Prosperity Bancshares (PB) 10-Q 8 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	1-May-14
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
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	'	69,731,610

CONSOLIDATED_BALANCE_SHEETS_UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
ASSETS	'	'
Cash and due from banks	$349,860	$380,990
Federal funds sold	382	400
Total cash and cash equivalents	350,242	381,390
Available for sale securities, at fair value	143,382	157,478
Held to maturity securities, at cost (fair value of $8,410,919 and $7,987,342, respectively)	8,417,955	8,066,970
Total securities	8,561,337	8,224,448
Loans held for sale	3,558	2,210
Loans held for investment	7,748,842	7,773,011
Total loans	7,752,400	7,775,221
Less: allowance for credit losses	-67,096	-67,282
Loans, net	7,685,304	7,707,939
Accrued interest receivable	45,054	49,246
Goodwill	1,672,004	1,671,520
Core deposit intangibles, net	39,702	42,049
Bank premises and equipment, net	280,812	282,925
Other real estate owned	7,372	7,299
Bank owned life insurance (BOLI)	178,530	177,532
Federal Home Loan Bank of Dallas stock	23,857	24,499
Other assets	68,919	73,181
TOTAL ASSETS	18,913,133	18,642,028
Deposits:	'	'
Noninterest-bearing	4,142,042	4,108,835
Interest-bearing	11,318,015	11,182,436
Total deposits	15,460,057	15,291,271
Other borrowings	40,451	10,689
Securities sold under repurchase agreements	349,074	364,357
Junior subordinated debentures	124,231	124,231
Accrued interest payable	2,372	2,500
Other liabilities	96,194	62,162
Total liabilities	16,072,379	15,855,210
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; 66,298,176 and 66,085,179 shares issued at March 31, 2014 and December 31, 2013, respectively; 66,261,088 and 66,048,091 shares outstanding at March 31, 2014 and December 31, 2013,respectively	66,298	66,085
Capital surplus	1,801,659	1,798,862
Retained earnings	968,839	917,595
Accumulated other comprehensive income-net unrealized gain on available for sale securities, net of tax of $2,458 and $2,630, respectively	4,565	4,883
Less treasury stock, at cost, 37,088 shares	-607	-607
Total shareholders' equity	2,840,754	2,786,818
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$18,913,133	$18,642,028

CONSOLIDATED_BALANCE_SHEETS_UN1

CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Statement Of Financial Position [Abstract]	'	'
Held to maturity securities, Fair value	$8,410,919	$7,987,342
Preferred stock, par value	$1	$1
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$1	$1
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	66,298,176	66,085,179
Common stock, shares outstanding	66,261,088	66,048,091
Accumulated other comprehensive income - unrealized gain on available for sale securities, tax	$2,458	$2,630
Treasury stock, shares	37,088	37,088

CONSOLIDATED_STATEMENTS_OF_INC

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
INTEREST INCOME:	'	'
Loans, including fees	$107,144	$81,464
Securities	47,056	36,548
Federal funds sold	48	19
Total interest income	154,248	118,031
INTEREST EXPENSE:	'	'
Deposits	9,387	8,690
Securities sold under repurchase agreements	237	292
Junior subordinated debentures	775	605
Other borrowings	158	362
Total interest expense	10,557	9,949
NET INTEREST INCOME	143,691	108,082
Provision for credit losses	600	2,800
NET INTEREST INCOME AFTER PROVISION FOR CREDIT LOSSES	143,091	105,282
NONINTEREST INCOME:	'	'
Nonsufficient funds (NSF) fees	8,870	8,509
Credit card, debit card and ATM card income	4,724	6,487
Service charges on deposit accounts	4,037	2,931
Trust income	1,800	1,017
Mortgage income	593	991
Brokerage income	1,269	303
Net gain on sale of assets	3,310	1
Other	4,001	3,202
Total noninterest income	28,604	23,441
NONINTEREST EXPENSE:	'	'
Salaries and employee benefits	43,408	33,209
Net occupancy and equipment	5,339	4,278
Debit card, data processing and software amortization	3,184	2,570
Regulatory assessments and FDIC insurance	2,726	2,395
Core deposit intangibles amortization	2,045	1,755
Depreciation	3,201	2,378
Communications	2,737	2,196
Other real estate expense	396	223
Other	7,998	6,763
Total noninterest expense	71,034	55,767
INCOME BEFORE INCOME TAXES	100,661	72,956
PROVISION FOR INCOME TAXES	33,524	23,651
NET INCOME	$67,137	$49,305
EARNINGS PER SHARE:	'	'
Basic	$1.01	$0.87
Diluted	$1.01	$0.86

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]	'	'
Net income	$67,137	$49,305
Securities available for sale:	'	'
Change in unrealized gain during period	-489	-1,771
Total other comprehensive loss	-489	-1,771
Deferred tax benefit related to other comprehensive income	171	620
Other comprehensive loss, net of tax	-318	-1,151
Comprehensive income	$66,819	$48,154

CONSOLIDATED_STATEMENTS_OF_CHA

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) (USD $)	Total	East Texas Financial Services, Inc. [Member]	Common Stock [Member]	Common Stock [Member]	Capital Surplus [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock [Member]
In Thousands, except Share data				East Texas Financial Services, Inc. [Member]		East Texas Financial Services, Inc. [Member]
BALANCE at Dec. 31, 2012	$2,089,389	'	$56,484	'	$1,274,290	'	$750,236	$8,986	($607)
BALANCE, Shares at Dec. 31, 2012	'	'	56,484,234	'	'	'	'	'	'
Net income	49,305	'	'	'	'	'	49,305	'	'
Other comprehensive loss	-1,151	'	'	'	'	'	'	-1,151	'
Common stock issued in connection with the exercise of stock options and restricted stock awards	670	'	36	'	634	'	'	'	'
Common stock issued in connection with the exercise of stock options and restricted stock awards (in shares)	'	'	35,758	'	'	'	'	'	'
Common stock issued in connection with the acquisition	'	22,300	'	531	'	21,769	'	'	'
Common stock issued in connection with the acquisition (in shares)	'	'	'	530,940	'	'	'	'	'
Stock based compensation expense	1,198	'	'	'	1,198	'	'	'	'
Cash dividends declared	-12,256	'	'	'	'	'	-12,256	'	'
BALANCE at Mar. 31, 2013	2,149,455	'	57,051	'	1,297,891	'	787,285	7,835	-607
BALANCE, Shares at Mar. 31, 2013	'	'	57,050,932	'	'	'	'	'	'
BALANCE at Dec. 31, 2013	2,786,818	'	66,085	'	1,798,862	'	917,595	4,883	-607
BALANCE, Shares at Dec. 31, 2013	'	'	66,085,179	'	'	'	'	'	'
Net income	67,137	'	'	'	'	'	67,137	'	'
Other comprehensive loss	-318	'	'	'	'	'	'	-318	'
Common stock issued in connection with the exercise of stock options and restricted stock awards	1,839	'	213	'	1,626	'	'	'	'
Common stock issued in connection with the exercise of stock options and restricted stock awards (in shares)	'	'	212,997	'	'	'	'	'	'
Stock based compensation expense	1,171	'	'	'	1,171	'	'	'	'
Cash dividends declared	-15,893	'	'	'	'	'	-15,893	'	'
BALANCE at Mar. 31, 2014	$2,840,754	'	$66,298	'	$1,801,659	'	$968,839	$4,565	($607)
BALANCE, Shares at Mar. 31, 2014	'	'	66,298,176	'	'	'	'	'	'

CONSOLIDATED_STATEMENTS_OF_CHA1

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement Of Stockholders Equity [Abstract]	'	'
Cash dividends declared, per share	$0.24	$0.22

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:	'	'
Net income	$67,137	$49,305
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and core deposit intangibles amortization	5,246	4,133
Provision for credit losses	600	2,800
Net amortization of premium on investments	12,279	22,710
Loss on sale or write down of premises, equipment and other real estate	60	103
Gain on sale of assets	-3,310	-1
Net accretion of discount on loans	-13,476	-14,292
Proceeds from sale of loans held for sale	23,698	42,131
Originations of loans held for sale	-25,046	-40,131
Stock based compensation expense	1,171	1,198
Decrease in accrued interest receivable and other assets	8,840	16,784
Increase in accrued interest payable and other liabilities	35,480	28,036
Net cash provided by operating activities	112,679	112,778
CASH FLOWS FROM INVESTING ACTIVITIES:	'	'
Proceeds from maturities and principal paydowns of held to maturity securities	314,135	589,924
Purchase of held to maturity securities	-677,436	-1,159,815
Proceeds from maturities, sales and principal paydowns of available for sale securities	263,643	403,912
Purchase of available for sale securities	-250,000	-384,999
Net decrease in loans held for investment	34,057	47,199
Purchase of bank premises and equipment	-2,478	-1,588
Proceeds from sale of bank premises, equipment and other real estate	5,041	1,425
Net cash used in investing activities	-313,038	-500,471
CASH FLOWS FROM FINANCING ACTIVITIES:	'	'
Net increase (decrease) in noninterest-bearing deposits	33,207	-32,934
Net increase (decrease) in interest-bearing deposits	135,579	-7,851
Net proceeds from other short-term borrowings	30,000	280,000
Repayments of other long-term borrowings	-238	-567
Net (decrease) increase in securities sold under repurchase agreements	-15,283	15,739
Proceeds from stock option exercises	1,839	670
Payments of cash dividends	-15,893	-12,256
Net cash provided by financing activities	169,211	242,801
NET DECREASE IN CASH AND CASH EQUIVALENTS	-31,148	-144,892
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	381,390	326,304
CASH AND CASH EQUIVALENTS, END OF PERIOD	350,242	181,412
NONCASH ACTIVITIES:	'	'
Acquisition of real estate through foreclosure of collateral	2,710	1,347
SUPPLEMENTAL INFORMATION:	'	'
Income taxes paid	5,000	'
Interest paid	10,694	10,034
East Texas Financial Services, Inc. [Member]	'	'
CASH FLOWS FROM INVESTING ACTIVITIES:	'	'
Net cash and cash equivalents acquired in the purchase	'	3,471
NONCASH ACTIVITIES:	'	'
Stock issued in connection with acquisition	'	$22,300

BASIS_OF_PRESENTATION

BASIS OF PRESENTATION	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
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, LLC. 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, 2013. Operating results for the three-month period ended March 31, 2014 are not necessarily indicative of the results that may be expected for the year ending December 31, 2014 or any other period.

INCOME_PER_COMMON_SHARE

INCOME PER COMMON SHARE	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
INCOME PER COMMON SHARE	'
	2. INCOME PER COMMON SHARE
	Outstanding stock options issued by the Company represent the only dilutive effect reflected in diluted weighted average shares. The following table illustrates the computation of basic and diluted earnings per share:
		Three Months Ended March 31,
		2014				2013
				Per Share				Per Share
		Amount		Amount		Amount		Amount
		(Amounts in thousands, except per share data)
	Net income	$	67,137			$	49,305
	Basic:
	Weighted average shares outstanding		66,186	$	1.01		56,988	$	0.87
	Diluted:
	Add incremental shares for:
	Effect of dilutive securities—options		94				146
	Total		66,280	$	1.01		57,134	$	0.86
	There were no stock options exercisable during the three months ended March 31, 2014 or 2013 that would have had an anti-dilutive effect on the above computation.

NEW_ACCOUNTING_STANDARDS

NEW ACCOUNTING STANDARDS	3 Months Ended
	Mar. 31, 2014
Accounting Changes And Error Corrections [Abstract]	'
NEW ACCOUNTING STANDARDS	'
	3. NEW ACCOUNTING STANDARDS
	Accounting Standards Updates (“ASU”)
	ASU 2014-04 “Receivables—Troubled Debt Restructurings by Creditors (Subtopic 310-40) — Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure”. ASU 2014-04 intends to reduce diversity by clarifying when an in substance repossession or foreclosure occurs, that is, when a creditor should be considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan such that the loan receivable should be derecognized and the real estate property recognized. ASU 2014-04 will become effective for the Company on January 1, 2015 and is not expected to have an impact on the Company’s financial statements.

SECURITIES

SECURITIES	3 Months Ended
	Mar. 31, 2014
Investments Debt And Equity Securities [Abstract]	'
SECURITIES	'
	4. SECURITIES
	The amortized cost and fair value of investment securities were as follows:
		March 31, 2014
		Amortized		Gross			Gross			Fair
		Cost		Unrealized			Unrealized			Value
				Gains			Losses
		(Dollars in thousands)
	Available for Sale
	States and political subdivisions	$	23,238	$	609		$	—		$	23,847
	Collateralized mortgage obligations		455		6			(3	)		458
	Mortgage-backed securities		100,077		6,476			(19	)		106,534
	Other securities		12,589		—			(46	)		12,543
	Total	$	136,359	$	7,091		$	(68	)	$	143,382
	Held to Maturity
	U.S. Treasury securities and obligations of U.S. Government agencies	$	62,966	$	213		$	(148	)	$	63,031
	States and political subdivisions		383,335		4,673			(982	)		387,026
	Corporate debt securities		508		4			—			512
	Collateralized mortgage obligations		42,327		739			(22	)		43,044
	Mortgage-backed securities		7,899,007		100,051			(113,846	)		7,885,212
	Qualified Zone Academy Bond (QZAB)		16,912		924			(307	)		17,529
	Qualified School Construction Bonds (QSCB)		12,900		1,665			—			14,565
	Total	$	8,417,955	$	108,269		$	(115,305	)	$	8,410,919
		31-Dec-13
		Amortized		Gross			Gross			Fair
		Cost		Unrealized			Unrealized			Value
				Gains			Losses
		(Dollars in thousands)
	Available for Sale
	States and political subdivisions	$	28,578	$	797		$	—		$	29,375
	Collateralized mortgage obligations		483		7			(1	)		489
	Mortgage-backed securities		108,316		6,843			(22	)		115,137
	Other securities		12,589		14			(126	)		12,477
	Total	$	149,966	$	7,661		$	(149	)	$	157,478
	Held to Maturity
	U.S. Treasury securities and obligations of U.S. Government agencies	$	62,931	$	46		$	(935	)	$	62,042
	States and political subdivisions		426,335		3,176			(2,207	)		427,304
	Corporate debt securities		513		5			—			518
	Collateralized mortgage obligations		50,034		1,017			(58	)		50,993
	Mortgage-backed securities		7,514,257		84,166			(165,979	)		7,432,444
	Qualified School Construction Bonds (QSCB)		12,900		1,141			—			14,041
	Total	$	8,066,970	$	89,551		$	(169,179	)	$	7,987,342
	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 evaluated for OTTI under Financial Accounting Standards Board (“FASB”): FASB Accounting Standards Codification (“ASC”) Topic 320, “Investments-Debt and Equity Securities.”
	In determining OTTI, 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.
	When OTTI occurs, 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 March 31, 2014, 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 March 31, 2014, 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 March 31, 2014, management believes any impairment in the Company’s securities is 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, that have been in a continuous loss position were as follows:
		March 31, 2014
		Less than 12 Months					More than 12 Months						Total
		Estimated		Unrealized			Estimated			Unrealized			Estimated		Unrealized
		Fair Value		Losses			Fair Value			Losses			Fair Value		Losses
		(Dollars in thousands)
	Available for Sale
	Collateralized mortgage obligations	$	186	$	(2	)	$	48		$	(1	)	$	234	$	(3	)
	Mortgage-backed securities		696		(2	)		3,021			(17	)		3,717		(19	)
	Other securities		12,542		(46	)		—			—			12,542		(46	)
	Total	$	13,424	$	(50	)	$	3,069		$	(18	)	$	16,493	$	(68	)
	Held to Maturity
	U.S. Treasury securities and obligations of U.S. Government agencies	$	26,620	$	(148	)	$	—		$	—		$	26,620	$	(148	)
	States and political subdivisions		69,880		(901	)		21,218			(388	)		91,098		(1,289	)
	Collateralized mortgage obligations		1,548		(18	)		437			(4	)		1,985		(22	)
	Mortgage-backed securities		2,582,055		(69,224	)		985,079			(44,622	)		3,567,134		(113,846	)
	Total	$	2,680,103	$	(70,291	)	$	1,006,734		$	(45,014	)	$	3,686,837	$	(115,305	)
		31-Dec-13
	Less than 12 Months					More than 12 Months						Total
	Estimated		Unrealized			Estimated			Unrealized			Estimated		Unrealized
	Fair Value		Losses			Fair Value			Losses			Fair Value		Losses
	(Dollars in thousands)
Available for Sale
Collateralized mortgage obligations	$	5	$	—		$	50		$	(1	)	$	55	$	(1	)
Mortgage-backed securities		651		(1	)		3,313			(21	)		3,964		(22	)
Other securities		6,911		(126	)		—			—			6,911		(126	)
Total	$	7,567	$	(127	)	$	3,363		$	(22	)	$	10,930	$	(149	)
Held to Maturity
U.S. Treasury securities and obligations of U.S. Government agencies	$	48,389	$	(935	)	$	—		$	—		$	48,389	$	(935	)
States and political subdivisions		113,063		(1,581	)		28,639			(626	)		141,702		(2,207	)
Collateralized mortgage obligations		2,109		(32	)		433			(26	)		2,542		(58	)
Mortgage-backed securities		3,702,569		(106,816	)		998,380			(59,163	)		4,700,949		(165,979	)
Total	$	3,866,130	$	(109,364	)	$	1,027,452		$	(59,815	)	$	4,893,582	$	(169,179	)
At March 31, 2014 and December 31, 2013, there were 432 securities and 450 securities, respectively, in an unrealized loss position for more than 12 months.
The amortized cost and fair value of investment securities at March 31, 2014, by contractual maturity, are shown below. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations at any time with or without call or prepayment penalties.
	Held to Maturity					Available for Sale
	Amortized		Fair			Amortized			Fair
	Cost		Value			Cost			Value
	(Dollars in thousands)
Due in one year or less	$	32,648	$	32,748		$	12,684		$	12,638
Due after one year through five years		158,614		159,787			4,833			5,000
Due after five years through ten years		205,727		208,084			16,638			17,047
Due after ten years		79,632		82,044			1,672			1,705
Subtotal		476,621		482,663			35,827			36,390
Mortgage-backed securities and collateralized mortgage obligations		7,941,334		7,928,256			100,532			106,992
Total	$	8,417,955	$	8,410,919		$	136,359		$	143,382
The Company recorded no gain or loss on sale of securities for the three months ended March 31, 2014 and 2013. As of March 31, 2014, the Company had eight non-agency collateralized mortgage obligations remaining with a total book value of $1.6 million and total market value of $1.6 million.
At March 31, 2014 and December 31, 2013, the Company did not own securities of any one issuer (other than the U.S. government and its agencies) for which aggregate adjusted cost exceeded 10% of the consolidated shareholders’ equity at such respective dates.
Securities with an amortized cost of $5.10 billion and $4.46 billion and a fair value of $5.09 billion and $4.47 billion at March 31, 2014 and December 31, 2013, respectively, were pledged to collateralize public deposits and for other purposes required or permitted by law.

LOANS_AND_ALLOWANCE_FOR_CREDIT

LOANS AND ALLOWANCE FOR CREDIT LOSSES	3 Months Ended
	Mar. 31, 2014
Text Block [Abstract]	'
LOANS AND ALLOWANCE FOR CREDIT LOSSES	'
	5. LOANS AND ALLOWANCE FOR CREDIT LOSSES
	The loan portfolio consists of various types of loans made principally to borrowers located within the states of Texas and Oklahoma and is classified by major type as follows:
			March 31,			December 31,
			2014			2013
			(Dollars in thousands)
	Residential mortgage loans held for sale		$	3,558		$	2,210
	Commercial and industrial			1,255,020			1,279,777
	Real estate:
	Construction, land development and other land loans			888,985			865,511
	1-4 family residential (including home equity)			2,166,888			2,129,510
	Commercial real estate (including multi-family residential)			2,709,386			2,753,797
	Farmland			337,021			332,648
	Agriculture			175,836			198,610
	Consumer and other (net of unearned discount)			215,706			213,158
	Total loans held for investment			7,748,842			7,773,011
	Total		$	7,752,400		$	7,775,221
	(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 Real Estate. The Company makes commercial real estate related loans collateralized by owner-occupied and non-owner-occupied real estate to finance the purchase of real estate. The Company’s commercial real estate related 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 March 31, 2014, approximately 52.8% of the outstanding principal balance of the Company’s commercial real estate related loans was secured by owner-occupied properties.
	(iii) 1-4 Family Residential Loans. The Company originates 1-4 family residential mortgage loans (including home equity loans and residential mortgage loans held for sale) collateralized by owner-occupied residential properties located in the Company’s market areas. The Company offers a variety of mortgage loan portfolio products which generally are amortized over five to 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 retains these portfolio loans for its own account rather than selling them into the secondary market. By doing so, the Company incurs interest rate risk as well as the risks associated with nonpayments on such loans. The Company’s Mortgage Department offers a variety of mortgage loan products which are generally amortized over 30 years, including FHA and VA loans. The Company sells the loans originated by the Mortgage Department into the secondary market.
	(iv) Construction, Land Development and Other Land 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. 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.
	(vi) Consumer Loans. Consumer loans made by the Company include direct “A” credit automobile loans, recreational vehicle loans, boat loans, home improvement loans, personal loans (collateralized and uncollateralized) and deposit account collateralized loans. The terms of these loans typically range from 12 to 180 months and vary based upon the nature of collateral and size of loan. Generally, consumer loans entail greater risk than do real estate secured loans, particularly in the case of consumer loans that are unsecured or collateralized by rapidly depreciating assets such as automobiles. In such cases, any repossessed collateral for a defaulted consumer loan may not provide an adequate source of repayment for the outstanding loan balance. The remaining deficiency often does not warrant further substantial collection efforts against the borrower beyond obtaining a deficiency judgment. In addition, consumer loan collections are dependent on the borrower’s continuing financial stability, and thus are more likely to be adversely affected by job loss, divorce, illness 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 states of Texas and Oklahoma. The majority of the Company’s loan portfolio consists of commercial and industrial, commercial real estate and 1-4 family residential loans. As of March 31, 2014 and December 31, 2013, 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 March 31, 2014 or December 31, 2013.
	Related Party Loans. As of March 31, 2014 and December 31, 2013, loans outstanding to directors, officers and their affiliates totaled $6.0 million and $6.2 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:
			March 31,			December 31,
			2014			2013
			(Dollars in thousands)
	Beginning balance on January 1		$	6,187		$	6,682
	New loans and reclassified related loans			2,814			306
	Repayments			(3,015	)		(801	)
	Ending balance		$	5,986		$	6,187
	Nonperforming Assets and Nonaccrual and Past Due Loans. The Company has several procedures in place to assist it in maintaining the overall quality of its loan portfolio. The Company has established underwriting guidelines to be followed by its officers 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.
	An aging analysis of past due loans, segregated by class of loans, was as follows:
			March 31, 2014
			Loans Past Due and Still Accruing
			30-89 Days			90 or More			Total Past			Nonaccrual			Current			Total
						Days			Due Loans			Loans			Loans			Loans
			(Dollars in thousands)
	Construction, land development and other land loans		$	10,291		$	227		$	10,518		$	377		$	878,090		$	888,985
	Agriculture and agriculture real estate (includes farmland)			1,351			—			1,351			84			511,422			512,857
	1-4 family (includes home equity) (1)			2,900			222			3,122			3,832			2,163,492			2,170,446
	Commercial real estate (includes multi-family residential)			28,130			44			28,174			1,629			2,679,583			2,709,386
	Commercial and industrial			17,669			3,026			20,695			1,636			1,232,689			1,255,020
	Consumer and other			1,704			—			1,704			156			213,846			215,706
	Total		$	62,045		$	3,519		$	65,564		$	7,714		$	7,679,122		$	7,752,400
			31-Dec-13
			Loans Past Due and Still Accruing
			30-89 Days			90 or More			Total Past			Nonaccrual			Current			Total
						Days			Due Loans			Loans			Loans			Loans
			(Dollars in thousands)
	Construction, land development and other land loans		$	6,258		$	2		$	6,260		$	386		$	858,865		$	865,511
	Agriculture and agriculture real estate (includes farmland)			5,634			218			5,852			62			525,344			531,258
	1-4 family (includes home equity) (1)			8,684			2,012			10,696			3,086			2,117,938			2,131,720
	Commercial real estate (includes multi-family residential)			8,163			1,752			9,915			4,333			2,739,549			2,753,797
	Commercial and industrial			9,552			933			10,485			2,208			1,267,084			1,279,777
	Consumer and other			1,344			30			1,374			156			211,628			213,158
	Total		$	39,635		$	4,947		$	44,582		$	10,231		$	7,720,408		$	7,775,221
	-1	Includes $3.6 million and $2.2 million of residential mortgage loans held for sale at March 31, 2014 and December 31, 2013, respectively.
The following table presents information regarding nonperforming assets as of the dates indicated:
		March 31,			December 31,
		2014			2013
		(Dollars in thousands)
Nonaccrual loans		$	7,714		$	10,231
Accruing loans 90 or more days past due			3,519			4,947
Total nonperforming loans			11,233			15,178
Repossessed assets			91			27
Other real estate			7,372			7,299
Total nonperforming assets		$	18,696		$	22,504
Nonperforming assets to total loans and other real estate			0.24	%		0.29	%
The Company’s conservative lending approach has resulted in sound asset quality. The Company had $18.7 million in nonperforming assets at March 31, 2014 compared with $22.5 million at December 31, 2013.
If interest on nonaccrual loans had been accrued under the original loan terms, approximately $234 thousand and $111 thousand would have been recorded as income for the three months ended March 31, 2014 and 2013, respectively.
Purchased Credit-Impaired (PCI) Loans. In connection with the acquisition of American State Financial Corporation (ASB) on July 1, 2012, Community National Bank on October 1, 2012, East Texas Financial Services, Inc. on January 1, 2013, Coppermark Bancshares, Inc. on April 1, 2013 and FVNB Corp. on November 1, 2013, the Company acquired loans both with and without evidence of credit quality deterioration since origination. The acquired loans were initially recorded at fair value with no carryover of any allowance for loan losses.
Loans acquired with evidence of credit quality deterioration at acquisition for which it was probable that the Company would not be able to collect all contractual amounts due were accounted for as PCI.
The carrying amount of acquired PCI loans included in the consolidated balance sheet and the related outstanding balance as of the dates indicated are presented in the table below.
		March 31,			December 31,
		2014			2013
		(Dollars in thousands)
Acquired PCI loans:
Outstanding balance		$	81,671		$	87,089
Discount			42,025			45,497
Recorded investment		$	39,646		$	41,592
The outstanding balance represents the total amount owed as of March 31, 2014 and December 31, 2013, including accrued but unpaid interest and any amounts previously charged off. No allowance for loan losses was required on the acquired PCI loans at both March 31, 2014 and December 31, 2013.
Changes in the accretable yield for acquired PCI loans as of the dates indicated below were as follows:
		Three Months Ended March 31,
		2014			2013
		(Dollars in thousands)
Balance at beginning of period		$	9,855		$	7,459
Additions			—			1,736
Reclassifications from nonaccretable			1,503			143
Accretion			(2,888	)		(1,769	)
Balance at March 31		$	8,470		$	7,569
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 are set forth in the following tables. No interest income was recognized on impaired loans subsequent to their classification as impaired. The average recorded investment presented in the tables below is reported on a year-to-date basis.
		March 31, 2014
		Recorded			Unpaid			Related			Average
		Investment			Principal			Allowance			Recorded
					Balance						Investment
		(Dollars in thousands)
With no related allowance recorded:
Construction, land development and other land loans		$	324		$	341		$	—		$	301
Agriculture and agriculture real estate (includes farmland)			27			137			—			21
1-4 family (includes home equity)			762			829			—			673
Commercial real estate (includes multi-family residential)			1,415			2,637			—			1,953
Commercial and industrial			293			452			—			198
Consumer and other			9			9			—			12
Total			2,830			4,405			—			3,158
With an allowance recorded:
Construction, land development and other land loans			—			—			—			—
Agriculture and agriculture real estate (includes farmland)			180			186			48			101
1-4 family (includes home equity)			2,187			2,220			767			2,353
Commercial real estate (includes multi-family residential)			7			8			7			810
Commercial and industrial			1,269			1,357			1,217			1,190
Consumer and other			140			152			92			118
Total			3,783			3,923			2,131			4,572
Total:
Construction, land development and other land loans			324			341			—			301
Agriculture and agriculture real estate (includes farmland)			207			323			48			122
1-4 family (includes home equity)			2,949			3,049			767			3,026
Commercial real estate (includes multi-family residential)			1,422			2,645			7			2,763
Commercial and industrial			1,562			1,809			1,217			1,388
Consumer and other			149			161			92			130
		$	6,613		$	8,328		$	2,131		$	7,730
		December 31, 2013
		Recorded			Unpaid			Related			Average
		Investment			Principal			Allowance			Recorded
					Balance						Investment
		(Dollars in thousands)
With no related allowance recorded:
Construction, land development and other land loans		$	277		$	289		$	—		$	711
Agriculture and agriculture real estate (includes farmland)			14			57			—			46
1-4 family (includes home equity)			584			664			—			538
Commercial real estate (includes multi-family residential)			2,490			3,798			—			1,470
Commercial and industrial			103			122			—			95
Consumer and other			15			16			—			13
Total			3,483			4,946			—			2,873
With an allowance recorded:
Construction, land development and other land loans			—			—			—			—
Agriculture and agriculture real estate (includes farmland)			21			27			18			28
1-4 family (includes home equity)			2,519			2,548			890			1,759
Commercial real estate (includes multi-family residential)			1,613			1,615			445			2,032
Commercial and industrial			1,111			1,192			1,029			1,077
Consumer and other			95			113			77			81
Total			5,359			5,495			2,459			4,977
Total:
Construction, land development and other land loans			277			289			—			711
Agriculture and agriculture real estate (includes farmland)			35			84			18			74
1-4 family (includes home equity)			3,103			3,212			890			2,297
Commercial real estate (includes multi-family residential)			4,103			5,413			445			3,502
Commercial and industrial			1,214			1,314			1,029			1,172
Consumer and other			110			129			77			94
		$	8,842		$	10,441		$	2,459		$	7,850
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 grades to be used as credit quality indicators. The following is a general description of the loan grades used:
Grade 1 – Credits in this category have risk potential that is virtually nonexistent. These loans may be secured by insured certificates of deposit, insured savings accounts, U.S. Government securities and highly rated municipal bonds.
Grade 2 – Credits in this category are of the highest quality. These borrowers represent top rated companies and individuals with unquestionable financial standing with excellent global cash flow coverage, net worth, liquidity and collateral coverage.
Grade 3 – Credits in this category are not immune from risk but are well protected by the collateral and paying capacity of the borrower. These loans may exhibit a minor unfavorable credit factor, but the overall credit is sufficiently strong to minimize the possibility of loss.
Grade 4 – Credits in this category are considered “pass/watch”. Loans in this category have sources of repayment that remain sufficient to preclude a larger than normal probability of default and secondary sources are likewise currently of sufficient quantity, quality, and liquidity to protect the Bank against loss of principal and interest. These borrowers have specific risk factors, but the overall strength of the credit is acceptable based on other mitigating credit and/or collateral factors and can repay the debt in the normal course of business.
Grade 5 – Credits in this category constitute an undue and unwarranted credit risk; however the factors do not rise to a level of substandard. These credits have potential weaknesses and/or declining trends that, if not corrected, could expose the Bank to risk at a future date. These loans are monitored on the Bank’s internally generated watch list and evaluated on a quarterly basis.
Grade 6 – Credits in this category are considered “substandard” but “non-impaired” loans in accordance with regulatory guidelines. Loans in this category have well-defined weaknesses that, if not corrected, could make default of principal and interest possible. Loans in this category are still accruing interest and may be dependent upon secondary sources of repayment and/or collateral liquidation.
Grade 7 – Credits in this category are deemed “substandard” and “impaired” pursuant to regulatory guidelines. As such, the Bank has determined that it is probable that less than 100% of the contractual principal and interest will be collected. These loans are individually evaluated for a specific reserve valuation and will typically have the accrual of interest stopped.
Grade 8 – Credits in this category include “doubtful” loans in accordance with regulatory guidance. Such loans are no longer accruing interest and factors indicate a loss is imminent. These loans are also deemed “impaired.” While a specific reserve may be in place while the loan and collateral is being evaluated, these loans are typically charged down to an amount the Bank estimates is collectible.
Grade 9 – Credits in this category are deemed a “loss” in accordance with regulatory guidelines and have been charged off or charged down. The Bank may continue collection efforts and may have partial recovery in the future.
The following table presents risk grades and classified loans by class of loan at March 31, 2014. Impaired loans include loans in risk grades 7, 8 and 9.
		Construction,			Agriculture and						Commercial
		Land			Agriculture Real			1-4 Family			Real Estate
		Development and			Estate (includes			(includes			(includes Multi-			Commercial			Consumer and
		other land loans			Farmland)			Home Equity) (1)			Family Residential)			and Industrial			Other			Total
		(Dollars in thousands)
Grade 1		$	—		$	4,869		$	—		$	—		$	48,682		$	32,948		$	86,499
Grade 2			—			—			—			—			—			—			—
Grade 3			883,334			502,053			2,154,734			2,659,042			1,183,149			182,419			7,564,731
Grade 4			—			—			—			—			—			—			—
Grade 5			978			4,998			3,877			10,484			13,181			123			33,641
Grade 6			955			138			4,943			12,115			3,052			67			21,270
Grade 7			324			207			2,939			1,422			1,546			149			6,587
Grade 8			—			—			10			—			16			—			26
Grade 9			—			—			—			—			—			—			—
PCI Loans (2)			3,394			592			3,943			26,323			5,394			—			39,646
Total		$	888,985		$	512,857		$	2,170,446		$	2,709,386		$	1,255,020		$	215,706		$	7,752,400
-1	Includes $3.6 million of residential mortgage loans held for sale at March 31, 2014.
-2	Of the total PCI loans, $17.3 million were classifed as substandard at March 31, 2014.
The following table presents risk grades and classified loans by class of loan at December 31, 2013. Impaired loans include loans in risk grades 7, 8 and 9.
		Construction,			Agriculture and						Commercial
		Land			Agriculture Real			1-4 Family			Real Estate
		Development and			Estate (includes			(includes			(includes Multi-			Commercial			Consumer and
		other land loans			Farmland)			Home Equity) (1)			Family Residential)			and Industrial			Other			Total
		(Dollars in thousands)
Grade 1		$	—		$	5,225		$	—		$	—		$	50,131		$	31,362		$	86,718
Grade 2			—			—			—			—			—			—			—
Grade 3			858,712			520,921			2,113,698			2,697,664			1,202,604			181,406			7,575,005
Grade 4			—			—			—			—			—			—			—
Grade 5			1,141			3,427			6,337			10,798			17,179			146			39,028
Grade 6			1,616			1,043			4,504			14,316			2,423			134			24,036
Grade 7			277			35			3,093			4,103			1,214			110			8,832
Grade 8			—			—			10			—			—			—			10
Grade 9			—			—			—			—			—			—			—
PCI Loans (2)			3,765			607			4,078			26,916			6,226			—			41,592
Total		$	865,511		$	531,258		$	2,131,720		$	2,753,797		$	1,279,777		$	213,158		$	7,775,221
-1	Includes $2.2 million of residential mortgage loans held for sale at December 31, 2013.
-2	Of the total PCI loans, $17.6 million were classifed as substandard at December 31, 2013.
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 probable 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 requiring a reserve. The specific reserves are determined on an individual loan basis. Impaired loans 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 impaired loan. 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 real estate loans and multifamily residential loans, the debt service coverage ratio (income from the property in excess of operating expenses compared to loan payment requirements), operating results of the owner in the case of owner-occupied properties, the loan to value ratio, the age and condition of the collateral and the volatility of income, property value and future operating results typical of properties of that type;
	•		for construction 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 agriculture real estate loans, the experience and financial capability of the borrower, projected debt service coverage of the operations of the borrower and loan to value ratio; and
	•		for non-real estate agriculture loans, the operating results, experience and financial capability of the borrower, historical and expected market conditions and the value, nature and marketability of collateral.
In addition, for each category, the Company considers secondary sources of income and the financial strength and credit history of the borrower and any guarantors.
At March 31, 2014, the allowance for credit losses totaled $67.1 million or 0.87% of total loans. At December 31, 2013, the allowance totaled $67.3 million or 0.87% of total loans.
The following table details activity in the allowance for loan losses by portfolio segment for the three months ended March 31, 2014 and 2013. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.
					Agriculture
		Construction,			and						Commercial
		Land			Agriculture			1-4 Family			Real Estate
		Development			Real Estate			(includes			(includes			Commercial
		and other			(includes			Home			Multi-Family			and			Consumer
		land loans			Farmland)			Equity)			Residential)			Industrial			and Other			Total
		(Dollars in thousands)
Allowance for credit losses:
Three Months Ended
Balance January 1, 2014		$	14,353		$	1,229		$	17,046		$	24,835		$	8,167		$	1,652		$	67,282
Provision for credit losses			(770	)		46			1,804			(1,404	)		567			357			600
Charge-offs			(2	)		(14	)		(139	)		(102	)		(143	)		(1,045	)		(1,445	)
Recoveries			19			95			7			42			62			434			659
Net charge-offs			17			81			(132	)		(60	)		(81	)		(611	)		(786	)
Balance March 31, 2014		$	13,600		$	1,356		$	18,718		$	23,371		$	8,653		$	1,398		$	67,096
Three Months Ended
Balance January 1, 2013		$	11,909		$	764		$	13,942		$	19,607		$	5,777		$	565		$	52,564
Provision for credit losses			270			116			272			2,205			(318	)		255			2,800
Charge-offs			—			—			(111	)		(68	)		(155	)		(606	)		(940	)
Recoveries			56			7			9			125			96			332			625
Net charge-offs			56			7			(102	)		57			(59	)		(274	)		(315	)
Balance March 31, 2013		$	12,235		$	887		$	14,112		$	21,869		$	5,400		$	546		$	55,049
The following table details the amount of the allowance for loan losses allocated to each portfolio segment as of March 31, 2014, December 31, 2013 and March 31, 2013, detailed on the basis of the impairment methodology used by the Company.
					Agriculture
		Construction,			and						Commercial
		Land			Agriculture			1-4 Family			Real Estate
		Development			Real Estate			(includes			(includes			Commercial
		and other			(includes			Home			Multi-Family			and			Consumer
		land loans			Farmland)			Equity)			Residential)			Industrial			and Other			Total
		(Dollars in thousands)
Allowance for credit losses related to:
March 31, 2014
Individually evaluated for impairment		$	—		$	48		$	767		$	7		$	1,217		$	92		$	2,131
Collectively evaluated for impairment			13,600			1,308			17,951			23,364			7,436			1,306			64,965
PCI loans			—			—			—			—			—			—			—
Total allowance for credit losses		$	13,600		$	1,356		$	18,718		$	23,371		$	8,653		$	1,398		$	67,096
December 31, 2013
Individually evaluated for impairment		$	—		$	18		$	890		$	445		$	1,029		$	77		$	2,459
Collectively evaluated for impairment			14,353			1,211			16,156			24,390			7,138			1,575			64,823
PCI loans			—			—			—			—			—			—			—
Total allowance for credit losses		$	14,353		$	1,229		$	17,046		$	24,835		$	8,167		$	1,652		$	67,282
March 31, 2013
Individually evaluated for impairment		$	134		$	27		$	94		$	786		$	1,467		$	65		$	2,573
Collectively evaluated for impairment			12,101			860			14,018			21,083			3,933			481			52,476
PCI loans			—			—			—			—			—			—			—
Total allowance for credit losses		$	12,235		$	887		$	14,112		$	21,869		$	5,400		$	546		$	55,049
The following table details the recorded investment in loans as of March 31, 2014, December 31, 2013 and March 31, 2013, excluding $3.6 million, $2.2 million and $8.5 million, respectively, of residential mortgage loans held for sale, related to each balance in the allowance for loan losses by portfolio segment.
					Agriculture
		Construction,			and						Commercial
		Land			Agriculture			1-4 Family			Real Estate
		Development			Real Estate			(includes			(includes			Commercial
		and other			(includes			Home			Multi-Family			and			Consumer
		land loans			Farmland)			Equity)			Residential)			Industrial			and Other			Total
		(Dollars in thousands)
Recorded investment in loans:
March 31, 2014
Individually evaluated for impairment		$	324		$	207		$	2,949		$	1,422		$	1,562		$	149		$	6,613
Collectively evaluated for impairment			885,267			512,058			2,159,996			2,681,641			1,248,064			215,557			7,702,583
PCI loans			3,394			592			3,943			26,323			5,394			—			39,646
Total loans evaluated for impairment		$	888,985		$	512,857		$	2,166,888		$	2,709,386		$	1,255,020		$	215,706		$	7,748,842
December 31, 2013
Individually evaluated for impairment		$	277		$	35		$	3,103		$	4,103		$	1,214		$	110		$	8,842
Collectively evaluated for impairment			861,469			530,616			2,122,329			2,722,778			1,272,337			213,048			7,722,577
PCI loans			3,765			607			4,078			26,916			6,226			—			41,592
Total loans evaluated for impairment		$	865,511		$	531,258		$	2,129,510		$	2,753,797		$	1,279,777		$	213,158		$	7,773,011
March 31, 2013
Individually evaluated for impairment		$	635		$	107		$	486		$	2,664		$	3,209		$	69		$	7,170
Collectively evaluated for impairment			574,657			286,254			1,539,085			1,969,385			726,168			132,277			5,227,826
PCI loans			15			428			3,180			21,469			2,931			5			28,028
Total loans evaluated for impairment		$	575,307		$	286,789		$	1,542,751		$	1,993,518		$	732,308		$	132,351		$	5,263,024
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 following table presents information regarding the recorded balance of loans modified in a troubled debt restructuring during the quarter ended March 31, 2014:
					Pre-			Post-
					Modification			Modification
					Outstanding			Outstanding
		Number of			Recorded			Recorded
		Contracts			Investment			Investment
		(Dollars in thousands)
Troubled Debt Restructurings
Construction, land development and other land loans			—		$	—		$	—
Agriculture and agriculture real estate			—			—			—
1-4 Family (includes home equity)			—			—			—
Commercial real estate (commercial mortgage and multi-family)			1			35			35
Commercial and industrial			1			16			16
Consumer and other			—			—			—
Total			2		$	51		$	51
There were no loans restructured during the three months ended March 31, 2013.
As of March 31, 2014, there have been no defaults on any loans that were modified as troubled debt restructurings during the preceding three months. Default is determined at 90 or more days past due. The modifications primarily related to extending the amortization periods of the loans, which includes loans modified during bankruptcy. The Company did not grant principal reductions on any restructured loans. For the three months ended March 31, 2014, the Company added $51 thousand in new troubled debt restructurings all of which were still outstanding on March 31, 2014. The remaining restructured loans from prior periods are performing and accruing loans. These modifications did not have a material impact on the Company’s determination of the allowance for credit losses.

FAIR_VALUE

FAIR VALUE	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
FAIR VALUE	'
	6. FAIR VALUE
	The Company uses fair value measurements to record fair value adjustments to certain assets and to determine fair value disclosures. Fair values represent the estimated price that would be received from selling an asset or paid to transfer a liability, otherwise known as an “exit price.” Securities available for sale are recorded at fair value on a recurring basis. Additionally, from time to time, the Company may be required to record at fair value other assets on a nonrecurring basis such as certain loans including residential mortgage loans held for sale, goodwill and other intangible assets and other real estate owned. These nonrecurring fair value adjustments typically involve application of lower-of-cost-or-market accounting or write downs of individual assets. ASC Topic 820 “Fair Value Measurements and Disclosures” establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets and liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows:
	Fair Value Hierarchy
	The Company groups financial assets and financial liabilities measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are:
		•		Level 1—Quoted prices in active markets for identical assets or liabilities.
		•		Level 2—Other significant observable inputs (including quoted prices in active markets for similar assets or liabilities) or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.
		•		Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
	The fair value of an asset or liability is the price that would be received to sell that asset or paid to transfer that liability in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. In estimating fair value, the Company utilizes valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. Such valuation techniques are consistently applied. Inputs to valuation techniques include the assumptions that market participants would use in pricing an asset or liability.
	The fair value disclosures below represent the Company’s estimates based on relevant market information and information about the financial instruments. Fair value estimates are based on judgments regarding 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 tables present fair values for assets and liabilities measured at fair value on a recurring basis:
			As of March 31, 2014
			Level 1		Level 2			Level 3		Total
			(Dollars in thousands)
	Assets:
	Available for sale securities:
	States and political subdivisions		$	—	$	23,847		$	—	$	23,847
	Collateralized mortgage obligations			—		458			—		458
	Mortgage-backed securities			—		106,534			—		106,534
	Other securities			12,543		—			—		12,543
	Total		$	12,543	$	130,839		$	—	$	143,382
	Non-hedging interest rate swap		$	—	$	153		$	—	$	153
	Liabilities:
	Non-hedging interest rate swap		$	—	$	(153	)	$	—	$	(153	)
			As of December 31, 2013
			Level 1		Level 2			Level 3		Total
			(Dollars in thousands)
	Assets:
	Available for sale securities:
	States and political subdivisions		$	—	$	29,375		$	—	$	29,375
	Collateralized mortgage obligations			—		489			—		489
	Mortgage-backed securities			—		115,137			—		115,137
	Other securities			12,477		—			—		12,477
	Total		$	12,477	$	145,001		$	—	$	157,478
	Non-hedging interest rate swap		$	—	$	38		$	—	$	38
	Liabilities:
	Non-hedging interest rate swap		$	—	$	(38	)	$	—	$	(38	)
	Certain assets and liabilities are measured at fair value on a nonrecurring basis; that is, the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances (for example, when there is evidence of impairment). These instruments include other real estate owned, repossessed assets, held to maturity debt securities, loans held for sale, and impaired loans. For the three months ended March 31, 2014, the Company had additions to other real estate owned of $2.7 million, of which $2.3 million were outstanding as of March 31, 2014. For the three months ended March 31, 2014, the Company had additions to impaired loans of $460 thousand, all of which were outstanding as of March 31, 2014. The remaining assets and liabilities measured at fair value on a nonrecurring basis that were recorded in 2014 and remained outstanding at March 31, 2014 were not significant.
	ASC Topic 825, “Financial Instruments” requires that the Company disclose estimated fair values for its financial instruments. The following table presents carrying and fair value information of financial instruments as of the dates indicated:
			As of March 31, 2014
			Carrying		Estimated Fair Value
			Amount		Level 1			Level 2		Level 3			Total
			(Dollars in thousands)
	Assets
	Cash and due from banks		$	349,860	$	349,860		$	—	$	—		$	349,860
	Federal funds sold			382		382			—		—			382
	Held to maturity securities			8,417,955		—			8,410,919		—			8,410,919
	Loans held for sale			3,558		—			3,558		—			3,558
	Loans held for investment, net of allowance			7,681,746		—			—		7,718,665			7,718,665
	Liabilities
	Deposits:
	Noninterest-bearing		$	4,142,042	$	—		$	4,142,042	$	—		$	4,142,042
	Interest-bearing			11,318,015		—			11,330,483		—			11,330,483
	Other borrowings			40,451		—			41,845		—			41,845
	Securities sold under repurchase agreements			349,074		—			349,149		—			349,149
	Junior subordinated debentures			124,231		—			119,384		—			119,384
			As of December 31, 2013
			Carrying		Estimated Fair Value
			Amount		Level 1			Level 2		Level 3			Total
			(Dollars in thousands)
	Assets
	Cash and due from banks		$	380,990	$	380,990		$	—	$	—		$	380,990
	Federal funds sold			400		400			—		—			400
	Held to maturity securities			8,066,970		—			7,987,342		—			7,987,342
Loans held for sale			2,210		2,210			—		—			2,210
Loans held for investment, net of allowance			7,705,729		—			—		7,749,786			7,749,786
Liabilities
Deposits:
Noninterest-bearing		$	4,108,835	$	—		$	4,108,835	$	—		$	4,108,835
Interest-bearing			11,182,436		—			11,196,241		—			11,196,241
Other borrowings			10,689		—			12,014		—			12,014
Securities sold under repurchase agreements			364,357		—			364,477		—			364,477
Junior subordinated debentures			124,231		—			119,325		—			119,325
The following is a description of the fair value estimates, methods and assumptions that are used by the Company in estimating the fair values of financial instruments.
Cash and due from banks—For these short-term instruments, the carrying amount is a reasonable estimate of fair value. The Company classifies the estimated fair value of these instruments as Level 1.
Federal funds sold—For these short-term instruments, the carrying amount is a reasonable estimate of fair value. The Company classifies the estimated fair value of these instruments as Level 1.
Securities — Fair value measurements based upon quoted prices are considered Level 1 inputs. Level 1 securities consist of U.S. Treasury securities and certain equity securities which are included in the available for sale portfolio. For all other available for sale and held to maturity securities, if quoted prices are not available, fair values are measured using Level 2 inputs. For these securities, the Company generally obtains fair value measurements from an independent pricing service. The fair value measurements consider observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the bond’s terms and conditions, among other things. The Company reviews the prices supplied by the independent pricing service, as well as their underlying pricing methodologies, for reasonableness.
Securities available for sale are recorded at fair value on a recurring basis.
Loans held for sale— Loans held for sale are carried at the lower of cost or estimated fair value. Fair value for consumer mortgages held for sale is based on commitments on hand from investors or prevailing market prices. As such, the Company classifies loans subjected to nonrecurring fair value adjustments as Level 2.
Loans held for investment — The Company does not record loans at fair value on a recurring basis. As such, valuation techniques discussed herein for loans are primarily for estimating fair value disclosures. However, from time to time, the Company records nonrecurring fair value adjustments to impaired loans to reflect (1) partial write downs that are based on the observable market price or current appraised value of the collateral, or (2) the full charge-off of the loan carrying value. Where appraisals are not available, estimated cash flows are discounted using a rate commensurate with the credit risk associated with those cash flows. Assumptions regarding credit risk, cash flows and discount rates are judgmentally determined using available market information and specific borrower information.
The estimated fair value approximates carrying value for variable-rate loans that reprice frequently and with no significant change in credit risk. The fair value of fixed-rate loans and variable-rate loans which reprice on an infrequent basis is estimated by discounting future cash flows using the current interest rates at which similar loans with similar terms would be made to borrowers of similar credit quality. An overall valuation adjustment is made for specific credit risks as well as general portfolio credit risk. The Company classifies the estimated fair value of loans held for investment as Level 3.
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. Deposits fair value measurements utilize Level 2 inputs.
Junior subordinated debentures—The fair value of the junior subordinated debentures was 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. Junior subordinated debentures fair value measurements utilize Level 2 inputs.
Other borrowings—Rates currently available to the Company for debt with similar terms and remaining maturities are used to estimate the fair value of other borrowings using a discounted cash flows methodology and are measured utilizing Level 2 inputs.
Securities sold under repurchase agreements—The fair value of securities sold under repurchase agreements is the amount payable on demand at the reporting date and are measured utilizing Level 2 inputs.
Derivative financial instruments—The fair value of the underlying non-hedging derivative contracts offset each other and are measured utilizing Level 2 inputs.
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 has reviewed the unfunded portion of commitments to extend credit as well as standby and other letters of credit, and has determined that the fair value of such financial instruments is not material. The Company classifies the estimated fair value of credit-related financial instruments as Level 3.
The Company’s off-balance sheet commitments including letters of credit, which totaled $1.58 billion at March 31, 2014, 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 March 31, 2014. 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.

GOODWILL_AND_CORE_DEPOSIT_INTA

GOODWILL AND CORE DEPOSIT INTANGIBLES	3 Months Ended
	Mar. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]	'
GOODWILL AND CORE DEPOSIT INTANGIBLES	'
	7. GOODWILL AND CORE DEPOSIT INTANGIBLES
	Changes in the carrying amount of the Company’s goodwill and core deposit intangibles (“CDI”) for the three months ended March 31, 2014 and the year ended December 31, 2013 were as follows:
		Goodwill			Core Deposit
					Intangibles
		(Dollars in thousands)
	Balance as of December 31, 2012	$	1,217,162		$	26,159
	Less:
	Amortization		—			(6,145	)
	Add:
	Measurement period adjustments		(1,225	)		2,110
	Acquisition of East Texas Financial Services, Inc.		15,007			—
	Acquisition of Coppermark Bancshares, Inc.		117,544			1,514
	Acquisition of FVNB Corp.		323,032			18,411
	Balance as of December 31, 2013		1,671,520			42,049
	Less:
	Amortization		—			(2,045	)
	Add:
	Measurement period adjustments		484			(302	)
	Balance as of March 31, 2014	$	1,672,004		$	39,702
	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, liabilities, shareholders’ equity, net income or cash flows. Management performs an evaluation annually and more frequently if a triggering event occurs, of whether any impairment of the goodwill and other intangibles has occurred. If any such impairment is determined, a write-down is recorded. As of March 31, 2014, there were no impairments recorded on goodwill.
	The measurement period for the Company to determine the fair value of acquired identifiable assets and assumed liabilities will be at the end of the earlier of (i) twelve months from the date of acquisition or (ii) as soon as the Company receives the information it was seeking about facts and circumstances that existed as of the date of acquisition. As such, certain acquisitions completed during 2014 and 2013 may be subject to adjustment.
	Core deposit intangibles are amortized on an accelerated basis over their estimated lives, which the Company believes is between 8 and 15 years. Amortization expense related to intangible assets totaled $2.0 million and $1.8 million for the three months ended March 31, 2014 and 2013, respectively. The estimated aggregate future amortization expense for CDI remaining as of March 31, 2014 is as follows (dollars in thousands):
	Remaining 2014	$	5,550
	2015		6,549
	2016		5,798
	2017		3,843
	2018		3,134
	Thereafter		14,828
	Total	$	39,702

STOCK_BASED_COMPENSATION

STOCK BASED COMPENSATION	3 Months Ended
	Mar. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
STOCK BASED COMPENSATION	'
	8. STOCK BASED COMPENSATION
	At March 31, 2014, 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.
	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.
	On February 21, 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 March 31, 2014, no options or other awards have been granted under the 2012 Plan.
	The Company received $1.8 million and $670 thousand in cash from the exercise of stock options during the three-month periods ended March 31, 2014 and 2013, respectively. There was no tax benefit realized from option exercises of the share-based payment arrangements during the three month periods ended March 31, 2014 and 2013.
	As of March 31, 2014, there was $16.1 million of total unrecognized compensation expense related to stock-based compensation arrangements. That cost is expected to be recognized over a weighted average period of 2.2 years.

CONTRACTUAL_OBLIGATIONS_AND_OF

CONTRACTUAL OBLIGATIONS AND OFF-BALANCE SHEET ITEMS	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
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 March 31, 2014 (other than deposit obligations and securities sold under repurchase agreements). The Company’s future cash payments associated with its contractual obligations pursuant to its junior subordinated debentures, FHLB borrowings and operating leases as of March 31, 2014 are summarized below. Payments for junior subordinated debentures include interest of $60.4 million that will be paid over the future periods. The future interest payments were calculated using the current rate in effect at March 31, 2014. The current principal balance of the junior subordinated debentures at March 31, 2014 was $124.2 million. Payments for FHLB borrowings include interest of $2.2 million that will be paid over the future periods. Payments related to leases are based on actual payments specified in underlying contracts.
				More than 1		3 years or
				year but less		more but less		5 years
		1 year or less		than 3 years		than 5 years		or more		Total
		(Dollars in thousands)
	Junior subordinated debentures	$	2,250	$	6,000	$	5,999	$	170,419	$	184,668
	Federal Home Loan Bank notes payable		31,201		3,456		5,665		2,337		42,659
	Operating leases		4,193		7,806		3,405		6,532		21,936
	Total	$	37,644	$	17,262	$	15,069	$	179,288	$	249,263
	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 expiring by periods as of March 31, 2014 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.
				More than 1		3 years or
				year but less		more but less		5 years
		1 year or less		than 3 years		than 5 years		or more		Total
		(Dollars in thousands)
	Standby letters of credit	$	39,700	$	8,143	$	45	$	150	$	48,038
	Commitments to extend credit		699,303		407,180		67,717		362,239		1,536,439
	Total	$	739,003	$	415,323	$	67,762	$	362,389	$	1,584,477

OTHER_COMPREHENSIVE_LOSS_INCOM

OTHER COMPREHENSIVE (LOSS) INCOME	3 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
OTHER COMPREHENSIVE (LOSS) INCOME	'
	10. OTHER COMPREHENSIVE (LOSS) INCOME
	The tax effects allocated to each component of other comprehensive (loss) income were as follows:
		Three Months Ended March 31,
		2014								2013
		Before Tax			Tax Benefit		Net of Tax			Before Tax			Tax Benefit		Net of Tax
		Amount					Amount			Amount					Amount
		(Dollars in thousands)
	Other comprehensive loss:
	Securities available for sale:
	Change in unrealized gain during period	$	(489	)	$	171	$	(318	)	$	(1,771	)	$	620	$	(1,151	)
	Total securities available for sale		(489	)		171		(318	)		(1,771	)		620		(1,151	)
	Total other comprehensive loss	$	(489	)	$	171	$	(318	)	$	(1,771	)	$	620	$	(1,151	)
	Activity in accumulated other comprehensive income associated with securities available for sale, net of tax, was as follows:
		Accumulated
		Other
		Comprehensive
		Income
		(Dollars in thousands)
	Balance at January 1, 2014	$	4,883
	Other comprehensive loss		(318	)
	Balance at March 31, 2014	$	4,565
	Balance at January 1, 2013	$	8,986
	Other comprehensive loss		(1,151	)
	Balance at March 31, 2013	$	7,835

DERIVATIVE_FINANCIAL_INSTRUMEN

DERIVATIVE FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2014
Derivative Instruments And Hedging Activities Disclosure [Abstract]	'
DERIVATIVE FINANCIAL INSTRUMENTS	'
	11. DERIVATIVE FINANCIAL INSTRUMENTS
	On November 1, 2013, the Company acquired FVNB Corp. and assumed the following derivative contracts relating to loans made to certain commercial customers. The interest rate derivative contracts outstanding at March 31, 2014 are presented in the following table:
		Current Notional		Estimated			Maturity Date	Fixed Pay			Variable Rate
		Amount		Fair Value				Rate
											Received
		(Dollars in thousands)
	Commercial Loan Interest Rate Swap	$	4,387	$	106		August 1, 2020		4.3	%	1-Month USD - LIBOR BBA+2.50
	Commercial Loan Interest Rate Swap		1,612		42		August 15, 2020		5.49	%	1-Month USD - LIBOR BBA+3.00
	Commercial Loan Interest Rate Swap		1,463		26		15-Aug-20		4.3	%	1-Month USD - LIBOR BBA+2.50
	Commercial Loan Interest Rate Swap		1,882		(21	)	1-May-22		5.6	%	1-Month USD - LIBOR BBA+3.50
		$	9,344	$	153
	In these transactions, the Company has made a loan to a borrower at a variable rate of interest which the borrower pays directly to the Company. The Company also enters into an interest rate swap with a customer to accommodate the customer’s desired terms while at the same time entering into an identical offsetting interest rate swap with another financial institution, thus fully eliminating any interest rate risk to the Company. In connection with each swap transaction, the Company agrees to pay interest to the borrowing customer on a notional amount at a variable interest rate and receive interest from the customer on the same notional amount at a fixed interest rate. At the same time, the Company agrees to pay another financial institution the same fixed interest rate on the same notional amount and receive the same variable interest rate on the same notional amount. The transaction allows the Company’s customer to effectively convert a variable-rate loan to a fixed-rate. Because the Company acts solely as an intermediary for its customer, changes in the fair value of the underlying derivative contracts offset each other and do not materially impact the Company’s results of operations. Derivative assets of $153 thousand and derivative liabilities of $153 thousand are recorded in other assets and other liabilities, respectively. The notional amounts and estimated fair values of interest rate derivative contracts outstanding at March 31, 2014 are presented in the following table:
		Current Notional		Estimated
		Amount		Fair Value
		(Dollars in thousands)
	Financial Institution Counterparties:
	Swaps - assets	$	1,882	$	21
	Swaps - liabilities		7,462		(174	)
	Bank Customer Counterparties:
	Swaps - assets	$	7,462	$	174
	Swaps - liabilities		1,882		(21	)
	Credit risk arises from the possible inability of counterparties to meet the terms of their contracts. The Company’s exposure is limited to the replacement value of the contracts rather than the notional, principal or contract amounts. Credit risk is minimized through credit approvals, limits, counterparty collateral and monitoring procedures. The Company’s derivative assets and liabilities include certain contractual features in which the Company requires the counterparties to provide collateral in the form of cash and securities to offset changes in the fair value of the derivatives. When necessary, the Company posts collateral primarily in the form of cash to offset changes in fair value of the derivatives, including changes in fair value due to the Company’s credit risk. As of March 31, 2014 and December 31, 2013, the balance of collateral posted by the Company for derivatives was $260 thousand.

ACQUISITIONS

ACQUISITIONS	3 Months Ended
	Mar. 31, 2014
Business Combinations [Abstract]	'
ACQUISITIONS	'
	12. ACQUISITIONS
	Acquisition of F&M Bancorporation Inc. —On April 1, 2014, the Company completed the acquisition of F&M Bancorporation Inc. (“FMBC”) and its wholly-owned subsidiary The F&M Bank & Trust Company (“F&M Bank”) headquartered in Tulsa, Oklahoma. The acquisition was not considered significant to the Company’s financial statements and therefore pro forma financial data and related disclosures are not included. Refer to Note 13 – Subsequent Events for further information regarding the F&M Bank acquisition.
	Acquisition of FVNB Corp. — On November 1, 2013, the Company completed the acquisition of FVNB Corp. and its wholly owned subsidiary, First Victoria National Bank (collectively, “FVNB”) headquartered in Victoria, Texas. FVNB operated 33 banking locations; 4 in Victoria, Texas; 7 in the South Texas area including Corpus Christi; 6 in the Bryan/College Station area; 5 in the Central Texas area including New Braunfels; and 11 in the Houston area including The Woodlands. The Company acquired FVNB to expand its Central and South Texas markets. The acquisition is not considered significant to the Company’s financial statements and therefore pro forma financial data and related disclosures are not included.
	As of September 30, 2013, FVNB, on a consolidated basis, reported total assets of $2.47 billion, total loans of $1.65 billion and total deposits of $2.20 billion. Under the terms of the acquisition agreement, the Company issued 5,570,667 shares of Company common stock plus $91.3 million in cash for all outstanding shares of FVNB Corp. capital stock for total merger consideration of $439.1 million based on the Company’s closing stock price of $62.45. As of March 31, 2014, the Company recognized $323.4 million in goodwill. Goodwill recognized does not include subsequent fair value adjustments that are still being finalized. Goodwill is calculated as the excess of both the consideration exchanged and liabilities assumed as compared to the fair value of identifiable assets acquired, none of which is expected to be deductible for tax purposes. Additionally, the Company recognized $18.4 million of core deposit intangibles. For the three months ended March 31, 2014, the Company incurred approximately $542 thousand of pre-tax merger related expenses related to the FVNB acquisition.
	Acquisition of Coppermark Bancshares, Inc.—On April 1, 2013, the Company completed the acquisition of Coppermark Bancshares, Inc. and its wholly-owned subsidiary, Coppermark Bank (collectively, “Coppermark”). Coppermark operated 9 full-service banking offices: 6 in Oklahoma City, Oklahoma and surrounding areas and 3 in the Dallas, Texas area. The Company acquired Coppermark to expand its market into Oklahoma. The acquisition was not considered significant to the Company’s financial statements and therefore pro forma financial data and related disclosures are not included.
	As of March 31, 2013, Coppermark reported, on a consolidated basis, total assets of $1.25 billion, total loans of $847.6 million and total deposits of $1.11 billion. Under the terms of the acquisition agreement, the Company issued 3,258,718 shares of Company common stock plus $60.0 million in cash for all outstanding shares of Coppermark Bancshares, Inc. capital stock, for total merger consideration of $214.4 million based on the Company’s closing stock price of $47.39. As of March 31, 2014, the Company recognized goodwill of $117.7 million, after a $109 thousand measurement period adjustment recording during the first quarter of 2014. Additionally, the Company recognized $1.5 million of core deposit intangibles.
	Acquisition of East Texas Financial Services, Inc.—On January 1, 2013, the Company completed the acquisition of East Texas Financial Services, Inc. (OTC BB: FFBT) and its wholly-owned subsidiary, First Federal Bank Texas (collectively, “East Texas Financial Services”). East Texas Financial Services operated 4 banking offices in the Tyler MSA, including three locations in Tyler, Texas and one location in Gilmer, Texas. The Company acquired East Texas Financial Services to increase its market share in the East Texas area. The acquisition was not considered significant to the Company’s financial statements and therefore pro forma financial data and related disclosures are not included.
	As of December 31, 2012, East Texas Financial Services reported, on a consolidated basis, total assets of $165.0 million, total loans of $129.3 million and total deposits of $112.3 million. Under the terms of the acquisition agreement, the Company issued 530,940 shares of Company common stock for all outstanding shares of East Texas Financial Services capital stock, for total merger consideration of $22.3 million based on the Company’s closing stock price of $42.00. The Company recognized goodwill of $15.0 million.

SUBSEQUENT_EVENTS

SUBSEQUENT EVENTS	3 Months Ended
	Mar. 31, 2014
Subsequent Events [Abstract]	'
SUBSEQUENT EVENTS	'
	13. SUBSEQUENT EVENTS
	Acquisition of F&M Bancorporation Inc. — On April 1, 2014, Prosperity completed the acquisition of F&M Bancorporation Inc. and its wholly-owned subsidiary The F&M Bank & Trust Company headquartered in Tulsa, Oklahoma. F&M Bank operated 13 banking offices: 9 in Tulsa, Oklahoma and surrounding areas; 3 in Dallas, Texas and 1 loan production office in Oklahoma City, Oklahoma. The Company acquired FMBC to further expand its Oklahoma and Dallas, Texas area markets.
	As of March 31, 2014, FMBC, on a consolidated basis, reported total assets of $2.41 billion, total loans of $1.74 billion and total deposits of $2.27 billion. Under the terms of the definitive agreement, Prosperity issued 3,298,022 shares of Prosperity common stock plus $34.2 million in cash for all outstanding shares of FMBC capital stock for total merger consideration of $252.4 million based on the Company’s closing stock price of $66.15. The Company recognized initial goodwill of $148.4 million which does not include subsequent fair value adjustments that are still being finalized.

NEW_ACCOUNTING_STANDARDS_Polic

NEW ACCOUNTING STANDARDS (Policies)	3 Months Ended
	Mar. 31, 2014
Accounting Changes And Error Corrections [Abstract]	'
New Accounting Standards	'
	ASU 2014-04 “Receivables—Troubled Debt Restructurings by Creditors (Subtopic 310-40) — Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure”. ASU 2014-04 intends to reduce diversity by clarifying when an in substance repossession or foreclosure occurs, that is, when a creditor should be considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan such that the loan receivable should be derecognized and the real estate property recognized. ASU 2014-04 will become effective for the Company on January 1, 2015 and is not expected to have an impact on the Company’s financial statements.

INCOME_PER_COMMON_SHARE_Tables

INCOME PER COMMON SHARE (Tables)	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Computation of Basic and Diluted Earnings Per Share	'
	The following table illustrates the computation of basic and diluted earnings per share:
		Three Months Ended March 31,
		2014				2013
				Per Share				Per Share
		Amount		Amount		Amount		Amount
		(Amounts in thousands, except per share data)
	Net income	$	67,137			$	49,305
	Basic:
	Weighted average shares outstanding		66,186	$	1.01		56,988	$	0.87
	Diluted:
	Add incremental shares for:
	Effect of dilutive securities—options		94				146
	Total		66,280	$	1.01		57,134	$	0.86

SECURITIES_Tables

SECURITIES (Tables)	3 Months Ended
	Mar. 31, 2014
Investments Debt And Equity Securities [Abstract]	'
Schedule of Investment Securities	'
	The amortized cost and fair value of investment securities were as follows:
		March 31, 2014
		Amortized		Gross			Gross			Fair
		Cost		Unrealized			Unrealized			Value
				Gains			Losses
		(Dollars in thousands)
	Available for Sale
	States and political subdivisions	$	23,238	$	609		$	—		$	23,847
	Collateralized mortgage obligations		455		6			(3	)		458
	Mortgage-backed securities		100,077		6,476			(19	)		106,534
	Other securities		12,589		—			(46	)		12,543
	Total	$	136,359	$	7,091		$	(68	)	$	143,382
	Held to Maturity
	U.S. Treasury securities and obligations of U.S. Government agencies	$	62,966	$	213		$	(148	)	$	63,031
	States and political subdivisions		383,335		4,673			(982	)		387,026
	Corporate debt securities		508		4			—			512
	Collateralized mortgage obligations		42,327		739			(22	)		43,044
	Mortgage-backed securities		7,899,007		100,051			(113,846	)		7,885,212
	Qualified Zone Academy Bond (QZAB)		16,912		924			(307	)		17,529
	Qualified School Construction Bonds (QSCB)		12,900		1,665			—			14,565
	Total	$	8,417,955	$	108,269		$	(115,305	)	$	8,410,919
		31-Dec-13
		Amortized		Gross			Gross			Fair
		Cost		Unrealized			Unrealized			Value
				Gains			Losses
		(Dollars in thousands)
	Available for Sale
	States and political subdivisions	$	28,578	$	797		$	—		$	29,375
	Collateralized mortgage obligations		483		7			(1	)		489
	Mortgage-backed securities		108,316		6,843			(22	)		115,137
	Other securities		12,589		14			(126	)		12,477
	Total	$	149,966	$	7,661		$	(149	)	$	157,478
	Held to Maturity
	U.S. Treasury securities and obligations of U.S. Government agencies	$	62,931	$	46		$	(935	)	$	62,042
	States and political subdivisions		426,335		3,176			(2,207	)		427,304
	Corporate debt securities		513		5			—			518
	Collateralized mortgage obligations		50,034		1,017			(58	)		50,993
	Mortgage-backed securities		7,514,257		84,166			(165,979	)		7,432,444
	Qualified School Construction Bonds (QSCB)		12,900		1,141			—			14,041
	Total	$	8,066,970	$	89,551		$	(169,179	)	$	7,987,342
Schedule of Securities with Unrealized Losses	'
	Securities with unrealized losses, segregated by length of time, that have been in a continuous loss position were as follows:
		March 31, 2014
		Less than 12 Months					More than 12 Months						Total
		Estimated		Unrealized			Estimated			Unrealized			Estimated		Unrealized
		Fair Value		Losses			Fair Value			Losses			Fair Value		Losses
		(Dollars in thousands)
	Available for Sale
	Collateralized mortgage obligations	$	186	$	(2	)	$	48		$	(1	)	$	234	$	(3	)
	Mortgage-backed securities		696		(2	)		3,021			(17	)		3,717		(19	)
	Other securities		12,542		(46	)		—			—			12,542		(46	)
	Total	$	13,424	$	(50	)	$	3,069		$	(18	)	$	16,493	$	(68	)
	Held to Maturity
	U.S. Treasury securities and obligations of U.S. Government agencies	$	26,620	$	(148	)	$	—		$	—		$	26,620	$	(148	)
	States and political subdivisions		69,880		(901	)		21,218			(388	)		91,098		(1,289	)
	Collateralized mortgage obligations		1,548		(18	)		437			(4	)		1,985		(22	)
	Mortgage-backed securities		2,582,055		(69,224	)		985,079			(44,622	)		3,567,134		(113,846	)
	Total	$	2,680,103	$	(70,291	)	$	1,006,734		$	(45,014	)	$	3,686,837	$	(115,305	)
		31-Dec-13
		Less than 12 Months					More than 12 Months						Total
		Estimated		Unrealized			Estimated			Unrealized			Estimated		Unrealized
		Fair Value		Losses			Fair Value			Losses			Fair Value		Losses
		(Dollars in thousands)
	Available for Sale
	Collateralized mortgage obligations	$	5	$	—		$	50		$	(1	)	$	55	$	(1	)
	Mortgage-backed securities		651		(1	)		3,313			(21	)		3,964		(22	)
	Other securities		6,911		(126	)		—			—			6,911		(126	)
	Total	$	7,567	$	(127	)	$	3,363		$	(22	)	$	10,930	$	(149	)
	Held to Maturity
	U.S. Treasury securities and obligations of U.S. Government agencies	$	48,389	$	(935	)	$	—		$	—		$	48,389	$	(935	)
	States and political subdivisions		113,063		(1,581	)		28,639			(626	)		141,702		(2,207	)
	Collateralized mortgage obligations		2,109		(32	)		433			(26	)		2,542		(58	)
	Mortgage-backed securities		3,702,569		(106,816	)		998,380			(59,163	)		4,700,949		(165,979	)
	Total	$	3,866,130	$	(109,364	)	$	1,027,452		$	(59,815	)	$	4,893,582	$	(169,179	)
Amortized Cost and Fair Value of Investment Securities by Contractual Maturity	'
	The amortized cost and fair value of investment securities at March 31, 2014, by contractual maturity, are shown below. Actual maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations at any time with or without call or prepayment penalties.
		Held to Maturity					Available for Sale
		Amortized		Fair			Amortized			Fair
		Cost		Value			Cost			Value
		(Dollars in thousands)
	Due in one year or less	$	32,648	$	32,748		$	12,684		$	12,638
	Due after one year through five years		158,614		159,787			4,833			5,000
	Due after five years through ten years		205,727		208,084			16,638			17,047
	Due after ten years		79,632		82,044			1,672			1,705
	Subtotal		476,621		482,663			35,827			36,390
	Mortgage-backed securities and collateralized mortgage obligations		7,941,334		7,928,256			100,532			106,992
	Total	$	8,417,955	$	8,410,919		$	136,359		$	143,382

LOANS_AND_ALLOWANCE_FOR_CREDIT1

LOANS AND ALLOWANCE FOR CREDIT LOSSES (Tables)	3 Months Ended
	Mar. 31, 2014
Text Block [Abstract]	'
Schedule of Types of Loans in Loan Portfolio	'
	The loan portfolio consists of various types of loans made principally to borrowers located within the states of Texas and Oklahoma and is classified by major type as follows:
			March 31,			December 31,
			2014			2013
			(Dollars in thousands)
	Residential mortgage loans held for sale		$	3,558		$	2,210
	Commercial and industrial			1,255,020			1,279,777
	Real estate:
	Construction, land development and other land loans			888,985			865,511
	1-4 family residential (including home equity)			2,166,888			2,129,510
	Commercial real estate (including multi-family residential)			2,709,386			2,753,797
	Farmland			337,021			332,648
	Agriculture			175,836			198,610
	Consumer and other (net of unearned discount)			215,706			213,158
	Total loans held for investment			7,748,842			7,773,011
	Total		$	7,752,400		$	7,775,221
Schedule of Activity with Respect to Related-Party Loans	'
	An analysis of activity with respect to these related party loans is as follows:
			March 31,			December 31,
			2014			2013
			(Dollars in thousands)
	Beginning balance on January 1		$	6,187		$	6,682
	New loans and reclassified related loans			2,814			306
	Repayments			(3,015	)		(801	)
	Ending balance		$	5,986		$	6,187
Schedule of Past Due Loans with Age Analysis, Segregated by Class of Loans	'
	An aging analysis of past due loans, segregated by class of loans, was as follows:
			March 31, 2014
			Loans Past Due and Still Accruing
			30-89 Days			90 or More			Total Past			Nonaccrual			Current			Total
						Days			Due Loans			Loans			Loans			Loans
			(Dollars in thousands)
	Construction, land development and other land loans		$	10,291		$	227		$	10,518		$	377		$	878,090		$	888,985
	Agriculture and agriculture real estate (includes farmland)			1,351			—			1,351			84			511,422			512,857
	1-4 family (includes home equity) (1)			2,900			222			3,122			3,832			2,163,492			2,170,446
	Commercial real estate (includes multi-family residential)			28,130			44			28,174			1,629			2,679,583			2,709,386
	Commercial and industrial			17,669			3,026			20,695			1,636			1,232,689			1,255,020
	Consumer and other			1,704			—			1,704			156			213,846			215,706
	Total		$	62,045		$	3,519		$	65,564		$	7,714		$	7,679,122		$	7,752,400
			31-Dec-13
			Loans Past Due and Still Accruing
			30-89 Days			90 or More			Total Past			Nonaccrual			Current			Total
						Days			Due Loans			Loans			Loans			Loans
			(Dollars in thousands)
	Construction, land development and other land loans		$	6,258		$	2		$	6,260		$	386		$	858,865		$	865,511
	Agriculture and agriculture real estate (includes farmland)			5,634			218			5,852			62			525,344			531,258
	1-4 family (includes home equity) (1)			8,684			2,012			10,696			3,086			2,117,938			2,131,720
	Commercial real estate (includes multi-family residential)			8,163			1,752			9,915			4,333			2,739,549			2,753,797
	Commercial and industrial			9,552			933			10,485			2,208			1,267,084			1,279,777
	Consumer and other			1,344			30			1,374			156			211,628			213,158
	Total		$	39,635		$	4,947		$	44,582		$	10,231		$	7,720,408		$	7,775,221
	-1	Includes $3.6 million and $2.2 million of residential mortgage loans held for sale at March 31, 2014 and December 31, 2013, respectively.
Schedule of Nonperforming Assets	'
	The following table presents information regarding nonperforming assets as of the dates indicated:
			March 31,			December 31,
			2014			2013
			(Dollars in thousands)
	Nonaccrual loans		$	7,714		$	10,231
	Accruing loans 90 or more days past due			3,519			4,947
	Total nonperforming loans			11,233			15,178
	Repossessed assets			91			27
	Other real estate			7,372			7,299
	Total nonperforming assets		$	18,696		$	22,504
	Nonperforming assets to total loans and other real estate			0.24	%		0.29	%
Summary of Carrying Value and Outstanding Balance for Purchased Credit Impaired Loans	'
	The carrying amount of acquired PCI loans included in the consolidated balance sheet and the related outstanding balance as of the dates indicated are presented in the table below.
			March 31,			December 31,
			2014			2013
			(Dollars in thousands)
	Acquired PCI loans:
	Outstanding balance		$	81,671		$	87,089
	Discount			42,025			45,497
	Recorded investment
Summary of Changes in Accretable Yield for Acquired PCI Loans	'
	Changes in the accretable yield for acquired PCI loans as of the dates indicated below were as follows:
			Three Months Ended March 31,
			2014			2013
			(Dollars in thousands)
	Balance at beginning of period		$	9,855		$	7,459
	Additions			—			1,736
	Reclassifications from nonaccretable			1,503			143
	Accretion			(2,888	)		(1,769	)
	Balance at March 31		$	8,470		$	7,569
Schedule of Impaired Loans	'
	Impaired loans are set forth in the following tables. No interest income was recognized on impaired loans subsequent to their classification as impaired. The average recorded investment presented in the tables below is reported on a year-to-date basis.
			March 31, 2014
			Recorded			Unpaid			Related			Average
			Investment			Principal			Allowance			Recorded
						Balance						Investment
			(Dollars in thousands)
	With no related allowance recorded:
	Construction, land development and other land loans		$	324		$	341		$	—		$	301
	Agriculture and agriculture real estate (includes farmland)			27			137			—			21
	1-4 family (includes home equity)			762			829			—			673
	Commercial real estate (includes multi-family residential)			1,415			2,637			—			1,953
	Commercial and industrial			293			452			—			198
	Consumer and other			9			9			—			12
	Total			2,830			4,405			—			3,158
	With an allowance recorded:
	Construction, land development and other land loans			—			—			—			—
	Agriculture and agriculture real estate (includes farmland)			180			186			48			101
	1-4 family (includes home equity)			2,187			2,220			767			2,353
	Commercial real estate (includes multi-family residential)			7			8			7			810
	Commercial and industrial			1,269			1,357			1,217			1,190
	Consumer and other			140			152			92			118
	Total			3,783			3,923			2,131			4,572
	Total:
	Construction, land development and other land loans			324			341			—			301
	Agriculture and agriculture real estate (includes farmland)			207			323			48			122
	1-4 family (includes home equity)			2,949			3,049			767			3,026
	Commercial real estate (includes multi-family residential)			1,422			2,645			7			2,763
	Commercial and industrial			1,562			1,809			1,217			1,388
	Consumer and other			149			161			92			130
			$	6,613		$	8,328		$	2,131		$	7,730
			December 31, 2013
			Recorded			Unpaid			Related			Average
			Investment			Principal			Allowance			Recorded
						Balance						Investment
			(Dollars in thousands)
	With no related allowance recorded:
	Construction, land development and other land loans		$	277		$	289		$	—		$	711
	Agriculture and agriculture real estate (includes farmland)			14			57			—			46
	1-4 family (includes home equity)			584			664			—			538
	Commercial real estate (includes multi-family residential)			2,490			3,798			—			1,470
	Commercial and industrial			103			122			—			95
	Consumer and other			15			16			—			13
	Total			3,483			4,946			—			2,873
	With an allowance recorded:
	Construction, land development and other land loans			—			—			—			—
	Agriculture and agriculture real estate (includes farmland)			21			27			18			28
	1-4 family (includes home equity)			2,519			2,548			890			1,759
	Commercial real estate (includes multi-family residential)			1,613			1,615			445			2,032
	Commercial and industrial			1,111			1,192			1,029			1,077
	Consumer and other			95			113			77			81
	Total			5,359			5,495			2,459			4,977
	Total:
	Construction, land development and other land loans			277			289			—			711
	Agriculture and agriculture real estate (includes farmland)			35			84			18			74
	1-4 family (includes home equity)			3,103			3,212			890			2,297
	Commercial real estate (includes multi-family residential)			4,103			5,413			445			3,502
	Commercial and industrial			1,214			1,314			1,029			1,172
	Consumer and other			110			129			77			94
			$	8,842		$	10,441		$	2,459		$	7,850
Schedule Showing Risk Grades and Classified Loans by Class of Loan	'
	The following table presents risk grades and classified loans by class of loan at March 31, 2014. Impaired loans include loans in risk grades 7, 8 and 9.
			Construction,			Agriculture and						Commercial
			Land			Agriculture Real			1-4 Family			Real Estate
			Development and			Estate (includes			(includes			(includes Multi-			Commercial			Consumer and
			other land loans			Farmland)			Home Equity) (1)			Family Residential)			and Industrial			Other			Total
			(Dollars in thousands)
	Grade 1		$	—		$	4,869		$	—		$	—		$	48,682		$	32,948		$	86,499
	Grade 2			—			—			—			—			—			—			—
	Grade 3			883,334			502,053			2,154,734			2,659,042			1,183,149			182,419			7,564,731
	Grade 4			—			—			—			—			—			—			—
	Grade 5			978			4,998			3,877			10,484			13,181			123			33,641
	Grade 6			955			138			4,943			12,115			3,052			67			21,270
	Grade 7			324			207			2,939			1,422			1,546			149			6,587
	Grade 8			—			—			10			—			16			—			26
	Grade 9			—			—			—			—			—			—			—
	PCI Loans (2)			3,394			592			3,943			26,323			5,394			—			39,646
	Total		$	888,985		$	512,857		$	2,170,446		$	2,709,386		$	1,255,020		$	215,706		$	7,752,400
	-1	Includes $3.6 million of residential mortgage loans held for sale at March 31, 2014.
	-2	Of the total PCI loans, $17.3 million were classifed as substandard at March 31, 2014.
			Construction,			Agriculture and						Commercial
			Land			Agriculture Real			1-4 Family			Real Estate
			Development and			Estate (includes			(includes			(includes Multi-			Commercial			Consumer and
			other land loans			Farmland)			Home Equity) (1)			Family Residential)			and Industrial			Other			Total
			(Dollars in thousands)
	Grade 1		$	—		$	5,225		$	—		$	—		$	50,131		$	31,362		$	86,718
	Grade 2			—			—			—			—			—			—			—
	Grade 3			858,712			520,921			2,113,698			2,697,664			1,202,604			181,406			7,575,005
	Grade 4			—			—			—			—			—			—			—
	Grade 5			1,141			3,427			6,337			10,798			17,179			146			39,028
	Grade 6			1,616			1,043			4,504			14,316			2,423			134			24,036
	Grade 7			277			35			3,093			4,103			1,214			110			8,832
	Grade 8			—			—			10			—			—			—			10
	Grade 9			—			—			—			—			—			—			—
	PCI Loans (2)			3,765			607			4,078			26,916			6,226			—			41,592
	Total		$	865,511		$	531,258		$	2,131,720		$	2,753,797		$	1,279,777		$	213,158		$	7,775,221
	-1	Includes $2.2 million of residential mortgage loans held for sale at December 31, 2013.
	-2	Of the total PCI loans, $17.6 million were classifed as substandard at December 31, 2013.
Schedule of Recorded Investment in Loans and Activity in Allowance for Credit Losses by Portfolio Segment	'
	The following table details activity in the allowance for loan losses by portfolio segment for the three months ended March 31, 2014 and 2013. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.
						Agriculture
			Construction,			and						Commercial
			Land			Agriculture			1-4 Family			Real Estate
			Development			Real Estate			(includes			(includes			Commercial
			and other			(includes			Home			Multi-Family			and			Consumer
			land loans			Farmland)			Equity)			Residential)			Industrial			and Other			Total
			(Dollars in thousands)
	Allowance for credit losses:
	Three Months Ended
	Balance January 1, 2014		$	14,353		$	1,229		$	17,046		$	24,835		$	8,167		$	1,652		$	67,282
	Provision for credit losses			(770	)		46			1,804			(1,404	)		567			357			600
	Charge-offs			(2	)		(14	)		(139	)		(102	)		(143	)		(1,045	)		(1,445	)
	Recoveries			19			95			7			42			62			434			659
	Net charge-offs			17			81			(132	)		(60	)		(81	)		(611	)		(786	)
	Balance March 31, 2014		$	13,600		$	1,356		$	18,718		$	23,371		$	8,653		$	1,398		$	67,096
	Three Months Ended
	Balance January 1, 2013		$	11,909		$	764		$	13,942		$	19,607		$	5,777		$	565		$	52,564
	Provision for credit losses			270			116			272			2,205			(318	)		255			2,800
	Charge-offs			—			—			(111	)		(68	)		(155	)		(606	)		(940	)
	Recoveries			56			7			9			125			96			332			625
	Net charge-offs			56			7			(102	)		57			(59	)		(274	)		(315	)
	Balance March 31, 2013		$	12,235		$	887		$	14,112		$	21,869		$	5,400		$	546		$	55,049
	The following table details the amount of the allowance for loan losses allocated to each portfolio segment as of March 31, 2014, December 31, 2013 and March 31, 2013, detailed on the basis of the impairment methodology used by the Company.
						Agriculture
			Construction,			and						Commercial
			Land			Agriculture			1-4 Family			Real Estate
			Development			Real Estate			(includes			(includes			Commercial
			and other			(includes			Home			Multi-Family			and			Consumer
			land loans			Farmland)			Equity)			Residential)			Industrial			and Other			Total
			(Dollars in thousands)
	Allowance for credit losses related to:
	March 31, 2014
	Individually evaluated for impairment		$	—		$	48		$	767		$	7		$	1,217		$	92		$	2,131
	Collectively evaluated for impairment			13,600			1,308			17,951			23,364			7,436			1,306			64,965
	PCI loans			—			—			—			—			—			—			—
	Total allowance for credit losses		$	13,600		$	1,356		$	18,718		$	23,371		$	8,653		$	1,398		$	67,096
	December 31, 2013
	Individually evaluated for impairment		$	—		$	18		$	890		$	445		$	1,029		$	77		$	2,459
	Collectively evaluated for impairment			14,353			1,211			16,156			24,390			7,138			1,575			64,823
	PCI loans			—			—			—			—			—			—			—
	Total allowance for credit losses		$	14,353		$	1,229		$	17,046		$	24,835		$	8,167		$	1,652		$	67,282
	March 31, 2013
	Individually evaluated for impairment		$	134		$	27		$	94		$	786		$	1,467		$	65		$	2,573
	Collectively evaluated for impairment			12,101			860			14,018			21,083			3,933			481			52,476
	PCI loans			—			—			—			—			—			—			—
	Total allowance for credit losses		$	12,235		$	887		$	14,112		$	21,869		$	5,400		$	546		$	55,049
	The following table details the recorded investment in loans as of March 31, 2014, December 31, 2013 and March 31, 2013, excluding $3.6 million, $2.2 million and $8.5 million, respectively, of residential mortgage loans held for sale, related to each balance in the allowance for loan losses by portfolio segment.
						Agriculture
			Construction,			and						Commercial
			Land			Agriculture			1-4 Family			Real Estate
			Development			Real Estate			(includes			(includes			Commercial
			and other			(includes			Home			Multi-Family			and			Consumer
			land loans			Farmland)			Equity)			Residential)			Industrial			and Other			Total
			(Dollars in thousands)
	Recorded investment in loans:
	March 31, 2014
	Individually evaluated for impairment		$	324		$	207		$	2,949		$	1,422		$	1,562		$	149		$	6,613
	Collectively evaluated for impairment			885,267			512,058			2,159,996			2,681,641			1,248,064			215,557			7,702,583
	PCI loans			3,394			592			3,943			26,323			5,394			—			39,646
	Total loans evaluated for impairment		$	888,985		$	512,857		$	2,166,888		$	2,709,386		$	1,255,020		$	215,706		$	7,748,842
	December 31, 2013
	Individually evaluated for impairment		$	277		$	35		$	3,103		$	4,103		$	1,214		$	110		$	8,842
Collectively evaluated for impairment			861,469			530,616			2,122,329			2,722,778			1,272,337			213,048			7,722,577
PCI loans			3,765			607			4,078			26,916			6,226			—			41,592
Total loans evaluated for impairment		$	865,511		$	531,258		$	2,129,510		$	2,753,797		$	1,279,777		$	213,158		$	7,773,011
March 31, 2013
Individually evaluated for impairment		$	635		$	107		$	486		$	2,664		$	3,209		$	69		$	7,170
Collectively evaluated for impairment			574,657			286,254			1,539,085			1,969,385			726,168			132,277			5,227,826
PCI loans			15			428			3,180			21,469			2,931			5			28,028
Total loans evaluated for impairment		$	575,307		$	286,789		$	1,542,751		$	1,993,518		$	732,308		$	132,351		$	5,263,024
Schedule of Loans Modified in Troubled Debt Restructuring	'
	The following table presents information regarding the recorded balance of loans modified in a troubled debt restructuring during the quarter ended March 31, 2014:
						Pre-			Post-
						Modification			Modification
						Outstanding			Outstanding
			Number of			Recorded			Recorded
			Contracts			Investment			Investment
			(Dollars in thousands)
	Troubled Debt Restructurings
	Construction, land development and other land loans			—		$	—		$	—
	Agriculture and agriculture real estate			—			—			—
	1-4 Family (includes home equity)			—			—			—
	Commercial real estate (commercial mortgage and multi-family)			1			35			35
	Commercial and industrial			1			16			16
	Consumer and other			—			—			—
	Total			2		$	51		$	51

FAIR_VALUE_Tables

FAIR VALUE (Tables)	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis	'
	The following tables present fair values for assets and liabilities measured at fair value on a recurring basis:
		As of March 31, 2014
		Level 1		Level 2			Level 3		Total
		(Dollars in thousands)
	Assets:
	Available for sale securities:
	States and political subdivisions	$	—	$	23,847		$	—	$	23,847
	Collateralized mortgage obligations		—		458			—		458
	Mortgage-backed securities		—		106,534			—		106,534
	Other securities		12,543		—			—		12,543
	Total	$	12,543	$	130,839		$	—	$	143,382
	Non-hedging interest rate swap	$	—	$	153		$	—	$	153
	Liabilities:
	Non-hedging interest rate swap	$	—	$	(153	)	$	—	$	(153	)
		As of December 31, 2013
		Level 1		Level 2			Level 3		Total
		(Dollars in thousands)
	Assets:
	Available for sale securities:
	States and political subdivisions	$	—	$	29,375		$	—	$	29,375
	Collateralized mortgage obligations		—		489			—		489
	Mortgage-backed securities		—		115,137			—		115,137
	Other securities		12,477		—			—		12,477
	Total	$	12,477	$	145,001		$	—	$	157,478
	Non-hedging interest rate swap	$	—	$	38		$	—	$	38
	Liabilities:
	Non-hedging interest rate swap	$	—	$	(38	)	$	—	$	(38	)
Summary of Financial Assets and Liabilities Measured on Recurring and Non-Recurring Basis	'
	The following table presents carrying and fair value information of financial instruments as of the dates indicated:
		As of March 31, 2014
		Carrying		Estimated Fair Value
		Amount		Level 1			Level 2		Level 3			Total
		(Dollars in thousands)
	Assets
	Cash and due from banks	$	349,860	$	349,860		$	—	$	—		$	349,860
	Federal funds sold		382		382			—		—			382
	Held to maturity securities		8,417,955		—			8,410,919		—			8,410,919
	Loans held for sale		3,558		—			3,558		—			3,558
	Loans held for investment, net of allowance		7,681,746		—			—		7,718,665			7,718,665
	Liabilities
	Deposits:
	Noninterest-bearing	$	4,142,042	$	—		$	4,142,042	$	—		$	4,142,042
	Interest-bearing		11,318,015		—			11,330,483		—			11,330,483
	Other borrowings		40,451		—			41,845		—			41,845
	Securities sold under repurchase agreements		349,074		—			349,149		—			349,149
	Junior subordinated debentures		124,231		—			119,384		—			119,384
		As of December 31, 2013
		Carrying		Estimated Fair Value
		Amount		Level 1			Level 2		Level 3			Total
		(Dollars in thousands)
	Assets
	Cash and due from banks	$	380,990	$	380,990		$	—	$	—		$	380,990
	Federal funds sold		400		400			—		—			400
	Held to maturity securities		8,066,970		—			7,987,342		—			7,987,342
	Loans held for sale		2,210		2,210			—		—			2,210
	Loans held for investment, net of allowance		7,705,729		—			—		7,749,786			7,749,786
	Liabilities
	Deposits:
	Noninterest-bearing	$	4,108,835	$	—		$	4,108,835	$	—		$	4,108,835
	Interest-bearing		11,182,436		—			11,196,241		—			11,196,241
	Other borrowings		10,689		—			12,014		—			12,014
	Securities sold under repurchase agreements		364,357		—			364,477		—			364,477
	Junior subordinated debentures		124,231		—			119,325		—			119,325

GOODWILL_AND_CORE_DEPOSIT_INTA1

GOODWILL AND CORE DEPOSIT INTANGIBLES (Tables)	3 Months Ended
	Mar. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]	'
Schedule of Goodwill and Core Deposit Intangibles	'
	Changes in the carrying amount of the Company’s goodwill and core deposit intangibles (“CDI”) for the three months ended March 31, 2014 and the year ended December 31, 2013 were as follows:
		Goodwill			Core Deposit
					Intangibles
		(Dollars in thousands)
	Balance as of December 31, 2012	$	1,217,162		$	26,159
	Less:
	Amortization		—			(6,145	)
	Add:
	Measurement period adjustments		(1,225	)		2,110
	Acquisition of East Texas Financial Services, Inc.		15,007			—
	Acquisition of Coppermark Bancshares, Inc.		117,544			1,514
	Acquisition of FVNB Corp.		323,032			18,411
	Balance as of December 31, 2013		1,671,520			42,049
	Less:
	Amortization		—			(2,045	)
	Add:
	Measurement period adjustments		484			(302	)
	Balance as of March 31, 2014	$	1,672,004		$	39,702
Schedule of Estimated Aggregate Future Amortization Expense for Intangible Assets	'
	The estimated aggregate future amortization expense for CDI remaining as of March 31, 2014 is as follows (dollars in thousands):
	Remaining 2014	$	5,550
	2015		6,549
	2016		5,798
	2017		3,843
	2018		3,134
	Thereafter		14,828
	Total	$	39,702

CONTRACTUAL_OBLIGATIONS_AND_OF1

CONTRACTUAL OBLIGATIONS AND OFF-BALANCE SHEET ITEMS (Tables)	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Contractual Obligations and Other Commitments	'
	Payments related to leases are based on actual payments specified in underlying contracts.
				More than 1		3 years or
				year but less		more but less		5 years
		1 year or less		than 3 years		than 5 years		or more		Total
		(Dollars in thousands)
	Junior subordinated debentures	$	2,250	$	6,000	$	5,999	$	170,419	$	184,668
	Federal Home Loan Bank notes payable		31,201		3,456		5,665		2,337		42,659
	Operating leases		4,193		7,806		3,405		6,532		21,936
	Total	$	37,644	$	17,262	$	15,069	$	179,288	$	249,263
Letters of Credit and Commitments	'
	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.
				More than 1		3 years or
				year but less		more but less		5 years
		1 year or less		than 3 years		than 5 years		or more		Total
		(Dollars in thousands)
	Standby letters of credit	$	39,700	$	8,143	$	45	$	150	$	48,038
	Commitments to extend credit		699,303		407,180		67,717		362,239		1,536,439
	Total	$	739,003	$	415,323	$	67,762	$	362,389	$	1,584,477

OTHER_COMPREHENSIVE_LOSS_INCOM1

OTHER COMPREHENSIVE (LOSS) INCOME (Tables)	3 Months Ended
	Mar. 31, 2014
Equity [Abstract]	'
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:
		Three Months Ended March 31,
		2014								2013
		Before Tax			Tax Benefit		Net of Tax			Before Tax			Tax Benefit		Net of Tax
		Amount					Amount			Amount					Amount
		(Dollars in thousands)
	Other comprehensive loss:
	Securities available for sale:
	Change in unrealized gain during period	$	(489	)	$	171	$	(318	)	$	(1,771	)	$	620	$	(1,151	)
	Total securities available for sale		(489	)		171		(318	)		(1,771	)		620		(1,151	)
	Total other comprehensive loss	$	(489	)	$	171	$	(318	)	$	(1,771	)	$	620	$	(1,151	)
Activity in Accumulated Other Comprehensive Income Associated Securities Available for Sale, Net of Tax	'
	Activity in accumulated other comprehensive income associated with securities available for sale, net of tax, was as follows:
		Accumulated
		Other
		Comprehensive
		Income
		(Dollars in thousands)
	Balance at January 1, 2014	$	4,883
	Other comprehensive loss		(318	)
	Balance at March 31, 2014	$	4,565
	Balance at January 1, 2013	$	8,986
	Other comprehensive loss		(1,151	)
	Balance at March 31, 2013	$	7,835

DERIVATIVE_FINANCIAL_INSTRUMEN1

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2014
Derivative Instruments And Hedging Activities Disclosure [Abstract]	'
Interest Rate Derivative Contracts Outstanding	'
	The interest rate derivative contracts outstanding at March 31, 2014 are presented in the following table:
		Current Notional		Estimated			Maturity Date	Fixed Pay			Variable Rate
		Amount		Fair Value				Rate			Received
		(Dollars in thousands)
	Commercial Loan Interest Rate Swap	$	4,387	$	106		August 1, 2020		4.3	%	1-Month USD - LIBOR BBA+2.50
	Commercial Loan Interest Rate Swap		1,612		42		August 15, 2020		5.49	%	1-Month USD - LIBOR BBA+3.00
	Commercial Loan Interest Rate Swap		1,463		26		15-Aug-20		4.3	%	1-Month USD - LIBOR BBA+2.50
	Commercial Loan Interest Rate Swap		1,882		(21	)	1-May-22		5.6	%	1-Month USD - LIBOR BBA+3.50
		$	9,344	$	153
Notional Amounts and Estimated Fair Values of Interest Rate Derivative Contracts Outstanding	'
	The notional amounts and estimated fair values of interest rate derivative contracts outstanding at March 31, 2014 are presented in the following table:
		Current Notional		Estimated
		Amount		Fair Value
		(Dollars in thousands)
	Financial Institution Counterparties:
	Swaps - assets	$	1,882	$	21
	Swaps - liabilities		7,462		(174	)
	Bank Customer Counterparties:
	Swaps - assets	$	7,462	$	174
	Swaps - liabilities		1,882		(21	)

Income_Per_Common_Share_Comput

Income Per Common Share - Computation of Basic and Diluted Earnings Per Share (Detail) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'
Net income	$67,137	$49,305
Weighted average shares outstanding (basic)	66,186	56,988
Effect of dilutive securities - options	94	146
Total	66,280	57,134
Basic earnings per common share	$1.01	$0.87
Diluted earnings per common share	$1.01	$0.86

Income_Per_Common_Share_Additi

Income Per Common Share - Additional Information (Detail)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'
Stock options exercisable that would have had an anti-dilutive effect	0	0

Securities_Schedule_of_Investm

Securities - Schedule of Investment Securities (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investment Securities [Line Items]	'	'
Amortized Cost	$136,359	$149,966
Gross Unrealized Gains	7,091	7,661
Gross Unrealized Losses	-68	-149
Fair Value	143,382	157,478
Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	8,417,955	8,066,970
Gross Unrealized Gains	108,269	89,551
Gross Unrealized Losses	-115,305	-169,179
Fair Value	8,410,919	7,987,342
States and political subdivisions [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	23,238	28,578
Gross Unrealized Gains	609	797
Gross Unrealized Losses	'	'
Fair Value	23,847	29,375
States and political subdivisions [Member] | Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	383,335	426,335
Gross Unrealized Gains	4,673	3,176
Gross Unrealized Losses	-982	-2,207
Fair Value	387,026	427,304
Collateralized mortgage obligations [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	455	483
Gross Unrealized Gains	6	7
Gross Unrealized Losses	-3	-1
Fair Value	458	489
Collateralized mortgage obligations [Member] | Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	42,327	50,034
Gross Unrealized Gains	739	1,017
Gross Unrealized Losses	-22	-58
Fair Value	43,044	50,993
Mortgage-backed securities [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	100,077	108,316
Gross Unrealized Gains	6,476	6,843
Gross Unrealized Losses	-19	-22
Fair Value	106,534	115,137
Mortgage-backed securities [Member] | Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	7,899,007	7,514,257
Gross Unrealized Gains	100,051	84,166
Gross Unrealized Losses	-113,846	-165,979
Fair Value	7,885,212	7,432,444
Other securities [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	12,589	12,589
Gross Unrealized Gains	'	14
Gross Unrealized Losses	-46	-126
Fair Value	12,543	12,477
U.S. Treasury securities and obligations of U.S. government agencies [Member] | Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	62,966	62,931
Gross Unrealized Gains	213	46
Gross Unrealized Losses	-148	-935
Fair Value	63,031	62,042
Corporate debt securities [Member] | Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	508	513
Gross Unrealized Gains	4	5
Gross Unrealized Losses	'	'
Fair Value	512	518
Qualified Zone Academy Bond (QZAB) [Member] | Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	16,912	'
Gross Unrealized Gains	924	'
Gross Unrealized Losses	-307	'
Fair Value	17,529	'
Qualified School Construction Bonds (QSCB) [Member] | Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Amortized Cost	12,900	12,900
Gross Unrealized Gains	1,665	1,141
Gross Unrealized Losses	'	'
Fair Value	$14,565	$14,041

Securities_Schedule_of_Securit

Securities - Schedule of Securities with Unrealized Losses (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investment Securities [Line Items]	'	'
Available for Sale, Estimated Fair Value, Less than 12 Months	$13,424	$7,567
Available for Sale, Unrealized Losses, Less than 12 Months	-50	-127
Available for Sale, Estimated Fair Value, More than 12 Months	3,069	3,363
Available for Sale, Unrealized Losses, More than 12 Months	-18	-22
Available for Sale, Estimated Fair Value, Total	16,493	10,930
Available for Sale, Unrealized Losses, Total	-68	-149
Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Held to Maturity, Estimated Fair Value, Less than 12 Months	2,680,103	3,866,130
Held to Maturity, Unrealized Losses, Less than 12 Months	-70,291	-109,364
Held to Maturity, Estimated Fair Value, More than 12 Months	1,006,734	1,027,452
Held to Maturity, Unrealized Losses, More than 12 Months	-45,014	-59,815
Held to Maturity, Estimated Fair Value, Total	3,686,837	4,893,582
Held to Maturity, Unrealized Losses, Total	-115,305	-169,179
Collateralized mortgage obligations [Member]	'	'
Investment Securities [Line Items]	'	'
Available for Sale, Estimated Fair Value, Less than 12 Months	186	5
Available for Sale, Unrealized Losses, Less than 12 Months	-2	'
Available for Sale, Estimated Fair Value, More than 12 Months	48	50
Available for Sale, Unrealized Losses, More than 12 Months	-1	-1
Available for Sale, Estimated Fair Value, Total	234	55
Available for Sale, Unrealized Losses, Total	-3	-1
Collateralized mortgage obligations [Member] | Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Held to Maturity, Estimated Fair Value, Less than 12 Months	1,548	2,109
Held to Maturity, Unrealized Losses, Less than 12 Months	-18	-32
Held to Maturity, Estimated Fair Value, More than 12 Months	437	433
Held to Maturity, Unrealized Losses, More than 12 Months	-4	-26
Held to Maturity, Estimated Fair Value, Total	1,985	2,542
Held to Maturity, Unrealized Losses, Total	-22	-58
Mortgage-backed securities [Member]	'	'
Investment Securities [Line Items]	'	'
Available for Sale, Estimated Fair Value, Less than 12 Months	696	651
Available for Sale, Unrealized Losses, Less than 12 Months	-2	-1
Available for Sale, Estimated Fair Value, More than 12 Months	3,021	3,313
Available for Sale, Unrealized Losses, More than 12 Months	-17	-21
Available for Sale, Estimated Fair Value, Total	3,717	3,964
Available for Sale, Unrealized Losses, Total	-19	-22
Mortgage-backed securities [Member] | Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Held to Maturity, Estimated Fair Value, Less than 12 Months	2,582,055	3,702,569
Held to Maturity, Unrealized Losses, Less than 12 Months	-69,224	-106,816
Held to Maturity, Estimated Fair Value, More than 12 Months	985,079	998,380
Held to Maturity, Unrealized Losses, More than 12 Months	-44,622	-59,163
Held to Maturity, Estimated Fair Value, Total	3,567,134	4,700,949
Held to Maturity, Unrealized Losses, Total	-113,846	-165,979
Other securities [Member]	'	'
Investment Securities [Line Items]	'	'
Available for Sale, Estimated Fair Value, Less than 12 Months	12,542	6,911
Available for Sale, Unrealized Losses, Less than 12 Months	-46	-126
Available for Sale, Estimated Fair Value, More than 12 Months	'	'
Available for Sale, Unrealized Losses, More than 12 Months	'	'
Available for Sale, Estimated Fair Value, Total	12,542	6,911
Available for Sale, Unrealized Losses, Total	-46	-126
U.S. Treasury securities and obligations of U.S. government agencies [Member] | Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Held to Maturity, Estimated Fair Value, Less than 12 Months	26,620	48,389
Held to Maturity, Unrealized Losses, Less than 12 Months	-148	-935
Held to Maturity, Estimated Fair Value, More than 12 Months	'	'
Held to Maturity, Unrealized Losses, More than 12 Months	'	'
Held to Maturity, Estimated Fair Value, Total	26,620	48,389
Held to Maturity, Unrealized Losses, Total	-148	-935
States and political subdivisions [Member] | Held to Maturity Securities [Member]	'	'
Investment Securities [Line Items]	'	'
Held to Maturity, Estimated Fair Value, Less than 12 Months	69,880	113,063
Held to Maturity, Unrealized Losses, Less than 12 Months	-901	-1,581
Held to Maturity, Estimated Fair Value, More than 12 Months	21,218	28,639
Held to Maturity, Unrealized Losses, More than 12 Months	-388	-626
Held to Maturity, Estimated Fair Value, Total	91,098	141,702
Held to Maturity, Unrealized Losses, Total	($1,289)	($2,207)

Securities_Additional_Informat

Securities - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
	Security		Security
	Investment
Investment Securities [Line Items]	'	'	'
Securities in unrealized loss position	432	'	450
Gain (Loss) on sale of securities	$0	$0	'
Number of non-agency collateralized mortgage obligations	8	'	'
Book value of remaining non agency CMO's	1,600,000	'	'
Fair value of remaining non-agency CMO's	1,600,000	'	'
Aggregate adjusted cost exceeded consolidated shareholders' equity	10.00%	'	10.00%
Amortized Cost	136,359,000	'	149,966,000
Available for sale securities	143,382,000	'	157,478,000
Collateralized Securities [Member]	'	'	'
Investment Securities [Line Items]	'	'	'
Amortized Cost	5,100,000,000	'	4,460,000,000
Available for sale securities	$5,090,000,000	'	$4,470,000,000

Securities_Amortized_Cost_and_

Securities - Amortized Cost and Fair Value of Investment Securities by Contractual Maturity (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Amortized Cost And Fair Value Debt Securities [Abstract]	'	'
Due in one year or less, Held to Maturity, Amortized Cost	$32,648	'
Due after one year through five years, Held to Maturity, Amortized Cost	158,614	'
Due after five years through ten years, Held to Maturity, Amortized Cost	205,727	'
Due after ten years, Held to Maturity, Amortized Cost	79,632	'
Subtotal, Held to Maturity, Amortized Cost	476,621	'
Mortgage-backed securities and collateralized mortgage obligations, Held to Maturity, Amortized Cost	7,941,334	'
Total, Held to Maturity, Amortized Cost	8,417,955	8,066,970
Due in one year or less, Held to Maturity, Fair Value	32,748	'
Due after one year through five years, Held to Maturity, Fair Value	159,787	'
Due after five years through ten years, Held to Maturity, Fair Value	208,084	'
Due after ten years, Held to Maturity, Fair Value	82,044	'
Subtotal, Held to Maturity, Fair Value	482,663	'
Mortgage-backed securities and collateralized mortgage obligations, Held to Maturity, Fair Value	7,928,256	'
Total, Held to Maturity, Fair Value	8,410,919	7,987,342
Due in one year or less, Available for Sale, Amortized Cost	12,684	'
Due after one year through five years, Available for Sale, Amortized Cost	4,833	'
Due after five years through ten years, Available for Sale, Amortized Cost	16,638	'
Due after ten years, Available for Sale, Amortized Cost	1,672	'
Subtotal, Available for Sale, Amortized Cost	35,827	'
Mortgage-backed securities and collateralized mortgage obligations, Available for Sale, Amortized Cost	100,532	'
Total, Available for Sale, Amortized Cost	136,359	'
Due in one year or less, Available for Sale, Fair Value	12,638	'
Due after one year through five years, Available for Sale, Fair Value	5,000	'
Due after five years through ten years, Available for Sale, Fair Value	17,047	'
Due after ten years, Available for Sale, Fair Value	1,705	'
Subtotal, Available for Sale, Fair Value	36,390	'
Mortgage-backed securities and collateralized mortgage obligations, Available for Sale, Fair Value	106,992	'
Fair Value	$143,382	$157,478

Recovered_Sheet1

Loans and Allowance for Credit Losses - Schedule of Types of Loans in Loan Portfolio (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Commercial and industrial	$1,255,020	$1,279,777	'
Agriculture	175,836	198,610	'
Consumer and other (net of unearned discount)	215,706	213,158	'
Total loans held for investment	7,748,842	7,773,011	5,263,024
Total	7,752,400	7,775,221	'
Residential mortgage loans held for sale [Member]	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Residential mortgage loans held for sale	3,558	2,210	8,500
Construction, land development and other land loans [Member]	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Real estate	888,985	865,511	'
Total loans held for investment	888,985	865,511	575,307
Total	888,985	865,511	'
1-4 Family residential (includes home equity) [Member]	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Real estate	2,166,888	2,129,510	'
Total loans held for investment	2,166,888	2,129,510	1,542,751
Total	2,170,446	2,131,720	'
Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Real estate	2,709,386	2,753,797	'
Total loans held for investment	2,709,386	2,753,797	1,993,518
Total	2,709,386	2,753,797	'
Farmland [Member]	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'
Real estate	$337,021	$332,648	'

Recovered_Sheet2

Loans and Allowance for Credit Losses - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
	Y
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Fixed rate, in years	5	'	'	'	'
Percentage of loans related to single industry on total loans, maximum	10.00%	10.00%	10.00%	'	'
Loans outstanding to directors, officers and affiliates	$5,986,000	$6,187,000	$6,187,000	'	$6,682,000
Minimum period for ceases accruing interest, in days	'90 days	'	'	'	'
Total nonperforming assets	18,696,000	22,504,000	22,504,000	'	'
Interest on nonaccrual loans	234,000	111,000	'	'	'
Allowance for loan losses	0	'	0	'	'
Interest income recognized on impaired loans	0	'	'	'	'
Maximum principal and interest collectible on substandard impaired loans, percentage	100.00%	'	'	'	'
Allowance for credit losses totaled	67,100,000	67,300,000	67,300,000	'	'
Allowance for credit losses as a percentage of total loans	0.87%	0.87%	0.87%	'	'
Restructured Loans	'	'	'	0	'
Determined period of default, minimum number of days past due	'90 days	'	'	'	'
New troubled debt restructurings	51,000	'	'	'	'
Outstanding troubled debt restructurings	51,000	'	'	'	'
Residential mortgage loans held for sale [Member]	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Residential mortgage loans held for sale	$3,558,000	$2,210,000	$2,210,000	$8,500,000	'
Minimum [Member]	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Term of consumer loans	'12 months	'	'	'	'
Maximum [Member]	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Term of consumer loans	'180 months	'	'	'	'
Commercial Mortgages [Member]	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Percentage of outstanding principal balance, commercial real estate loans	52.80%	'	'	'	'
Commercial Mortgages [Member] | Minimum [Member]	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Term of consumer loans	'15 years	'	'	'	'
Commercial Mortgages [Member] | Maximum [Member]	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Term of consumer loans	'20 years	'	'	'	'
1-4 Family Residential Loans [Member]	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Originated loan maximum percentage of appraised value	89.00%	'	'	'	'
1-4 Family Residential Loans [Member] | Minimum [Member]	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Term of consumer loans	'5 years	'	'	'	'
1-4 Family Residential Loans [Member] | Maximum [Member]	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Term of consumer loans	'25 years	'	'	'	'
Veteran Administration And Federal Housing Administration Loan [Member]	'	'	'	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'	'	'	'
Term of consumer loans	'30 years	'	'	'	'

Loans_and_Allowance_for_Credit2

Loans and Allowance for Credit Losses - Schedule of Activity with Respect to Related-Party Loans (Detail) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Receivables [Abstract]	'	'
Beginning balance	$6,187	$6,682
New loans and reclassified related loans	2,814	306
Repayments	-3,015	-801
Ending balance	$5,986	$6,187

Loans_and_Allowance_for_Credit3

Loans and Allowance for Credit Losses - Schedule of Past Due Loans with Age Analysis, Segregated by Class of Loans (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
30-89 Days	$62,045	$39,635
90 or More Days	3,519	4,947
Total Past Due Loans	65,564	44,582
Nonaccrual Loans	7,714	10,231
Current Loans	7,679,122	7,720,408
Total Loans	7,752,400	7,775,221
Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
30-89 Days	10,291	6,258
90 or More Days	227	2
Total Past Due Loans	10,518	6,260
Nonaccrual Loans	377	386
Current Loans	878,090	858,865
Total Loans	888,985	865,511
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
30-89 Days	1,351	5,634
90 or More Days	'	218
Total Past Due Loans	1,351	5,852
Nonaccrual Loans	84	62
Current Loans	511,422	525,344
Total Loans	512,857	531,258
1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
30-89 Days	2,900	8,684
90 or More Days	222	2,012
Total Past Due Loans	3,122	10,696
Nonaccrual Loans	3,832	3,086
Current Loans	2,163,492	2,117,938
Total Loans	2,170,446	2,131,720
Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
30-89 Days	28,130	8,163
90 or More Days	44	1,752
Total Past Due Loans	28,174	9,915
Nonaccrual Loans	1,629	4,333
Current Loans	2,679,583	2,739,549
Total Loans	2,709,386	2,753,797
Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
30-89 Days	17,669	9,552
90 or More Days	3,026	933
Total Past Due Loans	20,695	10,485
Nonaccrual Loans	1,636	2,208
Current Loans	1,232,689	1,267,084
Total Loans	1,255,020	1,279,777
Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'
30-89 Days	1,704	1,344
90 or More Days	'	30
Total Past Due Loans	1,704	1,374
Nonaccrual Loans	156	156
Current Loans	213,846	211,628
Total Loans	$215,706	$213,158

Loans_and_Allowance_for_Credit4

Loans and Allowance for Credit Losses - Schedule of Past Due Loans with Age Analysis, Segregated by Class of Loans (Parenthetical) (Detail) (Residential mortgage loans held for sale [Member], USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
In Thousands, unless otherwise specified
Residential mortgage loans held for sale [Member]	'	'	'
Financing Receivable, Recorded Investment, Past Due [Line Items]	'	'	'
Residential mortgage loans held for sale	$3,558	$2,210	$8,500

Loans_and_Allowance_for_Credit5

Loans and Allowance for Credit Losses - Schedule of Nonperforming Assets (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Receivables [Abstract]	'	'
Nonaccrual Loans	$7,714	$10,231
Accruing loans 90 or more days past due	3,519	4,947
Total nonperforming loans	11,233	15,178
Repossessed assets	91	27
Other real estate	7,372	7,299
Total nonperforming assets	$18,696	$22,504
Nonperforming assets to total loans and other real estate	0.24%	0.29%

Loans_and_Allowance_for_Credit6

Loans and Allowance for Credit Losses - Summary of Carrying Value and Outstanding Balance for Purchased Credit Impaired Loans (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Acquired PCI loans:	'	'
Outstanding balance	$81,671	$87,089
Discount	42,025	45,497
Recorded investment	$39,646	$41,592

Loans_and_Allowance_for_Credit7

Loans and Allowance for Credit Losses - Summary of Changes in Accretable Yield for Acquired PCI Loans (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Business Combinations [Abstract]	'	'
Balance at beginning of period	$9,855	$7,459
Additions	'	1,736
Reclassifications from nonaccretable	1,503	143
Accretion	-2,888	-1,769
Balance at ending of period	$8,470	$7,569

Loans_and_Allowances_for_Credi

Loans and Allowances for Credit Losses - Schedule of Impaired Loans (Detail) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	$6,613	$8,842
Unpaid Principal Balance	8,328	10,441
Related Allowance	2,131	2,459
Average Recorded Investment	7,730	7,850
Construction, land development and other land loans [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	324	277
Unpaid Principal Balance	341	289
Related Allowance	'	'
Average Recorded Investment	301	711
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	207	35
Unpaid Principal Balance	323	84
Related Allowance	48	18
Average Recorded Investment	122	74
1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	2,949	3,103
Unpaid Principal Balance	3,049	3,212
Related Allowance	767	890
Average Recorded Investment	3,026	2,297
Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	1,422	4,103
Unpaid Principal Balance	2,645	5,413
Related Allowance	7	445
Average Recorded Investment	2,763	3,502
Commercial and Industrial [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	1,562	1,214
Unpaid Principal Balance	1,809	1,314
Related Allowance	1,217	1,029
Average Recorded Investment	1,388	1,172
Consumer and other [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	149	110
Unpaid Principal Balance	161	129
Related Allowance	92	77
Average Recorded Investment	130	94
With No Related Allowance Recorded [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	2,830	3,483
Unpaid Principal Balance	4,405	4,946
Related Allowance	'	'
Average Recorded Investment	3,158	2,873
With No Related Allowance Recorded [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	324	277
Unpaid Principal Balance	341	289
Related Allowance	'	'
Average Recorded Investment	301	711
With No Related Allowance Recorded [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	27	14
Unpaid Principal Balance	137	57
Related Allowance	'	'
Average Recorded Investment	21	46
With No Related Allowance Recorded [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	762	584
Unpaid Principal Balance	829	664
Related Allowance	'	'
Average Recorded Investment	673	538
With No Related Allowance Recorded [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	1,415	2,490
Unpaid Principal Balance	2,637	3,798
Related Allowance	'	'
Average Recorded Investment	1,953	1,470
With No Related Allowance Recorded [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	293	103
Unpaid Principal Balance	452	122
Related Allowance	'	'
Average Recorded Investment	198	95
With No Related Allowance Recorded [Member] | Consumer and other [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	9	15
Unpaid Principal Balance	9	16
Related Allowance	'	'
Average Recorded Investment	12	13
With an Allowance Recorded [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	3,783	5,359
Unpaid Principal Balance	3,923	5,495
Related Allowance	2,131	2,459
Average Recorded Investment	4,572	4,977
With an Allowance Recorded [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	'	'
Unpaid Principal Balance	'	'
Related Allowance	'	'
Average Recorded Investment	'	'
With an Allowance Recorded [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	180	21
Unpaid Principal Balance	186	27
Related Allowance	48	18
Average Recorded Investment	101	28
With an Allowance Recorded [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	2,187	2,519
Unpaid Principal Balance	2,220	2,548
Related Allowance	767	890
Average Recorded Investment	2,353	1,759
With an Allowance Recorded [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	7	1,613
Unpaid Principal Balance	8	1,615
Related Allowance	7	445
Average Recorded Investment	810	2,032
With an Allowance Recorded [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	1,269	1,111
Unpaid Principal Balance	1,357	1,192
Related Allowance	1,217	1,029
Average Recorded Investment	1,190	1,077
With an Allowance Recorded [Member] | Consumer and other [Member]	'	'
Financing Receivable, Impaired [Line Items]	'	'
Recorded Investment	140	95
Unpaid Principal Balance	152	113
Related Allowance	92	77
Average Recorded Investment	$118	$81

Loans_and_Allowance_for_Credit8

Loans and Allowance for Credit Losses - Schedule Showing Risk Grades and Impaired Loans by Class of Loan (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	$7,752,400	$7,775,221
Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	888,985	865,511
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	512,857	531,258
1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	2,170,446	2,131,720
Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	2,709,386	2,753,797
Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	1,255,020	1,279,777
Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	215,706	213,158
PCI Loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	39,646	41,592
PCI Loans [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	3,394	3,765
PCI Loans [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	592	607
PCI Loans [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	3,943	4,078
PCI Loans [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	26,323	26,916
PCI Loans [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	5,394	6,226
PCI Loans [Member] | Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 1 [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	86,499	86,718
Grade 1 [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 1 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	4,869	5,225
Grade 1 [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 1 [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 1 [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	48,682	50,131
Grade 1 [Member] | Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	32,948	31,362
Grade 2 [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 2 [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 2 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 2 [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 2 [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 2 [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 2 [Member] | Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 3 [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	7,564,731	7,575,005
Grade 3 [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	883,334	858,712
Grade 3 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	502,053	520,921
Grade 3 [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	2,154,734	2,113,698
Grade 3 [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	2,659,042	2,697,664
Grade 3 [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	1,183,149	1,202,604
Grade 3 [Member] | Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	182,419	181,406
Grade 4 [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 4 [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 4 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 4 [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 4 [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 4 [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 4 [Member] | Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 5 [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	33,641	39,028
Grade 5 [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	978	1,141
Grade 5 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	4,998	3,427
Grade 5 [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	3,877	6,337
Grade 5 [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	10,484	10,798
Grade 5 [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	13,181	17,179
Grade 5 [Member] | Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	123	146
Grade 6 [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	21,270	24,036
Grade 6 [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	955	1,616
Grade 6 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	138	1,043
Grade 6 [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	4,943	4,504
Grade 6 [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	12,115	14,316
Grade 6 [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	3,052	2,423
Grade 6 [Member] | Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	67	134
Grade 7 [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	6,587	8,832
Grade 7 [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	324	277
Grade 7 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	207	35
Grade 7 [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	2,939	3,093
Grade 7 [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	1,422	4,103
Grade 7 [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	1,546	1,214
Grade 7 [Member] | Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	149	110
Grade 8 [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	26	10
Grade 8 [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 8 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 8 [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	10	10
Grade 8 [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 8 [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	16	'
Grade 8 [Member] | Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 9 [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 9 [Member] | Construction, land development and other land loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 9 [Member] | Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 9 [Member] | 1-4 Family residential (includes home equity) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 9 [Member] | Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 9 [Member] | Commercial and Industrial [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'
Grade 9 [Member] | Consumer and other [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Loans held for investment	'	'

Loans_and_Allowance_for_Credit9

Loans and Allowance for Credit Losses - Schedule Showing Risk Grades and Impaired Loans by Class of Loan (Parenthetical) (Detail) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]	'	'
Mortgage loans held for sale	$3,600,000	$2,200,000
Substandard loan	7,752,400,000	7,775,221,000
PCI Loans [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Substandard loan	39,646,000	41,592,000
PCI Loans [Member] | Substandard [Member]	'	'
Financing Receivable, Recorded Investment [Line Items]	'	'
Substandard loan	$17,300,000	$17,600,000

Recovered_Sheet3

Loans and Allowance for Credit Losses - Schedule of Recorded Investment in Loans and Activity in Allowance for Credit Losses by Portfolio Segment (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Allowance for credit losses, Beginning Balance	$67,282	$52,564	'
Provision for credit losses	600	2,800	'
Charge-offs	-1,445	-940	'
Recoveries	659	625	'
Net charge-offs	-786	-315	'
Allowance for credit losses, Ending Balance	67,096	55,049	'
Individually evaluated for impairment	2,131	2,573	2,459
Collectively evaluated for impairment	64,965	52,476	64,823
Total allowance for credit losses	67,096	55,049	'
Total loans evaluated for impairment	7,748,842	5,263,024	7,773,011
Loans [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Individually evaluated for impairment	6,613	7,170	8,842
Collectively evaluated for impairment	7,702,583	5,227,826	7,722,577
PCI loans	39,646	28,028	41,592
Construction, land development and other land loans [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Allowance for credit losses, Beginning Balance	14,353	11,909	'
Provision for credit losses	-770	270	'
Charge-offs	-2	'	'
Recoveries	19	56	'
Net charge-offs	17	56	'
Allowance for credit losses, Ending Balance	13,600	12,235	'
Individually evaluated for impairment	'	134	'
Collectively evaluated for impairment	13,600	12,101	14,353
Total allowance for credit losses	13,600	12,235	'
Total loans evaluated for impairment	888,985	575,307	865,511
Construction, land development and other land loans [Member] | Loans [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Individually evaluated for impairment	324	635	277
Collectively evaluated for impairment	885,267	574,657	861,469
PCI loans	3,394	15	3,765
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Allowance for credit losses, Beginning Balance	1,229	764	'
Provision for credit losses	46	116	'
Charge-offs	-14	'	'
Recoveries	95	7	'
Net charge-offs	81	7	'
Allowance for credit losses, Ending Balance	1,356	887	'
Individually evaluated for impairment	48	27	18
Collectively evaluated for impairment	1,308	860	1,211
Total allowance for credit losses	1,356	887	'
Total loans evaluated for impairment	512,857	286,789	531,258
Agriculture and Agriculture Real Estate (Includes Farmland) [Member] | Loans [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Individually evaluated for impairment	207	107	35
Collectively evaluated for impairment	512,058	286,254	530,616
PCI loans	592	428	607
1-4 Family residential (includes home equity) [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Allowance for credit losses, Beginning Balance	17,046	13,942	'
Provision for credit losses	1,804	272	'
Charge-offs	-139	-111	'
Recoveries	7	9	'
Net charge-offs	-132	-102	'
Allowance for credit losses, Ending Balance	18,718	14,112	'
Individually evaluated for impairment	767	94	890
Collectively evaluated for impairment	17,951	14,018	16,156
Total allowance for credit losses	18,718	14,112	'
Total loans evaluated for impairment	2,166,888	1,542,751	2,129,510
1-4 Family residential (includes home equity) [Member] | Loans [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Individually evaluated for impairment	2,949	486	3,103
Collectively evaluated for impairment	2,159,996	1,539,085	2,122,329
PCI loans	3,943	3,180	4,078
Commercial Real Estate (Includes Multi-Family Residential) [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Allowance for credit losses, Beginning Balance	24,835	19,607	'
Provision for credit losses	-1,404	2,205	'
Charge-offs	-102	-68	'
Recoveries	42	125	'
Net charge-offs	-60	57	'
Allowance for credit losses, Ending Balance	23,371	21,869	'
Individually evaluated for impairment	7	786	445
Collectively evaluated for impairment	23,364	21,083	24,390
Total allowance for credit losses	23,371	21,869	'
Total loans evaluated for impairment	2,709,386	1,993,518	2,753,797
Commercial Real Estate (Includes Multi-Family Residential) [Member] | Loans [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Individually evaluated for impairment	1,422	2,664	4,103
Collectively evaluated for impairment	2,681,641	1,969,385	2,722,778
PCI loans	26,323	21,469	26,916
Commercial and Industrial [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Allowance for credit losses, Beginning Balance	8,167	5,777	'
Provision for credit losses	567	-318	'
Charge-offs	-143	-155	'
Recoveries	62	96	'
Net charge-offs	-81	-59	'
Allowance for credit losses, Ending Balance	8,653	5,400	'
Individually evaluated for impairment	1,217	1,467	1,029
Collectively evaluated for impairment	7,436	3,933	7,138
Total allowance for credit losses	8,653	5,400	'
Total loans evaluated for impairment	1,255,020	732,308	1,279,777
Commercial and Industrial [Member] | Loans [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Individually evaluated for impairment	1,562	3,209	1,214
Collectively evaluated for impairment	1,248,064	726,168	1,272,337
PCI loans	5,394	2,931	6,226
Consumer and other [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Allowance for credit losses, Beginning Balance	1,652	565	'
Provision for credit losses	357	255	'
Charge-offs	-1,045	-606	'
Recoveries	434	332	'
Net charge-offs	-611	-274	'
Allowance for credit losses, Ending Balance	1,398	546	'
Individually evaluated for impairment	92	65	77
Collectively evaluated for impairment	1,306	481	1,575
Total allowance for credit losses	1,398	546	'
Total loans evaluated for impairment	215,706	132,351	213,158
Consumer and other [Member] | Loans [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Individually evaluated for impairment	149	69	110
Collectively evaluated for impairment	215,557	132,277	213,048
PCI loans	'	$5	'

Recovered_Sheet4

Loans and Allowance for Credit Losses - Schedule of Loans Modified in Troubled Debt Restructuring (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
	TDRs
Financing Receivable, Modifications [Line Items]	'
Number of Contracts	2
Pre- Modification Outstanding Recorded Investment	$51
Post- Modification Outstanding Recorded Investment	51
Construction, land development and other land loans [Member]	'
Financing Receivable, Modifications [Line Items]	'
Number of Contracts	'
Pre- Modification Outstanding Recorded Investment	'
Post- Modification Outstanding Recorded Investment	'
Agriculture and Agriculture Real Estate (Includes Farmland) [Member]	'
Financing Receivable, Modifications [Line Items]	'
Number of Contracts	'
Pre- Modification Outstanding Recorded Investment	'
Post- Modification Outstanding Recorded Investment	'
1-4 Family residential (includes home equity) [Member]	'
Financing Receivable, Modifications [Line Items]	'
Number of Contracts	'
Pre- Modification Outstanding Recorded Investment	'
Post- Modification Outstanding Recorded Investment	'
Commercial Real Estate (Includes Multi-Family Residential) [Member]	'
Financing Receivable, Modifications [Line Items]	'
Number of Contracts	1
Pre- Modification Outstanding Recorded Investment	35
Post- Modification Outstanding Recorded Investment	35
Commercial and Industrial [Member]	'
Financing Receivable, Modifications [Line Items]	'
Number of Contracts	1
Pre- Modification Outstanding Recorded Investment	16
Post- Modification Outstanding Recorded Investment	16
Consumer and other [Member]	'
Financing Receivable, Modifications [Line Items]	'
Number of Contracts	'
Pre- Modification Outstanding Recorded Investment	'
Post- Modification Outstanding Recorded Investment	'

Fair_Value_Schedule_of_Fair_Va

Fair Value - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	$143,382	$157,478
States and Political Subdivisions [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	23,847	29,375
Collateralized mortgage obligations [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	458	489
Mortgage - Backed Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	106,534	115,137
Other securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	12,543	12,477
Non Hedging Interest Rate Swaps [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Estimated Fair Value	153	38
Estimated Fair Value	-153	-38
Level 1 [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	12,543	12,477
Level 1 [Member] | States and Political Subdivisions [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Level 1 [Member] | Collateralized mortgage obligations [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Level 1 [Member] | Mortgage - Backed Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Level 1 [Member] | Other securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	12,543	12,477
Level 1 [Member] | Non Hedging Interest Rate Swaps [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Estimated Fair Value	'	'
Estimated Fair Value	'	'
Level 2 [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	130,839	145,001
Level 2 [Member] | States and Political Subdivisions [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	23,847	29,375
Level 2 [Member] | Collateralized mortgage obligations [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	458	489
Level 2 [Member] | Mortgage - Backed Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	106,534	115,137
Level 2 [Member] | Other securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Level 2 [Member] | Non Hedging Interest Rate Swaps [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Estimated Fair Value	153	38
Estimated Fair Value	-153	-38
Level 3 [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Level 3 [Member] | States and Political Subdivisions [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Level 3 [Member] | Collateralized mortgage obligations [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Level 3 [Member] | Mortgage - Backed Securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Level 3 [Member] | Other securities [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Available for sale securities	'	'
Level 3 [Member] | Non Hedging Interest Rate Swaps [Member]	'	'
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]	'	'
Estimated Fair Value	'	'
Estimated Fair Value	'	'

Fair_Value_Additional_Informat

Fair Value - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Additions to other real estate	$2,700,000
Real estate owned outstanding	2,300,000
Additions to impaired loans	460,000
Off balance sheet commitments	$1,580,000,000

Fair_Value_Summary_of_Financia

Fair Value - Summary of Financial Assets and Liabilities Measured on Recurring and Non-Recurring Basis (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]	'	'
Cash and due from banks	$349,860	$380,990
Federal funds sold	382	400
Held to maturity securities	8,410,919	7,987,342
Noninterest-bearing	4,142,042	4,108,835
Interest-bearing	11,318,015	11,182,436
Other borrowings	40,451	10,689
Securities sold under repurchase agreements	349,074	364,357
Junior subordinated debentures	124,231	124,231
Carrying Amount [Member]	'	'
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]	'	'
Cash and due from banks	349,860	380,990
Federal funds sold	382	400
Held to maturity securities	8,417,955	8,066,970
Loans held for sale	3,558	2,210
Loans held for investment, net of allowance	7,681,746	7,705,729
Noninterest-bearing	4,142,042	4,108,835
Interest-bearing	11,318,015	11,182,436
Other borrowings	40,451	10,689
Securities sold under repurchase agreements	349,074	364,357
Junior subordinated debentures	124,231	124,231
Estimated Fair Value [Member]	'	'
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]	'	'
Cash and due from banks	349,860	380,990
Federal funds sold	382	400
Held to maturity securities	8,410,919	7,987,342
Loans held for sale	3,558	2,210
Loans held for investment, net of allowance	7,718,665	7,749,786
Noninterest-bearing	4,142,042	4,108,835
Interest-bearing	11,330,483	11,196,241
Other borrowings	41,845	12,014
Securities sold under repurchase agreements	349,149	364,477
Junior subordinated debentures	119,384	119,325
Estimated Fair Value [Member] | Level 1 [Member]	'	'
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]	'	'
Cash and due from banks	349,860	380,990
Federal funds sold	382	400
Held to maturity securities	'	'
Loans held for sale	'	2,210
Loans held for investment, net of allowance	'	'
Noninterest-bearing	'	'
Interest-bearing	'	'
Other borrowings	'	'
Securities sold under repurchase agreements	'	'
Junior subordinated debentures	'	'
Estimated Fair Value [Member] | Level 2 [Member]	'	'
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]	'	'
Cash and due from banks	'	'
Federal funds sold	'	'
Held to maturity securities	8,410,919	7,987,342
Loans held for sale	3,558	'
Loans held for investment, net of allowance	'	'
Noninterest-bearing	4,142,042	4,108,835
Interest-bearing	11,330,483	11,196,241
Other borrowings	41,845	12,014
Securities sold under repurchase agreements	349,149	364,477
Junior subordinated debentures	119,384	119,325
Estimated Fair Value [Member] | Level 3 [Member]	'	'
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Line Items]	'	'
Cash and due from banks	'	'
Federal funds sold	'	'
Held to maturity securities	'	'
Loans held for sale	'	'
Loans held for investment, net of allowance	7,718,665	7,749,786
Noninterest-bearing	'	'
Interest-bearing	'	'
Other borrowings	'	'
Securities sold under repurchase agreements	'	'
Junior subordinated debentures	'	'

Recovered_Sheet5

Goodwill and Core Deposit Intangibles - Schedule of Goodwill and Core Deposit Intangibles (Detail) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Goodwill And Intangible Assets [Line Items]	'	'	'
Goodwill, Beginning Balance	$1,671,520	$1,217,162	$1,217,162
Goodwill, Amortization	'	'	'
Goodwill, Measurement period adjustment	484	'	-1,225
Goodwill, Ending Balance	1,672,004	'	1,671,520
Core Deposit Intangibles, Beginning Balance	42,049	26,159	26,159
Core Deposit Intangibles, Amortization	-2,045	-1,755	-6,145
Core Deposit Intangibles, Measurement period adjustment	-302	'	2,110
Core Deposit Intangibles, Ending Balance	39,702	'	42,049
East Texas Financial Services, Inc. [Member]	'	'	'
Goodwill And Intangible Assets [Line Items]	'	'	'
Goodwill, Beginning Balance	'	15,000	15,000
Goodwill, Acquisition	'	'	15,007
Core Deposit Intangibles, Acquisition	'	'	'
Coppermark Bancshares, Inc. [Member]	'	'	'
Goodwill And Intangible Assets [Line Items]	'	'	'
Goodwill, Measurement period adjustment	109	'	'
Goodwill, Acquisition	'	'	117,544
Goodwill, Ending Balance	117,700	'	'
Core Deposit Intangibles, Acquisition	'	'	1,514
FVNB Corp. [Member]	'	'	'
Goodwill And Intangible Assets [Line Items]	'	'	'
Goodwill, Acquisition	'	'	323,032
Goodwill, Ending Balance	323,400	'	'
Core Deposit Intangibles, Acquisition	$18,400	'	$18,411

Recovered_Sheet6

Goodwill and Core Deposit Intangibles - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Goodwill And Intangible Assets [Line Items]	'	'	'
Impairments recorded on goodwill	$0	'	'
Amortization expense related to intangible assets	$2,045,000	$1,755,000	$6,145,000
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	'15 years	'	'

Goodwill_and_Core_Deposit_Inta2

Goodwill and Core Deposit Intangibles - Schedule of Estimated Aggregate Future Amortization Expense for Intangible Assets (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Goodwill And Intangible Assets Disclosure [Abstract]	'	'	'
Remaining 2014	$5,550	'	'
2015	6,549	'	'
2016	5,798	'	'
2017	3,843	'	'
2018	3,134	'	'
Thereafter	14,828	'	'
Total	$39,702	$42,049	$26,159

Stock_Based_Compensation_Addit

Stock Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
	OptionPlan
Compensation Related Costs Share Based Payments Disclosure [Line Items]	'	'
Number of stock-based employee compensation plans	4	'
Number of stock option plans	1	'
Number of stock-based employee compensation plans expired	2	'
Proceeds from stock options exercised	$1,839,000	$670,000
Tax benefit from option exercises	0	0
Unrecognized compensation expense	$16,100,000	'
Expected weighted average period of unrecognized compensation expense recognized, in years	'2 years 2 months 12 days	'
2004 Stock Incentive Plan [Member] | Maximum [Member]	'	'
Compensation Related Costs Share Based Payments Disclosure [Line Items]	'	'
Number of shares authorizes the issuance	1,250,000	'
Share based compensation arrangement by share based payment award award vesting period in years	'5 years	'
2004 Stock Incentive Plan [Member] | Minimum [Member]	'	'
Compensation Related Costs Share Based Payments Disclosure [Line Items]	'	'
Share based compensation arrangement by share based payment award award vesting period in years	'1 year	'
2012 Stock Incentive Plan [Member]	'	'
Compensation Related Costs Share Based Payments Disclosure [Line Items]	'	'
Options or other awards granted	0	'
2012 Stock Incentive Plan [Member] | Maximum [Member]	'	'
Compensation Related Costs Share Based Payments Disclosure [Line Items]	'	'
Number of shares authorizes the issuance	1,250,000	'

Recovered_Sheet7

Contractual Obligations and Off-Balance Sheet Items - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Contractual Obligation [Line Items]	'	'
Interest portion of junior subordinated	$775,000	$605,000
Interest to be paid over future periods included in FHLB payments	2,200,000	'
Contractual Obligations [Member]	'	'
Contractual Obligation [Line Items]	'	'
Interest portion of junior subordinated	60,400,000	'
Current principal balance of the junior subordinated debentures	$124,200,000	'

Recovered_Sheet8

Contractual Obligations and Off-Balance Sheet Items - Contractual Obligations and Other Commitments (Detail) (USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Contractual Obligation Fiscal Year Maturity [Line Items]	'
1 year or less	$739,003
More than 1 year but less than 3 years	415,323
3 years or more but less than 5 years	67,762
5 years or more	362,389
Total	1,584,477
Federal Home Loan Bank notes payable [Member]	'
Contractual Obligation Fiscal Year Maturity [Line Items]	'
1 year or less	31,201
More than 1 year but less than 3 years	3,456
3 years or more but less than 5 years	5,665
5 years or more	2,337
Total	42,659
Operating leases [Member]	'
Contractual Obligation Fiscal Year Maturity [Line Items]	'
1 year or less	4,193
More than 1 year but less than 3 years	7,806
3 years or more but less than 5 years	3,405
5 years or more	6,532
Total	21,936
Junior subordinated debentures [Member]	'
Contractual Obligation Fiscal Year Maturity [Line Items]	'
1 year or less	2,250
More than 1 year but less than 3 years	6,000
3 years or more but less than 5 years	5,999
5 years or more	170,419
Total	184,668
Lease, Total [Member]	'
Contractual Obligation Fiscal Year Maturity [Line Items]	'
1 year or less	37,644
More than 1 year but less than 3 years	17,262
3 years or more but less than 5 years	15,069
5 years or more	179,288
Total	$249,263

Contractual_Obligations_and_Of2

Contractual Obligations and Off-Balance Sheet Items - Letters of Credit and Commitments (Detail) (USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Contractual Obligation Fiscal Year Maturity [Line Items]	'
1 year or less	$739,003
More than 1 year but less than 3 years	415,323
3 years or more but less than 5 years	67,762
5 years or more	362,389
Total	1,584,477
Commitments to extend credit [Member]	'
Contractual Obligation Fiscal Year Maturity [Line Items]	'
1 year or less	699,303
More than 1 year but less than 3 years	407,180
3 years or more but less than 5 years	67,717
5 years or more	362,239
Total	1,536,439
Standby letters of credit [Member]	'
Contractual Obligation Fiscal Year Maturity [Line Items]	'
1 year or less	39,700
More than 1 year but less than 3 years	8,143
3 years or more but less than 5 years	45
5 years or more	150
Total	$48,038

Recovered_Sheet9

Other Comprehensive (Loss) Income - Schedule of Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Other Comprehensive Income Loss Net Of Tax Period Increase Decrease [Abstract]	'	'
Change in unrealized gain during period, Before Tax Amount	($489)	($1,771)
Total securities available for sale, Before Tax Amount	-489	-1,771
Total other comprehensive loss, Before Tax Amount	-489	-1,771
Change in unrealized gain during period, Tax Benefit	171	620
Total securities available for sale, Tax Benefit	171	620
Total other comprehensive loss, Tax Benefit	171	620
Change in unrealized gain during period, Net of Tax Amount	-318	-1,151
Total securities available for sale, Net of Tax Amount	-318	-1,151
Total other comprehensive loss, Net of Tax Amount	($318)	($1,151)

Recovered_Sheet10

Other Comprehensive (Loss) Income - Activity in Accumulated Other Comprehensive Income, Net of Tax (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]	'	'
Beginning Balance, Accumulated Other Comprehensive Income	$4,883	$8,986
Other comprehensive loss, Accumulated Other Comprehensive Income	-318	-1,151
Ending Balance, Accumulated Other Comprehensive Income	$4,565	$7,835

Recovered_Sheet11

Derivative Financial Instruments - Interest Rate Derivative Contracts Outstanding (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
Derivative Financial Instruments [Line Items]	'
Notional Amount	$9,344
Estimated Fair Value	153
Commercial Loan Interest Rate Swap [Member] | Derivative Instrument Maturity Date August 1, 2020 [Member]	'
Derivative Financial Instruments [Line Items]	'
Notional Amount	4,387
Estimated Fair Value	106
Maturity Date	1-Aug-20
Fixed Pay Rate	4.30%
Variable Rate Received	'1-Month USD - LIBOR BBA+2.50
Commercial Loan Interest Rate Swap [Member] | Derivative Instrument Maturity Date August 15, 2020 [Member]	'
Derivative Financial Instruments [Line Items]	'
Notional Amount	1,612
Estimated Fair Value	42
Maturity Date	15-Aug-20
Fixed Pay Rate	5.49%
Variable Rate Received	'1-Month USD - LIBOR BBA+3.00
Commercial Loan Interest Rate Swap [Member] | Derivative Instrument Maturity Date August 15, 2020 [Member]	'
Derivative Financial Instruments [Line Items]	'
Notional Amount	1,463
Estimated Fair Value	26
Maturity Date	15-Aug-20
Fixed Pay Rate	4.30%
Variable Rate Received	'1-Month USD - LIBOR BBA+2.50
Commercial Loan Interest Rate Swap [Member] | Derivative Instrument Maturity Date May 01, 2022 [Member]	'
Derivative Financial Instruments [Line Items]	'
Notional Amount	1,882
Estimated Fair Value	($21)
Maturity Date	1-May-22
Fixed Pay Rate	5.60%
Variable Rate Received	'1-Month USD - LIBOR BBA+3.50

Recovered_Sheet12

Derivative Financial Instruments - Additional Information (Detail) (USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Offsetting [Abstract]	'
Derivative Assets	$153
Derivative Liabilities	153
Collateral Derivatives	$260

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Notional Amounts and Estimated Fair Values of Interest Rate Derivative Contracts (Detail) (USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Financial Institution Counterparties [Member] | Derivative Financial Instruments, Assets [Member]	'
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]	'
Notional amount of interest rate derivative contracts, Assets	$1,882
Estimated fair value of interest rate derivatives, Assets	21
Financial Institution Counterparties [Member] | Derivative Financial Instruments, Liabilities [Member]	'
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]	'
Notional amount of interest rate derivative contracts, Liabilities	7,462
Estimated fair value of interest rate derivatives, Liabilities	-174
Interest Rate Swaps With Bank Customers [Member] | Derivative Financial Instruments, Assets [Member]	'
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]	'
Notional amount of interest rate derivative contracts, Assets	7,462
Estimated fair value of interest rate derivatives, Assets	174
Interest Rate Swaps With Bank Customers [Member] | Derivative Financial Instruments, Liabilities [Member]	'
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]	'
Notional amount of interest rate derivative contracts, Liabilities	1,882
Estimated fair value of interest rate derivatives, Liabilities	($21)

Acquisitions_Additional_Inform

Acquisitions - Additional Information (Detail) (USD $)

3 Months Ended

12 Months Ended

12 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

3 Months Ended

12 Months Ended

0 Months Ended

Mar. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Jan. 02, 2013

Jan. 02, 2013

Jan. 02, 2013

Nov. 01, 2013

Mar. 31, 2014

Sep. 30, 2013

Dec. 31, 2013

Nov. 01, 2013

Nov. 01, 2013

Nov. 01, 2013

Nov. 01, 2013

Nov. 01, 2013

Apr. 02, 2013

Mar. 31, 2013

Mar. 31, 2014

Dec. 31, 2013

Apr. 02, 2013

Apr. 02, 2013

East Texas Financial Services, Inc. [Member]

East Texas Financial Services, Inc. [Member]

East Texas Financial Services, Inc. [Member]

East Texas Financial Services, Inc. [Member]

East Texas Financial Services, Inc. [Member]

FVNB Corp. [Member]

FVNB Corp. [Member]

FVNB Corp. [Member]

FVNB Corp. [Member]

FVNB Corp. [Member]

FVNB Corp. [Member]

FVNB Corp. [Member]

FVNB Corp. [Member]

FVNB Corp. [Member]

Coppermark Bancshares, Inc. [Member]

Coppermark Bancshares, Inc. [Member]

Coppermark Bancshares, Inc. [Member]

Coppermark Bancshares, Inc. [Member]

Coppermark Bancshares, Inc. [Member]

Coppermark Bancshares, Inc. [Member]

TEXAS [Member]

Tyler, Texas [Member]

Gilmer, Texas [Member]

Bank

Victoria Texas [Member]

South Texas [Member]

Bryan/College Station [Member]

Central Texas Area including New Braunfels [Member]

Houston [Member]

Bank

Oklahoma City, Oklahoma [Member]

Dallas, Texas [Member]

Bank

Bank

Bank

Bank

Bank

Bank

Bank

Bank

Bank

Bank

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of banking offices

'

'

'

'

'

'

3

1

33

'

'

'

4

7

6

5

11

9

'

'

'

6

3

Total assets

'

'

'

'

$165,000,000

'

'

'

'

'

$2,470,000,000

'

'

'

'

'

'

'

$1,250,000,000

'

'

'

'

Total loans

'

'

'

'

129,300,000

'

'

'

'

'

1,650,000,000

'

'

'

'

'

'

'

847,600,000

'

'

'

'

Total deposits

'

'

'

'

112,300,000

'

'

'

'

'

2,200,000,000

'

'

'

'

'

'

'

1,110,000,000

'

'

'

'

Common stock shares issued

'

'

'

'

530,940

'

'

'

'

'

5,570,667

'

'

'

'

'

'

'

3,258,718

'

'

'

'

Cash paid

'

'

'

'

'

'

'

'

'

'

91,300,000

'

'

'

'

'

'

'

60,000,000

'

'

'

'

Closing stock price per share

'

'

'

'

$42

'

'

'

'

$62.45

'

'

'

'

'

'

'

'

$47.39

'

'

'

'

Capital stock merger consideration

'

'

'

'

'

'

'

'

'

439,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Goodwill

1,672,004,000

1,671,520,000

1,217,162,000

'

15,000,000

'

'

'

'

323,400,000

'

'

'

'

'

'

'

'

'

117,700,000

'

'

'

Core Deposit Intangibles, Acquisition

'

'

'

'

'

'

'

'

'

18,400,000

'

18,411,000

'

'

'

'

'

'

'

'

1,514,000

'

'

Merger Related Expense

'

'

'

'

'

'

'

'

'

542,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Total merger consideration

'

'

'

'

22,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

214,400,000

'

'

'

'

Core deposit intangibles

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,500,000

'

'

'

Goodwill adjustment

$484,000

($1,225,000)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$109,000

'

'

'

Number of banking offices operated

'

'

'

'

'

4

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Subsequent_Event_Additional_In

Subsequent Event - Additional Information (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2014	Apr. 02, 2014	Apr. 02, 2014	Apr. 02, 2014	Apr. 02, 2014
				F&M Bancorporation Inc. [Member]	F&M Bancorporation Inc. [Member]	Oklahoma City, Oklahoma [Member]	Dallas [Member]	Tulsa, Oklahoma [Member]
					Subsequent Event [Member]	Loan Production Office [Member]	Subsequent Event [Member]	Subsequent Event [Member]
					Bank	Subsequent Event [Member]	Bank	Bank
						Bank
Subsequent Event [Line Items]	'	'	'	'	'	'	'	'
Number of banking offices	'	'	'	'	13	1	3	9
Total assets	'	'	'	$2,410,000,000	'	'	'	'
Total loans	'	'	'	1,740,000,000	'	'	'	'
Total deposits	'	'	'	2,270,000,000	'	'	'	'
Common stock shares issued	'	'	'	3,298,022	'	'	'	'
Cash paid	'	'	'	34,200,000	'	'	'	'
Total merger consideration	'	'	'	252,400,000	'	'	'	'
Closing stock price per share	'	'	'	$66.15	'	'	'	'
Goodwill	$1,672,004,000	$1,671,520,000	$1,217,162,000	$148,400,000	'	'	'	'