable investments and loans, a tax-equivalent adjustment has been computed using a federal income tax rate of 35%.

(4) Annualized. Average yield and average rate are calculated on an actual/365 or 366 day basis except for the average yield on securities which is calculated on a 30/360 day basis.

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	Nine Months Ended September 30,
	2012								2011
	Average Outstanding Balance			Interest Earned/ Paid		Average Yield/ Rate (4)			Average Outstanding Balance			Interest Earned/ Paid		Average Yield/ Rate (4)
	(Dollars in thousands)
Assets
Interest-earning assets:
Loans	$	4,303,984		$	188,597		5.85	%	$	3,614,590		$	160,374		5.93	%
Securities (1)		5,983,102			113,418		2.53			4,635,880			121,861		3.50
Federal funds sold and other temporary investments		66,771			108		0.22			15,031			15		0.13
Total interest-earning assets		10,353,857			302,123		3.90	%		8,265,501			282,250		4.57	%
Less allowance for credit losses		(52,104	)							(51,924	)
Total interest-earning assets, net of allowance		10,301,753								8,213,577
Noninterest-earning assets		1,498,332								1,388,905
Total assets	$	11,800,085							$	9,602,482
Liabilities and shareholders’ equity
Interest-bearing liabilities:
Interest-bearing demand deposits	$	1,861,954		$	6,425		0.46	%	$	1,403,477		$	5,966		0.57	%
Savings and money market accounts		3,031,269			8,020		0.35			2,377,423			9,386		0.53
Certificates of deposit		2,080,606			11,824		0.76			2,162,112			16,941		1.05
Junior subordinated debentures		85,055			1,962		3.08			87,058			2,352		3.61
Securities sold under repurchase agreements		197,775			411		0.28			70,425			306		0.58
Federal funds purchased and other borrowings		465,505			1,076		0.31			181,656			718		0.53
Total interest-bearing liabilities		7,722,164			29,718		0.51	%		6,282,151			35,669		0.76	%
Noninterest-bearing liabilities:
Noninterest-bearing demand deposits		2,267,876								1,758,182
Other liabilities		53,320								62,765
Total liabilities		10,043,360								8,103,098
Shareholders’ equity		1,756,725								1,499,384
Total liabilities and shareholders’ equity	$	11,800,085							$	9,602,482
Net interest rate spread							3.41	%							3.81	%
Net interest income and margin (2)				$	272,405		3.51	%				$	246,581		3.99	%
Net interest income and margin (tax-equivalent basis) (3)				$	276,271		3.56	%				$	249,345		4.03	%

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

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

(3) In order to make pretax income and resultant yields on tax-exempt investments and loans comparable to those on taxable investments and loans, a tax-equivalent adjustment has been computed using a federal income tax rate of 35%.

(4) Annualized. Average yield and average rate are calculated on an actual/365 or 366 day basis except for the average yield on securities which is calculated on a 30/360 day basis.

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The following tables present the dollar amount of changes in interest income and interest expense for the major components of interest-earning assets and interest-bearing liabilities and distinguish between the increase (decrease) related to outstanding balances and the volatility of interest rates. For purposes of these tables, changes attributable to both rate and volume which cannot be segregated have been allocated to rate.

	Three Months Ended September 30,
	2012 vs. 2011
	Increase (Decrease) Due to
	Volume		Rate			Total
	(Dollars in thousands)
Interest-earning assets:
Loans	$	21,751	$	4,365		$	26,116
Securities		22,100		(23,789	)		(1,689	)
Federal funds sold and other temporary investments		7		10			17
Total increase (decrease) in interest income		43,858		(19,414	)		24,444
Interest-bearing liabilities:
Interest-bearing demand deposits		1,089		(483	)		606
Savings and money market accounts		1,308		(1,023	)		285
Certificates of deposit		635		(1,848	)		(1,213	)
Junior subordinated debentures		—		44			44
Securities sold under repurchase agreements		486		(298	)		188
Federal funds purchased and other borrowings		558		(379	)		179
Total increase (decrease) in interest expense		4,076		(3,987	)		89
Increase (decrease) in net interest income	$	39,782	$	(15,427	)	$	24,355

	Nine Months Ended September 30,
	2012 vs. 2011
	Increase (Decrease) Due to
	Volume			Rate			Total
	(Dollars in thousands)
Interest-earning assets:
Loans	$	30,587		$	(2,364	)	$	28,223
Securities		35,414			(43,857	)		(8,443	)
Federal funds sold and other temporary investments		52			41			93
Total increase (decrease) in interest income		66,053			(46,180	)		19,873
Interest-bearing liabilities:
Interest-bearing demand deposits		1,949			(1,490	)		459
Savings and money market accounts		2,581			(3,947	)		(1,366	)
Certificates of deposit		(639	)		(4,478	)		(5,117	)
Junior subordinated debentures		(54	)		(336	)		(390	)
Securities sold under repurchase agreements		553			(448	)		105
Federal funds purchased and other borrowings		1,122			(764	)		358
Total decrease in interest expense		5,512			(11,463	)		(5,951	)
Increase (decrease) in net interest income	$	60,541		$	(34,717	)	$	25,824

Provision for Credit Losses

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

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

The Company made a $1.8 million provision for credit losses for the quarter ended September 30, 2012 and a $950,000 provision for the quarter ended September 30, 2011. The Company made a $2.6 million provision for credit losses for the nine months ended September 30, 2012 and a $4.1 million provision for the nine months ended September 30, 2011. The ratio of the allowance for credit losses to end of period nonperforming loans was 980.3% at September 30, 2012 compared with 1,442.0% at December 31, 2011. The ratio of allowance for credit losses to total loans was 1.00% at September 30, 2012 compared with 1.37% at December 31, 2011. For the quarter ended September 30, 2012, net charge-offs were $1.3 million compared with net charge-offs of $368,000 for the quarter ended September 30, 2011. Net charge-offs were $3.2 million for the nine months ended September 30, 2012 compared with $3.1 million for the nine months ended September 30, 2011.

Noninterest Income

The Company’s primary sources of recurring noninterest income are non-sufficient funds fees (NSF fees), debit and ATM card income and service charges on deposit accounts. Noninterest income does not include loan origination fees on loans held for investment which are recognized over the life of the related loan as an adjustment to yield using the interest method. However mortgage origination fees on loans held for sale originated in the mortgage lending departments assumed in the ASB acquisition are included in noninterest income. Noninterest income totaled $23.8 million for the three months ended September 30, 2012 compared with $14.6 million for the same period in 2011, an increase of $9.2 million, or 63.4%. Noninterest income increased $9.5 million, or 22.5%, to $51.4 million for the nine months ended September 30, 2012 compared with $42.0 million for the same period in 2011. The increases during both periods were primarily due to increases in NSF fees, debit card and ATM card income and service charges on deposit accounts resulting from the acquisition of ASB.

Additionally, noninterest income for the three and nine months ended September 30, 2012 includes income generated from several lines of business assumed in the ASB acquisition, including (i) trust operations reflected under trust income (ii) mortgage lending operations which originates residential mortgages and sells into the secondary market, reflected under held for sale mortgage origination fees and; (iii) Independent Sales Organization (“ISO”) sponsorship operations, in which the Bank sponsors ISO’s (non-bank entities which own ATM’s throughout the United States) into various payment networks such as VISA and Mastercard, reflected under other noninterest income.

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

	Three Months Ended September 30,					Nine Months Ended September 30,
	2012			2011		2012			2011
	(Dollars in thousands)
Non-sufficient funds (NSF)	$	9,265		$	6,249	$	19,821		$	18,582
Debit card and ATM card income		6,246			3,941		14,374			11,202
Service charges on deposit accounts		3,362			2,472		8,235			7,466
Banking related service fees		818			565		1,923			1,589
Bank owned life insurance (BOLI)		736			355		1,430			1,035
Trust income		831			—		831			—
Held for sale mortgage origination fees		1,350			—		1,350			—
Net (loss) gain on sale of assets		(50	)		17		13			377
Net (loss) gain on sale of other real estate		(597	)		95		(344	)		(431	)
Net loss on sale of securities		—			—		—			(581	)
Other noninterest income		1,867			887		3,796			2,739
Total noninterest income	$	23,828		$	14,581	$	51,429		$	41,978

Noninterest Expense

Noninterest expense totaled $60.2 million for the quarter ended September 30, 2012 compared with $41.2 million for the quarter ended September 30, 2011, an increase of $19.1 million, or 46.4%. Noninterest expense totaled $141.5 million and $125.4 million for the nine months ended September 30, 2012 and September 30, 2011, respectively. The increases were primarily due to increases in salaries and employee benefits and general administrative expenses related to the acquisition of ASB. The Company also incurred one-time merger expenses of $5.1 million and $5.4 million, for the respective periods, which are included in total noninterest expenses primarily in the categories of salaries and employee benefits and professional fees.

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

	Three Months Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
	(Dollars in thousands)
Salaries and employee benefits (1)	$	36,701	$	23,601	$	83,525	$	70,799
Non-staff expenses:
Occupancy and equipment		4,614		3,784		11,663		10,979
Depreciation		2,369		2,041		6,432		6,099
Debit card, data processing and software amortization		2,901		1,954		6,339		5,406
Communications		2,226		1,749		5,777		5,188
Printing and supplies		601		467		1,546		1,371
Professional fees		1,686		674		3,231		1,918
Regulatory assessments and FDIC insurance		2,107		1,488		5,314		7,383
Ad valorem and franchise taxes		1,290		1,005		3,333		3,016
Core deposit intangibles amortization		2,007		1,924		5,297		5,901
Other real estate		271		235		1,345		821
Other		3,469		2,229		7,687		6,479
Total non-staff expenses		23,541		17,550		57,964		54,561
Total noninterest expense	$	60,242	$	41,151	$	141,489	$	125,360

(1) Includes stock-based compensation expense of $1.1 million and $961,000 for the three months ended September 30, 2012 and 2011, respectively, and $3.2 million and $2.6 million for the nine months ended September 30, 2012 and 2011, respectively.

Salaries and employee benefit expenses were $36.7 million for the quarter ended September 30, 2012 compared with $23.6 million for the quarter ended September 30, 2011, an increase of $13.1 million, or 55.5%. For the nine months ended September 30, 2012, salaries and employee benefit expenses were $83.5 million, an increase of $12.7 million or 18.0% compared with $70.8 million for the nine months ended September 30, 2011. The increase during both periods was principally due to the acquisition of ASB. The number of full-time equivalent (FTE) associates employed by the Company was 2,260 at September 30, 2012 and 1,678 at September 30, 2011.

Non-staff expenses increased $6.0 million, or 34.1%, to $23.5 million for the quarter ended September 30, 2012 compared with $17.6 million during the same period in 2011. Non-staff expenses increased $3.4 million, or 6.2%, to $58.0 million for the nine months ended September 30, 2012 compared to $54.6 million during the same period in 2011. The increases for both periods were primarily due to the ASB acquisition and also include expenses related to the new lines of business acquired in the ASB acquisition described under “Noninterest Income” above.

Income Taxes

Income tax expense increased $3.9 million, or 20.7%, to $22.5 million for the quarter ended September 30, 2012 compared with $18.6 million for the same period in 2011. For the nine months ended September 30, 2012, income tax expense totaled $60.2 million, an increase of $6.4 million or 11.8% compared with $53.8 million for the same period in 2011. Both increases were primarily attributable to higher pretax net earnings for the quarter and nine months ended September 30, 2012 when compared to the same periods in 2011. The effective tax rates for the three months ended September 30, 2012 and 2011 were 32.8% and 33.9%, respectively and the effective tax rates for the nine months ended September 30, 2012 and 2011 were 33.5% and 33.8%, respectively.

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FINANCIAL CONDITION

Loan Portfolio

Total loans were $5.08 billion at September 30, 2012, an increase of $1.31 billion or 34.9% compared with $3.77 billion at December 31, 2011. Loan growth was impacted by the acquisition of Texas Bankers, Inc., The Bank Arlington and ASB. Loans attributed to these acquisitions totaled $24.2 million, $21.8 million and $1.13 billion at September 30, 2012, respectively.

The following table summarizes the loan portfolio of the Company by type of loan as of September 30, 2012 and December 31, 2011:

	September 30, 2012		December 31, 2011
	(Dollars in thousands)
Commercial and industrial	$	756,342	$	406,433
Real estate:
Construction and land development		496,417		482,140
1-4 family residential (1)		1,213,873		1,007,266
Home equity		183,844		146,999
Commercial mortgage		1,837,224		1,351,986
Agriculture real estate		205,333		136,008
Multi-family residential		138,888		89,240
Agriculture		98,801		34,226
Consumer (net of unearned discount)		112,476		78,187
Other		35,905		33,421
Total	$	5,079,103	$	3,765,906

(1) Includes $4.3 million in loans held for sale carried at the lower of cost or market.

Nonperforming Assets

The Company had $14.1 million in nonperforming assets at September 30, 2012 and $12.1 million in nonperforming assets at December 31, 2011, an increase of $2.0 million or 16.6%. The ratio of nonperforming assets to loans and other real estate was 0.28% at September 30, 2012 compared with 0.32% at December 31, 2011.

The Company generally places a loan on nonaccrual status and ceases accruing interest when the payment of principal or interest is delinquent for 90 days, or earlier in some cases if the collection of the principal is deemed unlikely, unless the loan is in the process of collection and the underlying collateral fully supports the carrying value of the loan. The Company generally charges off all loans before attaining nonaccrual status.

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

	September 30, 2012			December 31, 2011
	(Dollars in thousands)
Nonaccrual loans	$	5,063		$	3,578
Accruing loans 90 or more days past due		132			—
Total nonperforming loans		5,195			3,578
Repossessed assets		10			146
Other real estate		8,846			8,328
Total nonperforming assets	$	14,051		$	12,052
Nonperforming assets to total loans and other real estate		0.28	%		0.32	%
Nonperforming assets to average earning assets		0.14	%		0.15	%

Allowance for Credit Losses

Management actively monitors the Company’s asset quality and provides specific loss allowances when necessary. Loans are charged-off against the allowance for credit losses when appropriate. Although management believes it uses the best information available to make determinations with respect to the allowance for credit losses, future adjustments may be necessary if economic conditions differ from the assumptions used in making the initial determinations. As of September 30, 2012, the allowance for credit losses amounted to $50.9 million, or 1.00% of total loans, compared with $51.6 million, or 1.37% of total loans, at December 31, 2011.

44

Set forth below is an analysis of the allowance for credit losses for the nine months ended September 30, 2012 and the year ended December 31, 2011:

	As of and for the Nine Months Ended September 30,  2012			As of and for the Year Ended December 31, 2011
	(Dollars in thousands)
Average loans outstanding	$	4,303,984		$	3,648,701
Gross loans outstanding at end of period	$	5,079,103		$	3,765,906
Allowance for credit losses at beginning of period	$	51,594		$	51,584
Provision for credit losses		2,550			5,200
Charge-offs:
Commercial and industrial		(376	)		(1,694	)
Real estate and agriculture		(3,123	)		(3,927	)
Consumer		(2,102	)		(1,229	)
Recoveries:
Commercial and industrial		722			481
Real estate and agriculture		262			472
Consumer		1,400			707
Net charge-offs		(3,217	)		(5,190	)
Allowance for credit losses at end of period	$	50,927		$	51,594
Ratio of allowance to end of period loans		1.00	%		1.37	%
Ratio of net charge-offs to average loans (annualized)		0.10	%		0.14	%
Ratio of allowance to end of period nonperforming loans		980.3	%		1,442.0	%

Securities

The carrying cost of securities totaled $6.80 billion at September 30, 2012 compared with $4.66 billion at December 31, 2011, an increase of $2.14 billion or 45.9%. The increase is due to securities acquired from ASB. At September 30, 2012, securities represented 49.6% of total assets compared with 47.4% of total assets at December 31, 2011.

The Company had no gain or loss on sale of securities for the three months ended September 30, 2012 or 2011 and had no gain or loss on sale of securities for the nine months ended September 30, 2012 compared with a net loss of $581,000 for the nine months ended September 30, 2011. The Company sold two non-agency CMO’s with a total book value of $3.2 million due to a downgrade of the CMO’s to less than investment grade in the second quarter of 2011. As of September 30, 2012, the Company had eight non-agency CMO’s remaining with a total book value of $2.7 million and total market value of $2.5 million.

The following table summarizes the amortized cost of securities as of the dates shown (available for sale securities are not adjusted for unrealized gains or losses):

	September 30, 2012		December 31, 2011
	(In thousands)
U.S. Treasury securities and obligations of U.S. government agencies	$	10,597	$	8,696
States and political subdivisions		409,608		74,974
Corporate debt securities		2,996		2,990
Collateralized mortgage obligations		161,129		282,565
Mortgage-backed securities		6,178,004		4,248,796
Qualified School Construction Bonds (QSCB)		12,900		12,900
Equity securities		7,288		7,288
Total amortized cost	$	6,782,522	$	4,638,209
Total fair value	$	7,022,538	$	4,815,304

45

Management evaluates securities for other-than-temporary impairment (“OTTI”) at least on a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. The investment securities portfolio is evaluated for OTTI by segregating the portfolio into two general segments and applying the appropriate OTTI model. Investment securities classified as available for sale or held to maturity are generally evaluated for OTTI under FASB ASC Topic 320, Investments- Debt and Equity Securities. Certain purchased beneficial interests, including non-agency mortgage-backed securities, asset-backed securities, and collateralized debt obligations, that had credit ratings at the time of purchase of below AA are evaluated using the model outlined in ASC Topic 325, Investments-Other. The Company currently does not own any securities that are accounted for under ASC Topic 325.

In determining OTTI under ASC Topic 320, management considers many factors, including: (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer, (3) whether the market decline was affected by macroeconomic conditions, and (4) whether the entity has the intent to sell the debt security or more likely than not will be required to sell the debt security before its anticipated recovery. The assessment of whether an other-than-temporary decline exists involves a high degree of subjectivity and judgment and is based on the information available to management at a point in time. If applicable, the second segment of the portfolio uses the OTTI guidance provided by ASC Topic 325 that is specific to purchased beneficial interests that, on the purchase date, were rated below AA. Under the ASC Topic 325 model, the Company compares the present value of the remaining cash flows as estimated at the preceding evaluation date to the current expected remaining cash flows. An OTTI is deemed to have occurred if there has been an adverse change in the remaining expected future cash flows.

When OTTI occurs under either model, the amount of the other-than-temporary-impairment recognized in earnings depends on whether an entity intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss. If an entity intends to sell or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the OTTI shall be recognized in earnings equal to the entire difference between the investment’s amortized cost basis and its fair value at the balance sheet date. If an entity does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis less any current-period loss, the OTTI shall be separated into the amount representing the credit loss and the amount related to all other factors. The amount of the total OTTI related to the credit loss is determined based on the present value of cash flows expected to be collected and is recognized in earnings. The amount of the total OTTI related to other factors shall be recognized in other comprehensive income, net of applicable taxes. The previous amortized cost basis less the OTTI recognized in earnings shall become the new amortized cost basis of the investment.

Management believes the Company does not intend to sell any debt securities or more likely than not will not be required to sell any debt securities before their anticipated recovery, at which time the Company will receive full value for the securities. Furthermore, management has the ability and intent to hold the securities classified as available for sale that were in a loss position as of September 30, 2012 for a period of time sufficient for an entire recovery of the cost basis of the securities. The unrealized losses are largely due to increases in market interest rates over the yields available at the time the underlying securities were purchased. The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline. Management does not believe any of the securities are impaired due to reasons of credit quality. Accordingly, as of September 30, 2012, management believes any impairment in the Company’s securities are temporary and no impairment loss has been realized in the Company’s consolidated statements of income.

46

The following tables present the amortized cost and fair value of securities classified as available for sale and held to maturity at September 30, 2012:

	September 30, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	35,262	$	1,937	$	(11	)	$	37,188
Collateralized mortgage obligations		651		—		(13	)		638
Mortgage-backed securities		188,699		14,618		(56	)		203,261
Corporate debt securities and other		8,784		516		—			9,300
Total	$	233,396	$	17,071	$	(80	)	$	250,387
Held to Maturity
U.S. Treasury securities and obligations of U.S. government agencies	$	10,597	$	213	$	—		$	10,810
States and political subdivisions (including QSCB)		387,246		9,355		(151	)		396,450
Corporate debt securities		1,500		53		—			1,553
Collateralized mortgage obligations		160,478		2,994		(215	)		163,257
Mortgage-backed securities		5,989,305		211,153		(377	)		6,200,081
Total	$	6,549,126	$	223,768	$	(743	)	$	6,772,151

Bank Premises and Equipment

Premises and equipment, net of accumulated depreciation, totaled $201.4 million and $159.7 million at September 30, 2012 and December 31, 2011, respectively, an increase of $41.8 million or 26.2%. The increase is primarily due to the addition of the ASB banking centers.

Deposits

Total deposits were $10.95 billion at September 30, 2012 compared with $8.06 billion at December 31, 2011, an increase of $2.89 billion or 35.9%. Deposit growth was impacted by the acquisition of Texas Bankers, Inc., The Bank Arlington and ASB. Deposits for these acquisitions totaled $69.8 million, $33.6 million and $2.52 billion at September 30, 2012, respectively. At September 30, 2012, noninterest-bearing deposits accounted for approximately 25.8% of total deposits compared with 24.5% of total deposits at December 31, 2011. Interest-bearing demand deposits totaled $8.13 billion or 74.2% of total deposits at September 30, 2012 compared with $6.09 billion or 75.5% of total deposits at December 31, 2011.

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

	Nine Months Ended September 30, 2012					Year Ended December 31, 2011
	Average Balance		Average Rate			Average Balance		Average Rate
	(Dollars in thousands)
Interest-bearing demand	$	1,861,954		0.46	%	$	1,393,501		0.53	%
Regular savings		785,883		0.23			472,983		0.32
Money market savings		2,245,386		0.40			1,948,752		0.53
Time deposits		2,080,606		0.76			2,135,858		1.02
Total interest-bearing deposits		6,973,829		0.50			5,951,094		0.69
Noninterest-bearing deposits		2,267,876		—			1,800,102		—
Total deposits	$	9,241,705		0.38	%	$	7,751,196		0.53	%

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Other Borrowings

The Company utilizes borrowings to supplement deposits to fund its lending and investment activities. Borrowings consist of funds from the Federal Home Loan Bank (“FHLB”) and correspondent banks. FHLB advances are considered short-term, overnight borrowings. At September 30, 2012, the Company had $100.0 million in FHLB advances compared with no FHLB advances at December 31, 2011. The highest outstanding balance of FHLB advances during the nine months ended September 30, 2012 was $1.01 billion compared with $474.0 million for the year ended December 31, 2011. The annualized average rate paid on FHLB advances for the quarter ended September 30, 2012 was 0.17%. At September 30, 2012, the Company had $12.0 million in FHLB long-term notes payable compared with $12.8 million at December 31, 2011. The weighted average interest rate paid on the FHLB notes payable at September 30, 2012 was 5.3%. The maturity dates on the FHLB notes payable range from the years 2013 to 2028 and have interest rates ranging from 4.1% to 6.1%. FHLB borrowings are available to the Company under a security and pledge agreement. At September 30, 2012, the Company had total funds of $2.92 billion available under this agreement, of which $112.0 million was outstanding.

At September 30, 2012, the Company had $443.9 million in securities sold under repurchase agreements compared with $54.9 million at December 31, 2011, an increase of $389.0 million or 708.7%. The weighted average rates paid on securities sold under repurchase agreements were 0.28% and 0.54% for the same periods, respectively. The increase is due to the acquisition of ASB. Of the $443.9 million in securities sold under repurchase agreements outstanding at September 30, 2012, $26.4 million were time deposits with maturities ranging from 2012 to 2014.

The following table presents the Company’s borrowings at September 30, 2012 and December 31, 2011:

	September 30, 2012		December 31, 2011
	(In thousands)
FHLB advances	$	100,000	$	—
FHLB long-term notes payable		12,017		12,790
Total other borrowings		112,017		12,790
Securities sold under repurchase agreements		443,856		54,883
Total	$	555,873	$	67,673

Junior Subordinated Debentures

At September 30, 2012 and December 31, 2011, the Company had outstanding $85.1 million in junior subordinated debentures issued to the Company’s unconsolidated subsidiary trusts.

A summary of pertinent information related to the Company’s seven issues of junior subordinated debentures outstanding at September 30, 2012 is set forth in the table below:

Description	Issuance Date		Trust Preferred Securities Outstanding		Interest Rate(1)	Junior Subordinated Debt Owed to Trusts		Maturity Date(2)
Prosperity Statutory Trust II		July 31, 2001	$	15,000,000	3 month LIBOR+ 3.58%, not to exceed 12.50%	$	15,464,000		July 31, 2031
Prosperity Statutory Trust III		Aug. 15, 2003		12,500,000	3 month LIBOR + 3.00%		12,887,000		Sept. 17, 2033
Prosperity Statutory Trust IV		Dec. 30, 2003		12,500,000	3 month LIBOR + 2.85%		12,887,000		Dec. 30, 2033
SNB Capital Trust IV(3)		Sept. 25, 2003		10,000,000	3 month LIBOR + 3.00%		10,310,000		Sept. 25, 2033
TXUI Statutory Trust II(4)		Dec. 19, 2003		5,000,000	3 month LIBOR + 2.85%		5,155,000		Dec. 19, 2033
TXUI Statutory Trust III(4)		Nov. 30, 2005		15,500,000	3 month LIBOR + 1.39%		15,980,000		Dec. 15, 2035
TXUI Statutory Trust IV(4)		Mar. 31, 2006		12,000,000	3 month LIBOR + 1.39%		12,372,000		June 30, 2036
						$	85,055,000

(1) The 3-month LIBOR in effect as of September 30, 2012 was 0.359%.

(2) All debentures are callable five years from issuance date.

(3) Assumed in connection with the SNB acquisition on April 1, 2006.

(4) Assumed in connection with the TXUI acquisition on January 31, 2007.

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Liquidity

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

As of September 30, 2012, the Company had outstanding $886.1 million in commitments to extend credit and $25.4 million in commitments associated with outstanding standby letters of credit. Since commitments associated with letters of credit and commitments to extend credit may expire unused, the total outstanding may not necessarily reflect the actual future cash funding requirements.

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

Asset liquidity is provided by cash and assets which are readily marketable or which will mature in the near future. As of September 30, 2012, the Company had cash and cash equivalents of $207.7 million compared with $213.4 million at December 31, 2011, a decrease of $5.7 million. The decrease was primarily due to an increase in deposits of $295.2 million, proceeds from the maturities and repayments of securities of $2.94 billion, net amortization of investments of $42.9 million, a net increase in securities sold under repurchase agreements of $37.7 million, proceeds from short-term borrowings of $100.0 million, cash acquired in acquisitions of $179.6 million and net earnings of $119.6 million partially offset by purchases of securities of $3.61 billion, dividends paid of $29.4 million and an increase in loans of $84.9 million.

Contractual Obligations

The following table summarizes the Company’s contractual obligations and other commitments to make future payments as of September 30, 2012 (other than deposit obligations). The payments do not include pre-payment options that may be available to the Company. The Company’s future cash payments associated with its contractual obligations pursuant to its junior subordinated debentures, FHLB borrowings and operating leases as of September 30, 2012 are summarized below. Payments for junior subordinated debentures include interest of $52.0 million that will be paid over the future periods. The future interest payments were calculated using the current rate in effect at September 30, 2012. The current principal balance of the junior subordinated debentures at September 30, 2012 was $85.1 million. Payments for FHLB borrowings include interest of $3.0 million that will be paid over the future periods. Payments related to leases are based on actual payments specified in underlying contracts.

	Payments due in:
	Remaining Fiscal 2012		Fiscal 2013-2014		Fiscal 2015-2016		Thereafter		Total
	(Dollars in thousands)
Junior subordinated debentures	$	1,222	$	4,888	$	4,888	$	126,017	$	137,015
Federal Home Loan Bank borrowings		100,282		3,258		3,456		8,001		114,997
Operating leases		1,324		8,547		4,013		759		14,643
Total	$	102,828	$	16,693	$	12,357	$	134,777	$	266,655

Off-Balance Sheet Items

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

The Company’s commitments associated with outstanding standby letters of credit and commitments to extend credit as of September 30, 2012 are summarized below. Since commitments associated with letters of credit and commitments to extend credit may expire unused, the amounts shown do not necessarily reflect the actual future cash funding requirements.

49

	Remaining Fiscal 2012		Fiscal 2013-2014		Fiscal 2015-2016		Thereafter		Total
	(Dollars in thousands)
Standby letters of credit	$	4,472	$	20,399	$	564	$	—	$	25,435
Commitments to extend credit		114,567		445,549		50,391		275,538		886,045
Total	$	119,039	$	465,948	$	50,955	$	275,538	$	911,480

Capital Resources

Total shareholders’ equity was $2.04 billion at September 30, 2012 compared with $1.57 billion at December 31, 2011, an increase of $470.9 million or 30.0%. The increase was due primarily to net earnings of $119.6 million and the issuance of common stock in connection with acquisitions and the exercise of stock options of $379.9 million, partially offset by dividends paid of $29.4 million for the nine months ended September 30, 2012.

Both the Board of Governors of the Federal Reserve System with respect to the Company, and the Federal Deposit Insurance Corporation (“FDIC”) with respect to the Bank, have established certain minimum risk-based capital standards that apply to bank holding companies and federally insured banks. The following table sets forth the Company’s total risk-based capital, Tier 1 risk-based capital, and Tier 1 to average assets (leverage) ratios as of September 30, 2012:

Consolidated Capital Ratios:
Total capital (to risk weighted assets)	15.26	%
Tier 1 capital (to risk weighted assets)	14.43	%
Tier 1 capital (to average assets)	6.92	%

As of September 30, 2012, the Bank’s risk-based capital ratios were above the levels required for the Bank to be designated as “well capitalized” by the FDIC. To be designated as “well capitalized”, the minimum ratio requirements for the Bank’s total risk-based capital, Tier 1 risk-based capital, and Tier 1 to average assets (leverage) capital ratios must be 10.0%, 6.0% and 5.0%, respectively. The following table sets forth the Bank’s total risk-based capital, Tier 1 risk-based capital, and Tier 1 to average assets (leverage) capital ratios as of September 30, 2012:

Capital Ratios (Bank Only):
Total capital (to risk weighted assets)	14.82	%
Tier 1 capital (to risk weighted assets)	13.99	%
Tier 1 capital (to average assets)	6.68	%

ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

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

The Company uses simulation analysis to examine the potential effects of market changes on net interest income and market value. The Company considers macroeconomic variables, Company strategy, liquidity and other factors as it quantifies market risk. See the Company’s Annual Report on Form 10-K, Item 7 “Management’s Discussion and Analysis of Financial Condition and Results of Operations-Interest Rate Sensitivity and Liquidity” which was filed on February 29, 2012 for further discussion.

ITEM 4. CONTROLS AND PROCEDURES

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

Changes in internal control over financial reporting. There were no changes in the Company’s internal control over financial reporting (as such term is defined in Rules 13a-15(f) and 15d-15(f) under the Exchange Act) during the quarter ended September 30, 2012 that have materially affected, or are reasonably likely to materially affect, the Company’s internal control over financial reporting.

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PART II—OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS

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

ITEM 1A. RISK FACTORS

There have been no material changes in the Company’s risk factors from those disclosed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2011.

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

a. Not applicable

b. Not applicable

c. Not applicable

ITEM 3. DEFAULTS UPON SENIOR SECURITIES

Not applicable

ITEM 4. MINE SAFETY DISCLOSURES

None.

ITEM 5. OTHER INFORMATION

Not applicable

ITEM 6. EXHIBITS

a. Exhibits:

Exhibit Number	Description of Exhibit
3.1	Amended and Restated Articles of Incorporation of Prosperity Bancshares, Inc. (incorporated herein by reference to Exhibit 3.1 to the Company’s Registration Statement on Form S-1 (Registration No. 333-63267) (the “Registration Statement”))
3.2	Articles of Amendment to Amended and Restated Articles of Incorporation of Prosperity Bancshares, Inc. (incorporated herein by reference to Exhibit 3.2 to the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2006)
3.3	Amended and Restated Bylaws of Prosperity Bancshares, Inc. (incorporated herein by reference to Exhibit 3.1 to the Company’s Current Report on Form 8-K filed on October 19, 2007)
4.1	Form of certificate representing shares of the Company’s common stock (incorporated by reference to Exhibit 4 to the Registration Statement)
31.1*	Certification of the Chief Executive Officer pursuant to Rule 13a-14(a) of the Securities Exchange Act of 1934, as amended
31.2*	Certification of the Chief Financial Officer pursuant to Rule 13a-14(a) of the Securities Exchange Act of 1934, as amended
32.1**	Certification of the Chief Executive Officer pursuant to 18 U.S.C. Section 1350, adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
32.2**	Certification of the Chief Financial Officer pursuant to 18 U.S.C. Section 1350, adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002
101*	Interactive Financial Data

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

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

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SIGNATURES

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

	PROSPERITY BANCSHARES, INC. ® (Registrant)
Date: 11/09/12	/s/ DAVID ZALMAN
	David Zalman Chairman and Chief Executive Officer
Date: 11/09/12	/s/ DAVID HOLLAWAY
	David Hollaway Chief Financial Officer

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EX-31.1

Exhibit 31.1

CERTIFICATION PURSUANT TO RULE 13a-14(a) OF THE SECURITIES EXCHANGE

ACT OF 1934, AS AMENDED

I, David Zalman, certify that:

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

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

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

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

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

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

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

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

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

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

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

Date: November 9, 2012

/S/ DAVID ZALMAN

David Zalman

Chairman and Chief Executive Officer

EX-31.2

Exhibit 31.2

CERTIFICATION PURSUANT TO RULE 13a-14(a) OF THE SECURITIES EXCHANGE

ACT OF 1934, AS AMENDED

I, David Hollaway, certify that:

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

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

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

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

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

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

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

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

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

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

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

Date: November 9, 2012

/S/ DAVID HOLLAWAY

David Hollaway

Chief Financial Officer

EX-32.1

Exhibit 32.1

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

Section 906 of the Sarbanes-Oxley Act of 2002

In connection with the quarterly report of Prosperity Bancshares, Inc. (the “Company”) on Form 10-Q for the period ending September 30, 2012 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, David Zalman, Chairman and Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

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

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

/S/ DAVID ZALMAN

David Zalman

Chairman and Chief Executive Officer

November 9, 2012

EX-32.2

Exhibit 32.2

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

Section 906 of the Sarbanes-Oxley Act of 2002

In connection with the quarterly report of Prosperity Bancshares, Inc. (the “Company”) on Form 10-Q for the period ending September 30, 2012 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, David Hollaway, Chief Financial Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

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

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

/S/ DAVID HOLLAWAY

David Hollaway

Chief Financial Officer

November 9, 2012

XML

Loans and Allowance for Credit Losses - Schedule of Charge-Off Recoveries (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Schedule Of Net Charge Offs Recoveries Segregated By Class Of Loans [Line Items]
Charge-offs/recoveries	$ (1,255)	$ (368)	$ (3,217)	$ (3,121)
Construction and Land Development [Member]
Schedule Of Net Charge Offs Recoveries Segregated By Class Of Loans [Line Items]
Charge-offs/recoveries	(155)	197	(1,356)	(955)
1-4 Family (Includes Home Equity) [Member]
Schedule Of Net Charge Offs Recoveries Segregated By Class Of Loans [Line Items]
Charge-offs/recoveries	(251)	(134)	(392)	(517)
Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]
Schedule Of Net Charge Offs Recoveries Segregated By Class Of Loans [Line Items]
Charge-offs/recoveries	(770)	(271)	(1,080)	(768)
Commercial and Industrial [Member]
Schedule Of Net Charge Offs Recoveries Segregated By Class Of Loans [Line Items]
Charge-offs/recoveries	511	(7)	345	(492)
Consumer and Other [Member]
Schedule Of Net Charge Offs Recoveries Segregated By Class Of Loans [Line Items]
Charge-offs/recoveries	$ (590)	$ (153)	$ (734)	$ (389)

XML

Securities - Schedule of Securities with Unrealized Losses (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Investment Securities [Line Items]
Available for Sale, Estimated Fair Value, Less than 12 Months	$ 162
Available for Sale, Unrealized Losses, Less than 12 Months
Available for Sale, Estimated Fair Value, More than 12 Months	7,920
Available for Sale, Unrealized Losses, Less than 12 Months	(80)
Available for Sale, Estimated Fair Value, Total	8,082
Available for Sale, Unrealized Losses, Total	(80)
Held to Maturity, Unrealized Losses, Less than 12 Months	33,236
Held to Maturity, Unrealized Losses, Less than 12 Months	(721)
Held to Maturity, Estimated Fair Value, More than 12 Months	1,460
Held to Maturity, Unrealized Losses, More than 12 Months	(22)
Held to Maturity, Estimated Fair Value, Total	34,696
Held to Maturity, Unrealized Losses, Total	(743)
States and Political Subdivisions (Including QZAB) [Member]
Investment Securities [Line Items]
Available for Sale, Unrealized Losses, Less than 12 Months
Available for Sale, Estimated Fair Value, More than 12 Months	503
Available for Sale, Unrealized Losses, Less than 12 Months	(11)
Available for Sale, Estimated Fair Value, Total	503
Available for Sale, Unrealized Losses, Total	(11)
Held to Maturity, Unrealized Losses, Less than 12 Months	14,301
Held to Maturity, Unrealized Losses, Less than 12 Months	(131)
Held to Maturity, Estimated Fair Value, More than 12 Months	1,140
Held to Maturity, Unrealized Losses, More than 12 Months	(19)
Held to Maturity, Estimated Fair Value, Total	15,441
Held to Maturity, Unrealized Losses, Total	(150)
Collateralized Mortgage Obligations [Member]
Investment Securities [Line Items]
Available for Sale, Unrealized Losses, Less than 12 Months
Available for Sale, Estimated Fair Value, More than 12 Months	638
Available for Sale, Unrealized Losses, Less than 12 Months	(13)
Available for Sale, Estimated Fair Value, Total	638
Available for Sale, Unrealized Losses, Total	(13)
Held to Maturity, Unrealized Losses, Less than 12 Months	2,384
Held to Maturity, Unrealized Losses, Less than 12 Months	(215)
Held to Maturity, Estimated Fair Value, Total	2,384
Held to Maturity, Unrealized Losses, Total	(215)
Mortgage Backed Securities [Member]
Investment Securities [Line Items]
Available for Sale, Estimated Fair Value, Less than 12 Months	162
Available for Sale, Unrealized Losses, Less than 12 Months
Available for Sale, Estimated Fair Value, More than 12 Months	6,779
Available for Sale, Unrealized Losses, Less than 12 Months	(56)
Available for Sale, Estimated Fair Value, Total	6,941
Available for Sale, Unrealized Losses, Total	(56)
Held to Maturity, Unrealized Losses, Less than 12 Months	16,551
Held to Maturity, Unrealized Losses, Less than 12 Months	(375)
Held to Maturity, Estimated Fair Value, More than 12 Months	320
Held to Maturity, Unrealized Losses, More than 12 Months	(3)
Held to Maturity, Estimated Fair Value, Total	16,871
Held to Maturity, Unrealized Losses, Total	$ (378)

XML

Stock Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended			9 Months Ended
	Sep. 30, 2012 OptionPlan Y	Sep. 30, 2011	Sep. 30, 2012 Y OptionPlan	Sep. 30, 2011	Feb. 22, 2012 2012 Stock Incentive Plan [Member] Maximum [Member]	Sep. 30, 2012 2004 Stock Incentive Plan [Member]	Dec. 31, 2004 2004 Stock Incentive Plan [Member] Maximum [Member]
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Number of stock-based employee compensation plans	4		4
Number of stock option plans	1		1
Number of stock-based employee compensation plans expired	2		2
Allocated stock-based compensation expense	$ 1,100,000	$ 961,000	$ 3,200,000	$ 2,600,000
Employee service-based compensation tax benefit from compensation expense	364,000	322,000	1,100,000	870,000
Number of shares authorizes the issuance under 2012 Stock Incentive Plan					1,250,000		1,250,000
Stock-based compensation arrangement by stock-based payment award vesting period in years			1
Stock-based compensation arrangement by stock-based payment award vesting period in years			5
Option to purchase shares of common stock						162,250
Options exercisable	280,000		280,000			98,375
Shares of restricted stock outstanding						446,146
Weighted average price of restricted stock outstanding						$ 38.06
Remaining shares available for grant under the 2004 Plan						477,625
Contractual term of stock options, years	10		10
Intrinsic value of the options exercised	1,800,000	1,400,000	1,800,000	1,400,000
Total fair value of shares vested			234,000	368,000
Proceeds from stock options exercised			2,691,000	4,175,000
Tax benefit from option exercised			0	0
Unrecognized compensation expense	$ 8,900,000		$ 8,900,000
Expected weighted average period of unrecognized compensation expense recognized, in years			2.6

XML

Securities - Amortized Cost and Fair Value of Investment Securities by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Investment Securities [Line Items]
Due in one year or less, Held to Maturity, Amortized Cost	$ 30,938
Due after one year through five years, Held to Maturity, Amortized Cost	118,902
Due after five years through ten years, Held to Maturity, Amortized Cost	148,003
Due after ten years, Held to Maturity, Amortized Cost	101,500
Subtotal, Held to Maturity, Amortized Cost	399,343
Mortgage-backed securities and collateralized mortgage obligations, Held to Maturity, Amortized Cost	6,149,783
Total, Held to Maturity, Amortized Cost	6,549,126
Due in one year or less, Held to Maturity, Fair Value	31,294
Due after one year through five years, Held to Maturity, Fair Value	120,003
Due after five year through ten years, Held to Maturity, Fair Value	150,818
Due after ten year, Held to Maturity, Fair Value	106,698
Subtotal, Held to Maturity, Fair Value	408,813
Mortgage-backed securities and collateralized mortgage obligations, Held to Maturity, Fair Value	6,363,338
Total, Held to Maturity, Fair Value	6,772,151
Due in one year or less, Available for Sale, Amortized Cost	8,874
Due after one year through five years, Available for Sale, Amortized Cost	2,942
Due after five years through ten years, Available for Sale, Amortized Cost	23,562
Due after ten years, Available for Sale, Amortized Cost	8,668
Subtotal, Available for Sale, Amortized Cost	44,046
Mortgage-backed securities and collateralized mortgage obligations, Available for Sale, Amortized Cost	189,350
Total, Available for Sale, Amortized Cost	233,396
Due in one year or less, Available for Sale, Fair Value	9,392
Due after one year through five years, Available for Sale, Fair Value	3,116
Due after five years through ten years, Available for Sale, Fair Value	24,862
Due after ten years, Available for Sale, Fair Value	9,118
Subtotal, Available for Sale, Fair Value	46,488
Mortgage-backed securities and collateralized mortgage obligations, Available for Sale, Fair Value	203,899
Fair Value	$ 250,387	$ 322,316

XML

Goodwill and Core Deposit Intangibles - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Goodwill And Intangible Assets [Line Items]
Impairments recorded on goodwill or other intangibles			$ 0
Gross core deposit intangibles outstanding	91,500,000		91,500,000		79,200,000
Net core deposit intangibles outstanding	28,092,000		28,092,000		20,996,000
Amortization expense related to intangible assets	$ 2,007,000	$ 1,924,000	$ 5,297,000	$ 5,901,000
Minimum [Member]
Goodwill And Intangible Assets [Line Items]
Intangible assets, estimated life in years			8 years
Maximum [Member]
Goodwill And Intangible Assets [Line Items]
Intangible assets, estimated life in years			10 years

XML

Loans and Allowance for Credit Losses - Schedule of Activity with Respect to Related-Party Loans (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Related Party Transaction [Line Items]
Beginning balance	$ 9,809	$ 12,783
New loans and reclassified related loans	736	4,168
Repayments	(3,851)	(7,142)
Ending balance	$ 6,694	$ 9,809

XML

Contractual Obligations and Off-Balance Sheet Items - Contractual Obligations and Other Commitments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Commitments And Guarantee Obligations [Line Items]
Payments due in Remaining Fiscal 2012	$ 119,039
Payments due in Fiscal 2013-2014	465,948
Payments due in Fiscal 2015-2016	50,955
Payments due, Thereafter	275,538
Payments due, Total	911,480
Junior Subordinated Debentures [Member]
Commitments And Guarantee Obligations [Line Items]
Payments due in Remaining Fiscal 2012	1,222
Payments due in Fiscal 2013-2014	4,888
Payments due in Fiscal 2015-2016	4,888
Payments due, Thereafter	126,017
Payments due, Total	137,015
Federal Home Loan Bank Borrowings [Member]
Commitments And Guarantee Obligations [Line Items]
Payments due in Remaining Fiscal 2012	100,282
Payments due in Fiscal 2013-2014	3,258
Payments due in Fiscal 2015-2016	3,456
Payments due, Thereafter	8,001
Payments due, Total	114,997
Operating Lease [Member]
Commitments And Guarantee Obligations [Line Items]
Payments due in Remaining Fiscal 2012	1,324
Payments due in Fiscal 2013-2014	8,547
Payments due in Fiscal 2015-2016	4,013
Payments due, Thereafter	759
Payments due, Total	14,643
Lease, Total [Member]
Commitments And Guarantee Obligations [Line Items]
Payments due in Remaining Fiscal 2012	102,828
Payments due in Fiscal 2013-2014	16,693
Payments due in Fiscal 2015-2016	12,357
Payments due, Thereafter	134,777
Payments due, Total	$ 266,655

XML

STOCK BASED COMPENSATION (Tables)

9 Months Ended

Sep. 30, 2012

Summary of Fair Value of Options Estimated Using Option-Pricing Model

The fair value of options was estimated using an option-pricing model with the following weighted average assumptions:

	September 30,
	2012			2011
Expected life in years		5.26			5.30
Risk free interest rate		3.67	%		3.67	%
Volatility		20.84	%		20.98	%
Dividend yield		1.26	%		1.25	%

Summary of Changes in Outstanding Options

A summary of changes in outstanding vested and unvested options during the nine months ended September 30, 2012 is set forth below:

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
	(In thousands)					(In years)		(In thousands)
Options outstanding, beginning of period		525		$	28.18
Options granted		—			—
Options forfeited		(6	)		31.63
Options exercised		(99	)		27.03
Options outstanding, end of period		420		$	28.36		3.36	$	5,982
Options vested or expected to vest		407		$	27.98		3.32	$	5,956
Options exercisable, end of period		280		$	27.62		2.83	$	4,198

Summary of Changes in Non-Vested Options

A summary of changes in unvested options is set forth below:

	Nine Months Ended September 30,
	2012					2011
	Number of Options			Weighted Average Grant Date Fair Value		Number of Options			Weighted Average Grant Date Fair Value
	(In thousands)					(In thousands)
Unvested options outstanding, beginning of period		177		$	6.96		313		$	6.89
Options granted		—			—		—			—
Unvested options forfeited		(4	)		6.76		—			—
Options vested		(33	)		7.07		(59	)		6.31
Unvested options outstanding, end of period		140		$	6.92		254		$	6.96

XML

Stock Based Compensation - Summary of Changes in Outstanding Options (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, Average Intrinsic Value, end of period	$ 5,982
Options vested or expected to vest, Average Intrinsic Value	5,956
Options exercisable, Average Intrinsic Value, end of period	$ 4,198
Options outstanding, Weighted Average Remaining Contractual Term (in years), end of period	3 years 4 months 10 days
Options vested or expected to vest, Weighted Average Remaining Contractual Term (in years)	3 years 3 months 26 days
Options exercisable, Weighted Average Remaining Contractual Term (in years), end of period	2 years 9 months 29 days
Options outstanding, Weighted Average Exercise Price, beginning of period	$ 28.18
Options granted, Weighted Average Exercise Price
Options forfeited, Weighted Average Exercise Price	$ 31.63
Options exercised, Weighted Average Exercise Price	$ 27.03
Options outstanding, Weighted Average Exercise Price, end of period	$ 28.36
Options vested or expected to vest, Weighted Average Exercise Price	$ 27.98
Options exercisable, Weighted Average Exercise Price, end of period	$ 27.62
Number of Options outstanding, beginning of period	525
Options granted, Number of Options
Options forfeited, Number of Options	(6)
Options exercised, Number of options	(99)
Number of Options outstanding, end of period	420
Options vested or expected to vest, Number of Options	407
Options exercisable, end of period, Number of Options	280

XML

Fair Value Disclosure - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
TOTAL	$ 250,387	$ 322,316
States and Political Subdivisions (Including QZAB) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale securities	37,188	39,076
Corporate Debt Securities and Other [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale securities	9,300	9,269
Collateralized Mortgage Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale securities	638	765
Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale securities	203,261	273,206
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
TOTAL	7,747	7,656
Level 1 [Member] | Corporate Debt Securities and Other [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale securities	7,747	7,656
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
TOTAL	242,640	314,660
Level 2 [Member] | States and Political Subdivisions (Including QZAB) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale securities	37,188	39,076
Level 2 [Member] | Corporate Debt Securities and Other [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale securities	1,553	1,613
Level 2 [Member] | Collateralized Mortgage Obligations [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale securities	638	765
Level 2 [Member] | Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale securities	$ 203,261	$ 273,206

XML

Loans and Allowance for Credit Losses - Schedule of Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		9 Months Ended												12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended	9 Months Ended										12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		9 Months Ended
	Dec. 31, 2011 Construction and Land Development [Member]	Sep. 30, 2012 Construction and Land Development [Member]	Dec. 31, 2011 Agriculture and Agriculture Real Estate [Member]	Sep. 30, 2012 Agriculture and Agriculture Real Estate [Member]	Dec. 31, 2011 1-4 Family (Includes Home Equity) [Member]	Sep. 30, 2012 1-4 Family (Includes Home Equity) [Member]	Dec. 31, 2011 Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Sep. 30, 2012 Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Dec. 31, 2011 Commercial and Industrial [Member]	Sep. 30, 2012 Commercial and Industrial [Member]	Dec. 31, 2011 Consumer and Other [Member]	Sep. 30, 2012 Consumer and Other [Member]	Sep. 30, 2012 Quarter To Date [Member] Construction and Land Development [Member]	Sep. 30, 2012 Quarter To Date [Member] Agriculture and Agriculture Real Estate [Member]	Sep. 30, 2012 Quarter To Date [Member] 1-4 Family (Includes Home Equity) [Member]	Sep. 30, 2012 Quarter To Date [Member] Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Sep. 30, 2012 Quarter To Date [Member] Commercial and Industrial [Member]	Sep. 30, 2012 Quarter To Date [Member] Consumer and Other [Member]	Sep. 30, 2012 Year To Date [Member] Construction and Land Development [Member]	Sep. 30, 2012 Year To Date [Member] Agriculture and Agriculture Real Estate [Member]	Sep. 30, 2012 Year To Date [Member] 1-4 Family (Includes Home Equity) [Member]	Sep. 30, 2012 Year To Date [Member] Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Sep. 30, 2012 Year To Date [Member] Commercial and Industrial [Member]	Sep. 30, 2012 Year To Date [Member] Consumer and Other [Member]	Dec. 31, 2011 With No Related Allowance Recorded [Member] Construction and Land Development [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Construction and Land Development [Member]	Dec. 31, 2011 With No Related Allowance Recorded [Member] Agriculture and Agriculture Real Estate [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Agriculture and Agriculture Real Estate [Member]	Dec. 31, 2011 With No Related Allowance Recorded [Member] 1-4 Family (Includes Home Equity) [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] 1-4 Family (Includes Home Equity) [Member]	Dec. 31, 2011 With No Related Allowance Recorded [Member] Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Dec. 31, 2011 With No Related Allowance Recorded [Member] Commercial and Industrial [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Commercial and Industrial [Member]	Dec. 31, 2011 With No Related Allowance Recorded [Member] Consumer and Other [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Quarter To Date [Member] Construction and Land Development [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Quarter To Date [Member] Agriculture and Agriculture Real Estate [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Quarter To Date [Member] 1-4 Family (Includes Home Equity) [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Quarter To Date [Member] Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Quarter To Date [Member] Commercial and Industrial [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Year To Date [Member] Construction and Land Development [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Year To Date [Member] Agriculture and Agriculture Real Estate [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Year To Date [Member] 1-4 Family (Includes Home Equity) [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Year To Date [Member] Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Sep. 30, 2012 With No Related Allowance Recorded [Member] Year To Date [Member] Commercial and Industrial [Member]	Dec. 31, 2011 With An Allowance Recorded [Member] Construction and Land Development [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Construction and Land Development [Member]	Dec. 31, 2011 With An Allowance Recorded [Member] Agriculture and Agriculture Real Estate [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Agriculture and Agriculture Real Estate [Member]	Dec. 31, 2011 With An Allowance Recorded [Member] 1-4 Family (Includes Home Equity) [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] 1-4 Family (Includes Home Equity) [Member]	Dec. 31, 2011 With An Allowance Recorded [Member] Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Dec. 31, 2011 With An Allowance Recorded [Member] Commercial and Industrial [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Commercial and Industrial [Member]	Dec. 31, 2011 With An Allowance Recorded [Member] Consumer and Other [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Consumer and Other [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Quarter To Date [Member] Construction and Land Development [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Quarter To Date [Member] Agriculture and Agriculture Real Estate [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Quarter To Date [Member] 1-4 Family (Includes Home Equity) [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Quarter To Date [Member] Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Quarter To Date [Member] Commercial and Industrial [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Quarter To Date [Member] Consumer and Other [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Year To Date [Member] Construction and Land Development [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Year To Date [Member] Agriculture and Agriculture Real Estate [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Year To Date [Member] 1-4 Family (Includes Home Equity) [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Year To Date [Member] Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Year To Date [Member] Commercial and Industrial [Member]	Sep. 30, 2012 With An Allowance Recorded [Member] Year To Date [Member] Consumer and Other [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment	$ 1,175	$ 86	$ 49	$ 143	$ 990	$ 1,448	$ 1,151	$ 3,170	$ 633	$ 1,395	$ 8	$ 20													$ 111	$ 60	$ 6	$ 77	$ 313	$ 362	$ 668	$ 396	$ 112	$ 157												$ 1,064	$ 26	$ 43	$ 66	$ 677	$ 1,086	$ 483	$ 2,774	$ 521	$ 1,238	$ 8	$ 20
Unpaid Principal Balance	1,175	87	52	149	1,075	1,510	1,190	3,207	2,048	1,705	20	34													111	61	6	77	344	407	705	421	1,513	158												1,064	26	46	72	731	1,103	485	2,786	535	1,547	20	34
Related Allowance	312	26	39	61	362	336	165	567	300	1,180	8	20																																		312	26	39	61	362	336	165	567	300	1,180	8	20
Average Recorded Investment	$ 642		$ 26		$ 954		$ 946		$ 895		$ 21		$ 207	$ 93	$ 1,039	$ 3,145	$ 949	$ 13	$ 732	$ 70	$ 1,003	$ 3,527	$ 786	$ 10	$ 58		$ 5		$ 291		$ 637		$ 253		$ 3	$ 143	$ 41	$ 379	$ 379	$ 80	$ 168	$ 23	$ 353	$ 733	$ 69	$ 584		$ 21		$ 663		$ 309		$ 642		$ 18		$ 64	$ 52	$ 660	$ 2,766	$ 869	$ 13	$ 564	$ 47	$ 650	$ 2,794	$ 717	$ 10

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Securities - Additional Information (Detail) (USD $)	9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Jun. 30, 2011
Investment Securities [Line Items]
Carrying cost of securities	$ 6,800,000,000		$ 4,660,000,000
Changes in securities	2,140,000,000
Percentage of securities increase	45.90%
Represented securities with total assets	49.60%		47.40%
Loss on sale of securities		581,000
Book value of sale of non agency CMO's				3,200,000
Number of non-agency collateralized mortgage obligations	8
Book value of remaining non-agency CMO's	2,700,000
Fair value of remaining non-agency CMO's	2,500,000
Aggregate adjusted cost exceeded consolidated shareholders' equity	10.00%		10.00%
Amortized Cost	233,396,000		301,589,000
Collateralized Securities[Member]
Investment Securities [Line Items]
Amortized Cost	4,220,000,000		2,480,000,000
Securities fair value	$ 4,370,000,000		$ 2,570,000,000

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Acquisitions - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended							9 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012 Y	Sep. 30, 2012 Maximum [Member]	Sep. 30, 2012 Minimum [Member]	Sep. 30, 2012 Texas Bankers, Inc Austin [Member] Bank	Sep. 30, 2012 Texas Bankers, Inc Downtown Austin [Member] Bank	Sep. 30, 2012 American State Financial Corporation [Member] Bank Country	Jun. 30, 2012 American State Financial Corporation [Member]	Sep. 30, 2012 The Bank Arlington [Member]	Mar. 31, 2012 The Bank Arlington [Member]	Sep. 30, 2012 Texas Bankers, Inc [Member]	Dec. 31, 2011 Texas Bankers, Inc [Member]
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Number of banking offices					3	1	37
Number of counties bank operates							18
Total assets	$ 3,379,402,000	$ 3,379,402,000						$ 3,160,000,000		$ 37,300,000		$ 77,000,000
Total loans	2,842,596,000	2,842,596,000						1,240,000,000		22,800,000		27,600,000
Total deposits								2,510,000,000		33,200,000		70,400,000
Common stock shares issued							8,524,835		135,347		314,953
Cash payment to acquire shares								178,500,000
Merger Consideration								$ 536,800,000
Merger Consideration Premium								240,400,000	2,800,000		5,200,000
Acquisition date to determine fair value of acquired assets and liabilities	12 months	12 months
Goodwill	266,700,000	266,700,000
Goodwill Maturity period		10
Merger Related Expense	5,100	5,400
Estimated Merger Related Expense			5,400	6,000
Business Acquisition Legal And Professiona lFees					$ 352,000				$ 163,000

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Goodwill and Core Deposit Intangibles - Schedule of Estimated Aggregate Future Amortization Expense for Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Finite Lived Intangible Assets Amortization Expense [Line Items]
2013	$ 6,186
2014	4,866
2015	4,219
2016	3,781
Thereafter	7,107
Total	$ 28,092	$ 20,996

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BASIS OF PRESENTATION

9 Months Ended

Sep. 30, 2012

BASIS OF PRESENTATION

1. BASIS OF PRESENTATION

The interim consolidated financial statements include the accounts of Prosperity Bancshares, Inc.^® (the “Company”) and its wholly-owned subsidiaries, Prosperity Bank ^®(the “Bank”) and Prosperity Holdings of Delaware, L.L.C. All intercompany transactions and balances have been eliminated.

The accompanying unaudited interim consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, the statements reflect all adjustments necessary for a fair presentation of the financial position, results of operations and cash flows of the Company on a consolidated basis, and all such adjustments are of a normal recurring nature. These financial statements and the notes thereto should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2011. Operating results for the nine month period ended September 30, 2012 are not necessarily indicative of the results that may be expected for the year ending December 31, 2012 or any other period.

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Acquisitions - Preliminary Estimates Considered for Obtaining Fair Values for Certain Acquired Assets and Assumed Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Business Acquisition [Line Items]
Cash and due from banks	$ 98,720
Federal funds sold	202,810
Total cash and cash equivalents	301,530
Securities available for sale	524,959
Securities held to maturity	994,873
Loans held for sale	13,770
Loans held for investment	1,133,867
Bank premises and equipment	36,502
Other real estate owned	1,232
Goodwill	266,679
Core deposit intangibles	12,393
Federal Home Loan Bank stock	2,355
Other assets	91,242
Total assets acquired	3,379,402
Deposits	2,495,652
Other borrowings	318,692
Other liabilities	28,252
Total liabilities assumed	2,842,596
Common stock and capital surplus	536,806
Total liabilities assumed and shareholders' equity	$ 3,379,402

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Fair Value Disclosure - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Fair Value Disclosures [Line Items]
Additions to impaired loans	$ 8.2
Impaired loans, outstanding	4.3
Additions to other real estate	10.9
Real estate owned outstanding	5.2
Adjustments in basis points	25.00%
Off balance sheet commitments	$ 911.5

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ACQUISITIONS (Tables)

9 Months Ended

Sep. 30, 2012

Preliminary Estimates Considered for Obtatining Fair Values for Certain Acquired Assets and Assumed Liabilities

The Company is currently in the process of obtaining fair values for certain acquired assets and assumed liabilities and therefore the following estimates are preliminary.

	As of July 1, 2012
	(In thousands)
Cash and due from banks	$	98,720
Federal funds sold		202,810
Total cash and cash equivalents		301,530
Securities available for sale		524,959
Securities held to maturity		994,873
Loans held for sale		13,770
Loans held for investment		1,133,867
Bank premises and equipment		36,502
Other real estate owned		1,232
Goodwill		266,679
Core deposit intangibles		12,393
Federal Home Loan Bank stock		2,355
Other assets		91,242
Total assets acquired	$	3,379,402
Deposits		2,495,652
Other borrowings		318,692
Other liabilities		28,252
Total liabilities assumed		2,842,596
Common stock and capital surplus		536,806
Total liabilities assumed and shareholders’ equity	$	3,379,402

Information Regarding Results of Operations on Acquisition

	Three Months Ended				Nine Months Ended
	September 30				September 30
	2012		2011		2012		2011
	(Dollars in thousands, except per share data)
Net interest income	$	106,893	$	113,858	$	336,249	$	337,096
Net income	$	49,479	$	48,081	$	163,333	$	149,425
Basic earnings per share	$	0.88	$	0.87	$	2.78	$	2.70
Diluted earnings per share	$	0.88	$	0.87	$	2.77	$	2.69

Summary of Acquired Loans

The following table discloses the preliminary fair value and contractual value of loans acquired as of July 1, 2012:

	Purchased Credit Impaired Loans		Non-PCI Loans		Total Acquired Loans
	(Dollars in thousands)
Commercial and industrial	$	3,568	$	221,341	$	224,909
Real estate
Construction and land development		1,326		112,011		113,337
1-4 family residential		155		126,954		127,109
Home equity		—		24,851		24,851
Commercial mortgage		22,454		460,378		482,832
Agriculture real estate		—		53,979		53,979
Multi-family residential		—		48,423		48,423
Agriculture		78		—		78
Consumer		—		72,119		72,119
Other		—		—		—
Total fair value	$	27,581	$	1,120,056	$	1,147,637
Contractual principal balance	$	54,403	$	1,195,741	$	1,250,144

Additional Information on Purchased Credit Impaired Loans

The following presents additional information on purchased credit impaired loans (dollars in thousands):

Contractually required principal and interest	$	60,167
Non-accretable difference		(24,429	)
Cash flows expected to be collected		35,738
Accretable difference		(8,157	)
Fair value of purchased credit impaired loans	$	27,581

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OTHER COMPREHENSIVE INCOME (LOSS) (Tables)

9 Months Ended

Sep. 30, 2012

Schedule of Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss)

The tax effects allocated to each component of other comprehensive (loss) income were as follows (dollars in thousands):

	Three Months Ended September 30, 2012									Three Months Ended September 30, 2011
	Before Tax Amount			Tax Expense, (Benefit)			Net of Tax Amount			Before Tax Amount		Tax Expense, (Benefit)		Net of Tax Amount
Securities available for sale:
Change in net unrealized (loss) gain during the period	$	(718	)	$	(251	)	$	(467	)	$	632	$	222	$	410
Total other comprehensive (loss) income	$	(718	)	$	(251	)	$	(467	)	$	632	$	222	$	410
	Nine Months Ended September 30, 2012									Nine Months Ended September 30, 2011
	Before Tax Amount			Tax Expense, (Benefit)			Net of Tax Amount			Before Tax Amount		Tax Expense, (Benefit)		Net of Tax Amount
Securities available for sale:
Change in net unrealized (loss) gain during the period	$	(3,736	)	$	(1,308	)	$	(2,428	)	$	2,272	$	795	$	1,477
Total other comprehensive (loss) income	$	(3,736	)	$	(1,308	)	$	(2,428	)	$	2,272	$	795	$	1,477

Activity of Accumulated Other Comprehensive Income

Activity in accumulated other comprehensive income, net of tax, was as follows:

	Securities Available For Sale			Accumulated Other Comprehensive Income
	(Dollars in thousands)
Balance January 1, 2012	$	13,472		$	13,472
Other comprehensive (loss) income		(2,428	)		(2,428	)
Balance September 30, 2012	$	11,044		$	11,044
Balance as of January 1, 2011	$	14,304		$	14,304
Other comprehensive (loss) income		1,477			1,477
Balance September 30, 2011	$	15,781		$	15,781

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Contractual Obligations and Off-Balance Sheet Items - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Commitments And Guarantee Obligations [Line Items]
Interest portion junior subordinated debentures	$ 651,000	$ 607,000	$ 1,962,000	$ 2,352,000
Interest to be paid over future periods included in FHLB payments			3,000,000
Contractual Obligations [Member]
Commitments And Guarantee Obligations [Line Items]
Interest portion junior subordinated debentures			52,000,000
Current principal balance of the junior subordinated debentures	$ 85,100,000		$ 85,100,000

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Fair Value Disclosure - Summary of Financial Assets and Liabilities Measured on Recurring and Non-Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Cash and due from banks	$ 207,401	$ 212,800
Federal funds sold	302	642
Held to maturity securities	6,772,151	4,492,988
Available for sale securities	250,387	322,316
Deposits	10,954,597	8,060,254
Junior subordinated debentures	85,055	85,055
Other borrowings	112,017	12,790
Securities sold under repurchase agreements	443,856	54,883
Carrying Amount [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Cash and due from banks	207,401	212,800
Federal funds sold	302	642
Interest-bearing time deposits in other financial institutions	249
Held to maturity securities	6,549,126	4,336,620
Available for sale securities	250,387	322,316
Loans held for sale	4,332
Loans held for investment, net of allowance for credit losses	5,023,844	3,714,312
Total	12,035,641	8,586,690
Deposits	10,954,597	8,060,254
Junior subordinated debentures	85,055	85,055
Other borrowings	112,017	12,790
Securities sold under repurchase agreements	443,856	54,883
Total	11,595,525	8,212,982
Estimate Fair Value [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]
Cash and due from banks	207,401	212,800
Federal funds sold	302	642
Interest-bearing time deposits in other financial institutions	249
Held to maturity securities	6,772,151	4,492,988
Available for sale securities	250,387	322,316
Loans held for sale	4,332
Loans held for investment, net of allowance for credit losses	5,098,007	3,814,858
Total	12,332,829	8,843,604
Deposits	10,971,925	8,074,093
Junior subordinated debentures	72,242	71,001
Other borrowings	114,170	14,974
Securities sold under repurchase agreements	443,976	54,883
Total	$ 11,602,313	$ 8,214,951

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Earnings Per Share - Computation of Basic and Diluted Earnings per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share [Line Items]
Net income available to common shareholders	$ 46,176	$ 36,373	$ 119,635	$ 105,343
Weighted average common shares outstanding	55,958	46,890	50,239	46,830
Potential dilutive common shares	135	143	154	183
Weighted average common shares and equivalents outstanding	56,093	47,033	50,393	47,013
Basic earnings per common share	$ 0.83	$ 0.78	$ 2.38	$ 2.25
Diluted earnings per common share	$ 0.82	$ 0.77	$ 2.37	$ 2.24
Stock options exercisable that would have had an anti-dilutive effect			0	0

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Loans and Allowance for Credit Losses - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2012 Y D	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans	$ 5,028,176,000		$ 3,714,312,000
Percentage increase in loans	34.90%
Increase in loans	1,310,000,000
Fair value of loans	5,079,103,000		3,765,906,000
Preliminary discount on loans	104,900,000
Loans held for sales	4,300,000
Fixed rate, in years	5
Percentage of loans related to single industry on total loans, maximum	10.00%		10.00%
Loans outstanding to directors, officers and affiliates	6,694,000		9,809,000	12,783,000
Minimum period for ceases accruing interest, in days
Total nonperforming assets	14,051,000		12,052,000
Interest on non-accrual loans	252,000	156,000
Maximum principal and interest collectible on substandard impaired loans, percentage	100.00%
Allowance for credit losses totaled	50,900,000		51,600,000
Allowance for credit losses as a percentage of total loans	1.00%		1.37%
Determined period of default, minimum number of days past due	90
Loans restructured, non-accrual	972,000
Texas Bankers, Inc [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value of loans	24,200,000
The Bank Arlington [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value of loans	21,800,000
American State Financial Corporation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair value of loans	1,130,000,000
Impaired Loans At Acquisition [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Preliminary discount on loans	27,100,000
Non Impaired Loans At Acquisition [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Preliminary discount on loans	77,800,000
Commercial Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term of consumer loans	15
Commercial real estate loans, net	$ 2,470,000,000
Percentage of outstanding principal balance, commercial real estate loans	43.30%
1-4 Family Residential Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originated loan to appraised value without mortgage insurance, percentage	89.00%
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term of agriculture loans, Maximum	P15Y
Maximum [Member] | Commercial Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term of consumer loans	20
Maximum [Member] | 1-4 Family Residential Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term of consumer loans	25
Maximum [Member] | Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term of consumer loans	120
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term of agriculture loans, Maximum	P5Y
Minimum [Member] | 1-4 Family Residential Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term of consumer loans	5
Minimum [Member] | Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term of consumer loans	12

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CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 119,635	$ 105,343
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	11,729	12,000
Stock based compensation expense	3,218	2,604
Net proceeds from the sale of held for sale loans	9,438
Net accretion of discount on loans and deposits	(11,988)	(27)
Provision for credit losses	2,550	4,050	5,200
Net amortization of premium on investments	42,897	19,686
Net loss on sale of other real estate	344	431
Net gain on sale of premises and equipment	(13)	(377)
Net (increase) decrease in accrued interest receivable and other assets	(19,623)	19,352
Net increase in accrued interest payable and other liabilities	42,510	19,314
Net cash provided by operating activities	200,697	182,376
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities and principal paydowns of securities held to maturity	1,238,538	875,900
Purchase of securities held to maturity	(2,499,561)	(781,977)
Proceeds from maturities, sales and principal paydowns of securities available for sale	1,703,676	1,075,249
Purchase of securities available for sale	(1,109,999)	(1,000,000)
Net increase in loans held for investment	(128,225)	(263,587)
Purchase of bank premises and equipment	(7,924)	(7,621)
Net proceeds from sale of bank premises, equipment and other real estate	12,004	10,699
Net cash used in investing activities	(611,882)	(91,337)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase in noninterest-bearing deposits	193,360	188,717
Net increase in interest-bearing deposits	101,866	155,408
Net proceeds from (repayments of) short-term debt	100,000	(360,000)
Net repayments of long-term debt	(772)	(850)
Redemption of junior subordinated debentures		(7,210)
Net increase in securities sold under repurchase agreements	37,711	5,507
Proceeds from exercise of stock options	2,691	4,175
Payments of cash dividends	(29,410)	(24,599)
Net cash provided by (used in) financing activities	405,446	(38,852)
NET DECREASE IN CASH AND CASH EQUIVALENTS	(5,739)	52,187
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	213,442	159,368	159,368
CASH AND CASH EQUIVALENTS, END OF PERIOD	207,703	211,555	213,442
NONCASH ACTIVITIES:
Stock issued in connection with the Texas Bankers, Inc. acquisition	12,708
SUPPLEMENTAL DISCLOSURES:
Cash paid for income taxes	53,737	51,438
Cash paid for interest	30,434	36,616
Noncash investing and financing activities - acquisition of real estate through foreclosure of collateral	11,354	9,414
Texas Bankers, Inc. [Member]
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash and cash equivalents acquired in the purchase	44,550
The Bank Arlington [Member]
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash and cash equivalents acquired in the purchase	12,037
NONCASH ACTIVITIES:
Stock issued in connection with the American State Financia Corporation acquisition	6,198
American State Financial Corporation [Member]
CASH FLOWS FROM INVESTING ACTIVITIES:
Net cash and cash equivalents acquired in the purchase	123,022
NONCASH ACTIVITIES:
Stock issued in connection with the American State Financia Corporation acquisition	$ 358,299

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Loans and Allowance for Credit Losses - Schedule of Types of Loans in Loan Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	$ 756,342	$ 406,433
Agriculture	98,801	34,226
Consumer (net of unearned discount)	112,476	78,187
Other	35,905	33,421
Total	5,079,103	3,765,906
Construction and Land Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real estate	496,417	482,140
Total	496,417	482,140
1-4 Family Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real estate	1,213,873	1,007,266
Home Equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real estate	183,844	146,999
Commercial Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real estate	1,837,224	1,351,986
Agriculture Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real estate	205,333	136,008
Multi-Family Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real estate	$ 138,888	$ 89,240

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Loans and Allowance for Credit Losses - Schedule of Recorded Investment in Loans and Activity in Allowance for Credit Losses by Portfolio Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance			$ 51,594	$ 51,584	$ 51,584
Provision for credit losses	1,800	950	2,550	4,050	5,200
Charge-offs			(5,601)		(6,850)
Recoveries			2,384		1,660
Net charge-offs			(3,217)		(5,190)
Ending balance	50,927		50,927		51,594
Ending balance: individually evaluated for impairment	2,190		2,190		1,186
Ending balance: collectively evaluated for impairment	48,737		48,737		50,408
Ending balance	5,079,103		5,079,103		3,765,906
Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance: individually evaluated for impairment	6,262		6,262		4,006
Ending balance: collectively evaluated for impairment	5,072,841		5,072,841		3,761,900
Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance			12,094	12,994	12,994
Provision for credit losses			(469)		209
Charge-offs			(1,368)		(1,509)
Recoveries			12		400
Net charge-offs			(1,356)		(1,109)
Ending balance	10,269		10,269		12,094
Ending balance: individually evaluated for impairment	26		26		312
Ending balance: collectively evaluated for impairment	10,243		10,243		11,782
Ending balance	496,417		496,417		482,140
Construction and Land Development [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance: individually evaluated for impairment	86		86		1,175
Ending balance: collectively evaluated for impairment	496,331		496,331		480,965
Agriculture and Agriculture Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance			511	271	271
Provision for credit losses			226		239
Recoveries			33		1
Net charge-offs			33		1
Ending balance	770		770		511
Ending balance: individually evaluated for impairment	61		61		39
Ending balance: collectively evaluated for impairment	709		709		472
Ending balance	304,134		304,134		170,234
Agriculture and Agriculture Real Estate [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance: individually evaluated for impairment	143		143		49
Ending balance: collectively evaluated for impairment	303,991		303,991		170,185
1-4 Family (Includes Home Equity) [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance			12,645	12,837	12,837
Provision for credit losses			1,121		1,168
Charge-offs			(478)		(1,392)
Recoveries			86		32
Net charge-offs			(392)		(1,360)
Ending balance	13,374		13,374		12,645
Ending balance: individually evaluated for impairment	336		336		362
Ending balance: collectively evaluated for impairment	13,038		13,038		12,283
Ending balance	1,397,717		1,397,717		1,154,265
1-4 Family (Includes Home Equity) [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance: individually evaluated for impairment	1,448		1,448		990
Ending balance: collectively evaluated for impairment	1,396,269		1,396,269		1,153,275
Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance			21,460	20,436	20,436
Provision for credit losses			(250)		2,011
Charge-offs			(1,278)		(1,027)
Recoveries			165		40
Net charge-offs			(1,113)		(987)
Ending balance	20,097		20,097		21,460
Ending balance: individually evaluated for impairment	567		567		165
Ending balance: collectively evaluated for impairment	19,530		19,530		21,295
Ending balance	1,976,112		1,976,112		1,441,226
Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance: individually evaluated for impairment	3,170		3,170		1,151
Ending balance: collectively evaluated for impairment	1,972,942		1,972,942		1,440,075
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance			3,826	3,891	3,891
Provision for credit losses			1,237		1,103
Charge-offs			(376)		(1,694)
Recoveries			721		526
Net charge-offs			345		(1,168)
Ending balance	5,408		5,408		3,826
Ending balance: individually evaluated for impairment	1,180		1,180		300
Ending balance: collectively evaluated for impairment	4,228		4,228		3,526
Ending balance	756,342		756,342		406,433
Commercial and Industrial [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance: individually evaluated for impairment	1,395		1,395		633
Ending balance: collectively evaluated for impairment	754,947		754,947		405,800
Consumer and Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance			1,058	1,155	1,155
Provision for credit losses			685		470
Charge-offs			(2,101)		(1,228)
Recoveries			1,367		661
Net charge-offs			(734)		(567)
Ending balance	1,009		1,009		1,058
Ending balance: individually evaluated for impairment	20		20		8
Ending balance: collectively evaluated for impairment	989		989		1,050
Ending balance	148,381		148,381		111,608
Consumer and Other [Member] | Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Ending balance: individually evaluated for impairment	20		20		8
Ending balance: collectively evaluated for impairment	$ 148,361		$ 148,361		$ 111,600

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Securities - Schedule of Investment Securities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Investment Securities [Line Items]
Amortized Cost	$ 233,396	$ 301,589
Fair Value	250,387	322,316
Available For Sale Securities [Member]
Investment Securities [Line Items]
Amortized Cost	233,396	301,589
Gross Unrealized Gains	17,071	20,820
Gross Unrealized Losses	(80)	(93)
Fair Value	250,387	322,316
Held- To Maturity [Member]
Investment Securities [Line Items]
Amortized Cost	6,549,126	4,336,620
Gross Unrealized Gains	223,768	156,893
Gross Unrealized Losses	(743)	(525)
Fair Value	6,772,151	4,492,988
States and Political Subdivisions (Including QZAB) [Member] | Available For Sale Securities [Member]
Investment Securities [Line Items]
Amortized Cost	35,262	37,060
Gross Unrealized Gains	1,937	2,022
Gross Unrealized Losses	(11)	(6)
Fair Value	37,188	39,076
States and Political Subdivisions (Including QZAB) [Member] | Held- To Maturity [Member]
Investment Securities [Line Items]
Amortized Cost	387,246	50,814
Gross Unrealized Gains	9,355	3,324
Gross Unrealized Losses	(151)	(284)
Fair Value	396,450	53,854
Collateralized Mortgage Obligations [Member] | Available For Sale Securities [Member]
Investment Securities [Line Items]
Amortized Cost	651	786
Gross Unrealized Losses	(13)	(21)
Fair Value	638	765
Collateralized Mortgage Obligations [Member] | Held- To Maturity [Member]
Investment Securities [Line Items]
Amortized Cost	160,478	281,778
Gross Unrealized Gains	2,994	5,009
Gross Unrealized Losses	(215)	(150)
Fair Value	163,257	286,637
Mortgage Backed Securities [Member] | Available For Sale Securities [Member]
Investment Securities [Line Items]
Amortized Cost	188,699	254,965
Gross Unrealized Gains	14,618	18,307
Gross Unrealized Losses	(56)	(66)
Fair Value	203,261	273,206
Mortgage Backed Securities [Member] | Held- To Maturity [Member]
Investment Securities [Line Items]
Amortized Cost	5,989,305	3,993,832
Gross Unrealized Gains	211,153	147,991
Gross Unrealized Losses	(377)	(91)
Fair Value	6,200,081	4,141,732
Corporate Debt Securities And Other [Member] | Available For Sale Securities [Member]
Investment Securities [Line Items]
Amortized Cost	8,784	8,778
Gross Unrealized Gains	516	491
Fair Value	9,300	9,269
Corporate Debt Securities And Other [Member] | Held- To Maturity [Member]
Investment Securities [Line Items]
Amortized Cost	1,500	1,500
Gross Unrealized Gains	53	114
Fair Value	1,553	1,614
U.S. Treasury Securities And Obligations Of U.S. Government Agencies [Member] | Held- To Maturity [Member]
Investment Securities [Line Items]
Amortized Cost	10,597	8,696
Gross Unrealized Gains	213	455
Fair Value	$ 10,810	$ 9,151

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CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
ASSETS
Cash and due from banks	$ 207,401	$ 212,800
Federal funds sold	302	642
Total cash and cash equivalents	207,703	213,442
Interest-bearing time deposits in other financial institutions	249
Securities available for sale, at fair value (amortized cost of $233,396 and $301,589, respectively)	250,387	322,316
Securities held to maturity, at cost (fair value of $6,772,151 and $4,492,988, respectively)	6,549,126	4,336,620
Loans held for investment	5,074,771	3,765,906
Loans held for sale	4,332
Allowance for credit losses	(50,927)	(51,594)
Loans, net	5,028,176	3,714,312
Accrued interest receivable	39,661	29,405
Goodwill	1,200,098	924,537
Core deposit intangibles, net of accumulated amortization of $63,455 and $58,158, respectively	28,092	20,996
Bank premises and equipment, net	201,445	159,656
Other real estate owned	8,846	8,328
Bank Owned Life Insurance (BOLI)	107,859	50,029
Federal Home Loan Bank stock	42,417	11,601
Other assets	48,060	31,429
TOTAL ASSETS	13,712,119	9,822,671
Deposits:
Noninterest-bearing	2,827,748	1,972,226
Interest-bearing	8,126,849	6,088,028
Total deposits	10,954,597	8,060,254
Other borrowings	112,017	12,790
Securities sold under repurchase agreements	443,856	54,883
Accrued interest payable	2,089	2,803
Other liabilities	76,329	39,621
Junior subordinated debentures	85,055	85,055
Total liabilities	11,673,943	8,255,406
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS' EQUITY:
Preferred stock, $1 par value; 20,000,000 shares authorized; none issued or outstanding
Common stock, $1 par value; 200,000,000 shares authorized; 56,095,248 and 46,947,415 shares issued at September 30, 2012 and December 31, 2011, respectively; 56,058,160 and 46,910,327 shares outstanding at September 30, 2012 and December 31, 2011, respectively	56,095	46,947
Capital surplus	1,257,541	883,575
Retained earnings	714,103	623,878
Accumulated other comprehensive income-net unrealized gain on available for sale securities, net of tax of $5,947 and $7,254, respectively	11,044	13,472
Less treasury stock, at cost, 37,088 shares	(607)	(607)
Total shareholders' equity	2,038,176	1,567,265
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 13,712,119	$ 9,822,671

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Goodwill and Core Deposit Intangibles - Schedule of Goodwill and Core Deposit Intangibles (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Goodwill And Intangible Assets [Line Items]
Goodwill, Balance as of December 31, 2011			$ 924,537
Goodwill, Amortization
Goodwill, Balance as of September 30, 2012	1,200,098		1,200,098
Core Deposit Intangibles, Balance as of December 31, 2010			20,996
Core Deposit Intangibles, Amortization	(2,007)	(1,924)	(5,297)	(5,901)
Core Deposit Intangibles,Balance as of September 30, 2011	28,092		28,092
Texas Bankers, Inc [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill, Acquisition			5,869
The Bank Arlington [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill, Acquisition			3,013
American State Financial Corporation [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill, Acquisition			266,679
Core Deposit Intangibles, Acquisition			$ 12,393

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CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data	Total	The Bank Arlington [Member]	American State Financial Corporation [Member]	Common Stock [Member]	Common Stock [Member] The Bank Arlington [Member]	Common Stock [Member] American State Financial Corporation [Member]	Capital Surplus [Member]	Capital Surplus [Member] The Bank Arlington [Member]	Capital Surplus [Member] American State Financial Corporation [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock [Member]
BALANCE at Dec. 31, 2010	$ 1,452,339			$ 46,721			$ 876,050			$ 515,871	$ 14,304	$ (607)
BALANCE, Shares at Dec. 31, 2010				46,721,114
Net income	105,343									105,343
Other comprehensive income	1,477										1,477
Common stock issued in connection with the exercise of stock options and restricted stock awards	4,175			209			3,966
Common stock issued in connection with the exercise of stock options and restricted stock awards (in shares)				208,918
Stock based compensation expense	2,604						2,604
Cash dividends declared	(24,599)									(24,599)
BALANCE at Sep. 30, 2011	1,541,339			46,930			882,620			596,615	15,781	(607)
BALANCE, Shares at Sep. 30, 2011				46,930,032
BALANCE at Dec. 31, 2011	1,567,265			46,947			883,575			623,878	13,472	(607)
BALANCE, Shares at Dec. 31, 2011				46,947,415
Net income	119,635									119,635
Other comprehensive income	(2,428)										(2,428)
Common stock issued in connection with the exercise of stock options and restricted stock awards	2,691			173			2,518
Common stock issued in connection with the exercise of stock options and restricted stock awards (in shares)				172,698
Common stock issued in connection with the acquisition of Texas Bankers, Inc.	12,708			315			12,393
Common stock issued in connection with the acquisition of Texas Bankers, Inc.(in shares)				314,953
Common stock issued in connection with the acquisition of American State Financial Corporation		6,198	358,299		135	8,525		6,063	349,774
Common stock issued in connection with the acquisition of American State Financial Corporation(in shares)					135,347	8,524,835
Stock based compensation expense	3,218						3,218
Cash dividends declared	(29,410)									(29,410)
BALANCE at Sep. 30, 2012	$ 2,038,176			$ 56,095			$ 1,257,541			$ 714,103	$ 11,044	$ (607)
BALANCE, Shares at Sep. 30, 2012				56,095,248

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Other Comprehensive Income (Loss) - Tax Effects Allocated to Component of Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Comprehensive Income Loss [Line Items]
Change in net unrealized (loss) gain during the period	$ (718)	$ 632	$ (3,736)	$ 2,272
Total other comprehensive (loss) income, Before Tax	(718)	632	(3,736)	2,272
Change in net unrealized (loss) gain during the period, Tax Expenses (Benefit)	(251)	222	(1,308)	795
Total other comprehensive (loss) income, Tax Expenses (Benefit)	(251)	222	(1,308)	795
Change in net unrealized (loss) gain during the period, Net of Tax	(467)	410	(2,428)	1,477
Total other comprehensive (loss) income	$ (467)	$ 410	$ (2,428)	$ 1,477

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Loans and Allowance for Credit Losses - Schedule of Past Due Loans with Age Analysis, Segregated by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 30, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-89 Days Past Due	$ 23,965	$ 10,436
Loans 90 or More Days Past Due	2,307	1,218
Total Past Due Loans	26,272	11,654
Current Loans	5,052,831	3,754,252
Accruing Loans 90 or More Days Past Due	132
Construction and Land Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-89 Days Past Due	5,157	1,281
Loans 90 or More Days Past Due	86	111
Total Past Due Loans	5,243	1,392
Current Loans	491,174	480,748
Agriculture and Agriculture Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-89 Days Past Due	1,772	365
Loans 90 or More Days Past Due	362	9
Total Past Due Loans	2,134	374
Current Loans	302,000	169,860
1-4 Family (Includes Home Equity) [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-89 Days Past Due	1,756	1,527
Loans 90 or More Days Past Due	1,413	314
Total Past Due Loans	3,169	1,841
Current Loans	1,394,548	1,152,424
Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-89 Days Past Due	9,965	5,630
Loans 90 or More Days Past Due		390
Total Past Due Loans	9,965	6,020
Current Loans	1,966,147	1,435,206
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-89 Days Past Due	4,211	1,544
Loans 90 or More Days Past Due	426	394
Total Past Due Loans	4,637	1,938
Current Loans	751,705	404,495
Accruing Loans 90 or More Days Past Due	132
Consumer and Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans 30-89 Days Past Due	1,104	89
Loans 90 or More Days Past Due	20
Total Past Due Loans	1,124	89
Current Loans	$ 147,257	$ 111,519

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Acquisitions - Additional Information on Purchased Credit Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Purchased Credit Impaired Loans [Line Items]
Contractually required principal and interest	$ 60,167
Non-accretable difference	(24,429)
Cash flows expected to be collected	35,738
Accretable difference	(8,157)
Fair value of purchased credit impaired loans	$ 27,581

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LOANS AND ALLOWANCE FOR CREDIT LOSSES (Tables)

9 Months Ended

Sep. 30, 2012

Schedule of Types of Loans in Loan Portfolio

The loan portfolio consists of various types of loans made principally to borrowers located in Bryan/College Station, Central Texas, Dallas/Fort Worth, East Texas, Houston, South Texas and West Texas and is classified by major type as follows:

	September 30, 2012		December 31, 2011
	(Dollars in thousands)
Commercial and industrial	$	756,342	$	406,433
Real estate:
Construction and land development		496,417		482,140
1-4 family residential(1)		1,213,873		1,007,266
Home equity		183,844		146,999
Commercial mortgage		1,837,224		1,351,986
Agriculture real estate		205,333		136,008
Multi-family residential		138,888		89,240
Agriculture		98,801		34,226
Consumer (net of unearned discount)		112,476		78,187
Other		35,905		33,421
Total	$	5,079,103	$	3,765,906

Schedule of Activity with Respect to Related-Party Loans

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

	For the Nine Months Ended September  30, 2012			For the Year Ended December 31, 2011
	(Dollars in thousands)
Beginning balance	$	9,809		$	12,783
New loans and reclassified related loans		736			4,168
Repayments		(3,851	)		(7,142	)
Ending balance	$	6,694		$	9,809

Schedule of Nonaccrual Loans, Segregated by Class of Loans

As of the dates indicated, nonaccrual loans, segregated by class of loans, were as follows:

	September 30, 2012		December 31, 2011
	(Dollars in thousands)
Construction and land development	$	86	$	1,175
Agriculture and agriculture real estate		410		49
1-4 family (includes home equity)		1,694		923
Commercial real estate (commercial mortgage and multi-family residential)		1,292		790
Commercial and industrial		1,557		633
Consumer and other		24		8
Total	$	5,063	$	3,578

Schedule of Past Due Loans with Age Analysis, Segregated by Class of Loans

An age analysis of past due loans, segregated by class of loans, as of the dates indicated, was as follows:

	As of September 30, 2012
	Loans 30-89  Days Past Due		Loans 90 or  More Days Past Due		Total Past Due  Loans		Current Loans		Accruing Loans 90  or More Days Past Due
	(Dollars in thousands)
Construction and land development	$	5,157	$	86	$	5,243	$	491,174	$	—
Agriculture and agriculture real estate		1,772		362		2,134		302,000		—
1-4 family (includes home equity)		1,756		1,413		3,169		1,394,548		—
Commercial real estate (commercial mortgage and multi-family residential)		9,965		—		9,965		1,966,147		—
Commercial and industrial		4,211		426		4,637		751,705		132
Consumer and other		1,104		20		1,124		147,257		—
Total	$	23,965	$	2,307	$	26,272	$	5,052,831	$	132

	As of December 31, 2011
	Loans 30-89  Days Past Due		Loans 90 or  More Days Past Due		Total Past Due  Loans		Current Loans		Accruing Loans 90  or More Days Past Due
	(Dollars in thousands)
Construction and land development	$	1,281	$	111	$	1,392	$	480,748	$	—
Agriculture and agriculture real estate		365		9		374		169,860		—
1-4 family (includes home equity)		1,527		314		1,841		1,152,424		—
Commercial real estate (commercial mortgage and multi-family residential)		5,630		390		6,020		1,435,206		—
Commercial and industrial		1,544		394		1,938		404,495		—
Consumer and other		89		—		89		111,519		—
Total	$	10,436	$	1,218	$	11,654	$	3,754,252	$	—

Schedule of Past Due Loans and Nonperforming Assets

The following table presents information regarding past due loans and nonperforming assets at the dates indicated:

	September 30, 2012			December 31, 2011
	(Dollars in thousands)
Nonaccrual loans	$	5,063		$	3,578
Accruing loans 90 or more days past due		132			—
Total nonperforming loans		5,195			3,578
Repossessed assets		10			146
Other real estate		8,846			8,328
Total nonperforming assets	$	14,051		$	12,052
Nonperforming assets to total loans and other real estate		0.28	%		0.32	%

Schedule of Impaired Loans

Impaired loans as of September 30, 2012 are set forth in the following table. No interest income was recognized on impaired loans subsequent to their classification as impaired.

	September 30, 2012
	Recorded Investment		Unpaid Principal Balance		Related Allowance		Average Recorded Investment  Quarter to Date		Average Recorded Investment  Year to Date
	(Dollars in thousands)
With no related allowance recorded:
Construction and land development	$	60	$	61	$	—	$	143	$	168
Agriculture and agriculture real estate		77		77		—		41		23
1-4 family (includes home equity)		362		407		—		379		353
Commercial real estate (commercial mortgage and multi-family residential)		396		421		—		379		733
Commercial and industrial		157		158		—		80		69
Consumer and other		—		—		—		—		—
With an allowance recorded:
Construction and land development		26		26		26		64		564
Agriculture and agriculture real estate		66		72		61		52		47
1-4 family (includes home equity)		1,086		1,103		336		660		650
Commercial real estate (commercial mortgage and multi-family residential)		2,774		2,786		567		2,766		2,794
Commercial and industrial		1,238		1,547		1,180		869		717
Consumer and other		20		34		20		13		10
Total:
Construction and land development		86		87		26		207		732
Agriculture and agriculture real estate		143		149		61		93		70
1-4 family (includes home equity)		1,448		1,510		336		1,039		1,003
Commercial real estate (commercial mortgage and multi-family residential)		3,170		3,207		567		3,145		3,527
Commercial and industrial		1,395		1,705		1,180		949		786
Consumer and other		20		34		20		13		10

Impaired loans as of December 31, 2011 are set forth in the following table. No interest income was recognized on impaired loans subsequent to their classification as impaired. The average recorded investment is reported on a year-to-date basis.

	December 31, 2011
	Recorded Investment		Unpaid  Principal Balance		Related Allowance		Average  Recorded Investment
	(Dollars in thousands)
With no related allowance recorded:
Construction and land development	$	111	$	111	$	—	$	58
Agriculture and agriculture real estate		6		6		—		5
1-4 family (includes home equity)		313		344		—		291
Commercial real estate (commercial mortgage and multi-family residential)		668		705		—		637
Commercial and industrial		112		1,513		—		253
Consumer and other		—		—		—		3
With an allowance recorded:
Construction and land development		1,064		1,064		312		584
Agriculture and agriculture real estate		43		46		39		21
1-4 family (includes home equity)		677		731		362		663
Commercial real estate (commercial mortgage and multi-family residential)		483		485		165		309
Commercial and industrial		521		535		300		642
Consumer and other		8		20		8		18
Total:
Construction and land development		1,175		1,175		312		642
Agriculture and agriculture real estate		49		52		39		26
1-4 family (includes home equity)		990		1,075		362		954
Commercial real estate (commercial mortgage and multi-family residential)		1,151		1,190		165		946
Commercial and industrial		633		2,048		300		895
Consumer and other		8		20		8		21

Schedule Showing Risk Grades and Classified Loans by Class of Loan

The following table presents loan risk grades and classified loans by class of loan at September 30, 2012. Classified loans include loans in risk grades 5, 6 and 7.

	Construction and Land Development		Agriculture and Agriculture Real Estate		1-4 Family (Includes Home Equity)		Commercial Real Estate (Commercial Mortgage and Multi- Family)		Commercial and Industrial		Consumer and Other		Total
	(Dollars in thousands)
Grade 1	$	—	$	2,601	$	—	$	—	$	45,371	$	28,269	$	76,241
Grade 2		482,385		297,231		1,384,513		1,930,565		695,762		119,392		4,909,848
Grade 3		8,351		2,128		6,617		9,163		8,206		—		34,465
Grade 4		5,595		2,031		5,139		33,214		5,608		700		52,287
Grade 5		86		143		1,435		3,170		1,393		20		6,247
Grade 6		—		—		13		—		2		—		15
Grade 7		—		—		—		—		—		—		—
Total	$	496,417	$	304,134	$	1,397,717	$	1,976,112	$	756,342	$	148,381	$	5,079,103

The following table presents risk grades and classified loans by class of loan at December 31, 2011. Classified loans include loans in risk grades 5, 6 and 7.

	Construction and Land Development		Agriculture and Agriculture Real Estate		1-4 Family (Includes Home Equity)		Commercial Real Estate (Commercial Mortgage and Multi- Family)		Commercial and Industrial		Consumer and Other		Total
	(Dollars in thousands)
Grade 1	$	—	$	3,319	$	—	$	—	$	45,218	$	31,602	$	80,139
Grade 2		465,572		166,656		1,140,210		1,399,915		355,862		79,996		3,608,211
Grade 3		1,757		210		9,131		14,335		4,189		—		29,622
Grade 4		13,636		—		3,934		25,825		531		2		43,928
Grade 5		1,175		49		970		1,151		532		8		3,885
Grade 6		—		—		20		—		101		—		121
Grade 7		—		—		—		—		—		—		—
Total	$	482,140	$	170,234	$	1,154,265	$	1,441,226	$	406,433	$	111,608	$	3,765,906

Schedule of Charge-Off Recoveries

Net charge-offs/recoveries, segregated by class of loans, for the three and nine months ended September 30, 2012 and 2011 were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2012			2011			2012			2011
Construction and land development	$	(155	)	$	197		$	(1,356	)	$	(955	)
1-4 family (includes home equity)		(251	)		(134	)		(392	)		(517	)
Commercial real estate and agriculture (includes multi-family)		(770	)		(271	)		(1,080	)		(768	)
Commercial and industrial		511			(7	)		345			(492	)
Consumer and other		(590	)		(153	)		(734	)		(389	)
Total	$	(1,255	)	$	(368	)	$	(3,217	)	$	(3,121	)

Schedule of Recorded Investment in Loans and Activity in Allowance for Credit Losses by Portfolio Segment

The following table details the recorded investment in loans and activity in the allowance for credit losses by portfolio segment for the nine months ended September 30, 2012. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.

	Construction and Land Development			Agriculture and Agriculture Real Estate		1-4 Family (includes Home Equity)			Commercial Real Estate (Commercial Mortgage and Multi-Family)			Commercial and Industrial			Consumer and Other			Total
	(Dollars in thousands)
Allowance for credit losses:
Beginning balance	$	12,094		$	511	$	12,645		$	21,460		$	3,826		$	1,058		$	51,594
Provision for credit losses		(469	)		226		1,121			(250	)		1,237			685			2,550
Charge-offs		(1,368	)		—		(478	)		(1,278	)		(376	)		(2,101	)		(5,601	)
Recoveries		12			33		86			165			721			1,367			2,384
Net charge-offs		(1,356	)		33		(392	)		(1,113	)		345			(734	)		(3,217	)
Ending balance		10,269			770		13,374			20,097			5,408			1,009			50,927
Ending balance: individually evaluated for impairment		26			61		336			567			1,180			20			2,190
Ending balance: collectively evaluated for impairment	$	10,243		$	709	$	13,038		$	19,530		$	4,228		$	989		$	48,737
Loans:
Ending balance: individually evaluated for impairment		86			143		1,448			3,170			1,395			20			6,262
Ending balance: collectively evaluated for impairment		496,331			303,991		1,396,269			1,972,942			754,947			148,361			5,072,841
Ending balance	$	496,417		$	304,134	$	1,397,717		$	1,976,112		$	756,342		$	148,381		$	5,079,103

The following table details the recorded investment in loans and activity in the allowance for credit losses by portfolio segment for the year ended December 31, 2011. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.

	Construction and Land Development			Agriculture and Agriculture Real Estate		1-4 Family (includes Home Equity)			Commercial Real Estate (Commercial Mortgage and Multi-Family)			Commercial and Industrial			Consumer and Other			Total
	(Dollars in thousands)
Allowance for credit losses:
Beginning balance	$	12,994		$	271	$	12,837		$	20,436		$	3,891		$	1,155		$	51,584
Provision for credit losses		209			239		1,168			2,011			1,103			470			5,200
Charge-offs		(1,509	)		—		(1,392	)		(1,027	)		(1,694	)		(1,228	)		(6,850	)
Recoveries		400			1		32			40			526			661			1,660
Net charge-offs		(1,109	)		1		(1,360	)		(987	)		(1,168	)		(567	)		(5,190	)
Ending balance		12,094			511		12,645			21,460			3,826			1,058			51,594
Ending balance: individually evaluated for impairment		312			39		362			165			300			8			1,186
Ending balance: collectively evaluated for impairment	$	11,782		$	472	$	12,283		$	21,295		$	3,526		$	1,050		$	50,408
Loans:
Ending balance: individually evaluated for impairment		1,175			49		990			1,151			633			8			4,006
Ending balance: collectively evaluated for impairment		480,965			170,185		1,153,275			1,440,075			405,800			111,600			3,761,900
Ending balance	$	482,140		$	170,234	$	1,154,265		$	1,441,226		$	406,433		$	111,608		$	3,765,906

Schedule of Troubled Debt Restructurings Outstanding

The Company had the following troubled debt restructurings outstanding as of the dates indicated:

	As of September 30, 2012						As of December 31, 2011
	Number of Contracts		Pre- Modification Outstanding Recorded Investment		Post- Modification Outstanding Recorded Investment		Number of Contracts		Pre- Modification Outstanding Recorded Investment		Post- Modification Outstanding Recorded Investment
	(Dollars in thousands)
Troubled Debt Restructurings
Construction and land development		—	$	—	$	—		—	$	—	$	—
Agriculture and agriculture real estate		—		—		—		—		—		—
1-4 family (includes home equity)		4		109		66		4		109		84
Commercial real estate (commercial mortgage and multi-family)		1		2,560		2,469		2		5,264		5,171
Commercial and industrial		7		1,086		1,061		3		114		93
Consumer and other		—		—		—		—		—		—
Total		12	$	3,755	$	3,596		9	$	5,487	$	5,348

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Loans and Allowance for Credit Losses - Schedule of Past Due Loans and Nonperforming Assets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule Of Past Due Loans And Non performing Assets [Line Items]
Nonaccrual loans	$ 5,063	$ 3,578
Accruing Loans 90 or More Days Past Due	132
Total nonperforming loans	5,195	3,578
Repossessed assets	10	146
Other real estate	8,846	8,328
Total nonperforming assets	$ 14,051	$ 12,052
Nonperforming assets to total loans and other real estate	0.28%	0.32%

XML

GOODWILL AND CORE DEPOSIT INTANGIBLES (Tables)

9 Months Ended

Sep. 30, 2012

Schedule of Goodwill and Core Deposit Intangibles

Changes in the carrying amount of the Company’s goodwill and core deposit intangibles (CDI) for nine months ended September 30, 2012 were as follows:

	Goodwill		Core Deposit Intangibles
	(Dollars in thousands)
Balance as of December 31, 2011	$	924,537	$	20,996
Amortization		—		(5,297	)
Acquisition of Texas Bankers, Inc.		5,869		—
Acquisition of The Bank Arlington		3,013		—
Acquisition of American State Financial Corp.		266,679		12,393
Balance as of September 30, 2012	$	1,200,098	$	28,092

Schedule of Estimated Aggregate Future Amortization Expense for Intangible Assets

Remaining 2012	$	1,933
2013		6,186
2014		4,866
2015		4,219
2016		3,781
Thereafter		7,107
Total	$	28,092

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CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Cash dividends declared, per share	$ 0.195	$ 0.175	$ 0.585	$ 0.525

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CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Available for sale securities, amortized cost	$ 233,396	$ 301,589
Held to maturity securities, fair value	6,772,151	4,492,988
Core deposit intangibles, accumulated amortization	63,455	58,158
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued
Preferred stock, shares outstanding
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	56,095,248	46,947,415
Common stock, shares outstanding	56,058,160	46,910,327
Accumulated other comprehensive income - unrealized gain on available for sale securities, of tax	$ 5,947	$ 7,254
Treasury stock, shares	37,088	37,088

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CONTRACTUAL OBLIGATIONS AND OFF-BALANCE SHEET ITEMS

9 Months Ended

Sep. 30, 2012

CONTRACTUAL OBLIGATIONS AND OFF-BALANCE SHEET ITEMS

9. CONTRACTUAL OBLIGATIONS AND OFF-BALANCE SHEET ITEMS

Contractual Obligations

The following table summarizes the Company’s contractual obligations and other commitments to make future payments as of September 30, 2012 (other than deposit obligations). The payments do not include pre-payment options that may be available to the Company. The Company’s future cash payments associated with its contractual obligations pursuant to its junior subordinated debentures, FHLB borrowings and operating leases as of September 30, 2012 are summarized below. Payments for junior subordinated debentures include interest of $52.0 million that will be paid over the future periods. The future interest payments were calculated using the current rate in effect at September 30, 2012. The current principal balance of the junior subordinated debentures at September 30, 2012 was $85.1 million. Payments for FHLB borrowings include interest of $3.0 million that will be paid over the future periods. Payments related to leases are based on actual payments specified in underlying contracts.

	Payments due in:
	Remaining Fiscal 2012		Fiscal 2013-2014		Fiscal 2015-2016		Thereafter		Total
	(Dollars in thousands)
Junior subordinated debentures	$	1,222	$	4,888	$	4,888	$	126,017	$	137,015
Federal Home Loan Bank borrowings		100,282		3,258		3,456		8,001		114,997
Operating leases		1,324		8,547		4,013		759		14,643
Total	$	102,828	$	16,693	$	12,357	$	134,777	$	266,655

Off-Balance Sheet Items

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

The Company’s commitments associated with outstanding standby letters of credit and commitments to extend credit as of September 30, 2012 are summarized below. Since commitments associated with letters of credit and commitments to extend credit may expire unused, the amounts shown do not necessarily reflect the actual future cash funding requirements.

	Remaining Fiscal 2012		Fiscal 2013-2014		Fiscal 2015-2016		Thereafter		Total
	(Dollars in thousands)
Standby letters of credit	$	4,472	$	20,399	$	564	$	—	$	25,435
Commitments to extend credit		114,567		445,549		50,391		275,538		886,045
Total	$	119,039	$	465,948	$	50,955	$	275,538	$	911,480

XML

Document and Entity Information	9 Months Ended
	Sep. 30, 2012	Nov. 05, 2012
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q3
Trading Symbol	PB
Entity Registrant Name	PROSPERITY BANCSHARES INC
Entity Central Index Key	0001068851
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		56,430,192

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OTHER COMPREHENSIVE INCOME (LOSS)

9 Months Ended

Sep. 30, 2012

OTHER COMPREHENSIVE INCOME (LOSS)

10. OTHER COMPREHENSIVE (LOSS) INCOME

The tax effects allocated to each component of other comprehensive (loss) income were as follows (dollars in thousands):

	Three Months Ended September 30, 2012									Three Months Ended September 30, 2011
	Before Tax Amount			Tax Expense, (Benefit)			Net of Tax Amount			Before Tax Amount		Tax Expense, (Benefit)		Net of Tax Amount
Securities available for sale:
Change in net unrealized (loss) gain during the period	$	(718	)	$	(251	)	$	(467	)	$	632	$	222	$	410
Total other comprehensive (loss) income	$	(718	)	$	(251	)	$	(467	)	$	632	$	222	$	410
	Nine Months Ended September 30, 2012									Nine Months Ended September 30, 2011
	Before Tax Amount			Tax Expense, (Benefit)			Net of Tax Amount			Before Tax Amount		Tax Expense, (Benefit)		Net of Tax Amount
Securities available for sale:
Change in net unrealized (loss) gain during the period	$	(3,736	)	$	(1,308	)	$	(2,428	)	$	2,272	$	795	$	1,477
Total other comprehensive (loss) income	$	(3,736	)	$	(1,308	)	$	(2,428	)	$	2,272	$	795	$	1,477

Activity in accumulated other comprehensive income, net of tax, was as follows:

	Securities Available For Sale			Accumulated Other Comprehensive Income
	(Dollars in thousands)
Balance January 1, 2012	$	13,472		$	13,472
Other comprehensive (loss) income		(2,428	)		(2,428	)
Balance September 30, 2012	$	11,044		$	11,044
Balance as of January 1, 2011	$	14,304		$	14,304
Other comprehensive (loss) income		1,477			1,477
Balance September 30, 2011	$	15,781		$	15,781

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CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
INTEREST INCOME:
Loans, including fees	$ 80,587	$ 54,471	$ 188,597	$ 160,374
Securities	37,025	38,714	113,418	121,861
Federal funds sold	21	4	108	15
Total interest income	117,633	93,189	302,123	282,250
INTEREST EXPENSE:
Deposits	9,395	9,717	26,269	32,293
Junior subordinated debentures	651	607	1,962	2,352
Federal funds purchased and other borrowings	379	200	1,076	718
Securities sold under repurchase agreements	315	127	411	306
Total interest expense	10,740	10,651	29,718	35,669
NET INTEREST INCOME	106,893	82,538	272,405	246,581
Provision for credit losses	1,800	950	2,550	4,050
NET INTEREST INCOME AFTER PROVISION FOR CREDIT LOSSES	105,093	81,588	269,855	242,531
NONINTEREST INCOME:
Customer service fees	18,873	12,662	42,430	37,250
Other	4,955	1,919	8,999	4,728
Total noninterest income	23,828	14,581	51,429	41,978
NONINTEREST EXPENSE:
Salaries and employee benefits	36,701	23,601	83,525	70,799
Net occupancy	4,614	3,784	11,663	10,979
Debit card, data processing and software amortization	2,901	1,954	6,339	5,406
Core deposit intangible amortization	2,007	1,924	5,297	5,901
Depreciation	2,369	2,041	6,432	6,099
Other	11,650	7,847	28,233	26,176
Total noninterest expense	60,242	41,151	141,489	125,360
INCOME BEFORE INCOME TAXES	68,679	55,018	179,795	159,149
PROVISION FOR INCOME TAXES	22,503	18,645	60,160	53,806
NET INCOME AVAILABLE TO COMMON SHAREHOLDERS	$ 46,176	$ 36,373	$ 119,635	$ 105,343
EARNINGS PER SHARE
Basic	$ 0.83	$ 0.78	$ 2.38	$ 2.25
Diluted	$ 0.82	$ 0.77	$ 2.37	$ 2.24
DIVIDENDS PAID PER SHARE	$ 0.195	$ 0.175	$ 0.585	$ 0.525

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LOANS AND ALLOWANCE FOR CREDIT LOSSES

9 Months Ended

Sep. 30, 2012

LOANS AND ALLOWANCE FOR CREDIT LOSSES

4. LOANS AND ALLOWANCE FOR CREDIT LOSSES

Total loans were $5.08 billion at September 30, 2012, an increase of $1.31 billion or 34.9% compared with $3.77 billion at December 31, 2011. Loan growth was impacted by the acquisition of Texas Bankers, Inc., The Bank Arlington and American State Financial Corporation (“ASB”). The fair value of loans attributed to these acquisitions totaled $24.2 million, $21.8 million and $1.13 billion at September 30, 2012, respectively. The Company recorded a preliminary discount on loans of $104.9 million, of which $27.1 million related to purchased credit impaired loans accounted for under ASC Topic 310-30 (formerly SOP 03-03) and $77.8 million related to loans accounted for under ASC Topic 310-20 (formerly SFAS No. 91). Acquired loans included in the tables below are reported at fair value. See Note 11-Acquisitions for more information on acquired loans and purchased credit impaired loans.

The loan portfolio consists of various types of loans made principally to borrowers located in Bryan/College Station, Central Texas, Dallas/Fort Worth, East Texas, Houston, South Texas and West Texas and is classified by major type as follows:

	September 30, 2012		December 31, 2011
	(Dollars in thousands)
Commercial and industrial	$	756,342	$	406,433
Real estate:
Construction and land development		496,417		482,140
1-4 family residential(1)		1,213,873		1,007,266
Home equity		183,844		146,999
Commercial mortgage		1,837,224		1,351,986
Agriculture real estate		205,333		136,008
Multi-family residential		138,888		89,240
Agriculture		98,801		34,226
Consumer (net of unearned discount)		112,476		78,187
Other		35,905		33,421
Total	$	5,079,103	$	3,765,906

(1) Includes $4.3 million in loans held for sale carried at the lower of cost or market.

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

(ii) Commercial Mortgages. The Company makes commercial mortgage loans collateralized by owner-occupied and non-owner-occupied real estate to finance the purchase of real estate. The Company’s commercial mortgage loans are collateralized by first liens on real estate, typically have variable interest rates (or five year or less fixed rates) and amortize over a 15 to 20 year period. Payments on loans secured by such properties are often dependent on the successful operation or management of the properties. Accordingly, repayment of these loans may be subject to adverse conditions in the real estate market or the economy to a greater extent than other types of loans. The Company seeks to minimize these risks in a variety of ways, including giving careful consideration to the property’s operating history, future operating projections, current and projected occupancy, location and physical condition in connection with underwriting these loans. The underwriting analysis also includes credit verification, analysis of global cash flow, appraisals and a review of the financial condition of the borrower. At September 30, 2012, approximately 43.3% of the outstanding principal balance of the Company’s commercial real estate loans was secured by owner-occupied properties. At September 30, 2012, the Company had commercial real estate loans totaling $2.47 billion which include the categories of construction and land development loans, commercial mortgage loans and multi-family residential loans.

(iii) 1-4 Family Residential Loans. The Company originates 1-4 family residential mortgage loans collateralized by owner-occupied residential properties located in the Company’s market areas. The Company offers a variety of mortgage loan products which generally are amortized over five to 25 years. Loans collateralized by 1-4 family residential real estate generally have been originated in amounts of no more than 89% of appraised value or have mortgage insurance. The Company requires mortgage title insurance and hazard insurance. The Company has elected to keep all 1-4 family residential loans for its own account rather than selling such loans into the secondary market. By doing so, the Company is able to realize a higher yield on these loans; however, the Company also incurs interest rate risk as well as the risks associated with nonpayments on such loans.

(iv) Construction and Land Development Loans. The Company makes loans to finance the construction of residential and, to a lesser extent, nonresidential properties. Construction loans generally are collateralized by first liens on real estate and have floating interest rates. The Company conducts periodic inspections, either directly or through an agent, prior to approval of periodic draws on these loans. Underwriting guidelines similar to those described above are also used in the Company’s construction lending activities. Construction loans involve additional risks attributable to the fact that loan funds are advanced upon the security of a project under construction, and the project is of uncertain value prior to its completion. Because of uncertainties inherent in estimating construction costs, the market value of the completed project and the effects of governmental regulation on real property, it can be difficult to accurately evaluate the total funds required to complete a project and the related loan to value ratio. As a result of these uncertainties, construction lending often involves the disbursement of substantial funds with repayment dependent, in part, on the success of the ultimate project rather than the ability of a borrower or guarantor to repay the loan. If the Company is forced to foreclose on a project prior to completion, there is no assurance that the Company will be able to recover all of the unpaid portion of the loan. In addition, the Company may be required to fund additional amounts to complete a project and may have to hold the property for an indeterminate period of time. While the Company has underwriting procedures designed to identify what it believes to be acceptable levels of risks in construction lending, no assurance can be given that these procedures will prevent losses from the risks described above.

(v) Agriculture Loans and Farmland. The Company provides agriculture loans for short-term crop production, including rice, cotton, milo and corn, farm equipment financing and agriculture real estate financing. The Company evaluates agriculture borrowers primarily based on their historical profitability, level of experience in their particular agriculture industry, overall financial capacity and the availability of secondary collateral to withstand economic and natural variations common to the industry. Because agriculture loans present a higher level of risk associated with events caused by nature, the Company routinely makes on-site visits and inspections in order to identify and monitor such risks. The Company’s farmland loans are collateralized by first liens on real estate and typically have five to 15 year fixed rates.

(vi) Consumer Loans. Consumer loans made by the Company include direct credit automobile loans, recreational vehicle loans, boat loans, home improvement loans, home equity loans, personal loans (collateralized and uncollateralized) and deposit account collateralized loans. The terms of these loans typically range from 12 to 120 months and vary based upon the nature of collateral and size of loan. Generally, consumer loans present greater risk than do real estate secured loans, particularly in the case of consumer loans that are unsecured or collateralized by rapidly depreciating assets such as automobiles. In such cases, any repossessed collateral for a defaulted consumer loan may not provide an adequate source of repayment for the outstanding loan balance. The remaining deficiency often does not warrant further substantial collection efforts against the borrower beyond obtaining a deficiency judgment. In addition, consumer loan collections are dependent on the borrower’s continuing financial stability, and thus are more likely to be adversely affected by job loss, divorce, illness or personal bankruptcy. Furthermore, the application of various federal and state laws may limit the amount which can be recovered on such loans.

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

Concentrations of Credit. Most of the Company’s lending activity occurs within the State of Texas, including the four largest metropolitan areas of Austin, Dallas/Ft. Worth, Houston and San Antonio. The majority of the Company’s loan portfolio consists of commercial real estate loans, 1-4 family residential loans and commercial and industrial loans. As of September 30, 2012 and December 31, 2011, there were no concentrations of loans related to any single industry in excess of 10% of total loans.

Foreign Loans. The Company has U.S. dollar denominated loans and commitments to borrowers in Mexico. The outstanding balance of these loans and the unfunded amounts available under these commitments were not significant at September 30, 2012 or December 31, 2011.

Related Party Loans. As of September 30, 2012 and December 31, 2011, loans outstanding to directors, officers and their affiliates totaled $6.7 million and $9.8 million, respectively. All transactions entered into between the Company and such related parties are done in the ordinary course of business, made on the same terms and conditions as similar transactions with unaffiliated persons.

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

	For the Nine Months Ended September  30, 2012			For the Year Ended December 31, 2011
	(Dollars in thousands)
Beginning balance	$	9,809		$	12,783
New loans and reclassified related loans		736			4,168
Repayments		(3,851	)		(7,142	)
Ending balance	$	6,694		$	9,809

Nonaccrual and Past Due Loans. The Company has several procedures in place to assist it in maintaining the overall quality of its loan portfolio. The Company has established underwriting guidelines to be followed by its officers and the Company also monitors its delinquency levels for any negative or adverse trends. There can be no assurance, however, that the Company’s loan portfolio will not become subject to increasing pressures from deteriorating borrower credit due to general economic conditions.

The Company generally places a loan on nonaccrual status and ceases accruing interest when the payment of principal or interest is delinquent for 90 days, or earlier in some cases, unless the loan is in the process of collection and the underlying collateral fully supports the carrying value of the loan.

The Company requires appraisals on loans collateralized by real estate. With respect to potential problem loans, an evaluation of the borrower’s overall financial condition is made to determine the need, if any, for possible writedowns or appropriate additions to the allowance for credit losses.

As of the dates indicated, nonaccrual loans, segregated by class of loans, were as follows:

	September 30, 2012		December 31, 2011
	(Dollars in thousands)
Construction and land development	$	86	$	1,175
Agriculture and agriculture real estate		410		49
1-4 family (includes home equity)		1,694		923
Commercial real estate (commercial mortgage and multi-family residential)		1,292		790
Commercial and industrial		1,557		633
Consumer and other		24		8
Total	$	5,063	$	3,578

An age analysis of past due loans, segregated by class of loans, as of the dates indicated, was as follows:

	As of September 30, 2012
	Loans 30-89  Days Past Due		Loans 90 or  More Days Past Due		Total Past Due  Loans		Current Loans		Accruing Loans 90  or More Days Past Due
	(Dollars in thousands)
Construction and land development	$	5,157	$	86	$	5,243	$	491,174	$	—
Agriculture and agriculture real estate		1,772		362		2,134		302,000		—
1-4 family (includes home equity)		1,756		1,413		3,169		1,394,548		—
Commercial real estate (commercial mortgage and multi-family residential)		9,965		—		9,965		1,966,147		—
Commercial and industrial		4,211		426		4,637		751,705		132
Consumer and other		1,104		20		1,124		147,257		—
Total	$	23,965	$	2,307	$	26,272	$	5,052,831	$	132

	As of December 31, 2011
	Loans 30-89  Days Past Due		Loans 90 or  More Days Past Due		Total Past Due  Loans		Current Loans		Accruing Loans 90  or More Days Past Due
	(Dollars in thousands)
Construction and land development	$	1,281	$	111	$	1,392	$	480,748	$	—
Agriculture and agriculture real estate		365		9		374		169,860		—
1-4 family (includes home equity)		1,527		314		1,841		1,152,424		—
Commercial real estate (commercial mortgage and multi-family residential)		5,630		390		6,020		1,435,206		—
Commercial and industrial		1,544		394		1,938		404,495		—
Consumer and other		89		—		89		111,519		—
Total	$	10,436	$	1,218	$	11,654	$	3,754,252	$	—

The following table presents information regarding past due loans and nonperforming assets at the dates indicated:

	September 30, 2012			December 31, 2011
	(Dollars in thousands)
Nonaccrual loans	$	5,063		$	3,578
Accruing loans 90 or more days past due		132			—
Total nonperforming loans		5,195			3,578
Repossessed assets		10			146
Other real estate		8,846			8,328
Total nonperforming assets	$	14,051		$	12,052
Nonperforming assets to total loans and other real estate		0.28	%		0.32	%

The Company had $14.1 million in nonperforming assets at September 30, 2012 compared with $12.1 million at December 31, 2011. If interest on nonaccrual loans had been accrued under the original loan terms, approximately $252,000 and $156,000 would have been recorded as income for the nine months ended September 30, 2012 and 2011, respectively.

Impaired Loans. Loans are considered impaired when, based on current information and events, it is probable the Company will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreement, including scheduled principal and interest payments. Impairment is evaluated in total for smaller-balance loans of a similar nature and on an individual loan basis for other loans. If a loan is impaired, a specific valuation allowance is allocated, if necessary, so that the loan is reported net, at the present value of estimated future cash flows using the loan’s existing rate or at the fair value of collateral if repayment is expected solely from the collateral. 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 uncollectible.

Impaired loans as of September 30, 2012 are set forth in the following table. No interest income was recognized on impaired loans subsequent to their classification as impaired.

	September 30, 2012
	Recorded Investment		Unpaid Principal Balance		Related Allowance		Average Recorded Investment  Quarter to Date		Average Recorded Investment  Year to Date
	(Dollars in thousands)
With no related allowance recorded:
Construction and land development	$	60	$	61	$	—	$	143	$	168
Agriculture and agriculture real estate		77		77		—		41		23
1-4 family (includes home equity)		362		407		—		379		353
Commercial real estate (commercial mortgage and multi-family residential)		396		421		—		379		733
Commercial and industrial		157		158		—		80		69
Consumer and other		—		—		—		—		—
With an allowance recorded:
Construction and land development		26		26		26		64		564
Agriculture and agriculture real estate		66		72		61		52		47
1-4 family (includes home equity)		1,086		1,103		336		660		650
Commercial real estate (commercial mortgage and multi-family residential)		2,774		2,786		567		2,766		2,794
Commercial and industrial		1,238		1,547		1,180		869		717
Consumer and other		20		34		20		13		10
Total:
Construction and land development		86		87		26		207		732
Agriculture and agriculture real estate		143		149		61		93		70
1-4 family (includes home equity)		1,448		1,510		336		1,039		1,003
Commercial real estate (commercial mortgage and multi-family residential)		3,170		3,207		567		3,145		3,527
Commercial and industrial		1,395		1,705		1,180		949		786
Consumer and other		20		34		20		13		10

Impaired loans as of December 31, 2011 are set forth in the following table. No interest income was recognized on impaired loans subsequent to their classification as impaired. The average recorded investment is reported on a year-to-date basis.

	December 31, 2011
	Recorded Investment		Unpaid  Principal Balance		Related Allowance		Average  Recorded Investment
	(Dollars in thousands)
With no related allowance recorded:
Construction and land development	$	111	$	111	$	—	$	58
Agriculture and agriculture real estate		6		6		—		5
1-4 family (includes home equity)		313		344		—		291
Commercial real estate (commercial mortgage and multi-family residential)		668		705		—		637
Commercial and industrial		112		1,513		—		253
Consumer and other		—		—		—		3
With an allowance recorded:
Construction and land development		1,064		1,064		312		584
Agriculture and agriculture real estate		43		46		39		21
1-4 family (includes home equity)		677		731		362		663
Commercial real estate (commercial mortgage and multi-family residential)		483		485		165		309
Commercial and industrial		521		535		300		642
Consumer and other		8		20		8		18
Total:
Construction and land development		1,175		1,175		312		642
Agriculture and agriculture real estate		49		52		39		26
1-4 family (includes home equity)		990		1,075		362		954
Commercial real estate (commercial mortgage and multi-family residential)		1,151		1,190		165		946
Commercial and industrial		633		2,048		300		895
Consumer and other		8		20		8		21

Credit Quality Indicators. As part of the ongoing monitoring of the credit quality of the Company’s loan portfolio and methodology for calculating the allowance for credit losses, management assigns and tracks loan risk grades to be used as credit quality indicators. The following is a general description of the loan risk grades used (1-7):

Grade 1—Credits in this category are of the highest standards of credit quality with virtually no risk of loss. These borrowers would represent top rated companies and individuals with unquestionable financial standing with excellent global cash flow coverage, net worth, liquidity and collateral coverage and/or secured by CD/savings accounts.

Grade 2—Credits in this category are not immune from risk but are well-protected by the collateral and paying capacity of the borrower. These loans may exhibit a minor unfavorable credit factor, but the overall credit is sufficiently strong to minimize the possibility of loss.

Grade 3—Credits graded 3 constitute an undue and unwarranted credit risk, however the factors do not rise to a level of substandard. These credits have potential weaknesses and/or declining trends that, if not corrected, could expose the Bank to risk at a future date. Credits graded 3 are monitored on the Bank’s internally generated watch list and evaluated on a quarterly basis.

Grade 4—Credits in this category are deemed “substandard” loans in accordance with regulatory guidelines. Loans in this category have well-defined weakness that, if not corrected, could make default of principal and interest possible, but it is not yet certain. Loans in this category are still accruing interest and may be dependent upon secondary sources of repayment and/or collateral liquidation.

Grade 5—Credits in this category are deemed “substandard” and “impaired” pursuant to regulatory guidelines. As such, the Bank has determined that it is probable that less than 100% of the principal and interest will be collected. Loans graded 5 are individually evaluated for a specific reserve valuation and will typically have the accrual of interest stopped.

Grade 6—Credits in this category include “doubtful” loans in accordance with regulatory guidance. Such loans are on nonaccrual and factors have indicated a loss is imminent. These loans are also deemed “impaired.” While a specific reserve may be in place while the loan and collateral is being evaluated these loans are typically charged down to an amount the Bank deems can be collected.

Grade 7—Credits in this category are deemed a “loss” in accordance with regulatory guidelines and charged off or charged down. The Bank may continue collection efforts and may have partial recovery in the future.

The following table presents loan risk grades and classified loans by class of loan at September 30, 2012. Classified loans include loans in risk grades 5, 6 and 7.

	Construction and Land Development		Agriculture and Agriculture Real Estate		1-4 Family (Includes Home Equity)		Commercial Real Estate (Commercial Mortgage and Multi- Family)		Commercial and Industrial		Consumer and Other		Total
	(Dollars in thousands)
Grade 1	$	—	$	2,601	$	—	$	—	$	45,371	$	28,269	$	76,241
Grade 2		482,385		297,231		1,384,513		1,930,565		695,762		119,392		4,909,848
Grade 3		8,351		2,128		6,617		9,163		8,206		—		34,465
Grade 4		5,595		2,031		5,139		33,214		5,608		700		52,287
Grade 5		86		143		1,435		3,170		1,393		20		6,247
Grade 6		—		—		13		—		2		—		15
Grade 7		—		—		—		—		—		—		—
Total	$	496,417	$	304,134	$	1,397,717	$	1,976,112	$	756,342	$	148,381	$	5,079,103

The following table presents risk grades and classified loans by class of loan at December 31, 2011. Classified loans include loans in risk grades 5, 6 and 7.

	Construction and Land Development		Agriculture and Agriculture Real Estate		1-4 Family (Includes Home Equity)		Commercial Real Estate (Commercial Mortgage and Multi- Family)		Commercial and Industrial		Consumer and Other		Total
	(Dollars in thousands)
Grade 1	$	—	$	3,319	$	—	$	—	$	45,218	$	31,602	$	80,139
Grade 2		465,572		166,656		1,140,210		1,399,915		355,862		79,996		3,608,211
Grade 3		1,757		210		9,131		14,335		4,189		—		29,622
Grade 4		13,636		—		3,934		25,825		531		2		43,928
Grade 5		1,175		49		970		1,151		532		8		3,885
Grade 6		—		—		20		—		101		—		121
Grade 7		—		—		—		—		—		—		—
Total	$	482,140	$	170,234	$	1,154,265	$	1,441,226	$	406,433	$	111,608	$	3,765,906

Net charge-offs/recoveries, segregated by class of loans, for the three and nine months ended September 30, 2012 and 2011 were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2012			2011			2012			2011
Construction and land development	$	(155	)	$	197		$	(1,356	)	$	(955	)
1-4 family (includes home equity)		(251	)		(134	)		(392	)		(517	)
Commercial real estate and agriculture (includes multi-family)		(770	)		(271	)		(1,080	)		(768	)
Commercial and industrial		511			(7	)		345			(492	)
Consumer and other		(590	)		(153	)		(734	)		(389	)
Total	$	(1,255	)	$	(368	)	$	(3,217	)	$	(3,121	)

Allowance for Credit Losses. The allowance for credit losses is a valuation established through charges to earnings in the form of a provision for credit losses. Management has established an allowance for credit losses which it believes is adequate for estimated losses in the Company’s loan portfolio. The amount of the allowance for credit losses is affected by the following: (i) charge-offs of loans that occur when loans are deemed uncollectible and decrease the allowance, (ii) recoveries on loans previously charged off that increase the allowance and (iii) provisions for credit losses charged to earnings that increase the allowance. Based on an evaluation of the loan portfolio and consideration of the factors listed below, management presents a quarterly review of the allowance for credit losses to the Bank’s Board of Directors, indicating any change in the allowance since the last review and any recommendations as to adjustments in the allowance.

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

In setting the specific valuation allowance, the Company follows a loan review program to evaluate the credit risk in the loan portfolio. Through this loan review process, the Company maintains an internal list of impaired loans which, along with the delinquency list of loans, helps management assess the overall quality of the loan portfolio and the adequacy of the allowance for credit losses. All loans that have been identified as impaired are reviewed on a quarterly basis in order to determine whether a specific reserve is required. For each impaired loan, the Company allocates a specific loan loss reserve primarily based on the value of the collateral securing the impaired loan in accordance with ASC Topic 310, Receivables. The specific reserves are determined on an individual loan basis. Loans for which specific reserves are provided are excluded from the general valuation allowance described below.

In determining the amount of the general valuation allowance, management considers factors such as historical loan loss experience, industry diversification of the Company’s commercial loan portfolio, concentration risk of specific loan types, the volume, growth and composition of the Company’s loan portfolio, current economic conditions that may affect the borrower’s ability to pay and the value of collateral, the evaluation of the Company’s loan portfolio through its internal loan review process, general economic conditions and other qualitative risk factors both internal and external to the Company and other relevant factors in accordance with ASC Topic 450, Contingencies. Based on a review of these factors for each loan type, the Company applies an estimated percentage to the outstanding balance of each loan type, excluding any loan that has a specific reserve allocated to it. The Company uses this information to establish the amount of the general valuation allowance.

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

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

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

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

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

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

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

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

At September 30, 2012, the allowance for credit losses totaled $50.9 million or 1.00% of total loans. At December 31, 2011, the allowance aggregated $51.6 million or 1.37% of total loans.

The following table details the recorded investment in loans and activity in the allowance for credit losses by portfolio segment for the nine months ended September 30, 2012. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.

	Construction and Land Development			Agriculture and Agriculture Real Estate		1-4 Family (includes Home Equity)			Commercial Real Estate (Commercial Mortgage and Multi-Family)			Commercial and Industrial			Consumer and Other			Total
	(Dollars in thousands)
Allowance for credit losses:
Beginning balance	$	12,094		$	511	$	12,645		$	21,460		$	3,826		$	1,058		$	51,594
Provision for credit losses		(469	)		226		1,121			(250	)		1,237			685			2,550
Charge-offs		(1,368	)		—		(478	)		(1,278	)		(376	)		(2,101	)		(5,601	)
Recoveries		12			33		86			165			721			1,367			2,384
Net charge-offs		(1,356	)		33		(392	)		(1,113	)		345			(734	)		(3,217	)
Ending balance		10,269			770		13,374			20,097			5,408			1,009			50,927
Ending balance: individually evaluated for impairment		26			61		336			567			1,180			20			2,190
Ending balance: collectively evaluated for impairment	$	10,243		$	709	$	13,038		$	19,530		$	4,228		$	989		$	48,737
Loans:
Ending balance: individually evaluated for impairment		86			143		1,448			3,170			1,395			20			6,262
Ending balance: collectively evaluated for impairment		496,331			303,991		1,396,269			1,972,942			754,947			148,361			5,072,841
Ending balance	$	496,417		$	304,134	$	1,397,717		$	1,976,112		$	756,342		$	148,381		$	5,079,103

The following table details the recorded investment in loans and activity in the allowance for credit losses by portfolio segment for the year ended December 31, 2011. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.

	Construction and Land Development			Agriculture and Agriculture Real Estate		1-4 Family (includes Home Equity)			Commercial Real Estate (Commercial Mortgage and Multi-Family)			Commercial and Industrial			Consumer and Other			Total
	(Dollars in thousands)
Allowance for credit losses:
Beginning balance	$	12,994		$	271	$	12,837		$	20,436		$	3,891		$	1,155		$	51,584
Provision for credit losses		209			239		1,168			2,011			1,103			470			5,200
Charge-offs		(1,509	)		—		(1,392	)		(1,027	)		(1,694	)		(1,228	)		(6,850	)
Recoveries		400			1		32			40			526			661			1,660
Net charge-offs		(1,109	)		1		(1,360	)		(987	)		(1,168	)		(567	)		(5,190	)
Ending balance		12,094			511		12,645			21,460			3,826			1,058			51,594
Ending balance: individually evaluated for impairment		312			39		362			165			300			8			1,186
Ending balance: collectively evaluated for impairment	$	11,782		$	472	$	12,283		$	21,295		$	3,526		$	1,050		$	50,408
Loans:
Ending balance: individually evaluated for impairment		1,175			49		990			1,151			633			8			4,006
Ending balance: collectively evaluated for impairment		480,965			170,185		1,153,275			1,440,075			405,800			111,600			3,761,900
Ending balance	$	482,140		$	170,234	$	1,154,265		$	1,441,226		$	406,433		$	111,608		$	3,765,906

Troubled Debt Restructurings. The restructuring of a loan is considered a “troubled debt restructuring” if both (i) the borrower is experiencing financial difficulties and (ii) the creditor has granted a concession. Concessions may include interest rate reductions or below market interest rates, principal forgiveness, restructuring amortization schedules and other actions intended to minimize potential losses. Effective July 1, 2011, the Company adopted the provisions of ASU No. 2011-02, “Receivables (Topic 310)—A Creditor’s Determination of Whether a Restructuring Is a Troubled Debt Restructuring.” As such, the Company reassessed all loan modifications occurring since January 1, 2011 for identification as troubled debt restructurings.

The Company had the following troubled debt restructurings outstanding as of the dates indicated:

	As of September 30, 2012						As of December 31, 2011
	Number of Contracts		Pre- Modification Outstanding Recorded Investment		Post- Modification Outstanding Recorded Investment		Number of Contracts		Pre- Modification Outstanding Recorded Investment		Post- Modification Outstanding Recorded Investment
	(Dollars in thousands)
Troubled Debt Restructurings
Construction and land development		—	$	—	$	—		—	$	—	$	—
Agriculture and agriculture real estate		—		—		—		—		—		—
1-4 family (includes home equity)		4		109		66		4		109		84
Commercial real estate (commercial mortgage and multi-family)		1		2,560		2,469		2		5,264		5,171
Commercial and industrial		7		1,086		1,061		3		114		93
Consumer and other		—		—		—		—		—		—
Total		12	$	3,755	$	3,596		9	$	5,487	$	5,348

As of September 30, 2012, there have been no defaults on any loans that were modified as troubled debt restructurings during the preceding twelve months. Default is determined at 90 or more days past due. The modifications primarily related to extending the amortization periods of the loans, which may include loans modified during bankruptcy. The Company did not grant principal reductions on any restructured loan. Loans restructured during the nine months ended September 30, 2012 on non-accrual status as of September 30, 2012 totaled $972,000. The remaining restructured loans are performing and accruing loans. These modifications did not have a material impact on the Company’s determination of the allowance for credit losses.

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NEW ACCOUNTING STANDARDS

9 Months Ended

Sep. 30, 2012

NEW ACCOUNTING STANDARDS

3. NEW ACCOUNTING STANDARDS

Accounting Standards Updates

ASU 2011-03, “Transfers and Servicing (Topic 860)—Reconsideration of Effective Control for Repurchase Agreements.” ASU 2011-03 is intended to improve financial reporting of repurchase agreements and other agreements that both entitle and obligate a transferor to repurchase or redeem financial assets before their maturity. ASU 2011-03 removes from the assessment of effective control (i) the criterion requiring the transferor to have the ability to repurchase or redeem the financial assets on substantially the agreed terms, even in the event of default by the transferee, and (ii) the collateral maintenance guidance related to that criterion. ASU 2011-03 became effective for the Company on January 1, 2012 and did not have a significant impact on the Company’s financial statements.

ASU 2011-04, “Fair Value Measurement (Topic 820)—Amendments to Achieve Common Fair Value Measurements and Disclosure Requirements in U.S. GAAP and IFRSs.” ASU 2011-04 amends Topic 820, “Fair Value Measurements and Disclosures,” to converge the fair value measurement guidance in U.S. generally accepted accounting principles and International Financial Reporting Standards. ASU 2011-04 clarifies the application of existing fair value measurement requirements, changes certain principles in Topic 820 and requires additional fair value disclosures. ASU 2011-04 became effective for the Company on January 1, 2012 and did not have a significant impact on the Company’s financial statements (see Note 5-Fair Value).

ASU 2011-05, “Comprehensive Income (Topic 220)—Presentation of Comprehensive Income.” ASU 2011-05 amends Topic 220, “Comprehensive Income,” to require that all non-owner changes in stockholders’ equity be presented in either a single continuous statement of comprehensive income or in two separate but consecutive statements. Additionally, ASU 2011-05 requires entities to present, on the face of the financial statements, reclassification adjustments for items that are reclassified from other comprehensive income to net income in the statement or statements where the components of net income and the components of other comprehensive income are presented. The option to present components of other comprehensive income as part of the statement of changes in stockholders’ equity was eliminated. ASU 2011-05 became effective for the Company on January 1, 2012; however, certain provisions related to the presentation of reclassification adjustments have been deferred by ASU 2011-12 “Comprehensive Income (Topic 220)—Deferral of the Effective Date for Amendments to the Presentation of Reclassifications of Items Out of Accumulated Other Comprehensive Income in Accounting Standards Update No. 2011-05,” as further discussed below. In connection with the application of ASU 2011-05, the Company’s financial statements now include a separate statement of comprehensive income.

ASU 2011-08, “Intangibles—Goodwill and Other (Topic 350)—Testing Goodwill for Impairment.” ASU 2011-08 amends Topic 350, “Intangibles—Goodwill and Other,” to give entities the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, after assessing the totality of events or circumstances, an entity determines it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, then performing the two-step impairment test is unnecessary. However, if an entity concludes otherwise, then it is required to perform the first step of the two-step impairment test by calculating the fair value of the reporting unit and comparing the fair value with the carrying amount of the reporting unit. ASU 2011-08 became effective for the Company on January 1, 2012 and its adoption did not have a significant impact on its financial statements.

ASU 2011-11, “Balance Sheet (Topic 210)—“Disclosures about Offsetting Assets and Liabilities.” ASU 2011-11 amends Topic 210, “Balance Sheet,” to require an entity to disclose both gross and net information about financial instruments, such as sales and repurchase agreements and reverse sale and repurchase agreements and securities borrowing/lending arrangements, and derivative instruments that are eligible for offset in the statement of financial position and/or subject to a master netting arrangement or similar agreement. ASU 2011-11 is effective for annual and interim periods beginning on January 1, 2013, and is not expected to have a significant impact on the Company’s financial statements.

ASU 2011-12 “Comprehensive Income (Topic 220)—Deferral of the Effective Date for Amendments to the Presentation of Reclassifications of Items Out of Accumulated Other Comprehensive Income in Accounting Standards Update No. 2011-05.” ASU 2011-12 defers changes in ASU 2011-05 that relate to the presentation of reclassification adjustments to allow the FASB time to redeliberate whether to require presentation of such adjustments on the face of the financial statements to show the effects of reclassifications out of accumulated other comprehensive income on the components of net income and other comprehensive income. ASU 2011-12 allows entities to continue to report reclassifications out of accumulated other comprehensive income consistent with the presentation requirements in effect before ASU 2011-05. All other requirements in ASU 2011-05 are not affected by ASU 2011-12. ASU 2011-12 became effective for the Company on January 1, 2012. In connection with the application of ASU 2011-05, the Company’s financial statements now include a separate statement of comprehensive income.

ASU 2012-02 “Intangibles—Goodwill and Other (Topic 350)—Testing Indefinite-Lived Intangible Assets for Impairment.” ASU 2012-02 give entities the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that an indefinite-lived intangible asset is impaired. If, after assessing the totality of events or circumstances, an entity determines it is more likely than not that an indefinite-lived intangible asset is impaired, then the entity must perform the quantitative impairment test. If, under the quantitative impairment test, the carrying amount of the intangible asset exceeds its fair value, an entity should recognize an impairment loss in the amount of that excess. Permitting an entity to assess qualitative factors when testing indefinite-lived intangible assets for impairment results in guidance that is similar to the goodwill impairment testing guidance in ASU 2011-08. ASU 2012-02 is effective for the Company beginning January 1, 2013 (early adoption permitted) and is not expected to have a significant impact on the Company’s financial statements.

ASU 2012-03 “Technical Amendments and Corrections to SEC Sections—Amendments to SEC Paragraphs Pursuant to SEC Staff Bulletin No. 114, Technical Amendments Pursuant to SEC Release No. 33-9250, and Corrections Related to FASB Accounting Standards Update 2010-22.” ASU 2012-03 amends a number of SEC sections in the ASC as a result of (1) the issuance of SAB 114, (2) the issuance of SEC Final Rule 33-9250, and (3) necessary corrections related to ASU 2010-22. ASU 2012-03 is effective for the Company beginning January 1, 2013 and is not expected to have a significant impact on the Company’s financial statements.

ASU 2012-04 “Technical Corrections and Improvements.” ASU 2012-04 makes certain technical corrections and “conforming fair value amendments” to the FASB Accounting Standards Codification (the “Codification”). The amendments cover a wide range of Topics in the Codification, related to technical corrections and improvements and conforming amendments related to fair value measurements. The amendments represent changes to clarify the Codification, correct unintended application of guidance, or make minor improvements to the Codification that are not expected to have a significant effect on current accounting practice. The amendments apply to all reporting entities within the scope of those topics. ASU 2012-04 is effective for the Company beginning January 1, 2013 and is not expected to have a significant impact on the Company’s financial statements.

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FAIR VALUE DISCLOSURES (Tables)

9 Months Ended

Sep. 30, 2012

Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis

The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of September 30, 2012 and December 31, 2011, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value:

	September 30, 2012
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Available for sale securities (at fair value):
States and political subdivisions	$	—	$	37,188	$	—	$	37,188
Corporate debt securities and other		7,747		1,553		—		9,300
Collateralized mortgage obligations		—		638		—		638
Mortgage-backed securities		—		203,261		—		203,261
Total	$	7,747	$	242,640	$	—	$	250,387
	December 31, 2011
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Available for sale securities (at fair value):
States and political subdivisions	$	—	$	39,076	$	—	$	39,076
Corporate debt securities and other		7,656		1,613		—		9,269
Collateralized mortgage obligations		—		765		—		765
Mortgage-backed securities		—		273,206		—		273,206
Total	$	7,656	$	314,660	$	—	$	322,316

Summary of Financial Assets and Liabilities Measured on Non-Recurring Basis

All fair value measurements for remaining financial assets and financial liabilities utilized Level 2 inputs based on observable market data. The carrying amount and estimated fair value of the Company’s financial instruments, as of the dates indicated, are as follows:

	September 30, 2012				December 31, 2011
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
	(Dollars in thousands)
Financial Assets:
Cash and due from banks	$	207,401	$	207,401	$	212,800	$	212,800
Federal funds sold		302		302		642		642
Interest-bearing time deposits in other financial institutions		249		249		—		—
Held to maturity securities		6,549,126		6,772,151		4,336,620		4,492,988
Available for sale securities		250,387		250,387		322,316		322,316
Loans held for sale		4,332		4,332		—		—
Loans held for investment, net of allowance for credit losses		5,023,844		5,098,007		3,714,312		3,814,858
Total	$	12,035,641	$	12,332,829	$	8,586,690	$	8,843,604
Financial liabilities:
Deposits	$	10,954,597	$	10,971,925	$	8,060,254	$	8,074,093
Junior subordinated debentures		85,055		72,242		85,055		71,001
Other borrowings		112,017		114,170		12,790		14,974
Securities sold under repurchase agreements		443,856		443,976		54,883		54,883
Total	$	11,595,525	$	11,602,313	$	8,212,982	$	8,214,951

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ACQUISITIONS

9 Months Ended

Sep. 30, 2012

ACQUISITIONS

11. ACQUISITIONS

Acquisition of American State Financial Corporation—On July 1, 2012, the Company completed the previously announced acquisition of American State Financial Corporation and its wholly owned subsidiary American State Bank (collectively referred to as “ASB”). ASB operated thirty-seven (37) full service banking offices in eighteen (18) counties across West Texas.

As of June 30, 2012, ASB, on a consolidated basis, reported total assets of $3.16 billion, total loans of $1.24 billion and total deposits of $2.51 billion. Under the terms of the merger agreement, the Company issued 8,524,835 shares of Company common stock plus $178.5 million in cash for all outstanding shares of American State Financial Corporation capital stock, for total merger consideration of $536.8 million and an initial premium of $240.4 million.

The acquisition was accounted for under the acquisition method of accounting. Under this method of accounting, the identifiable assets acquired and assumed liabilities were recorded at their estimated fair value as of the date of the acquisition. Accordingly, the results of operations of the acquired company have been included in the Company’s results of operations since the date of acquisition.

FAIR VALUE: The measurement period for the Company to determine the fair values of acquired identifiable assets and assumed liabilities will end at the earlier of (i) twelve months from the date of the acquisition or (ii) as soon as the Company receives the information it was seeking about facts and circumstances that existed as of the acquisition date or learns that more information is not obtainable. The Company is currently in the process of obtaining fair values for certain acquired assets and assumed liabilities and therefore the following estimates are preliminary.

	As of July 1, 2012
	(In thousands)
Cash and due from banks	$	98,720
Federal funds sold		202,810
Total cash and cash equivalents		301,530
Securities available for sale		524,959
Securities held to maturity		994,873
Loans held for sale		13,770
Loans held for investment		1,133,867
Bank premises and equipment		36,502
Other real estate owned		1,232
Goodwill		266,679
Core deposit intangibles		12,393
Federal Home Loan Bank stock		2,355
Other assets		91,242
Total assets acquired	$	3,379,402
Deposits		2,495,652
Other borrowings		318,692
Other liabilities		28,252
Total liabilities assumed		2,842,596
Common stock and capital surplus		536,806
Total liabilities assumed and shareholders’ equity	$	3,379,402

The Company recognized goodwill of $266.7 million which is calculated as the excess of both the consideration exchanged and liabilities assumed as compared to the fair value of identifiable assets acquired. Goodwill resulted from a combination of expected operational synergies, an enhanced branching network, and cross-selling opportunities. Goodwill is not expected to be deductible for tax purposes while the core deposit intangible is expected to be deductible over 10 years.

MERGER RELATED EXPENSES AND PRO FORMA INFORMATION: For the three and nine months ended September 30, 2012, the Company incurred $5.1 million and $5.4 million of pre-tax merger related expenses related to the ASB acquisition, respectively and estimates total merger related expenses will range from $5.4 to $6.0 million, pre-tax. The merger expenses are reflected on the Company’s income statement for the applicable periods and are reported primarily in the categories of salaries and benefits, data processing and professional fees.

Operations of ASB have been included in the consolidated financial statements since July 1, 2012. The Company does not consider ASB a separate reporting segment and does not track the amount of revenue and net income attributable to ASB since acquisition. As such, it is impracticable to determine such amounts for the three and nine months ended September 30, 2012.

The following pro forma information presents the results of operations for the three and nine months ended September 30, 2012 and 2011, as if the ASB acquisition had occurred on January 1, 2011. The previously completed acquisitions of Texas Bankers, Inc. and The Bank Arlington are not deemed material in the aggregate and are therefore excluded from the pro forma information in the table below.

	Three Months Ended				Nine Months Ended
	September 30				September 30
	2012		2011		2012		2011
	(Dollars in thousands, except per share data)
Net interest income	$	106,893	$	113,858	$	336,249	$	337,096
Net income	$	49,479	$	48,081	$	163,333	$	149,425
Basic earnings per share	$	0.88	$	0.87	$	2.78	$	2.70
Diluted earnings per share	$	0.88	$	0.87	$	2.77	$	2.69

The above pro forma results are presented for illustrative purposes and are not intended to represent or be indicative of the actual results of operations of the merged companies that would have been achieved had the acquisition occurred at January 1, 2011, nor are they intended to represent or be indicative of future results of operations. These pro forma results require significant estimates and judgments particularly as it relates to accretion of income associated with acquired loans. Pro forma adjustments principally included:

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

• Reversing depreciation and amortization expense recorded by ASB and reporting depreciation and amortization based on estimated fair values and remaining lives of acquired premises, equipment, and leasehold improvements.

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

• Reporting acquisition-related charges and professional fees related to the acquisition as if they were incurred in 2011.

ACQUIRED LOANS AND PURCHASE CREDIT IMPAIRED LOANS: Acquired loans were preliminarily recorded at fair value based on a discounted cash flow valuation methodology that considers, among other things, projected default rates, loss given defaults and recovery rates. No allowance for credit losses was carried over from ASB.

The Company has identified certain loans which have experienced credit deterioration since origination (“purchased credit impaired loans” or “PCI loans”). PCI loan identification considers the following factors: payment history and past due status, debt service coverage, loan grading, collateral values and other factors that may indicate deterioration of credit quality since origination. Accretion of purchased discounts on PCI loans will be based on estimated future cash flows, regardless of contractual maturities. Accretion of purchased discounts on non-PCI loans will be recognized on a level-yield basis based on contractual maturity of individual loans per ASC Topic 310-30. See Note 4—Loans.

The following table discloses the preliminary fair value and contractual value of loans acquired as of July 1, 2012:

	Purchased Credit Impaired Loans		Non-PCI Loans		Total Acquired Loans
	(Dollars in thousands)
Commercial and industrial	$	3,568	$	221,341	$	224,909
Real estate
Construction and land development		1,326		112,011		113,337
1-4 family residential		155		126,954		127,109
Home equity		—		24,851		24,851
Commercial mortgage		22,454		460,378		482,832
Agriculture real estate		—		53,979		53,979
Multi-family residential		—		48,423		48,423
Agriculture		78		—		78
Consumer		—		72,119		72,119
Other		—		—		—
Total fair value	$	27,581	$	1,120,056	$	1,147,637
Contractual principal balance	$	54,403	$	1,195,741	$	1,250,144

The following presents additional information on purchased credit impaired loans (dollars in thousands):

Contractually required principal and interest	$	60,167
Non-accretable difference		(24,429	)
Cash flows expected to be collected		35,738
Accretable difference		(8,157	)
Fair value of purchased credit impaired loans	$	27,581

The process for identifying, valuing and determining pools (if any) of the loans that were (or may be) considered PCI loans as of the acquisition date remains on-going. Income recognition on PCI loans is subject to the Company’s ability to reasonably estimate both the timing and amount of future cash flows. PCI loans for which the Company is accruing interest income are not considered non-performing or impaired. The non-accretable difference represents contractual principal and interest the Company does not expect to collect.

Acquisition of The Bank Arlington—On April 1, 2012, the Company completed the previously announced acquisition of The Bank Arlington. The Bank Arlington operated one banking office in Arlington, Texas, in the Dallas/Fort Worth CMSA. The Company acquired The Bank Arlington to increase its market share in the Dallas/Fort Worth area. The acquisition is not considered significant to the Company’s financial statements and therefore pro forma financial data and related disclosures are not included. The Company incurred approximately $163,000 in expense related to this acquisition which is primarily recorded in legal and professional fees and data processing.

As of March 31, 2012, The Bank Arlington reported total assets of $37.3 million, total loans of $22.8 million and total deposits of $33.2 million. Under the terms of the agreement, the Company issued 135,347 shares of Company common stock for all outstanding shares of The Bank Arlington capital stock, which resulted in an initial premium of $2.8 million.

Acquisition of Texas Bankers, Inc.—On January 1, 2012, the Company completed the previously announced acquisition of Texas Bankers, Inc. and its wholly-owned subsidiary, Bank of Texas, Austin, Texas. The three (3) Bank of Texas banking offices in the Austin, Texas CMSA consisted of a location in Rollingwood, which was consolidated with the Company’s Westlake location and remains in Bank of Texas’ Rollingwood banking office; one banking center in downtown Austin, which was consolidated into the Company’s downtown Austin location; and another banking center in Thorndale. The Company acquired Texas Bankers, Inc. to increase is its market share in the Central Texas area. The acquisition is not considered significant to the Company’s financial statements and therefore pro forma financial data and related disclosures are not included. The Company incurred approximately $352,000 in expense related to this acquisition which is primarily recorded in legal and professional fees and data processing.

Texas Bankers, Inc. on a consolidated basis, reported total assets of $77.0 million, total loans of $27.6 million and total deposits of $70.4 million as of December 31, 2011. Under the terms of the agreement, the Company issued 314,953 shares of Company common stock for all outstanding shares of Texas Bankers capital stock, which resulted in an initial premium of $5.2 million.

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STOCK BASED COMPENSATION

9 Months Ended

Sep. 30, 2012

STOCK BASED COMPENSATION

7. STOCK BASED COMPENSATION

At September 30, 2012, the Company had four stock-based employee compensation plans and one stock option plan assumed in connection with an acquisition under which no additional options will be granted. Two of the four plans adopted by the Company have expired and therefore no additional awards may be issued under those plans. The Company accounts for stock-based employee compensation plans using the fair value-based method of accounting in accordance with ASC Topic 718. ASC Topic 718 was effective for companies in 2006; however, the Company has been recognizing compensation expense since January 1, 2003. The Company recognized $1.1 million and $961,000 in stock-based compensation expense for the three months ended September 30, 2012 and 2011, respectively, and $3.2 million and $2.6 million in stock-based compensation expense for the nine months ended September 30, 2012 and 2011, respectively. There was approximately $364,000 and $322,000 of income tax benefit recorded for the stock-based compensation expense for the three months ended September 30, 2012 and 2011, respectively, and $1.1 million and $870,000 of income tax benefit recorded for the stock-based compensation expense for the nine months ended September 30, 2012 and 2011, respectively.

On February 22, 2012, the Company’s Board of Directors adopted the Prosperity Bancshares, Inc. 2012 Stock Incentive Plan (the “2012 Plan”), subject to approval by the Company’s shareholders. The Company’s shareholders approved the 2012 Plan at the annual meeting of shareholders on April 17, 2012. The 2012 Plan authorizes the issuance of up to 1,250,000 shares of common stock upon the exercise of options granted under the 2012 Plan or pursuant to the grant or exercise, as the case may be, of other awards granted under the 2012 Plan, including restricted stock, stock appreciation rights, phantom stock awards and performance awards. As of September 30, 2012, no options or other awards have been granted under the 2012 Plan.

During 2004, the Company’s Board of Directors adopted the Prosperity Bancshares, Inc. 2004 Stock Incentive Plan (the “2004 Plan”) which authorizes the issuance of up to 1,250,000 shares of common stock pursuant to the exercise or grant, as the case may be, of awards under such plan and the shareholders approved the 2004 Plan in 2005. The Company has granted shares with forfeiture restrictions (“restricted stock”) to certain directors, officers and associates under the 2004 Plan. The awardee is not entitled to the shares until they vest, which is generally over a one to five year period, but the awardee is entitled to receive dividends on and vote the shares prior to vesting. The shares granted do not have a cost to the awardee and the only requirement of vesting is continued service to the Company. Compensation cost related to restricted stock is calculated based on the fair value of the shares at the date of grant. If the awardee leaves the Company before the shares vest, the unvested shares are forfeited. Options to purchase a total of 162,250 shares of common stock of the Company granted under the 2004 Plan were outstanding at September 30, 2012, of which 98,375 were exercisable. As of September 30, 2012, there were 446,146 shares of restricted stock outstanding with a weighted average grant date fair value of $38.06 per share. Remaining shares available for grant under the 2004 Plan totaled 477,625 at September 30, 2012.

Stock options are issued at the current market price on the date of the grant, subject to a pre-determined vesting period with a contractual term of 10 years. Options assumed in connection with acquisitions have contractual terms as established in the original option grant agreements entered into prior to acquisition. The fair value of stock options granted is estimated at the date of grant using the Black-Scholes option-pricing model. Stock-based compensation expense is recognized ratably over the requisite service period for all awards.

The fair value of options was estimated using an option-pricing model with the following weighted average assumptions:

	September 30,
	2012			2011
Expected life in years		5.26			5.30
Risk free interest rate		3.67	%		3.67	%
Volatility		20.84	%		20.98	%
Dividend yield		1.26	%		1.25	%

A summary of changes in outstanding vested and unvested options during the nine months ended September 30, 2012 is set forth below:

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
	(In thousands)					(In years)		(In thousands)
Options outstanding, beginning of period		525		$	28.18
Options granted		—			—
Options forfeited		(6	)		31.63
Options exercised		(99	)		27.03
Options outstanding, end of period		420		$	28.36		3.36	$	5,982
Options vested or expected to vest		407		$	27.98		3.32	$	5,956
Options exercisable, end of period		280		$	27.62		2.83	$	4,198

No options were granted during the nine months ended September 30, 2012 and 2011. The total intrinsic value of the options exercised during the nine month periods ended September 30, 2012 and 2011 was $1.8 million and $1.4 million, respectively. The total fair value of options vested during the nine month periods ended September 30, 2012 and 2011 was $234,000 and $368,000, respectively.

A summary of changes in unvested options is set forth below:

	Nine Months Ended September 30,
	2012					2011
	Number of Options			Weighted Average Grant Date Fair Value		Number of Options			Weighted Average Grant Date Fair Value
	(In thousands)					(In thousands)
Unvested options outstanding, beginning of period		177		$	6.96		313		$	6.89
Options granted		—			—		—			—
Unvested options forfeited		(4	)		6.76		—			—
Options vested		(33	)		7.07		(59	)		6.31
Unvested options outstanding, end of period		140		$	6.92		254		$	6.96

The Company received $2.7 million and $4.2 million in cash from the exercise of stock options during the nine month periods ended September 30, 2012 and 2011, respectively. There was no tax benefit realized from option exercises of the stock-based compensation arrangements during the nine month periods ended September 30, 2012 and 2011.

As of September 30, 2012, there was $8.9 million of total unrecognized compensation expense related to unvested stock-based compensation arrangements. That cost is expected to be recognized over a weighted average period of 2.6 years.

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Other Comprehensive Income (Loss) - Activity in Accumulated Other Comprehensive Income, Net of Tax (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Accumulated Other Comprehensive Income Loss [Line Items]
Balance as of January 1, 2011			$ 13,472	$ 14,304
Other comprehensive (loss) income	(467)	410	(2,428)	1,477
Balance September 30, 2011	11,044	15,781	11,044	15,781
Balance as of January 1, 2011			13,472	14,304
Other comprehensive (loss) income			(2,428)	1,477
Balance September 30, 2011	$ 11,044	$ 15,781	$ 11,044	$ 15,781

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FAIR VALUE DISCLOSURES

9 Months Ended

Sep. 30, 2012

FAIR VALUE DISCLOSURES

5. FAIR VALUE DISCLOSURES

Effective January 1, 2008, the Company adopted FASB ASC Topic 820, Fair Value Measurement and Disclosures. ASC Topic 820, which defines fair value, addresses aspects of the expanding application of fair value accounting and establishes a consistent framework for measuring fair value. Fair value represents the estimated price that would be received from selling an asset or paid to transfer a liability, otherwise known as an “exit price”.

Fair Value Hierarchy

ASC Topic 820 specifies a hierarchy of valuation techniques based on whether the inputs to those valuation techniques are observable or unobservable. In accordance with ASC Topic 820, these inputs are summarized in the three broad levels listed below:

• Level 1—Quoted prices in active markets for identical assets or liabilities. Level 1 assets include U.S. Treasury securities that are highly liquid and are actively traded in over-the-counter markets and CRA funds.

• Level 2—Other significant observable inputs (including quoted prices in active markets for similar assets or liabilities) or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company’s Level 2 assets include U.S. government and agency mortgage-backed debt securities, corporate securities and municipal bonds.

• Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair values requires significant management judgment or estimation.

In determining the appropriate levels, the Company performs a detailed analysis of the assets and liabilities that are subject to ASC Topic 820.

The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of September 30, 2012 and December 31, 2011, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value:

	September 30, 2012
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Available for sale securities (at fair value):
States and political subdivisions	$	—	$	37,188	$	—	$	37,188
Corporate debt securities and other		7,747		1,553		—		9,300
Collateralized mortgage obligations		—		638		—		638
Mortgage-backed securities		—		203,261		—		203,261
Total	$	7,747	$	242,640	$	—	$	250,387
	December 31, 2011
	Level 1		Level 2		Level 3		Total
	(Dollars in thousands)
Available for sale securities (at fair value):
States and political subdivisions	$	—	$	39,076	$	—	$	39,076
Corporate debt securities and other		7,656		1,613		—		9,269
Collateralized mortgage obligations		—		765		—		765
Mortgage-backed securities		—		273,206		—		273,206
Total	$	7,656	$	314,660	$	—	$	322,316

Certain assets and liabilities are measured at fair value on a non-recurring 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 measured at fair value on a non-recurring basis during the reported periods include certain impaired loans reported at the fair value of the underlying collateral if repayment is expected solely from the collateral. Collateral values are estimated using Level 2 inputs based on observable market data, typically in the case of real estate collateral. For the nine months ended September 30, 2012, the Company had additions to impaired loans of $8.2 million, of which $4.3 million were outstanding at September 30, 2012.

Assets measured at fair value on a non-recurring basis during the reported periods also include other real estate owned and repossessed assets. For the nine months ended September 30, 2012, the Company had additions to other real estate owned of $10.9 million, of which $5.2 million were outstanding at September 30, 2012. The remaining assets and liabilities measured at fair value on a non-recurring basis that were recorded in 2012 and remained outstanding at September 30, 2012 were not significant. During the reported periods, all fair value measurements for assets and liabilities measured at fair value on a non-recurring basis utilized Level 2 inputs based on observable market data. There were no transfers between Level 1 and Level 2 assets during the nine months ended September 30, 2012.

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

The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate that value:

Cash and Cash Equivalents—For these short-term instruments, the carrying amount is a reasonable estimate of fair value.

Federal Funds Sold—For these short-term instruments, the carrying amount is a reasonable estimate of fair value.

Securities —For securities held as investments, fair value equals quoted market price, if available. If a quoted market price is not available, fair value is estimated using quoted market prices for similar securities.

Loans Held for Investment—For fixed rate loans and certain homogeneous categories of loans (such as some residential mortgages and other consumer loans), fair value is estimated by discounting the future cash flows using the risk-free Treasury rate for the applicable maturity, adjusted for servicing and credit risk. An overall valuation adjustment is made for specific credit risks as well as general portfolio credit risk. The carrying value of variable rate loans approximates fair value because the loans reprice frequently to current market rates.

Loans Held for Sale—Loans held for sale are recorded at the lower of cost or fair value. Loans held for sale may be carried at fair value on a nonrecurring basis when fair value is less than cost. The fair value is based on what secondary markets are currently offering for portfolios with similar characteristics. As such, the Company classifies both loans held for sale subjected to nonrecurring fair value adjustments and the estimated fair value of loans held for sale as Level 2.

Deposits—The fair value of demand deposits, savings accounts and certain money market deposits is the amount payable on demand at the reporting date. The fair value of fixed-maturity certificates of deposit is estimated using the rates currently offered for deposits of similar remaining maturities.

Junior Subordinated Debentures—The fair value of the junior subordinated debentures is calculated using the quoted market prices, if available. If quoted market prices are not available, fair value is estimated using quoted market prices for similar subordinated debentures.

Other Borrowings—Rates currently available to the Company for debt with similar terms and remaining maturities are used to estimate the fair value of existing debt using a discounted cash flows methodology.

Securities Sold Under Repurchase Agreements—The fair value of securities sold under repurchase agreements is the amount payable on demand at the reporting date.

Off-Balance Sheet Financial Instruments—The fair value of commitments to extend credit and standby letters of credit is estimated using the fees currently charged to enter into similar agreements, taking into account the remaining terms of the agreement and the present creditworthiness of the counterparties. The Company’s off-balance sheet commitments are funded at current market rates at the date they are drawn upon. It is management’s opinion that the fair value of these commitments would approximate their carrying value, if drawn upon.

FASB ASC Topic 825, Financial Instruments, requires disclosure of the fair value of financial assets and financial liabilities, including those financial assets and financial liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis. The Company provides fair value estimates for loans not recorded at fair value. During the reported periods, fair value measurements for loans utilized Level 3 inputs. The estimated fair value is determined based on characteristics such as loan category, repricing features and remaining maturity, and includes prepayment and credit loss estimates. The model used to estimate fair value of loans employs a discount rate that reflects the Company’s current pricing for loans with similar characteristics and remaining maturity, adjusted by an amount for estimated credit losses inherent in the portfolio and liquidity risk, at the balance sheet date. The adjustment approximates 25 basis points for the reported periods. The rates take into account the expected yield curve, as well as an adjustment for prepayment risk, when applicable. The Company utilizes a third party to assist with its fair value measurements. Inputs used in the pricing model are validated by management.

All fair value measurements for remaining financial assets and financial liabilities utilized Level 2 inputs based on observable market data. The carrying amount and estimated fair value of the Company’s financial instruments, as of the dates indicated, are as follows:

	September 30, 2012				December 31, 2011
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
	(Dollars in thousands)
Financial Assets:
Cash and due from banks	$	207,401	$	207,401	$	212,800	$	212,800
Federal funds sold		302		302		642		642
Interest-bearing time deposits in other financial institutions		249		249		—		—
Held to maturity securities		6,549,126		6,772,151		4,336,620		4,492,988
Available for sale securities		250,387		250,387		322,316		322,316
Loans held for sale		4,332		4,332		—		—
Loans held for investment, net of allowance for credit losses		5,023,844		5,098,007		3,714,312		3,814,858
Total	$	12,035,641	$	12,332,829	$	8,586,690	$	8,843,604
Financial liabilities:
Deposits	$	10,954,597	$	10,971,925	$	8,060,254	$	8,074,093
Junior subordinated debentures		85,055		72,242		85,055		71,001
Other borrowings		112,017		114,170		12,790		14,974
Securities sold under repurchase agreements		443,856		443,976		54,883		54,883
Total	$	11,595,525	$	11,602,313	$	8,212,982	$	8,214,951

The Company’s off-balance sheet commitments, which total $911.5 million at September 30, 2012, are funded at current market rates at the date they are drawn upon. It is management’s opinion that the fair value of these commitments would approximate their carrying value, if drawn upon.

The fair value estimates presented herein are based on pertinent information available to management at September 30, 2012. Although management is not aware of any factors that would significantly affect the estimated fair value amounts, such amounts have not been comprehensively revalued for purposes of these financial statements since those dates and, therefore, current estimates of fair value may differ significantly from the amounts presented herein.

Under ASC Topic 825, entities may choose to measure eligible financial instruments at fair value at specified election dates. The fair value measurement option (i) may be applied instrument by instrument, with certain exceptions, (ii) is generally irrevocable and (iii) is applied only to entire instruments and not to portions of instruments. Unrealized gains and losses on items for which the fair value measurement option has been elected must be reported in earnings at each subsequent reporting date. During the reported periods, the Company had no financial instruments measured at fair value under the fair value measurement option.

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GOODWILL AND CORE DEPOSIT INTANGIBLES

9 Months Ended

Sep. 30, 2012

GOODWILL AND CORE DEPOSIT INTANGIBLES

6. GOODWILL AND CORE DEPOSIT INTANGIBLES

Changes in the carrying amount of the Company’s goodwill and core deposit intangibles (CDI) for nine months ended September 30, 2012 were as follows:

	Goodwill		Core Deposit Intangibles
	(Dollars in thousands)
Balance as of December 31, 2011	$	924,537	$	20,996
Amortization		—		(5,297	)
Acquisition of Texas Bankers, Inc.		5,869		—
Acquisition of The Bank Arlington		3,013		—
Acquisition of American State Financial Corp.		266,679		12,393
Balance as of September 30, 2012	$	1,200,098	$	28,092

Goodwill is recorded on the acquisition date of each entity. The Company may record subsequent adjustments to goodwill for amounts undeterminable at acquisition date, such as deferred taxes and real estate valuations, and therefore the goodwill amounts reflected in the table above may change accordingly. The Company initially records the total premium paid on acquisitions as goodwill. After finalizing the valuation, core deposit intangibles are identified and reclassified from goodwill to core deposit intangibles on the balance sheet. This reclassification has no effect on total assets or liabilities. Management performs an evaluation annually, and more frequently if a triggering event occurs, of whether any impairment of the goodwill and other intangibles has occurred. If any such impairment is determined, a write down is recorded. As of September 30, 2012, there were no impairments recorded on goodwill or other intangibles.

Although the Company completed the Texas Bankers, Inc. acquisition in January 2012, The Bank Arlington acquisition in April 2012 and the American State Financial Corporation acquisition in July 2012, the Company has not yet completed the allocation of the purchase price and therefore fair values for certain acquired assets and assumed liabilities are still being finalized (see Note 11-Acquisitions).

Core deposit intangibles are amortized on an accelerated basis over their estimated lives, which the Company believes is between 8 and 10 years. Gross core deposit intangibles outstanding were $91.5 million at September 30, 2012 and $79.2 million at December 31, 2011. Net core deposit intangibles outstanding were $28.1 million and $21.0 million at the same dates, respectively. Amortization expense related to intangible assets totaled $2.0 million and $1.9 million for the three months ended September 30, 2012 and 2011, respectively, and $5.3 million and $5.9 million for the nine months ended September 30, 2012 and 2011, respectively.

The estimated aggregate future amortization expense for intangible assets remaining as of September 30, 2012 is as follows (dollars in thousands):

Remaining 2012	$	1,933
2013		6,186
2014		4,866
2015		4,219
2016		3,781
Thereafter		7,107
Total	$	28,092

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SECURITIES

9 Months Ended

Sep. 30, 2012

SECURITIES

8. SECURITIES

The carrying cost of securities totaled $6.80 billion at September 30, 2012 compared with $4.66 billion at December 31, 2011, an increase of $2.14 billion or 45.9%. The increase is due to securities acquired from ASB. At September 30, 2012, securities represented 49.6% of total assets compared with 47.4% of total assets at December 31, 2011.

The amortized cost and fair value of investment securities as of September 30, 2012 are as follows:

	September 30, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	35,262	$	1,937	$	(11	)	$	37,188
Collateralized mortgage obligations		651		—		(13	)		638
Mortgage-backed securities		188,699		14,618		(56	)		203,261
Corporate debt securities and other		8,784		516		—			9,300
Total	$	233,396	$	17,071	$	(80	)	$	250,387
Held to Maturity
U.S. Treasury securities and obligations of U.S. government agencies	$	10,597	$	213	$	—		$	10,810
States and political subdivisions (including QSCB)		387,246		9,355		(151	)		396,450
Corporate debt securities		1,500		53		—			1,553
Collateralized mortgage obligations		160,478		2,994		(215	)		163,257
Mortgage-backed securities		5,989,305		211,153		(377	)		6,200,081
Total	$	6,549,126	$	223,768	$	(743	)	$	6,772,151

The amortized cost and fair value of investment securities as of December 31, 2011 are as follows:

	December 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	37,060	$	2,022	$	(6	)	$	39,076
Collateralized mortgage obligations		786		—		(21	)		765
Mortgage-backed securities		254,965		18,307		(66	)		273,206
Corporate debt securities and other		8,778		491		—			9,269
Total	$	301,589	$	20,820	$	(93	)	$	322,316
Held to Maturity
U.S. Treasury securities and obligations of U.S. government agencies	$	8,696	$	455	$	—		$	9,151
States and political subdivisions (including QSCB)		50,814		3,324		(284	)		53,854
Corporate debt securities		1,500		114		—			1,614
Collateralized mortgage obligations		281,778		5,009		(150	)		286,637
Mortgage-backed securities		3,993,832		147,991		(91	)		4,141,732
Total	$	4,336,620	$	156,893	$	(525	)	$	4,492,988

Management evaluates securities for other-than-temporary impairment at least on a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. The investment securities portfolio is evaluated for OTTI by segregating the portfolio into two general segments and applying the appropriate OTTI model. Investment securities classified as available for sale or held-to-maturity are evaluated for OTTI under FASB ASC Topic 320, “Investments—Debt and Equity Securities.” Certain purchased beneficial interests, including non-agency mortgage-backed securities, asset-backed securities, and collateralized debt obligations, that had credit ratings at the time of purchase of below AA are evaluated using the model outlined in ASC Topic 325, “Investments—Other.” The Company currently does not own any securities that are accounted for under ASC Topic 325.

In determining OTTI under ASC Topic 320, management considers many factors, including: (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer, (3) whether the market decline was affected by macroeconomic conditions, and (4) whether the entity has the intent to sell the debt security or more likely than not will be required to sell the debt security before its anticipated recovery. The assessment of whether an other-than-temporary decline exists involves a high degree of subjectivity and judgment and is based on the information available to management at a point in time. If applicable, the second segment of the portfolio uses the OTTI guidance provided by ASC Topic 325 that is specific to purchased beneficial interests that, on the purchase date, were rated below AA. Under the ASC Topic 325 model, an impairment is considered other than temporary if, based on the Company’s best estimate of cash flows that a market participant would use in determining the current fair value of the beneficial interest, there has been an adverse change in those estimated cash flows.

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

As of September 30, 2012, the Company does not intend to sell any debt securities and management believes that the Company more likely than not will not be required to sell any debt securities before their anticipated recovery, at which time the Company will receive full value for the securities. Furthermore, as of September 30, 2012, management does not have the intent to sell any of its securities and believes that it is more likely than not that the Company will not have to sell any such securities before a recovery of cost. The unrealized losses are largely due to increases in market interest rates over the yields available at the time the underlying securities were purchased. The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline. Management does not believe any of the securities are impaired due to reasons of credit quality. Accordingly, as of September 30, 2012, management believes any impairment in the Company’s securities are temporary and no impairment loss has been realized in the Company’s consolidated statements of income.

Securities with unrealized losses segregated by length of time such securities have been in a continuous loss position at September 30, 2012 were as follows:

	Less than 12 Months					More than 12 Months					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	—	$	—		$	503	$	(11	)	$	503	$	(11	)
Collateralized mortgage obligations		—		—			638		(13	)		638		(13	)
Mortgage-backed securities		162		—			6,779		(56	)		6,941		(56	)
Total	$	162	$	—		$	7,920	$	(80	)	$	8,082	$	(80	)
Held to Maturity
States and political subdivisions	$	14,301	$	(131	)	$	1,140	$	(19	)	$	15,441	$	(150	)
Collateralized mortgage obligations		2,384		(215	)		—		—			2,384		(215	)
Mortgage-backed securities		16,551		(375	)		320		(3	)		16,871		(378	)
Total	$	33,236	$	(721	)	$	1,460	$	(22	)	$	34,696	$	(743	)

The amortized cost and fair value of investment securities at September 30, 2012, by contractual maturity, are shown below. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations at any time with or without call or prepayment penalties.

	September 30, 2012
	Held to Maturity				Available for Sale
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
Due in one year or less	$	30,938	$	31,294	$	8,874	$	9,392
Due after one year through five years		118,902		120,003		2,942		3,116
Due after five years through ten years		148,003		150,818		23,562		24,862
Due after ten years		101,500		106,698		8,668		9,118
Subtotal		399,343		408,813		44,046		46,488
Mortgage-backed securities and collateralized mortgage obligations		6,149,783		6,363,338		189,350		203,899
Total	$	6,549,126	$	6,772,151	$	233,396	$	250,387

The Company had no gain or loss on sale of securities for the three months ended September 30, 2012 or 2011 and had no gain or loss on sale of securities for the nine months ended September 30, 2012 compared with a net loss of $581,000 for the nine months ended September 30, 2011. The Company sold two non-agency CMO’s with a total book value of $3.2 million due to a downgrade of the CMO’s to less than investment grade in the second quarter of 2011. As of September 30, 2012, the Company had eight non-agency CMO’s remaining with a total book value of $2.7 million and total market value of $2.5 million.

At September 30, 2012 and December 31, 2011, the Company did not own securities of any one issuer (other than the U.S. government and its agencies) for which aggregate adjusted cost exceeded 10% of the consolidated shareholders’ equity at such respective dates.

Securities with an amortized cost of $4.22 billion and $2.48 billion and a fair value of $4.37 billion and $2.57 billion at September 30, 2012 and December 31, 2011, respectively, were pledged to collateralize public deposits and for other purposes required or permitted by law.

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Acquisitions - Purchased Credits Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Purchased Credit Impaired Loans [Line Items]
Commercial and industrial	$ 756,342	$ 406,433
Real estate
Agriculture	98,801	34,226
Consumer	112,476	78,187
Other	35,905	33,421
Construction and Land Development [Member]
Real estate
1-4 family residential	496,417	482,140
1-4 Family Residential [Member]
Real estate
1-4 family residential	1,213,873	1,007,266
Home Equity [Member]
Real estate
1-4 family residential	183,844	146,999
Commercial Mortgage [Member]
Real estate
1-4 family residential	1,837,224	1,351,986
Agriculture Real Estate [Member]
Real estate
1-4 family residential	205,333	136,008
Purchased Credit Impaired Loans [Member]
Purchased Credit Impaired Loans [Line Items]
Commercial and industrial	3,568
Real estate
Agriculture	78
Other
Total fair value	27,581
Contractual principal balance	54,403
Purchased Credit Impaired Loans [Member] | Construction and Land Development [Member]
Real estate
1-4 family residential	1,326
Purchased Credit Impaired Loans [Member] | 1-4 Family Residential [Member]
Real estate
1-4 family residential	155
Purchased Credit Impaired Loans [Member] | Commercial Mortgage [Member]
Real estate
1-4 family residential	22,454
Non Purchased Credit Impaired Loans [Member]
Purchased Credit Impaired Loans [Line Items]
Commercial and industrial	221,341
Real estate
Consumer	72,119
Other
Total fair value	1,120,056
Contractual principal balance	1,195,741
Non Purchased Credit Impaired Loans [Member] | Construction and Land Development [Member]
Real estate
1-4 family residential	112,011
Non Purchased Credit Impaired Loans [Member] | 1-4 Family Residential [Member]
Real estate
1-4 family residential	126,954
Non Purchased Credit Impaired Loans [Member] | Home Equity [Member]
Real estate
1-4 family residential	24,851
Non Purchased Credit Impaired Loans [Member] | Commercial Mortgage [Member]
Real estate
1-4 family residential	460,378
Non Purchased Credit Impaired Loans [Member] | Agriculture Real Estate [Member]
Real estate
1-4 family residential	53,979
Non Purchased Credit Impaired Loans [Member] | Multi Family Residential Real Estate [Member]
Real estate
1-4 family residential	48,423
Acquired Loans [Member]
Purchased Credit Impaired Loans [Line Items]
Commercial and industrial	224,909
Real estate
Agriculture	78
Consumer	72,119
Other
Total fair value	1,147,637
Contractual principal balance	1,250,144
Acquired Loans [Member] | Construction and Land Development [Member]
Real estate
1-4 family residential	113,337
Acquired Loans [Member] | 1-4 Family Residential [Member]
Real estate
1-4 family residential	127,109
Acquired Loans [Member] | Home Equity [Member]
Real estate
1-4 family residential	24,851
Acquired Loans [Member] | Commercial Mortgage [Member]
Real estate
1-4 family residential	482,832
Acquired Loans [Member] | Agriculture Real Estate [Member]
Real estate
1-4 family residential	53,979
Acquired Loans [Member] | Multi Family Residential Real Estate [Member]
Real estate
1-4 family residential	$ 48,423

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Subsequent Events - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2012
Subsequent Event [Line Items]
Total assets	$ 3,379,402,000
Total loans	2,842,596,000
Community National Bank [Member]
Subsequent Event [Line Items]
Total assets	183,000,000
Total loans	68,000,000
Total deposits	164,600,000
Common stock shares issued	372,282
Cash payment to acquire shares	11,400,000
Merger Consideration Premium	10,600,000
Community National Bank [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Business Acquisition Legal And Professional Fees	326,000,000
East Texas Financial Services, Inc [Member]
Subsequent Event [Line Items]
Acquisition	2011-12-09
Firstbank [Member]
Subsequent Event [Line Items]
Total assets	191,100,000
Total loans	139,200,000
Total deposits	$ 116,000,000
East Texas Financial Services, Inc. [Member]
Subsequent Event [Line Items]
Common stock shares issued	531,000

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Acquisitions - Information Regarding Results of Operations on Acquisition (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Business Acquisition Pro Forma Information [Line Items]
Net interest income	$ 106,893	$ 113,858	$ 336,249	$ 337,096
Net income	$ 49,479	$ 48,081	$ 163,333	$ 149,425
Basic earnings per share	$ 0.88	$ 0.87	$ 2.78	$ 2.70
Diluted earnings per share	$ 0.88	$ 0.87	$ 2.77	$ 2.69

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Loans and Allowance for Credit Losses - Schedule of Non accrual Loans, Segregated by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
1-4 family (includes home equity)	$ 5,063	$ 3,578
Construction and Land Development [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
1-4 family (includes home equity)	86	1,175
Agriculture and Agriculture Real Estate [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
1-4 family (includes home equity)	410	49
1-4 Family (Includes Home Equity) [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
1-4 family (includes home equity)	1,694	923
Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
1-4 family (includes home equity)	1,292	790
Commercial and Industrial [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
1-4 family (includes home equity)	1,557	633
Consumer and Other [Member]
Financing Receivable Recorded Investment Nonaccrual Status [Line Items]
1-4 family (includes home equity)	$ 24	$ 8

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Stock Based Compensation - Summary of Changes in Non-Vested Options (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested options outstanding, beginning of period, Weighted Average Grant Date Fair Value	$ 6.96	$ 6.89
Options granted, Weighted Average Grant Date Fair Value
Unvested options forfeited, Weighted Average Grant Date Fair Value	$ 6.76
Options vested, Weighted Average Grant Date Fair Value	$ 7.07	$ 6.31
Unvested options outstanding, end of period, Weighted Average Grant Date Fair Value	$ 6.92	$ 6.96
Unvested options outstanding, beginning of period	177	313
Options granted, Number of Options
Unvested options forfeited, Number of Options	(4)
Options vested, Number of Options	(33)	(59)
Unvested options outstanding, end of period, Number of Options	140	254

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EARNINGS PER SHARE (Tables)

9 Months Ended

Sep. 30, 2012

Computation of Basic and Diluted Earnings per Share

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

	Three Months Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
	(In thousands, except per share amounts)
Net income available to common shareholders	$	46,176	$	36,373	$	119,635	$	105,343
Weighted average common shares outstanding		55,958		46,890		50,239		46,830
Potential dilutive common shares		135		143		154		183
Weighted average common shares and equivalents outstanding		56,093		47,033		50,393		47,013
Basic earnings per common share	$	0.83	$	0.78	$	2.38	$	2.25
Diluted earnings per common share	$	0.82	$	0.77	$	2.37	$	2.24

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SECURITIES (Tables)

9 Months Ended

Sep. 30, 2012

Schedule of Investment Securities

The amortized cost and fair value of investment securities as of September 30, 2012 are as follows:

	September 30, 2012
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	35,262	$	1,937	$	(11	)	$	37,188
Collateralized mortgage obligations		651		—		(13	)		638
Mortgage-backed securities		188,699		14,618		(56	)		203,261
Corporate debt securities and other		8,784		516		—			9,300
Total	$	233,396	$	17,071	$	(80	)	$	250,387
Held to Maturity
U.S. Treasury securities and obligations of U.S. government agencies	$	10,597	$	213	$	—		$	10,810
States and political subdivisions (including QSCB)		387,246		9,355		(151	)		396,450
Corporate debt securities		1,500		53		—			1,553
Collateralized mortgage obligations		160,478		2,994		(215	)		163,257
Mortgage-backed securities		5,989,305		211,153		(377	)		6,200,081
Total	$	6,549,126	$	223,768	$	(743	)	$	6,772,151

The amortized cost and fair value of investment securities as of December 31, 2011 are as follows:

	December 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	37,060	$	2,022	$	(6	)	$	39,076
Collateralized mortgage obligations		786		—		(21	)		765
Mortgage-backed securities		254,965		18,307		(66	)		273,206
Corporate debt securities and other		8,778		491		—			9,269
Total	$	301,589	$	20,820	$	(93	)	$	322,316
Held to Maturity
U.S. Treasury securities and obligations of U.S. government agencies	$	8,696	$	455	$	—		$	9,151
States and political subdivisions (including QSCB)		50,814		3,324		(284	)		53,854
Corporate debt securities		1,500		114		—			1,614
Collateralized mortgage obligations		281,778		5,009		(150	)		286,637
Mortgage-backed securities		3,993,832		147,991		(91	)		4,141,732
Total	$	4,336,620	$	156,893	$	(525	)	$	4,492,988

Schedule of Securities with Unrealized Losses

Securities with unrealized losses segregated by length of time such securities have been in a continuous loss position at September 30, 2012 were as follows:

	Less than 12 Months					More than 12 Months					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
	(Dollars in thousands)
Available for Sale
States and political subdivisions	$	—	$	—		$	503	$	(11	)	$	503	$	(11	)
Collateralized mortgage obligations		—		—			638		(13	)		638		(13	)
Mortgage-backed securities		162		—			6,779		(56	)		6,941		(56	)
Total	$	162	$	—		$	7,920	$	(80	)	$	8,082	$	(80	)
Held to Maturity
States and political subdivisions	$	14,301	$	(131	)	$	1,140	$	(19	)	$	15,441	$	(150	)
Collateralized mortgage obligations		2,384		(215	)		—		—			2,384		(215	)
Mortgage-backed securities		16,551		(375	)		320		(3	)		16,871		(378	)
Total	$	33,236	$	(721	)	$	1,460	$	(22	)	$	34,696	$	(743	)

Amortized Cost and Fair Value of Investment Securities by Contractual Maturity

	September 30, 2012
	Held to Maturity				Available for Sale
	Amortized Cost		Fair Value		Amortized Cost		Fair Value
	(Dollars in thousands)
Due in one year or less	$	30,938	$	31,294	$	8,874	$	9,392
Due after one year through five years		118,902		120,003		2,942		3,116
Due after five years through ten years		148,003		150,818		23,562		24,862
Due after ten years		101,500		106,698		8,668		9,118
Subtotal		399,343		408,813		44,046		46,488
Mortgage-backed securities and collateralized mortgage obligations		6,149,783		6,363,338		189,350		203,899
Total	$	6,549,126	$	6,772,151	$	233,396	$	250,387

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Stock Based Compensation - Summary of Fair Value of Options Estimated Using Option-Pricing Model (Detail)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years	5 years 3 months 4 days	5 years 3 months 18 days
Risk free interest rate	3.67%	3.67%
Volatility	20.84%	20.98%
Dividend yield	1.26%	1.25%

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Loans and Allowance for Credit Losses - Schedule of Troubled Debt Restructuring Outstanding (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Number of Contracts	12	9
Pre-Modification Outstanding Recorded Investment	$ 3,755	$ 5,487
Post- Modification Outstanding Recorded Investment	3,596	5,348
1-4 Family (Includes Home Equity) [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	4	4
Pre-Modification Outstanding Recorded Investment	109	109
Post- Modification Outstanding Recorded Investment	66	84
Commercial Real Estate (Commercial Mortgage And Multi Family) [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1	2
Pre-Modification Outstanding Recorded Investment	2,560	5,264
Post- Modification Outstanding Recorded Investment	2,469	5,171
Commercial and Industrial [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	7	3
Pre-Modification Outstanding Recorded Investment	1,086	114
Post- Modification Outstanding Recorded Investment	$ 1,061	$ 93

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CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net income	$ 46,176	$ 36,373	$ 119,635	$ 105,343
Securities available for sale:
Change in unrealized (loss) gain during period	(718)	632	(3,736)	2,272
Total other comprehensive (loss) income	(718)	632	(3,736)	2,272
Deferred tax benefit (expense) related to other comprehensive income	251	(222)	1,308	(795)
Other comprehensive (loss) income, net of tax	(467)	410	(2,428)	1,477
Comprehensive income	$ 45,709	$ 36,783	$ 117,207	$ 106,820

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EARNINGS PER SHARE

9 Months Ended

Sep. 30, 2012

EARNINGS PER SHARE

2. EARNINGS PER SHARE

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

	Three Months Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
	(In thousands, except per share amounts)
Net income available to common shareholders	$	46,176	$	36,373	$	119,635	$	105,343
Weighted average common shares outstanding		55,958		46,890		50,239		46,830
Potential dilutive common shares		135		143		154		183
Weighted average common shares and equivalents outstanding		56,093		47,033		50,393		47,013
Basic earnings per common share	$	0.83	$	0.78	$	2.38	$	2.25
Diluted earnings per common share	$	0.82	$	0.77	$	2.37	$	2.24

Basic earnings per share is computed by dividing net income by the weighted average number of shares outstanding during the applicable period using the two-class method. Diluted earnings per share is computed using the weighted-average number of shares determined for the basic computation plus the dilutive effect of stock options and non-vested restricted stock granted using the treasury stock method. There were no stock options exercisable at September 30, 2012 and 2011 that would have had an anti-dilutive effect on the above computation.

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Contractual Obligations and Off-Balance Sheet Items - Letters of Credit and Commitments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Contractual Obligation Fiscal Year Maturity [Line Items]
Remaining Fiscal 2012	$ 119,039
Fiscal 2013-2014	465,948
Fiscal 2015-2016	50,955
Thereafter	275,538
Total	911,480
Standby Letters of Credit [Member]
Contractual Obligation Fiscal Year Maturity [Line Items]
Remaining Fiscal 2012	4,472
Fiscal 2013-2014	20,399
Fiscal 2015-2016	564
Total	25,435
Commitments to extend credit [Member]
Contractual Obligation Fiscal Year Maturity [Line Items]
Remaining Fiscal 2012	114,567
Fiscal 2013-2014	445,549
Fiscal 2015-2016	50,391
Thereafter	275,538
Total	$ 886,045

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CONTRACTUAL OBLIGATIONS AND OFF-BALANCE SHEET ITEMS (Tables)

9 Months Ended

Sep. 30, 2012

Contractual Obligations and Other Commitments

	Payments due in:
	Remaining Fiscal 2012		Fiscal 2013-2014		Fiscal 2015-2016		Thereafter		Total
	(Dollars in thousands)
Junior subordinated debentures	$	1,222	$	4,888	$	4,888	$	126,017	$	137,015
Federal Home Loan Bank borrowings		100,282		3,258		3,456		8,001		114,997
Operating leases		1,324		8,547		4,013		759		14,643
Total	$	102,828	$	16,693	$	12,357	$	134,777	$	266,655

Letters of Credit and Commitments

	Remaining Fiscal 2012		Fiscal 2013-2014		Fiscal 2015-2016		Thereafter		Total
	(Dollars in thousands)
Standby letters of credit	$	4,472	$	20,399	$	564	$	—	$	25,435
Commitments to extend credit		114,567		445,549		50,391		275,538		886,045
Total	$	119,039	$	465,948	$	50,955	$	275,538	$	911,480

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Loans and Allowance for Credit Losses - Schedule Showing Risk Grades and Classified Loans by Class of Loan (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	$ 5,079,103	$ 3,765,906
Grade 1 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	76,241	80,139
Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	4,909,848	3,608,211
Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	34,465	29,622
Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	52,287	43,928
Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	6,247	3,885
Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	15	121
Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	496,417	482,140
Construction and Land Development [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	482,385	465,572
Construction and Land Development [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	8,351	1,757
Construction and Land Development [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	5,595	13,636
Construction and Land Development [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	86	1,175
Agriculture and Agriculture Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	304,134	170,234
Agriculture and Agriculture Real Estate [Member] | Grade 1 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	2,601	3,319
Agriculture and Agriculture Real Estate [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	297,231	166,656
Agriculture and Agriculture Real Estate [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	2,128	210
Agriculture and Agriculture Real Estate [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	2,031
Agriculture and Agriculture Real Estate [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	143	49
1-4 Family (Includes Home Equity) [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	1,397,717	1,154,265
1-4 Family (Includes Home Equity) [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	1,384,513	1,140,210
1-4 Family (Includes Home Equity) [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	6,617	9,131
1-4 Family (Includes Home Equity) [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	5,139	3,934
1-4 Family (Includes Home Equity) [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	1,435	970
1-4 Family (Includes Home Equity) [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	13	20
Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	1,976,112	1,441,226
Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	1,930,565	1,399,915
Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	9,163	14,335
Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	33,214	25,825
Commercial Real Estate (Commercial Mortgage and Multi-Family Residential) [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	3,170	1,151
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	756,342	406,433
Commercial and Industrial [Member] | Grade 1 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	45,371	45,218
Commercial and Industrial [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	695,762	355,862
Commercial and Industrial [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	8,206	4,189
Commercial and Industrial [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	5,608	531
Commercial and Industrial [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	1,393	532
Commercial and Industrial [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	2	101
Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	148,381	111,608
Consumer and Other [Member] | Grade 1 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	28,269	31,602
Consumer and Other [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	119,392	79,996
Consumer and Other [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	700	2
Consumer and Other [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans held for investment	$ 20	$ 8

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SUBSEQUENT EVENTS

9 Months Ended

Sep. 30, 2012

SUBSEQUENT EVENTS

12. SUBSEQUENT EVENTS

Acquisition of Community National Bank—On October 1, 2012, the Company completed the previously announced acquisition of Community National Bank, Bellaire, Texas. Community National Bank operated one (1) banking office in Bellaire, Texas, in the Houston Metropolitan Area. The acquisition is not considered significant to the Company’s financial statements and therefore pro forma financial data is not included. The Company incurred approximately $326,000 in expense related to this acquisition which is primarily recorded in legal and professional fees and data processing.

As of September 30, 2012, Community National Bank reported total assets of $183.0 million, total loans of $68.0 million and total deposits of $164.6 million. Under the terms of the acquisition agreement, the Company issued 372,282 shares of Company common stock plus $11.4 million in cash for all outstanding shares of Community National Bank capital stock which resulted in a premium of $10.6 million.

Pending Acquisition of East Texas Financial Services, Inc.—On December 9, 2011, the Company entered into a definitive agreement to acquire East Texas Financial Services, Inc. (OTC BB: FFBT) and its wholly-owned subsidiary, First Federal Bank Texas (“Firstbank”). Firstbank operates four banking offices in the Tyler MSA, including three locations in Tyler, Texas and one location in Gilmer, Texas.

As of September 30, 2012, Firstbank reported total assets of $191.1 million, total loans of $139.2 million and total deposits of $116.0 million. Under the terms of the definitive agreement, the Company will issue up to 531,000 shares of Company common stock for all outstanding shares of East Texas Financial Services capital stock, subject to certain conditions and potential adjustments. Pending the satisfaction of closing conditions, the closing is expected to occur in early 2013.