First Financial Bankshares (FFIN) 10-Q 29 Oct 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 29, 2013
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	30-Sep-13
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q3
Entity Registrant Name	FIRST FINANCIAL BANKSHARES INC
Entity Central Index Key	36029
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		31,977,670

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
In Thousands, unless otherwise specified
ASSETS
CASH AND DUE FROM BANKS	$164,666	$207,018	$128,606
FEDERAL FUNDS SOLD	14,300	14,045	23,400
INTEREST-BEARING DEPOSITS IN BANKS	48,634	139,676	25,633
Total cash and cash equivalents	227,600	360,739	177,639
INTEREST-BEARING TIME DEPOSITS IN BANKS	34,352	49,005	67,506
SECURITIES AVAILABLE-FOR-SALE, at fair value	1,975,303	1,819,035	1,882,617
SECURITIES HELD-TO-MATURITY (fair value of $810, $1,271 and $1,080 at September 30, 2013 and 2012 and December 31, 2012, respectively)	798	1,061	1,247
LOANS
Held for investment	2,609,085	2,077,166	1,993,820
Less - allowance for loan losses	-34,800	-34,839	-34,932
Net loans held for investment	2,574,285	2,042,327	1,958,888
Held for sale	5,724	11,457	10,034
Net loans	2,580,009	2,053,784	1,968,922
BANK PREMISES AND EQUIPMENT, net	94,676	84,122	80,580
INTANGIBLE ASSETS	97,429	71,973	72,001
OTHER ASSETS	65,468	62,293	60,035
Total assets	5,075,635	4,502,012	4,310,547
LIABILITIES AND SHAREHOLDERS' EQUITY
NONINTEREST-BEARING DEPOSITS	1,371,835	1,311,708	1,200,154
INTEREST-BEARING DEPOSITS	2,628,722	2,320,876	2,244,244
Total deposits	4,000,557	3,632,584	3,444,398
DIVIDENDS PAYABLE	8,314		7,872
SHORT-TERM BORROWINGS	466,500	259,697	254,480
OTHER LIABILITIES	32,023	52,768	53,885
Total liabilities	4,507,394	3,945,049	3,760,635
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS' EQUITY
Common stock - $0.01 par value, authorized 80,000,000 shares; 31,977,670, 31,488,530, and 31,496,881 shares issued at September 30, 2013 and 2012 and December 31, 2012, respectively)	320	315	315
Capital surplus	302,320	277,412	277,121
Retained earnings	261,052	227,927	217,483
Treasury stock (shares at cost: 269,334, 265,598, and 266,845 at September 30, 2013 and 2012 and December 31, 2012, respectively)	-5,364	-5,007	-4,908
Deferred compensation	5,364	5,007	4,908
Accumulated other comprehensive earnings (loss)	4,549	51,309	54,993
Total shareholders' equity	568,241	556,963	549,912
Total liabilities and shareholders' equity	$5,075,635	$4,502,012	$4,310,547

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
In Thousands, except Share data, unless otherwise specified
Statement Of Financial Position [Abstract]
SECURITIES HELD-TO-MATURITY, fair value	$810	$1,080	$1,271
Common stock, par value	$0.01	$0.01	$0.01
Common stock, shares authorized	80,000,000	80,000,000	80,000,000
Common stock, shares issued	31,977,670	31,496,881	31,488,530
Treasury stock, shares	269,334	266,845	265,598

Consolidated_Statements_of_Ear

Consolidated Statements of Earnings (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
INTEREST INCOME:
Interest and fees on loans	$32,936	$26,138	$88,260	$75,792
Interest on investment securities:
Taxable	6,130	7,480	18,818	24,498
Exempt from federal income tax	7,480	6,484	21,122	19,081
Interest on federal funds sold and interest-bearing deposits in banks	109	185	405	623
Total interest income	46,655	40,287	128,605	119,994
INTEREST EXPENSE:
Interest on deposits	1,038	1,094	2,758	3,887
Other	126	74	256	176
Total interest expense	1,164	1,168	3,014	4,063
Net interest income	45,491	39,119	125,591	115,931
PROVISION FOR LOAN LOSSES	1,349	787	2,582	2,842
Net interest income after provision for loan losses	44,142	38,332	123,009	113,089
NONINTEREST INCOME:
Trust fees	4,138	3,723	11,884	10,848
Service charges on deposit accounts	4,798	4,337	13,009	12,261
ATM, interchange and credit card fees	4,404	3,767	12,315	11,226
Real estate mortgage operations	2,008	1,495	5,149	3,763
Net gain (loss) on available-for-sale securities (includes ($108) and $1,479 for the three months ended September 30, 2013 and 2012, respectively, and $147 and $2,206 for the nine months ended September 30, 2013 and 2012, respectively, related to accumulated other comprehensive earnings (loss) reclassifications)	-108	1,479	147	2,206
Net gain (loss) on sale of foreclosed assets	36	-106	-263	-512
Other	1,799	804	4,019	2,469
Total noninterest income	17,075	15,499	46,260	42,261
NONINTEREST EXPENSE:
Salaries and employee benefits	17,501	14,845	48,831	43,263
Net occupancy expense	2,164	1,806	5,995	5,286
Equipment expense	2,490	2,269	7,146	6,521
FDIC insurance premiums	640	563	1,781	1,655
ATM, interchange and credit card expenses	1,474	1,317	4,161	4,017
Professional and service fees	1,363	838	3,198	2,263
Printing, stationery and supplies	534	468	1,504	1,483
Amortization of intangible assets	77	38	120	120
Other	9,291	5,059	20,181	15,807
Total noninterest expense	35,534	27,203	92,917	80,415
EARNINGS BEFORE INCOME TAXES	25,683	26,628	76,352	74,935
INCOME TAX EXPENSE (includes ($38) and $518 for the three months ended September 30, 2013 and 2012, respectively, and $51 and $772 for the nine months ended September 30, 2013 and 2012, respectively related to income tax expense from reclassification items)	6,121	6,828	18,723	19,028
NET EARNINGS	$19,562	$19,800	$57,629	$55,907
EARNINGS PER SHARE, BASIC	$0.61	$0.63	$1.82	$1.78
EARNINGS PER SHARE, ASSUMING DILUTION	$0.61	$0.63	$1.81	$1.78
DIVIDENDS PER SHARE	$0.26	$0.25	$0.77	$0.74

Consolidated_Statements_of_Ear1

Consolidated Statements of Earnings (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]
Reclassification adjustment for realized gains on investment securities included in net earnings (loss), before income tax	($108)	$1,479	$147	$2,206
Income tax expense from reclassification	($38)	$518	$51	$772

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Earnings (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Amounts Reclassified Out Of Accumulated Other Comprehensive Income Loss [Abstract]
Net Earnings	$19,562	$19,800	$57,629	$55,907
OTHER ITEMS OF COMPREHENSIVE EARNINGS (LOSS):
Change in unrealized gain (loss) on investment securities available-for-sale, before income taxes	-29,688	6,710	-71,791	14,157
Reclassification adjustment for realized losses (gains) on investment securities included in net earnings, before income tax	108	-1,479	-147	-2,206
Total other items of comprehensive earnings (losses)	-29,580	5,231	-71,938	11,951
Income tax benefit (expense) related to other items of comprehensive earnings (loss)	10,352	-1,831	25,178	-4,183
COMPREHENSIVE EARNINGS	$334	$23,200	$10,869	$63,675

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Shareholders' Equity (USD $)	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Deferred Compensation [Member]	Accumulated Other Comprehensive Earnings [Member]
In Thousands, except Share data
Beginning Balance at Dec. 31, 2011	$508,537	$314	$276,127	$184,871	($4,597)	$4,597	$47,225
Beginning Balance, shares at Dec. 31, 2011		31,459,635			-258,235
Net Earnings	55,907			55,907
Stock option exercises	627	1	626
Stock option exercises, shares		28,895
Cash dividends declared	-23,295			-23,295
Change in unrealized gain in investment securities available-for-sale, net of related income taxes	7,768						7,768
Additional tax benefit related to directors' deferred compensation plan	117		117
Shares purchased in connection with directors' deferred compensation plan, net					-311	311
Shares purchased in connection with directors' deferred compensation plan, net, shares					-7,363
Stock option expense	251		251
Ending Balance at Sep. 30, 2012	549,912	315	277,121	217,483	-4,908	4,908	54,993
Ending Balance, shares at Sep. 30, 2012		31,488,530			-265,598
Beginning Balance at Dec. 31, 2012	556,963	315	277,412	227,927	-5,007	5,007	51,309
Beginning Balance, shares at Dec. 31, 2012		31,496,881			-266,845
Net Earnings	57,629			57,629
Stock issued in acquisition of Orange Savings Bank, SSB	23,100	4	23,096
Stock issued in acquisition of Orange Savings Bank, SSB, shares		420,000
Stock option exercises	1,519	1	1,518
Stock option exercises, shares		60,789
Cash dividends declared	-24,504			-24,504
Change in unrealized gain in investment securities available-for-sale, net of related income taxes	-46,760						-46,760
Additional tax benefit related to directors' deferred compensation plan	30		30
Shares purchased in connection with directors' deferred compensation plan, net					-357	357
Shares purchased in connection with directors' deferred compensation plan, net, shares					-2,489
Stock option expense	264		264
Ending Balance at Sep. 30, 2013	$568,241	$320	$302,320	$261,052	($5,364)	$5,364	$4,549
Ending Balance, shares at Sep. 30, 2013		31,977,670			-269,334

Consolidated_Statements_of_Cha1

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Stockholders Equity [Abstract]
Cash dividend per share	$0.26	$0.25	$0.77	$0.74

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Earnings	$57,629	$55,907
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	6,376	5,908
PROVISION FOR LOAN LOSSES	2,582	2,842
Securities premium amortization (discount accretion), net	13,680	11,732
Gain on sale of assets, net	-62	-1,896
Deferred federal income tax benefit	-309	-1,857
Change in loans held for sale	5,731	595
Change in other assets	2,642	-153
Change in other liabilities	5,996	5,104
Total adjustments	36,636	22,275
Net cash provided by operating activities	94,265	78,182
CASH FLOWS FROM INVESTING ACTIVITIES:
Cash paid for acquisition of Orange Savings Bank, SSB, less cash acquired	-25,706
Net decrease (increase) in interest-bearing time deposits in banks	14,653	-6,331
Activity in available-for-sale securities:
Sales	121,420	114,090
Maturities	248,750	1,003,367
Purchases	-511,471	-1,171,322
Activity in held-to-maturity securities - maturities	263	2,361
Net increase in loans	-242,860	-220,551
Purchases of bank premises and equipment and other assets	-8,492	-10,904
Proceeds from sale of other assets	1,885	3,932
Net cash used in investing activities	-401,558	-285,358
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase (decrease) in noninterest-bearing deposits	-7,402	98,578
Net increase (decrease) in interest-bearing deposits	-10,575	11,023
Net increase in short-term borrowings	206,803	46,724
Common stock transactions:
Proceeds from stock issuances	1,519	627
Dividends paid	-16,191	-22,973
Net cash provided by financing activities	174,154	133,979
NET DECREASE IN CASH AND CASH EQUIVALENTS	-133,139	-73,197
CASH AND CASH EQUIVALENTS, beginning of period	360,739	250,836
CASH AND CASH EQUIVALENTS, end of period	227,600	177,639
SUPPLEMENTAL INFORMATION AND NONCASH TRANSACTIONS
Interest paid	2,988	4,317
Federal income tax paid	17,386	17,205
Transfer of loans to foreclosed assets	1,610	422
Investment securities purchased but not settled	$3,496	$6,260

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]
Basis of Presentation	Note 1 - Basis of Presentation
	The interim consolidated financial statements include the accounts of the Company, a Texas corporation and a financial holding company registered under the Bank Holding Company Act of 1956, as amended, or BHCA, and its wholly-owned subsidiaries: First Financial Bank, National Association, Abilene, Texas; First Technology Services, Inc.; First Financial Trust & Asset Management Company, National Association; First Financial Investments, Inc.; and First Financial Insurance Agency, Inc.
	Through our subsidiary bank, we conduct a full-service commercial banking business. Our banking centers are located primarily in Central, North Central, Southeast and West Texas. As of September 30, 2013, we had 60 financial centers across Texas, with eleven locations in Abilene, two locations in Cleburne, Stephenville and Granbury, three locations in San Angelo and Weatherford, and one location each in Acton, Albany, Aledo, Alvarado, Boyd, Bridgeport, Brock, Burleson, Cisco, Clyde, Decatur, Eastland, Fort Worth, Glen Rose, Grapevine, Hereford, Huntsville, Keller, Mauriceville, Merkel, Midlothian, Mineral Wells, Moran, Newton, Odessa, Orange, Port Arthur, Ranger, Rising Star, Roby, Southlake, Sweetwater, Trent, Trophy Club, Vidor, Waxahachie, and Willow Park. Our trust subsidiary has seven locations which are located in Abilene, Fort Worth, Odessa, Orange, San Angelo, Stephenville and Sweetwater, all in Texas.
	In the opinion of management, the unaudited interim consolidated financial statements reflect all adjustments necessary for a fair presentation of the Company’s financial position and unaudited results of operations and should be read in conjunction with the Company’s audited consolidated financial statements, and notes thereto in the Company’s Annual Report on Form 10-K, for the year ended December 31, 2012. All adjustments were of a normal recurring nature. However, the results of operations for the three and nine months ended September 30, 2013, are not necessarily indicative of the results to be expected for the year ending December 31, 2013, due to seasonality, changes in economic conditions and loan credit quality, interest rate fluctuations, regulatory and legislative changes and other factors. Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted under SEC rules and regulations. The Company evaluated subsequent events for potential recognition and/or disclosure through the date the consolidated financial statements were issued.
	Effective December 30, 2012, the Company consolidated its eleven bank charters into one charter. The Company cited regulatory, compliance and technology complexities and the opportunity for cost savings as its reason for making this change. The Company is operating the one charter as it previously did with eleven charters, with local management and board decisions to benefit the customers and communities it serves.
	On October 26, 2011, the Company’s Board of Directors authorized the repurchase of up to 750,000 common shares through September 30, 2014. The stock buyback plan authorizes management to repurchase the stock at such time as repurchases are considered beneficial to shareholders. Any repurchase of stock will be made through the open market, block trades or in privately negotiated transactions in accordance with applicable laws and regulations. Under the repurchase plan, there is no minimum number of shares that the Company is required to repurchase. Through September 30, 2013, no shares have been repurchased under this authorization.
	On April 24, 2012, the Company’s shareholders approved an amendment to the Company’s Amended and Restated Certificate of Formation to increase the number of authorized common shares to 80,000,000.
	On May 31, 2013, the Company acquired 100% of the outstanding capital stock of Orange Savings Bank, SSB, a wholly-owned subsidiary of OSB Financial Services, Inc. The results of operations of Orange Savings Bank, SSB subsequent to the acquisition date are included in the consolidated earnings of the Company. See Note 10 for more information.
	Goodwill and other intangible assets are evaluated annually for impairment as of the end of the second quarter. No such impairment has been noted in connection with the current or any prior evaluations.

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]
Earnings Per Share	Note 2 - Earnings Per Share
	Basic earnings per common share is computed by dividing net income available to common shareholders by the weighted average number of shares outstanding during the periods presented. In computing diluted earnings per common share for the three and nine months ended September 30, 2013 and 2012, the Company assumes that all dilutive outstanding options to purchase common stock have been exercised at the beginning of the period (or the time of issuance, if later). The dilutive effect of the outstanding options is reflected by application of the treasury stock method, whereby the proceeds from the exercised options are assumed to be used to purchase common stock at the average market price during the respective periods. The weighted average common shares outstanding used in computing basic earnings per common share for the three months ended September 30, 2013 and 2012, were 31,970,405 and 31,484,375 shares, respectively. The weighted average common shares outstanding used in computing basic earnings per common share for the nine months ended September 30, 2013 and 2012, were 31,722,272 and 31,476,715 shares, respectively. The weighted average common shares outstanding used in computing fully diluted earnings per common share for the three months ended September 30, 2013 and 2012, were 32,121,771 and 31,502,172 shares, respectively. The weighted average common shares outstanding used in computing fully diluted earnings per common share for the nine months ended September 30, 2013 and 2012, were 31,853,294 and 31,486,707 shares, respectively.

Interestbearing_Time_Deposits_

Interest-bearing Time Deposits in Banks and Securities	9 Months Ended
	Sep. 30, 2013
Investments Debt And Equity Securities [Abstract]
Interest-bearing Time Deposits in Banks and Securities	Note 3 - Interest-bearing Time Deposits in Banks and Securities
	Interest-bearing time deposits in banks totaled $34,352,000 and $49,005,000 at September 30, 2013 and December 31, 2012, respectively, and have original maturities generally ranging from one to two years. Of these amounts, $31,437,000 and $44,776,000 are time deposits with balances greater than $100,000 at September 30, 2013 and December 31, 2012, respectively.
	The Company records its available-for-sale and trading securities portfolio at fair value.
	Management classifies debt and equity securities as held-to-maturity, available-for-sale, or trading based on its intent. Debt securities that management has the positive intent and ability to hold to maturity are classified as held-to-maturity and recorded at cost, adjusted for amortization of premiums and accretion of discounts, which are recognized as adjustments to interest income using the interest method. Securities not classified as held-to-maturity or trading are classified as available-for-sale and recorded at estimated fair value, with all unrealized gains and unrealized losses judged to be temporary, net of deferred income taxes, excluded from earnings and reported in the consolidated statements of comprehensive earnings. Available-for-sale securities that have unrealized losses that are judged other than temporary are included in gain (loss) on sale of securities and a new cost basis is established. Securities classified as trading are recorded at estimated fair value with unrealized gains and losses included in earnings.
	Fair values of securities are determined based on methodologies in accordance with current authoritative accounting guidance. Fair values are volatile and may be influenced by a number of factors, including market interest rates, prepayment speeds, discount rates, credit ratings and yield curves. Fair values for investment securities are based on quoted market prices, where available. If quoted market prices are not available, fair values are based on the quoted prices of similar instruments or an estimate of fair value by using a range of fair value estimates in the market place as a result of the illiquid market specific to the type of security.
	When the fair value of a security is below its amortized cost, depending on the length of time the condition exists and the extent the fair value is below amortized cost, additional analysis is performed to determine whether an other-than-temporary impairment condition exists. Available-for-sale and held-to-maturity securities are analyzed quarterly for possible other-than-temporary impairment. The analysis considers (i) whether we have the intent to sell our securities prior to recovery and/or maturity, (ii) whether it is more likely than not that we will have to sell our securities prior to recovery and/or maturity, (iii) the length of time and extent to which the fair value has been less than amortized cost, and (iv) the financial condition of the issuer. Often, the information available to conduct these assessments is limited and rapidly changing, making estimates of fair value subject to judgment. If actual information or conditions are different than estimated, the extent of the impairment of the security may be different than previously estimated, which could have a material effect on the Company’s results of operations and financial condition.
	The Company’s investment portfolio consists of U. S. Treasury securities, obligations of U. S. government sponsored-enterprises and agencies, mortgage pass-through securities, corporate bonds and general obligation or revenue based municipal bonds. Pricing for such securities is generally readily available and transparent in the market. The Company utilizes independent third party pricing services to assist in valuing its investment securities. The Company reviews the prices supplied by the independent pricing services as well as the underlying pricing methodologies for reasonableness and to ensure such prices are aligned with pricing matrices. The Company validates quarterly, on a sample basis, prices supplied by the independent pricing services by comparison to prices obtained from other third party sources.
	A summary of available-for-sale and held-to-maturity securities follows (in thousands):
		September 30, 2013
		Amortized		Gross		Gross			Estimated
		Cost Basis		Unrealized		Unrealized			Fair Value
				Holding Gains		Holding Losses
	Securities available-for-sale:
	Obligations of U.S. government sponsored-enterprises and agencies	$	142,944	$	1,684	$	(14	)	$	144,614
	Obligations of states and political subdivisions		960,624		26,321		(14,767	)		972,178
	Corporate bonds and other		106,551		3,578		—			110,129
	Residential mortgage-backed securities		632,621		14,960		(7,492	)		640,089
	Commercial mortgage-backed securities		112,702		—		(4,409	)		108,293
	Total securities available-for-sale	$	1,955,442	$	46,543	$	(26,682	)	$	1,975,303
	Securities held-to-maturity:
	Obligations of states and political subdivisions	$	525	$	3	$	—		$	528
	Residential mortgage-backed securities		273		9		—			282
	Total debt securities held-to-maturity	$	798	$	12	$	—		$	810
		31-Dec-12
		Amortized		Gross		Gross			Estimated
		Cost Basis		Unrealized		Unrealized			Fair Value
				Holding Gains		Holding Losses
	Securities available-for-sale:
	U. S. Treasury securities	$	6,042	$	48	$	—		$	6,090
	Obligations of U.S. government sponsored-enterprises and agencies		219,420		4,060		—			223,480
	Obligations of states and political subdivisions		786,278		57,541		(129	)		843,690
	Corporate bonds and other		117,244		6,020		(73	)		123,191
	Residential mortgage-backed securities		564,434		23,285		(443	)		587,276
	Commercial mortgage-backed securities		33,819		1,739		(250	)		35,308
	Total securities available-for-sale	$	1,727,237	$	92,693	$	(895	)	$	1,819,035
	Securities held-to-maturity:
	Obligations of states and political subdivisions	$	735	$	7	$	—		$	742
	Residential mortgage-backed securities		294		11		—			305
	Commercial mortgage-backed securities		32		1		—			33
	Total debt securities held-to-maturity	$	1,061	$	19	$	—		$	1,080
	The Company invests in mortgage-backed securities that have expected maturities that differ from their contractual maturities. These differences arise because borrowers may have the right to call or prepay obligations with or without a prepayment penalty. These securities include collateralized mortgage obligations (CMOs) and other asset backed securities. The expected maturities of these securities at September 30, 2013, were computed by using scheduled amortization of balances and historical prepayment rates.
	The amortized cost and estimated fair value of debt securities at September 30, 2013, by contractual and expected maturity, are shown below (in thousands):
		Available-for-Sale				Held-to-Maturity
		Amortized		Estimated		Amortized			Estimated
		Cost Basis		Fair Value		Cost Basis			Fair Value
	Due within one year	$	82,447	$	83,490	$	525		$	528
	Due after one year through five years		533,039		547,624		—			—
	Due after five years through ten years		536,830		539,843		—			—
	Due after ten years		57,803		55,964		—			—
	Mortgage-backed securities		745,323		748,382		273			282
	Total	$	1,955,442	$	1,975,303	$	798		$	810
	The following tables disclose, as of September 30, 2013 and December 31, 2012, the Company’s investment securities that have been in a continuous unrealized-loss position for less than 12 months and for 12 months or longer (in thousands):
		Less than 12 Months				12 Months or Longer					Total
	September 30, 2013	Fair Value		Unrealized		Fair Value			Unrealized		Fair Value		Unrealized
				Loss					Loss				Loss
	Obligations of U.S. government sponsored-enterprises and agencies	$	10,941	$	14	$	—		$	—	$	10,941	$	14
	Obligations of states and political subdivisions		382,840		14,767		—			—		382,840		14,767
	Residential mortgage-backed securities		164,166		7,412		8,220			80		172,386		7,492
	Commercial mortgage-backed securities		108,293		4,409		—			—		108,293		4,409
	Total	$	666,240	$	26,602	$	8,220		$	80	$	674,460	$	26,682
		Less than 12 Months				12 Months or Longer					Total
	December 31, 2012	Fair Value		Unrealized		Fair Value			Unrealized		Fair Value		Unrealized
				Loss					Loss				Loss
	Obligations of states and political subdivisions	$	36,480	$	129	$	—		$	—	$	36,480	$	129
Residential mortgage-backed securities		17,344		401		3,574			42		20,918		443
Commercial mortgage-backed securities		12,453		250		—			—		12,453		250
Corporate bonds and other		4,994		73		—			—		4,994		73
Total	$	71,271	$	853	$	3,574		$	42	$	74,845	$	895
The number of investment positions in an unrealized loss position totaled 528 at September 30, 2013. We do not believe these unrealized losses are “other than temporary” as (i) we do not have the intent to sell our securities prior to recovery and/or maturity and (ii) it is more likely than not that we will not have to sell our securities prior to recovery and/or maturity. In making the determination, we also consider the length of time and extent to which fair value has been less than cost and the financial condition of the issuer. The unrealized losses noted are interest rate related due to the level of interest rates at September 30, 2013 compared to the time of purchase. We have reviewed the ratings of the issuers and have not identified any issues related to the ultimate repayment of principal as a result of credit concerns on these securities. On occasion, we sell certain securities prior to maturity to reposition our securities on the interest rate curve or to take advantage of shifts in interest rates. These sales result in gains/losses on sale of available-for-sale securities but do not change our overall intent to not sell our securities or our belief that we do not have to sell our securities prior to recovery and/or maturity as discussed in the prior sentences. Our mortgage related securities are backed by GNMA, FNMA and FHLMC or are collateralized by securities backed by these agencies.
Securities, carried at approximately $1,061,307,000 at September 30, 2013, were pledged as collateral for public or trust fund deposits, repurchase agreements and for other purposes required or permitted by law.
During the quarters ended September 30, 2013 and 2012, sales of investment securities that were classified as available-for-sale totaled $50,065,000 and $45,129,000, respectively. Gross realized gains from securities sales and calls during the third quarter of 2013 and 2012 totaled $1,114,000 and $1,522,000, respectively. Gross realized losses from securities sales and calls during the third quarter of 2013 and 2012 totaled $1,222,000 and $43,000, respectively. During the nine months ended September 30, 2013 and 2012, sales of investment securities that were classified as available-for-sale totaled $121,420,000 and $114,090,000, respectively. Gross realized gains from securities sales and calls during the nine-month periods ended September 30, 2013 and 2012 totaled $1,371,000 and $2,250,000, respectively. Gross realized losses from securities sales and calls during the nine-month periods ended September 30, 2013 and 2012 totaled $1,224,000 and $44,000, respectively. The specific identification method was used to determine cost in order to compute the realized gains and losses.

Loans_and_Allowance_for_Loan_L

Loans and Allowance for Loan Losses	9 Months Ended
	Sep. 30, 2013
Receivables [Abstract]
Loans and Allowance for Loan Losses	Note 4 - Loans and Allowance for Loan Losses
	Loans held for investment are stated at the amount of unpaid principal, reduced by unearned income and an allowance for loan losses. Interest on loans is calculated by using the simple interest method on daily balances of the principal amounts outstanding. The Company defers and amortizes net loan origination fees and costs as an adjustment to yield. The allowance for loan losses is established through a provision for loan losses charged to expense. Loans are charged against the allowance for loan losses when management believes the collectability of the principal is unlikely.
	The Company has certain lending policies and procedures in place that are designed to maximize loan income with an acceptable level of risk. Management reviews and approves these policies and procedures on a annual basis and makes changes as appropriate. Management receives and reviews monthly reports related to loan originations, quality, concentrations, delinquencies, non-performing and potential problem loans. Diversification in the loan portfolio is a means of managing risk associated with fluctuations in economic conditions, both by type of loan and geographic location.
	Commercial loans are underwritten after evaluating and understanding the borrower’s ability to operate profitably and effectively. Underwriting standards are designed to determine whether the borrower possesses sound business ethics and practices and to evaluate current and projected cash flows to determine the ability of the borrower to repay their obligations as agreed. Commercial loans are primarily made based on the identified cash flows of the borrower and, secondarily, on the underlying collateral provided by the borrower. Most commercial loans are secured by the assets being financed or other business assets, such as accounts receivable or inventory, and include personal guarantees.
	Agricultural loans are subject to underwriting standards and processes similar to commercial loans. These agricultural loans are based primarily on the identified cash flows of the borrower and secondarily on the underlying collateral provided by the borrower. Most agricultural loans are secured by the agriculture related assets being financed, such as farm land, cattle or equipment, and include personal guarantees.
	Real estate loans are also subject to underwriting standards and processes similar to commercial and agricultural loans. These loans are underwritten primarily based on projected cash flows and, secondarily, as loans secured by real estate. The repayment of real estate loans is generally largely dependent on the successful operation of the property securing the loans or the business conducted on the property securing the loan. Real estate loans may be more adversely affected by conditions in the real estate markets or in the general economy. The properties securing the Company’s real estate portfolio are generally diverse in terms of type and geographic location within Texas. This diversity helps reduce the exposure to adverse economic events that affect any single market or industry. Generally, real estate loans are owner occupied which further reduces the Company’s risk.
	Consumer loan underwriting utilizes methodical credit standards and analysis to supplement the Company’s underwriting policies and procedures. The Company’s loan policy addresses types of consumer loans that may be originated and the collateral, if secured, which must be perfected. The relatively smaller individual dollar amounts of consumer loans that are spread over numerous individual borrowers also minimize the Company’s risk.
	The allowance for loan losses is an amount management believes is appropriate to absorb probable losses that have been incurred on existing loans as of the balance sheet date based upon management’s review and evaluation of the loan portfolio. The allowance for loan losses is comprised of three elements: (i) specific reserves determined in accordance with current authoritative accounting guidance based on probable losses on specific classified loans; (ii) a general reserve determined in accordance with current authoritative accounting guidance that considers historical loss rates; and (iii) qualitative reserves determined in accordance with current authoritative accounting guidance based upon general economic conditions and other qualitative risk factors both internal and external to the Company. The allowance for loan losses is increased by charges to income and decreased by charge-offs (net of recoveries). Management’s periodic evaluation of the appropriateness of the allowance is based on general economic conditions, the financial condition of borrowers, the value and liquidity of collateral, delinquency, prior loan loss experience, and the results of periodic reviews of the portfolio. For purposes of determining our general reserve, the loan portfolio, less cash secured loans, government guaranteed loans and classified loans, is multiplied by the Company’s historical loss rate. Specific allocations are increased in accordance with deterioration in credit quality and a corresponding increase in risk of loss on a particular loan. In addition, we adjust our allowance for qualitative factors such as current local economic conditions and trends, including, without limitations, unemployment, changes in lending staff, policies and procedures, changes in credit concentrations, changes in the trends and severity of problem loans and changes in trends in volume and terms of loans. This qualitative reserve serves to compensate for additional areas of uncertainty inherent in our portfolio that are not reflected in our historic loss factors.
	Although we believe we use the best information available to make loan loss allowance determinations, future adjustments could be necessary if circumstances or economic conditions differ substantially from the assumptions used in making our initial determinations. A downturn in the economy and employment could result in increased levels of non-performing assets and charge-offs, increased loan provisions and reductions in income. Additionally, bank regulatory agencies periodically review our allowance for loan losses and methodology and could require additions to the loan loss allowance based on their judgment of information available to them at the time of their examination.
	Accrual of interest is discontinued on a loan and payments are applied to principal when management believes, after considering economic and business conditions and collection efforts, the borrower’s financial condition is such that collection of interest is doubtful. Except consumer loans, generally all loans past due greater than 90 days, based on contractual terms, are placed on non-accrual. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured. Consumer loans are generally charged-off when a loan becomes past due 90 days. For other loans in the portfolio, facts and circumstances are evaluated in making charge-off decisions.
	Loans are considered impaired when, based on current information and events, management determines that it is probable we will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreement, including scheduled principal and interest payments. If a loan is impaired, a specific valuation allowance is allocated, if necessary. Interest payments on impaired loans are typically applied to principal unless collectability of the principal amount is reasonably assured, in which case interest is recognized on a cash basis. Impaired loans, or portions thereof, are charged off when deemed uncollectable.
	The Company’s policy requires measurement of the allowance for an impaired, collateral dependent loan based on the fair value of the collateral. Other loan impairments are measured based on the present value of expected future cash flows or the loan’s observable market price. At September 30, 2013 and 2012, and December 31, 2012, all significant impaired loans have been determined to be collateral dependent and the allowance for loss has been measured utilizing the estimated fair value of the collateral.
	From time to time, the Company modifies its loan agreement with a borrower. A modified loan is considered a troubled debt restructuring when two conditions are met: (i) the borrower is experiencing financial difficulty and (ii) concessions are made by the Company that would not otherwise be considered for a borrower with similar credit risk characteristics. Modifications to loan terms may include a lower interest rate, a reduction of principal, or a longer term to maturity. To date, these troubled debt restructurings have been such that, after considering economic and business conditions and collection efforts, the collection of interest is doubtful and therefore the loan has been placed on non-accrual. Each of these loans is individually evaluated for impairment and a specific reserve is recorded based on probable losses, taking into consideration the related collateral and modified loan terms and cash flow. As of September 30, 2013 and 2012, and December 31, 2012, all of the Company’s troubled debt restructured loans are included in the non-accrual totals.
	The Company originates certain mortgage loans for sale in the secondary market. Accordingly, these loans are classified as held for sale and are carried at the lower of cost or fair value on an aggregate basis. Loans held for sale totaled $5,724,000, $10,034,000 and $11,457,000, at September 30, 2013 and 2012 and December 31, 2012, respectively, in which the carrying amounts approximate fair value. The mortgage loan sales contracts contain indemnification clauses should the loans default, generally in the first three to six months, or if documentation is determined not to be in compliance with regulations. The Company’s historic losses as a result of these indemnities have been insignificant.
	Loans acquired, including loans acquired in a business combination, are initially recorded at fair value with no valuation allowance. Acquired loans were segregated between those considered to be credit impaired and those deemed performing. To make this determination, management considered such factors as past due status, nonaccrual status and credit risk ratings. The fair value of acquired performing loans was determined by discounting expected cash flows, both principal and interest, at prevailing market interest rates. The difference between the fair value and principal balances due at acquisition date, the fair value discount, is accreted into income over the estimated life of each loan.
	Purchased credit impaired loans are those loans that showed evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all amounts contractually owed. Their fair value was initially based on the estimate of cash flows, both principal and interest, expected to be collected or estimated collateral values if cash flows are not estimable, discounted at prevailing market rates of interest. The difference between the undiscounted cash flows expected at acquisition and the investment in the loan, is recognized as interest income on a level-yield method over the life of the loan, unless management was unable to reasonable forecast cash flows in which case the loans were placed on nonaccrual. Contractually required payments for interest and principal that exceed the undiscounted cash flows expected at acquisition are not recognized as a yield adjustment. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition. The carrying amount of purchased credit impaired loans at September 30, 2013 was $2,954,000 compared to a contractual balance of $4,218,000. Other purchased credit impaired loan disclosures were omitted due to immateriality.
	Major classifications of loans held for investment are as follows (in thousands):
			September 30,								December 31,
			2013				2012				2012
	Commercial		$	571,973			$	482,655			$	509,609
	Agricultural			66,758				63,148				68,306
	Real estate			1,640,308				1,191,088				1,226,823
	Consumer			330,046				256,929				272,428
	Total loans held for investment		$	2,609,085			$	1,993,820			$	2,077,166
	The Company’s non-accrual loans, loans still accruing and past due 90 days or more and restructured loans are as follows (in thousands):
			September 30,								December 31,
			2013				2012				2012
	Non-accrual loans*		$	22,809			$	24,283			$	21,800
	Loans still accruing and past due 90 days or more			54				69				97
	Restructured loans**			—				—				—
	Total		$	22,863			$	24,352			$	21,897
	*	Includes $2,954,000 of purchased credit impaired loans as of September 30, 2013. There were no purchased credit impaired loan balances in prior periods.
	**	Restructured loans whose interest collection, after considering economic and business conditions and collection efforts, is doubtful are included in non-accrual loans.
	The Company’s recorded investment in impaired loans and the related valuation allowance are as follows (in thousands):
	September 30, 2013								September 30, 2012								December 31, 2012
	Recorded				Valuation				Recorded				Valuation				Recorded				Valuation
	Investment				Allowance				Investment				Allowance				Investment				Allowance
	$	22,809			$	4,605			$	24,283			$	6,093			$	21,800			$	6,010
	The average recorded investment in impaired loans for the three and nine months ended September 30, 2013 and the year ended December 31, 2012 was approximately $23,768,000, $22,530,000 and $24,025,000, respectively. The Company had $28,535,000, $30,725,000 and $25,462,000 in non-accrual, past due 90 days still accruing and restructured loans and foreclosed assets at September 30, 2013 and 2012, and December 31, 2012, respectively. Non-accrual loans totaled $22,809,000, $24,283,000 and $21,800,000 at September 30, 2013 and 2012, and December 31, 2012, respectively, and consisted of the following amounts by type (in thousands):
			September 30,								December 31,
			2013				2012				2012
	Commercial		$	1,986			$	2,890			$	2,251
	Agricultural			97				401				372
	Real estate			20,036				20,673				18,698
	Consumer			690				319				479
	Total		$	22,809			$	24,283			$	21,800
	No additional funds are committed to be advanced in connection with impaired loans.
	The Company’s impaired loans and related allowance as of September 30, 2013 and 2012, and December 31, 2012, are summarized in the following table (in thousands). No interest income was recognized on impaired loans subsequent to their classification as impaired.
	September 30, 2013		Unpaid				Recorded				Recorded				Total				Related				Year-to-Date		Three-
			Contractual				Investment				Investment				Recorded				Allowance				Average		month
			Principal				With No				With				Investment								Recorded		Average
			Balance				Allowance*				Allowance												Investment		Recorded
																									Investment
	Commercial		$	2,545			$	701			$	1,285			$	1,986			$	710			$	1,779	$	2,113
	Agricultural			105				91				6				97				6				104		99
	Real Estate			25,085				4,290				15,746				20,036				3,628				19,985		20,757
	Consumer			824				212				478				690				261				662		799
	Total		$	28,559			$	5,294			$	17,515			$	22,809			$	4,605			$	22,530	$	23,768
	*	Includes $2,954,000 of purchased credit impaired loans.
	September 30, 2012		Unpaid				Recorded				Recorded				Total				Related				Year-to-Date		Three-
			Contractual				Investment				Investment				Recorded				Allowance				Average		month
			Principal				With No				With				Investment								Recorded		Average
			Balance				Allowance				Allowance												Investment		Recorded
																									Investment
Commercial		$	3,568			$	63			$	2,827			$	2,890			$	1,488			$	3,943	$	3,728
Agricultural			408				—				401				401				130				455		416
Real Estate			24,866				3,049				17,624				20,673				4,341				21,537		20,686
Consumer			363				30				289				319				134				344		320
Total		$	29,205			$	3,142			$	21,141			$	24,283			$	6,093			$	26,279	$	25,150
December 31, 2012		Unpaid				Recorded				Recorded				Total				Related				Year-to-Date
		Contractual				Investment				Investment				Recorded				Allowance				Average
		Principal				With No				With				Investment								Recorded
		Balance				Allowance				Allowance												Investment
Commercial		$	2,677			$	20			$	2,231			$	2,251			$	1,350			$	2,966
Agricultural			381				—				372				372				131				437
Real Estate			22,569				2,049				16,649				18,698				4,356				20,164
Consumer			543				115				364				479				173				458
Total		$	26,170			$	2,184			$	19,616			$	21,800			$	6,010			$	24,025
The Company recognized interest income on impaired loans prior to being recognized as impaired of approximately $384,000 during the year ended December 31, 2012. Such amounts for the three-month and nine-month periods ended September 30, 2013 and 2012 were not significant.
From a credit risk standpoint, the Company classifies its loans in one of four categories: (i) pass, (ii) special mention, (iii) substandard, or (iv) doubtful. Loans classified as loss are charged-off.
The classifications of loans reflect a judgment about the risks of default and loss associated with the loan. The Company reviews the ratings on our credits as part of our on-going monitoring of the credit quality of our loan portfolio. Ratings are adjusted to reflect the degree of risk and loss that are felt to be inherent in each credit as of each reporting period. Our methodology is structured so that specific allocations are increased in accordance with deterioration in credit quality (and a corresponding increase in risk and loss) or decreased in accordance with improvement in credit quality (and a corresponding decrease in risk and loss).
Credits rated special mention show clear signs of financial weaknesses or deterioration in credit worthiness, however, such concerns are not so pronounced that the Company generally expects to experience significant loss within the short-term. Such credits typically maintain the ability to perform within standard credit terms and credit exposure is not as prominent as credits rated more harshly.
Credits rated substandard are those in which the normal repayment of principal and interest may be, or has been, jeopardized by reason of adverse trends or developments of a financial, managerial, economic or political nature, or important weaknesses exist in collateral. A protracted workout on these credits is a distinct possibility. Prompt corrective action is therefore required to strengthen the Company’s position, and/or to reduce exposure and to assure that adequate remedial measures are taken by the borrower. Credit exposure becomes more likely in such credits and a serious evaluation of the secondary support to the credit is performed.
Credits rated doubtful are those in which full collection of principal appears highly questionable, and which some degree of loss is anticipated, even though the ultimate amount of loss may not yet be certain and/or other factors exist which could affect collection of debt. Based upon available information, positive action by the Company is required to avert or minimize loss. Credits rated doubtful are generally also placed on non-accrual.
At September 30, 2013 and December 31, 2012, the following summarizes the Company’s internal ratings of its loans held for investment (in thousands):
September 30, 2013		Pass				Special				Substandard				Doubtful				Total
						Mention
Commercial		$	558,196			$	3,282			$	10,279			$	216			$	571,973
Agricultural			66,084				259				411				4				66,758
Real Estate			1,574,973				19,715				45,454				166				1,640,308
Consumer			328,164				673				1,197				12				330,046
Total		$	2,527,417			$	23,929			$	57,341			$	398			$	2,609,085
December 31, 2012		Pass				Special				Substandard				Doubtful				Total
						Mention
Commercial		$	498,188			$	2,193			$	9,198			$	30			$	509,609
Agricultural			64,397				342				3,559				8				68,306
Real Estate			1,176,330				14,680				35,673				140				1,226,823
Consumer			271,114				382				911				21				272,428
Total		$	2,010,029			$	17,597			$	49,341			$	199			$	2,077,166
At September 30, 2013 and December 31, 2012, the Company’s past due loans are as follows (in thousands):
September 30, 2013		15-59				60-89				Greater				Total				Current				Total Loans		90 Days
		Days				Days				Than				Past										Past Due
		Past				Past				90				Due										Still
		Due*				Due				Days														Accruing
Commercial		$	5,016			$	667			$	372			$	6,055			$	565,918			$	571,973	$	—
Agricultural			332				39				—				371				66,387				66,758		—
Real Estate			12,976				676				1,409				15,061				1,625,247				1,640,308		8
Consumer			2,099				527				160				2,786				327,260				330,046		46
Total		$	20,423			$	1,909			$	1,941			$	24,273			$	2,584,812			$	2,609,085	$	54
December 31, 2012		15-59				60-89				Greater				Total				Current				Total Loans		90 Days
		Days				Days				Than				Past										Past Due
		Past				Past				90				Due										Still
		Due*				Due				Days														Accruing
Commercial		$	1,708			$	470			$	247			$	2,425			$	507,184			$	509,609	$	—
Agricultural			467				95				—				562				67,744				68,306		—
Real Estate			10,141				2,711				1,237				14,089				1,212,734				1,226,823		34
Consumer			1,660				287				163				2,110				270,318				272,428		63
Total		$	13,976			$	3,563			$	1,647			$	19,186			$	2,057,980			$	2,077,166	$	97
*	The Company monitors commercial, agricultural and real estate loans after such loans are 15 days past due. Consumer loans are monitored after such loans are 30 days past due.
The allowance for loan losses as of September 30, 2013 and 2012, and December 31, 2012, is presented below. Management has evaluated the appropriateness of the allowance for loan losses by estimating the probable losses in various categories of the loan portfolio, which are identified below (in thousands):
		September 30,								December 31,
		2013				2012				2012
Allowance for loan losses provided for:
Loans specifically evaluated as impaired		$	4,605			$	6,093			$	6,010
Remaining portfolio			30,195				28,839				28,829
Total allowance for loan losses		$	34,800			$	34,932			$	34,839
The following table details the allowance for loan losses at September 30, 2013 and December 31, 2012 by portfolio segment (in thousands). There were no allowances for purchased credit impaired loans at September 30, 2013 or December 31, 2012. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.
September 30, 2013		Commercial				Agricultural				Real Estate				Consumer				Total
Loans individually evaluated for impairment		$	2,698			$	131			$	6,932			$	391			$	10,152
Loans collectively evaluated for impairment			4,315				287				18,362				1,684				24,648
Total		$	7,013			$	418			$	25,294			$	2,075			$	34,800
December 31, 2012		Commercial				Agricultural				Real Estate				Consumer				Total
Loans individually evaluated for impairment		$	3,253			$	388			$	8,380			$	308			$	12,329
Loans collectively evaluated for impairment			4,090				1,153				15,683				1,584				22,510
Total		$	7,343			$	1,541			$	24,063			$	1,892			$	34,839
Changes in the allowance for loan losses for the three and nine months ended September 30, 2013 and 2012 are summarized as follows (in thousands):
Three months ended September 30, 2013		Commercial				Agricultural				Real Estate				Consumer				Total
Beginning balance		$	6,736			$	1,493			$	23,902			$	1,968			$	34,099
Provision for loan losses			354				(999	)			1,644				350				1,349
Recoveries			141				10				42				104				297
Charge-offs			(218	)			(86	)			(294	)			(347	)			(945	)
Ending balance		$	7,013			$	418			$	25,294			$	2,075			$	34,800
Three months ended September 30, 2012		Commercial				Agricultural				Real Estate				Consumer				Total
Beginning balance		$	8,556			$	1,253			$	23,294			$	1,644			$	34,747
Provision for loan losses			(1,088	)			491				1,200				184				787
Recoveries			42				14				325				81				462
Charge-offs			(60	)			—				(845	)			(159	)			(1,064	)
Ending balance		$	7,450			$	1,758			$	23,974			$	1,750			$	34,932
Nine months ended September 30, 2013		Commercial				Agricultural				Real Estate				Consumer				Total
Beginning balance		$	7,343			$	1,541			$	24,063			$	1,892			$	34,839
Provision for loan losses			(77	)			(1,056	)			3,035				680				2,582
Recoveries			329				29				95				266				719
Charge-offs			(582	)			(96	)			(1,899	)			(763	)			(3,340	)
Ending balance		$	7,013			$	418			$	25,294			$	2,075			$	34,800
Nine months ended September 30, 2012		Commercial				Agricultural				Real Estate				Consumer				Total
Beginning balance		$	9,664			$	1,482			$	21,533			$	1,636			$	34,315
Provision for loan losses			(1,935	)			294				4,040				443				2,842
Recoveries			195				35				502				279				1,011
Charge-offs			(474	)			(53	)			(2,101	)			(608	)			(3,236	)
Ending balance		$	7,450			$	1,758			$	23,974			$	1,750			$	34,932
The Company’s recorded investment in loans as of September 30, 2013 and December 31, 2012 related to the balance in the allowance for loan losses on the basis of the Company’s impairment methodology was as follows (in thousands). Purchased credit impaired loans of $2,954,000 at September 30, 2013 are included in loans individually evaluated for impairment. There were no purchased credit impaired loans at December 31, 2012.
September 30, 2013		Commercial				Agricultural				Real Estate				Consumer				Total
Loans individually evaluated for impairment		$	13,777			$	674			$	65,335			$	1,882			$	81,668
Loans collectively evaluated for impairment			558,196				66,084				1,574,973				328,164				2,527,417
Total		$	571,973			$	66,758			$	1,640,308			$	330,046			$	2,609,085
December 31, 2012		Commercial				Agricultural				Real Estate				Consumer				Total
Loans individually evaluated for impairment		$	11,421			$	3,909			$	50,493			$	1,314			$	67,137
Loans collectively evaluated for impairment			498,188				64,397				1,176,330				271,114				2,010,029
Total		$	509,609			$	68,306			$	1,226,823			$	272,428			$	2,077,166
The Company’s loans that were modified in the three and nine months ended September 30, 2013 and 2012 and considered a troubled debt restructuring are as follows (in thousands):
		Three Months Ended September 30, 2013												Nine Months Ended September 30, 2013
						Pre-				Post-								Pre-				Post-
						Modification				Modification								Modification				Modification
						Recorded				Recorded								Recorded				Recorded
		Number				Investment				Investment				Number				Investment				Investment
Commercial			—			$	—			$	—				3			$	218			$	218
Agricultural			—				—				—				1				24				24
Real Estate			—				—				—				8				3,779				3,779
Consumer			4				86				86				5				123				123
Total			4			$	86			$	86				17			$	4,144			$	4,144
		Three Months Ended September 30, 2012												Nine Months Ended September 30, 2012
						Pre-				Post-								Pre-				Post-
						Modification				Modification								Modification				Modification
						Recorded				Recorded								Recorded				Recorded
		Number				Investment				Investment				Number				Investment				Investment
Commercial			2			$	9			$	9				11			$	796			$	796
Agricultural			—				—				—				5				354				354
Real Estate			4				1,093				1,093				31				8,761				8,761
Consumer			—				—				—				1				19				19
Total			6			$	1,102			$	1,102				48			$	9,930			$	9,930
The balances below provide information as to how the loans were modified as troubled debt restructured loans during the three and nine months ended September 30, 2013 and 2012 (in thousands):
		Three Months Ended September 30, 2013												Nine Months Ended September 30, 2013
		Adjusted				Extended				Combined				Adjusted				Extended				Combined
		Interest				Maturity				Rate and				Interest				Maturity				Rate and
		Rate								Maturity				Rate								Maturity
Commercial		$	—			$	—			$	—			$	—			$	218			$	—
Agricultural			—				—				—				—				24				—
Real Estate			—				—				—				420				350				3,009
Consumer			—				82				4				—				119				4
Total		$	—			$	82			$	4			$	420			$	711			$	3,013
		Three Months Ended September 30, 2012												Nine Months Ended September 30, 2012
		Adjusted				Extended				Combined				Adjusted				Extended				Combined
		Interest				Maturity				Rate and				Interest				Maturity				Rate and
		Rate								Maturity				Rate								Maturity
Commercial		$	—			$	—			$	9			$	508			$	120			$	168
Agricultural			—				—				—				243				15				95
Real Estate			—				717				376				935				1,825				6,002
Consumer			—				—				—				—				19				—
Total		$	—			$	717			$	385			$	1,686			$	1,979			$	6,265
During the three and nine month periods ended September 30, 2013, one and six loans, respectively, totaling $71,000 and $316,000, respectively, that had been modified as a troubled debt restructured loan within the previous 12 months defaulted on the modified loan. During the three and nine months ended September 30, 2012, two loans totaling $221,000 that had been modified as a troubled debt restructured loan within the previous 12 months defaulted on the modified loan. A default for purposes of this disclosure is a troubled debt restructured loan in which the borrower is 90 days past due or results in the foreclosure and repossession of the applicable collateral. The loans are as follows (dollars in thousands):
		Three Months Ended September 30, 2013								Nine Months Ended September 30, 2013
		Number				Balance				Number				Balance
Commercial			1			$	71				6			$	316
Agriculture			—				—				—				—
Real Estate			—				—				—				—
Consumer			—				—				—				—
Total			1			$	71				6			$	316
		Three Months Ended September 30, 2012								Nine Months Ended September 30, 2012
		Number				Balance				Number				Balance
Commercial			2			$	221				2			$	221
Agriculture			—				—				—				—
Real Estate			—				—				—				—
Consumer			—				—				—				—
Total			2			$	221				2			$	221
As of September 30, 2013, the Company has no commitments to lend additional funds to loan customers whose terms have been modified in troubled debt restructurings.
Our subsidiary bank has established a line of credit with the Federal Home Loan Bank of Dallas to provide liquidity and meet pledging requirements for those customers eligible to have securities pledged to secure certain uninsured deposits. At September 30, 2013, approximately $1,461,000,000 in loans held by the bank were subject to blanket liens as security for this line of credit. At September 30, 2013, $161,146,000 in advances were outstanding and $53,600,000 in letters of credit were outstanding under this line of credit. The letters of credit were pledged as collateral for public funds held by our bank.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Income Taxes	Note 5 - Income Taxes
	Income tax expense was $6,121,000 for the third quarter of 2013 as compared to $6,828,000 for the same period in 2012. The Company’s effective tax rates on pretax income were 23.83% and 25.64% for the third quarter of 2013 and 2012, respectively. Income tax expense was $18,723,000 for the nine months ended September 30, 2013 as compared to $19,028,000 for the same period in 2012. The Company’s effective tax rates on pretax income were 24.52% and 25.39% for the nine months ended September 30, 2013 and 2012, respectively. The effective tax rates differ from the statutory federal tax rate of 35% largely due to tax exempt interest income earned on certain investment securities and loans, the deductibility of dividends paid to our employee stock ownership plan and Texas state taxes.

Stock_Based_Compensation

Stock Based Compensation	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Based Compensation	Note 6 - Stock Based Compensation
	The Company grants incentive stock options for a fixed number of shares with an exercise price equal to the fair value of the shares at the date of grant to employees. At September 30, 2013, no stock options had been granted in 2013. No options were granted in 2012. On October 22, 2013, the Company granted 197,500 shares in incentive stock options to its employees. The Company recorded stock option expense totaling approximately $88,000 and $78,000 for the three-month periods ended September 30, 2013 and 2012, respectively. The Company recorded stock option expense totaling approximately $264,000 and $251,000 for the nine-month periods ended September 30, 2013 and 2012, respectively. The additional disclosure requirements under authoritative accounting guidance have been omitted due to immateriality.

Pension_Plan

Pension Plan	9 Months Ended
	Sep. 30, 2013
Compensation And Retirement Disclosure [Abstract]
Pension Plan	Note 7 - Pension Plan
	The Company’s defined benefit pension plan was frozen effective January 1, 2004, whereby no additional years of service will accrue to participants, unless the pension plan is reinstated at a future date. The pension plan covered substantially all of the Company’s employees at the time. The benefits for each employee were based on years of service and a percentage of the employee’s qualifying compensation during the final years of employment. The Company’s funding policy was and is to contribute annually the amount necessary to satisfy the Internal Revenue Service’s funding standards. Contributions to the pension plan, prior to freezing the plan, were intended to provide not only for benefits attributed to service to date but also for those expected to be earned in the future. As a result of the Pension Protection Act of 2006 (the “Protection Act”), the Company will be required to contribute amounts in future years to fund any shortfalls. The Company has evaluated the provisions of the Protection Act as well as the Internal Revenue Service’s funding standards to develop a plan for funding in future years. The Company made a contribution totaling $2,000,000 in 2012 and has to date made no contributions in 2013.
	Net periodic benefit costs totaling $208,000 and $185,000 were recorded, respectively, for the three months ended September 30, 2013 and 2012. Net periodic benefit costs totaling $623,000 and $555,000 were recorded, respectively, for the nine months ended September 30, 2013 and 2012.

Recently_Issued_Authoritative_

Recently Issued Authoritative Accounting Guidance	9 Months Ended
	Sep. 30, 2013
Accounting Changes And Error Corrections [Abstract]
Recently Issued Authoritative Accounting Guidance	Note 8 - Recently Issued Authoritative Accounting Guidance
	In 2011 and 2013, the Financial Accounting Standards Board (the “FASB”) amended its authoritative guidance related to offsetting assets and liabilities to require an entity to disclose both gross and net information about financial instruments, such as sales and repurchase agreements, reverse sales, repurchase agreements and securities borrowing/lending arrangements and derivative instruments that are eligible for offset in the statement of financial position and/or subject to a master netting arrangement or similar agreement. The new guidance was effective for annual and interim periods beginning on January 1, 2013, and did not have a significant impact on the Company’s financial statements.
	In 2013, the FASB amended its authoritative guidance related to reporting of reclassifications out of other comprehensive earnings. The new guidance sets requirements for presentation for significant items reclassified to net earnings during the period presented. The new guidance was effective for annual and interim periods beginning on January 1, 2013 and have been included in these financial statements.

Fair_Value_Disclosures

Fair Value Disclosures	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]
Fair Value Disclosures	Note 9 - Fair Value Disclosures
	The authoritative accounting guidance for fair value measurements defines fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. A fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. The price in the principal (or most advantageous) market used to measure the fair value of the asset or liability shall not be adjusted for transaction costs. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets and liabilities; it is not a forced transaction. Market participants are buyers and sellers in the principal market that are (i) independent, (ii) knowledgeable, (iii) able to transact, and (iv) willing to transact.
	The authoritative accounting guidance requires the use of valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets and liabilities. The income approach uses valuation techniques to convert future amounts, such as cash flows or earnings, to a single present amount on a discounted basis. The cost approach is based on the amount that currently would be required to replace the service capacity of an asset (replacement costs). Valuation techniques should be consistently applied. Inputs to valuation techniques refer to the assumptions that market participants would use in pricing the asset or liability. Inputs may be observable, meaning those that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from independent sources, or unobservable, meaning those that reflect the reporting entity’s own assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. In that regard, the authoritative guidance establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows:
		•		Level 1 Inputs – Unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date.
		•		Level 2 Inputs – Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. These include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (for example, interest rates, volatilities, prepayment speeds, loss severities, credit risks and default rates) or inputs that are derived principally from or corroborated by observable market data by correlation or other means.
		•		Level 3 Inputs – Significant unobservable inputs that reflect an entity’s own assumptions that market participants would use in pricing the assets or liabilities.
	A description of the valuation methodologies used for assets and liabilities measured at fair value, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below.
	In general, fair value is based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon internally developed models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. While management believes the Company’s valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date.
	Securities classified as available-for-sale and trading are reported at fair value utilizing Level 1 and Level 2 inputs. For these securities, the Company obtains fair value measurements from an independent pricing service. The fair value measurements consider observable data that may include market spreads, cash flows, the United States Treasury yield curve, live trading levels, trade execution data, dealer quotes, market consensus prepayments speeds, credit information and the security’s terms and conditions, among other items. Securities are considered to be measured with Level 1 inputs at the time of purchase and for 30 days following. After 30 days, the majority of securities are transferred to Level 2 as they are considered to be measured with Level 2 inputs, with the exception of U. S. Treasury securities and any other security for which there remain Level 1 inputs. Transfers are recognized on the actual date of transfer.
	There were no transfers between Level 2 and Level 3 during the three and nine months ended September 30, 2013 or 2012.
	The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of September 30, 2013, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (dollars in thousands):
			Level 1			Level 2			Level 3		Total Fair
			Inputs			Inputs			Inputs		Value
	Available-for-sale investment securities:
	Obligations of U. S. government sponsored-enterprises and agencies		$	—		$	144,614		$	—	$	144,614
	Obligations of states and political subdivisions			18,025			954,153			—		972,178
	Corporate bonds			—			106,096			—		106,096
	Residential mortgage-backed securities			44,936			595,153			—		640,089
	Commercial mortgage-backed securities			—			108,293			—		108,293
	Other securities			4,033			—			—		4,033
	Total		$	66,994		$	1,908,309		$	—	$	1,975,303
	Certain financial assets and financial liabilities are measured at fair value on a nonrecurring basis, that is, the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances (for example, when there is evidence of impairment). Financial assets and financial liabilities measured at fair value on a non-recurring basis include the following at September 30, 2013:
	Impaired Loans – Impaired loans are reported at the fair value of the underlying collateral if repayment is expected solely from the collateral. Collateral values are estimated using Level 2 inputs based on observable market data, or Level 3 input based on the discounting of the collateral. At September 30, 2013, impaired loans with a carrying value of $22,809,000 were reduced by specific valuation reserves totaling $4,605,000 resulting in a net fair value of $18,204,000.
	Loans Held for Sale – Loans held for sale are reported at the lower of cost or fair value. In determining whether the fair value of loans held for sale is less than cost when quoted market prices are not available, the Company considers investor commitments/contracts. These loans are considered Level 2 of the fair value hierarchy. At September 30, 2013, the Company’s mortgage loans held for sale were recorded at cost as fair value exceeded cost.
	Certain non-financial assets and non-financial liabilities measured at fair value on a non-recurring basis include other real estate owned, goodwill and other intangible assets and other non-financial long-lived assets. Non-financial assets measured at fair value on a non-recurring basis during the three and nine months ended September 30, 2013 and 2012 include other real estate owned which, subsequent to their initial transfer to other real estate owned from loans, were re-measured at fair value through a write-down included in gain (loss) on sale of foreclosed assets. During the reported periods, all fair value measurements for foreclosed assets utilized Level 2 inputs based on observable market data, generally third-party appraisals, or Level 3 inputs based on customized discounting criteria. These appraisals are evaluated individually and discounted as necessary due to the age of the appraisal, lack of comparable sales, expected holding periods of property or special use type of the property. Such discounts vary by appraisal based on the above factors but generally range from 5% to 25% of the appraised value. Reevaluation of other real estate owned is performed at least annually as required by regulatory guidelines or more often if particular circumstances arise. The following table presents other real estate owned that were re-measured subsequent to their initial transfer to other real estate owned (dollars in thousands):
			Three Months Ended
			September 30,
			2013			2012
	Carrying value of other real estate owned prior to re-measurement		$	238		$	3,140
	Write-downs included in gain (loss) on sale of other real estate owned			(65	)		(125	)
	Fair value		$	173		$	3,015
			Nine Months Ended
			September 30,
			2013			2012
	Carrying value of other real estate owned prior to re-measurement		$	2,065		$	4,993
	Write-downs included in gain (loss) on sale of other real estate owned			(369	)		(661	)
	Fair value		$	1,696		$	4,332
	At September 30, 2013 and 2012, and December 31, 2012, other real estate owned totaled $5,490,000, $6,300,000 and $3,505,000, respectively.
	The Company is required under current authoritative accounting guidance to disclose the estimated fair value of their financial instrument assets and liabilities including those subject to the requirements discussed above. For the Company, as for most financial institutions, substantially all of its assets and liabilities are considered financial instruments, as defined. Many of the Company’s financial instruments, however, lack an available trading market as characterized by a willing buyer and willing seller engaging in an exchange transaction.
	The estimated fair value amounts of financial instruments have been determined by the Company using available market information and appropriate valuation methodologies. However, considerable judgment is required to interpret data to develop the estimates of fair value. Accordingly, the estimates presented herein are not necessarily indicative of the amounts the Company could realize in a current market exchange. The use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts.
	In addition, reasonable comparability between financial institutions may not be likely due to the wide range of permitted valuation techniques and numerous estimates that must be made given the absence of active secondary markets for many of the financial instruments. This lack of uniform valuation methodologies also introduces a greater degree of subjectivity to these estimated fair values.
	Cash and due from banks, federal funds sold, interest-bearing deposits and time deposits in banks and accrued interest receivable and payable are liquid in nature and considered Level 1 or 2 of the fair value hierarchy.
	Financial instruments with stated maturities have been valued using a present value discounted cash flow with a discount rate approximating current market for similar assets and liabilities and are considered Levels 2 and 3 of the fair value hierarchy. Financial instrument liabilities with no stated maturities have an estimated fair value equal to both the amount payable on demand and the carrying value and are considered Level 1 of the fair value hierarchy.
	The carrying value and the estimated fair value of the Company’s contractual off-balance-sheet unfunded lines of credit, loan commitments and letters of credit, which are generally priced at market at the time of funding, are not material.
	The estimated fair values and carrying values of all financial instruments under current authoritative guidance at September 30, 2013 and December 31, 2012, were as follows (in thousands):
			September 30,						December 31,
			2013						2012
			Carrying			Estimated			Carrying		Estimated		Fair Value
			Value			Fair Value			Value		Fair Value		Hierarchy
	Cash and due from banks		$	164,666		$	164,666		$	207,018	$	207,018	Level 1
	Federal funds sold			14,300			14,300			14,045		14,045	Level 1
	Interest-bearing deposits in banks			48,634			48,634			139,676		139,676	Level 1
	Interest-bearing time deposits in banks			34,352			34,526			49,005		49,288	Level 2
	Available-for-sale securities			1,975,303			1,975,303			1,819,035		1,819,035	Levels 1 and 2
	Held-to-maturity securities			798			810			1,061		1,080	Level 2
	Loans			2,580,009			2,593,923			2,053,784		2,081,091	Level 3
	Accrued interest receivable			22,421			22,421			23,122		23,122	Level 2
	Deposits with stated maturities			681,236			683,548			637,040		638,227	Level 2
	Deposits with no stated maturities			3,319,321			3,319,321			2,995,544		2,995,544	Level 1
	Short term borrowings			466,500			466,500			259,697		259,697	Level 2
	Accrued interest payable			314			314			287		287	Level 2

Acquisition

Acquisition	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]
Acquisition	Note 10 - Acquisition
	On February 9, 2013, we entered into an agreement and plan of merger to acquire Orange Savings Bank, SSB. On May 31, 2013, the transaction was completed. Pursuant to the agreement, we paid $39,200,000 in cash and issued 420,000 shares of the Company’s common stock in exchange for all of the outstanding shares of Orange Savings Bank, SSB. At closing, Orange Savings Bank, SSB, was merged into First Financial Bank, N.A., Abilene, Texas, a wholly owned subsidiary of the Company.
	The primary purpose of the acquisition was to expand the Company’s market share along Interstate Highway 10 in Southeast Texas. Factors that contributed to a purchase price resulting in goodwill include Orange Savings Bank, SSB’s historic record of earnings, strong local economic environment and opportunity for growth. The results of operations from this acquisition are included in the consolidated earnings of the Company commencing June 1, 2013.
	The assets acquired and liabilities assumed were recorded on the consolidated balance sheet at estimated fair value on the acquisition date. Pending further review and analysis of tangible and intangible asset valuation and receipt of final valuations, the purchase price allocation may change. The acquisition was not considered to be a significant business combination. The following table presents the amounts recorded on the consolidated balance sheet on the acquisition date (in thousands):
	Fair value of consideration paid:
	Cash	$	39,200
	Common stock issued (420,000 shares)		23,100
	Total fair value of consideration paid		62,300
	Fair value of identifiable assets acquired:
	Cash and cash equivalents		13,494
	Securities available for sale		107,735
	Loans		293,288
	Identifiable intangible assets		2,300
	Other assets		12,569
	Total identifiable assets acquired		429,386
	Fair value of liabilities assumed:
	Deposits		385,950
	Other liabilities		4,154
	Total liabilities assumed		390,104
	Fair value of net identifiable assets acquired		39,282
	Goodwill resulting from acquisition	$	23,018
	Goodwill recorded in the acquisition of Orange Savings Bank, SSB was accounted for in accordance with the authoritative business combination guidance. Accordingly, goodwill will not be amortized, but will be tested for impairment annually. The goodwill recorded is expected to be deductible for federal income tax purposes.
	The fair value of total loans acquired was $293,288,000 at acquisition compared to contractual amounts of $299,252,000. The fair value of purchased credit impaired loans at acquisition was $4,475,000 compared to contractual amounts of $5,878,000. Additional purchased credit impaired loan disclosures were omitted due to immateriality. All other acquired loans were considered performing loans.
	Orange Savings Bank, SSB has branches in Orange, Vidor, Mauriceville, Port Arthur and Newton, all located east of Houston, Texas.

Interestbearing_Time_Deposits_1

Interest-bearing Time Deposits in Banks and Securities (Tables)	9 Months Ended
	Sep. 30, 2013
Investments Debt And Equity Securities [Abstract]
Summary of Available-for-Sale and Held-to-Maturity Securities	A summary of available-for-sale and held-to-maturity securities follows (in thousands):
		September 30, 2013
		Amortized		Gross		Gross			Estimated
		Cost Basis		Unrealized		Unrealized			Fair Value
				Holding Gains		Holding Losses
	Securities available-for-sale:
	Obligations of U.S. government sponsored-enterprises and agencies	$	142,944	$	1,684	$	(14	)	$	144,614
	Obligations of states and political subdivisions		960,624		26,321		(14,767	)		972,178
	Corporate bonds and other		106,551		3,578		—			110,129
	Residential mortgage-backed securities		632,621		14,960		(7,492	)		640,089
	Commercial mortgage-backed securities		112,702		—		(4,409	)		108,293
	Total securities available-for-sale	$	1,955,442	$	46,543	$	(26,682	)	$	1,975,303
	Securities held-to-maturity:
	Obligations of states and political subdivisions	$	525	$	3	$	—		$	528
	Residential mortgage-backed securities		273		9		—			282
	Total debt securities held-to-maturity	$	798	$	12	$	—		$	810
		December 31, 2012
		Amortized		Gross		Gross			Estimated
		Cost Basis		Unrealized		Unrealized			Fair Value
				Holding Gains		Holding Losses
	Securities available-for-sale:
	U. S. Treasury securities	$	6,042	$	48	$	—		$	6,090
	Obligations of U.S. government sponsored-enterprises and agencies		219,420		4,060		—			223,480
	Obligations of states and political subdivisions		786,278		57,541		(129	)		843,690
	Corporate bonds and other		117,244		6,020		(73	)		123,191
	Residential mortgage-backed securities		564,434		23,285		(443	)		587,276
	Commercial mortgage-backed securities		33,819		1,739		(250	)		35,308
	Total securities available-for-sale	$	1,727,237	$	92,693	$	(895	)	$	1,819,035
	Securities held-to-maturity:
	Obligations of states and political subdivisions	$	735	$	7	$	—		$	742
	Residential mortgage-backed securities		294		11		—			305
	Commercial mortgage-backed securities		32		1		—			33
	Total debt securities held-to-maturity	$	1,061	$	19	$	—		$	1,080
Amortized Cost and Estimated Fair Value of Debt Securities	The amortized cost and estimated fair value of debt securities at September 30, 2013, by contractual and expected maturity, are shown below (in thousands):
		Available-for-Sale				Held-to-Maturity
		Amortized		Estimated		Amortized			Estimated
		Cost Basis		Fair Value		Cost Basis			Fair Value
	Due within one year	$	82,447	$	83,490	$	525		$	528
	Due after one year through five years		533,039		547,624		—			—
	Due after five years through ten years		536,830		539,843		—			—
	Due after ten years		57,803		55,964		—			—
	Mortgage-backed securities		745,323		748,382		273			282
	Total	$	1,955,442	$	1,975,303	$	798		$	810
Continuous Unrealized-Loss Position of Available-for-Sale and Held-to-Maturity Securities	The following tables disclose, as of September 30, 2013 and December 31, 2012, the Company’s investment securities that have been in a continuous unrealized-loss position for less than 12 months and for 12 months or longer (in thousands):
		Less than 12 Months				12 Months or Longer					Total
	September 30, 2013	Fair Value		Unrealized		Fair Value			Unrealized		Fair Value		Unrealized
				Loss					Loss				Loss
	Obligations of U.S. government sponsored-enterprises and agencies	$	10,941	$	14	$	—		$	—	$	10,941	$	14
	Obligations of states and political subdivisions		382,840		14,767		—			—		382,840		14,767
	Residential mortgage-backed securities		164,166		7,412		8,220			80		172,386		7,492
	Commercial mortgage-backed securities		108,293		4,409		—			—		108,293		4,409
	Total	$	666,240	$	26,602	$	8,220		$	80	$	674,460	$	26,682
		Less than 12 Months				12 Months or Longer					Total
	December 31, 2012	Fair Value		Unrealized		Fair Value			Unrealized		Fair Value		Unrealized
				Loss					Loss				Loss
	Obligations of states and political subdivisions	$	36,480	$	129	$	—		$	—	$	36,480	$	129
	Residential mortgage-backed securities		17,344		401		3,574			42		20,918		443
	Commercial mortgage-backed securities		12,453		250		—			—		12,453		250
	Corporate bonds and other		4,994		73		—			—		4,994		73
	Total	$	71,271	$	853	$	3,574		$	42	$	74,845	$	895

Loans_and_Allowance_for_Loan_L1

Loans and Allowance for Loan Losses (Tables)	9 Months Ended
	Sep. 30, 2013
Receivables [Abstract]
Major Classifications of Loans Held for Investment	Major classifications of loans held for investment are as follows (in thousands):
			September 30,						December 31,
			2013			2012			2012
	Commercial		$	571,973		$	482,655		$	509,609
	Agricultural			66,758			63,148			68,306
	Real estate			1,640,308			1,191,088			1,226,823
	Consumer			330,046			256,929			272,428
	Total loans held for investment		$	2,609,085		$	1,993,820		$	2,077,166
Non-Accrual Loans, Loans Still Accruing and Past Due 90 Days or More and Restructured Loans	The Company’s non-accrual loans, loans still accruing and past due 90 days or more and restructured loans are as follows (in thousands):
			September 30,						December 31,
			2013			2012			2012
	Non-accrual loans*		$	22,809		$	24,283		$	21,800
	Loans still accruing and past due 90 days or more			54			69			97
	Restructured loans**			—			—			—
	Total		$	22,863		$	24,352		$	21,897
	*	Includes $2,954,000 of purchased credit impaired loans as of September 30, 2013. There were no purchased credit impaired loan balances in prior periods.
	**	Restructured loans whose interest collection, after considering economic and business conditions and collection efforts, is doubtful are included in non-accrual loans.
Recorded Investment in Impaired Loans and Related Valuation Allowance	The Company’s recorded investment in impaired loans and the related valuation allowance are as follows (in thousands):
	September 30, 2013					September 30, 2012						December 31, 2012
	Recorded		Valuation			Recorded			Valuation			Recorded			Valuation
	Investment		Allowance			Investment			Allowance			Investment			Allowance
	$22,809		$	4,605		$	24,283		$	6,093		$	21,800		$	6,010
Schedule of Non-Accrual Loans	Non-accrual loans totaled $22,809,000, $24,283,000 and $21,800,000 at September 30, 2013 and 2012, and December 31, 2012, respectively, and consisted of the following amounts by type (in thousands):
			September 30,						December 31,
			2013			2012			2012
	Commercial		$	1,986		$	2,890		$	2,251
	Agricultural			97			401			372
	Real estate			20,036			20,673			18,698
	Consumer			690			319			479
	Total		$	22,809		$	24,283		$	21,800
Schedule of Impaired Loans and Related Allowance	The Company’s impaired loans and related allowance as of September 30, 2013 and 2012, and December 31, 2012, are summarized in the following table (in thousands). No interest income was recognized on impaired loans subsequent to their classification as impaired.
	September 30, 2013		Unpaid			Recorded			Recorded			Total			Related			Year-to-Date		Three-
			Contractual			Investment			Investment			Recorded			Allowance			Average		month
			Principal			With No			With			Investment						Recorded		Average
			Balance			Allowance*			Allowance									Investment		Recorded
																				Investment
	Commercial		$	2,545			701			1,285			1,986			710			1,779		2,113
	Agricultural			105			91			6			97			6			104		99
	Real Estate			25,085			4,290			15,746			20,036			3,628			19,985		20,757
	Consumer			824			212			478			690			261			662		799
	Total		$	28,559			5,294			17,515			22,809			4,605			22,530		23,768
	*	Includes $2,954,000 of purchased credit impaired loans.
	September 30, 2012		Unpaid			Recorded			Recorded			Total			Related			Year-to-Date		Three-
			Contractual			Investment			Investment			Recorded			Allowance			Average		month
			Principal			With No			With			Investment						Recorded		Average
			Balance			Allowance			Allowance									Investment		Recorded
																				Investment
	Commercial		$	3,568		$	63		$	2,827		$	2,890		$	1,488		$	3,943	$	3,728
	Agricultural			408			—			401			401			130			455		416
	Real Estate			24,866			3,049			17,624			20,673			4,341			21,537		20,686
	Consumer			363			30			289			319			134			344		320
	Total		$	29,205		$	3,142		$	21,141		$	24,283		$	6,093		$	26,279	$	25,150
	December 31, 2012		Unpaid			Recorded			Recorded			Total			Related			Year-to-Date
			Contractual			Investment			Investment			Recorded			Allowance			Average
			Principal			With No			With			Investment						Recorded
			Balance			Allowance			Allowance									Investment
	Commercial		$	2,677		$	20		$	2,231		$	2,251		$	1,350		$	2,966
	Agricultural			381			—			372			372			131			437
	Real Estate			22,569			2,049			16,649			18,698			4,356			20,164
	Consumer			543			115			364			479			173			458
	Total		$	26,170		$	2,184		$	19,616		$	21,800		$	6,010		$	24,025
Schedule of Internal Ratings of Loans Held for Investment	At September 30, 2013 and December 31, 2012, the following summarizes the Company’s internal ratings of its loans held for investment (in thousands):
	September 30, 2013		Pass			Special			Substandard			Doubtful			Total
						Mention
	Commercial		$	558,196		$	3,282		$	10,279		$	216		$	571,973
	Agricultural			66,084			259			411			4			66,758
	Real Estate			1,574,973			19,715			45,454			166			1,640,308
	Consumer			328,164			673			1,197			12			330,046
	Total		$	2,527,417		$	23,929		$	57,341		$	398		$	2,609,085
	December 31, 2012		Pass			Special			Substandard			Doubtful			Total
						Mention
	Commercial		$	498,188		$	2,193		$	9,198		$	30		$	509,609
	Agricultural			64,397			342			3,559			8			68,306
	Real Estate			1,176,330			14,680			35,673			140			1,226,823
	Consumer			271,114			382			911			21			272,428
	Total		$	2,010,029		$	17,597		$	49,341		$	199		$	2,077,166
Schedule of Past Due Loans	At September 30, 2013 and December 31, 2012, the Company’s past due loans are as follows (in thousands):
	September 30, 2013		15-59			60-89			Greater			Total			Current			Total Loans		90 Days
			Days			Days			Than			Past								Past Due
			Past			Past			90			Due								Still
			Due*			Due			Days											Accruing
	Commercial		$	5,016		$	667		$	372		$	6,055		$	565,918		$	571,973	$	—
	Agricultural			332			39			—			371			66,387			66,758		—
	Real Estate			12,976			676			1,409			15,061			1,625,247			1,640,308		8
	Consumer			2,099			527			160			2,786			327,260			330,046		46
	Total		$	20,423		$	1,909		$	1,941		$	24,273		$	2,584,812		$	2,609,085	$	54
	December 31, 2012		15-59			60-89			Greater			Total Past			Current			Total Loans		90 Days
			Days			Days			Than			Due								Past Due
			Past			Past			90											Still
			Due*			Due			Days											Accruing
	Commercial		$	1,708		$	470		$	247		$	2,425		$	507,184		$	509,609	$	—
	Agricultural			467			95			—			562			67,744			68,306		—
	Real Estate			10,141			2,711			1,237			14,089			1,212,734			1,226,823		34
	Consumer			1,660			287			163			2,110			270,318			272,428		63
	Total		$	13,976		$	3,563		$	1,647		$	19,186		$	2,057,980		$	2,077,166	$	97
	*	The Company monitors commercial, agricultural and real estate loans after such loans are 15 days past due. Consumer loans are monitored after such loans are 30 days past due.
Allowance for Loan Losses by Estimating Probable Losses in Various Categories of Loan Portfolio	The allowance for loan losses as of September 30, 2013 and 2012, and December 31, 2012, is presented below. Management has evaluated the appropriateness of the allowance for loan losses by estimating the probable losses in various categories of the loan portfolio, which are identified below (in thousands):
			September 30,						December 31,
			2013			2012			2012
	Allowance for loan losses provided for:
	Loans specifically evaluated as impaired		$	4,605		$	6,093		$	6,010
	Remaining portfolio			30,195			28,839			28,829
	Total allowance for loan losses		$	34,800		$	34,932		$	34,839
Schedule of Allowance for Loan Losses by Portfolio Segment	The following table details the allowance for loan losses at September 30, 2013 and December 31, 2012 by portfolio segment (in thousands). There were no allowances for purchased credit impaired loans at September 30, 2013 or December 31, 2012. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.
	September 30, 2013		Commercial			Agricultural			Real Estate			Consumer			Total
	Loans individually evaluated for impairment		$	2,698		$	131		$	6,932		$	391		$	10,152
	Loans collectively evaluated for impairment			4,315			287			18,362			1,684			24,648
	Total		$	7,013		$	418		$	25,294		$	2,075		$	34,800
	December 31, 2012		Commercial			Agricultural			Real Estate			Consumer			Total
	Loans individually evaluated for impairment		$	3,253		$	388		$	8,380		$	308		$	12,329
	Loans collectively evaluated for impairment			4,090			1,153			15,683			1,584			22,510
	Total		$	7,343		$	1,541		$	24,063		$	1,892		$	34,839
Changes in Allowance for Loan Losses	Changes in the allowance for loan losses for the three and nine months ended September 30, 2013 and 2012 are summarized as follows (in thousands):
	Three months ended		Commercial			Agricultural			Real Estate			Consumer			Total
	September 30, 2013
	Beginning balance		$	6,736		$	1,493		$	23,902		$	1,968		$	34,099
	Provision for loan losses			354			(999	)		1,644			350			1,349
	Recoveries			141			10			42			104			297
	Charge-offs			(218	)		(86	)		(294	)		(347	)		(945	)
	Ending balance		$	7,013		$	418		$	25,294		$	2,075		$	34,800
	Three months ended		Commercial			Agricultural			Real Estate			Consumer			Total
	September 30, 2012
	Beginning balance		$	8,556		$	1,253		$	23,294		$	1,644		$	34,747
	Provision for loan losses			(1,088	)		491			1,200			184			787
	Recoveries			42			14			325			81			462
	Charge-offs			(60	)		—			(845	)		(159	)		(1,064	)
	Ending balance		$	7,450		$	1,758		$	23,974		$	1,750		$	34,932
	Nine months ended		Commercial			Agricultural			Real Estate			Consumer			Total
	September 30, 2013
	Beginning balance		$	7,343		$	1,541		$	24,063		$	1,892		$	34,839
	Provision for loan losses			(77	)		(1,056	)		3,035			680			2,582
	Recoveries			329			29			95			266			719
	Charge-offs			(582	)		(96	)		(1,899	)		(763	)		(3,340	)
	Ending balance		$	7,013		$	418		$	25,294		$	2,075		$	34,800
	Nine months ended		Commercial			Agricultural			Real Estate			Consumer			Total
	September 30, 2012
	Beginning balance		$	9,664		$	1,482		$	21,533		$	1,636		$	34,315
	Provision for loan losses			(1,935	)		294			4,040			443			2,842
	Recoveries			195			35			502			279			1,011
	Charge-offs			(474	)		(53	)		(2,101	)		(608	)		(3,236	)
	Ending balance		$	7,450		$	1,758		$	23,974		$	1,750		$	34,932
Schedule of Investment in Loans Related to Balance in Allowance for Loan Losses on Basis of Company's Impairment Methodology	The Company’s recorded investment in loans as of September 30, 2013 and December 31, 2012 related to the balance in the allowance for loan losses on the basis of the Company’s impairment methodology was as follows (in thousands). Purchased credit impaired loans of $3,252,000 at September 30, 2013 are included in loans individually evaluated for impairment. There were no purchased credit impaired loans at December 31, 2012.
	September 30, 2013		Commercial			Agricultural			Real Estate			Consumer			Total
	Loans individually evaluated for impairment		$	13,777		$	674		$	65,335		$	1,882		$	81,668
	Loans collectively evaluated for impairment			558,196			66,084			1,574,973			328,164			2,527,417
	Total		$	571,973		$	66,758		$	1,640,308		$	330,046		$	2,609,085
	December 31, 2012		Commercial			Agricultural			Real Estate			Consumer			Total
	Loans individually evaluated for impairment		$	11,421		$	3,909		$	50,493		$	1,314		$	67,137
	Loans collectively evaluated for impairment			498,188			64,397			1,176,330			271,114			2,010,029
	Total		$	509,609		$	68,306		$	1,226,823		$	272,428		$	2,077,166
Schedule of Loans Modified and Considered Troubled Debt Restructuring	The Company’s loans that were modified in the three and nine months ended September 30, 2013 and 2012 and considered a troubled debt restructuring are as follows (in thousands):
			Three Months Ended September 30, 2013									Nine Months Ended September 30, 2013
			Number			Pre-			Post-			Number			Pre-			Post-
						Modification			Modification						Modification			Modification
						Recorded			Recorded						Recorded			Recorded
						Investment			Investment						Investment			Investment
	Commercial			—		$	—		$	—			3		$	218		$	218
	Agricultural			—			—			—			1			24			24
	Real Estate			—			—			—			8			3,779			3,779
	Consumer			4			86			86			5			123			123
	Total			4		$	86		$	86			17		$	4,144		$	4,144
			Three Months Ended September 30, 2012									Nine Months Ended September 30, 2012
			Number			Pre-			Post-			Number			Pre-			Post-
						Modification			Modification						Modification			Modification
						Recorded			Recorded						Recorded			Recorded
						Investment			Investment						Investment			Investment
	Commercial			2		$	9		$	9			11		$	796		$	796
	Agricultural			—			—			—			5			354			354
	Real Estate			4			1,093			1,093			31			8,761			8,761
	Consumer			—			—			—			1			19			19
	Total			6		$	1,102		$	1,102			48		$	9,930		$	9,930
Schedule of How Loans Were Modified as Troubled Debt Restructured Loans	The balances below provide information as to how the loans were modified as troubled debt restructured loans during the three and nine months ended September 30, 2013 and 2012 (in thousands):
			Three Months Ended September 30, 2013									Nine Months Ended September 30, 2013
			Adjusted			Extended			Combined			Adjusted			Extended			Combined
			Interest			Maturity			Rate and			Interest			Maturity			Rate and
			Rate						Maturity			Rate						Maturity
	Commercial		$	—		$	—		$	—		$	—		$	218		$	—
	Agricultural			—			—			—			—			24			—
	Real Estate			—			—			—			420			350			3,009
	Consumer			—			82			4			—			119			4
	Total		$	—		$	82		$	4		$	420		$	711		$	3,013
			Three Months Ended September 30, 2012									Nine Months Ended September 30, 2012
			Adjusted			Extended			Combined			Adjusted			Extended			Combined
			Interest			Maturity			Rate and			Interest			Maturity			Rate and
			Rate						Maturity			Rate						Maturity
	Commercial		$	—		$	—		$	9		$	508		$	120		$	168
	Agricultural			—			—			—			243			15			95
	Real Estate			—			717			376			935			1,825			6,002
	Consumer			—			—			—			—			19			—
	Total		$	—		$	717		$	385		$	1,686		$	1,979		$	6,265
Schedule of Troubled Debt Restructuring	The loans are as follows (dollars in thousands):
			Three Months Ended September 30, 2013						Nine Months Ended September 30, 2013
			Number			Balance			Number			Balance
	Commercial			1		$	71			6		$	316
	Agriculture			—			—			—			—
	Real Estate			—			—			—			—
	Consumer			—			—			—			—
	Total			1		$	71			6		$	316
			Three Months Ended September 30, 2012						Nine Months Ended September 30, 2012
			Number			Balance			Number			Balance
	Commercial			2		$	221			2		$	221
	Agriculture			—			—			—			—
	Real Estate			—			—			—			—
	Consumer			—			—			—			—
	Total			2		$	221			2		$	221

Fair_Value_Disclosures_Tables

Fair Value Disclosures (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]
Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis	The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of September 30, 2013, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (dollars in thousands):
		Level 1			Level 2			Level 3		Total Fair
		Inputs			Inputs			Inputs		Value
	Available-for-sale investment securities:
	Obligations of U. S. government sponsored-enterprises and agencies	$	—		$	144,614		$	—	$	144,614
	Obligations of states and political subdivisions		18,025			954,153			—		972,178
	Corporate bonds		—			106,096			—		106,096
	Residential mortgage-backed securities		44,936			595,153			—		640,089
	Commercial mortgage-backed securities		—			108,293			—		108,293
	Other securities		4,033			—			—		4,033
	Total	$	66,994		$	1,908,309		$	—	$	1,975,303
Other Real Estate Owned	The following table presents other real estate owned that were re-measured subsequent to their initial transfer to other real estate owned (dollars in thousands):
		Three Months Ended
		September 30,
		2013			2012
	Carrying value of other real estate owned prior to re-measurement	$	238		$	3,140
	Write-downs included in gain (loss) on sale of other real estate owned		(65	)		(125	)
	Fair value	$	173		$	3,015
		Nine Months Ended
		September 30,
		2013			2012
	Carrying value of other real estate owned prior to re-measurement	$	2,065		$	4,993
	Write-downs included in gain (loss) on sale of other real estate owned		(369	)		(661	)
	Fair value	$	1,696		$	4,332
Schedule of Estimated Fair Values and Carrying Values of All Financial Instruments Under Current Authoritative Guidance	The estimated fair values and carrying values of all financial instruments under current authoritative guidance at September 30, 2013 and December 31, 2012, were as follows (in thousands):
		September 30,						December 31,
		2013						2012
		Carrying			Estimated			Carrying		Estimated		Fair Value
		Value			Fair Value			Value		Fair Value		Hierarchy
	Cash and due from banks	$	164,666		$	164,666		$	207,018	$	207,018	Level 1
	Federal funds sold		14,300			14,300			14,045		14,045	Level 1
	Interest-bearing deposits in banks		48,634			48,634			139,676		139,676	Level 1
	Interest-bearing time deposits in banks		34,352			34,526			49,005		49,288	Level 2
	Available-for-sale securities		1,975,303			1,975,303			1,819,035		1,819,035	Levels 1 and 2
	Held-to-maturity securities		798			810			1,061		1,080	Level 2
	Loans		2,580,009			2,593,923			2,053,784		2,081,091	Level 3
	Accrued interest receivable		22,421			22,421			23,122		23,122	Level 2
	Deposits with stated maturities		681,236			683,548			637,040		638,227	Level 2
	Deposits with no stated maturities		3,319,321			3,319,321			2,995,544		2,995,544	Level 1
	Short term borrowings		466,500			466,500			259,697		259,697	Level 2
	Accrued interest payable		314			314			287		287	Level 2

Acquisition_Tables

Acquisition (Tables)	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]
Schedule of Amounts Recorded on the Consolidated Balance Sheet on the Acquisition date	The following table presents the amounts recorded on the consolidated balance sheet on the acquisition date (in thousands):
	Fair value of consideration paid:
	Cash	$	39,200
	Common stock issued (420,000 shares)		23,100
	Total fair value of consideration paid		62,300
Schedule of Preliminary Estimated Fair Value Amounts Assigned to Major Asset and Liability Categories at Acquisition Date	Fair value of identifiable assets acquired:
	Cash and cash equivalents		13,494
	Securities available for sale		107,735
	Loans		293,288
	Identifiable intangible assets		2,300
	Other assets		12,569
	Total identifiable assets acquired		429,386
	Fair value of liabilities assumed:
	Deposits		385,950
	Other liabilities		4,154
	Total liabilities assumed		390,104
	Fair value of net identifiable assets acquired		39,282
	Goodwill resulting from acquisition	$	23,018

Basis_of_Presentation_Addition

Basis of Presentation - Additional Information (Detail)	Sep. 30, 2013	31-May-13	Dec. 31, 2012	Dec. 30, 2012	Sep. 30, 2012	Apr. 24, 2012	Oct. 26, 2011
Basis Of Presentation [Line Items]
Number of financial centers	60
Consolidation of bank charters description				Eleven bank charters into one charter
Stock repurchase program, number of shares authorized to be repurchased							750,000
Common stock, shares authorized	80,000,000		80,000,000		80,000,000	80,000,000
Percentage of common stock acquired		100.00%
Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of financial centers	7
Abilene [Member]
Basis Of Presentation [Line Items]
Number of financial centers	11
Abilene [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Cleburne [Member]
Basis Of Presentation [Line Items]
Number of financial centers	2
Stephenville [Member]
Basis Of Presentation [Line Items]
Number of financial centers	2
Stephenville [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Granbury [Member]
Basis Of Presentation [Line Items]
Number of financial centers	2
San Angelo [Member]
Basis Of Presentation [Line Items]
Number of financial centers	3
San Angelo [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Weatherford [Member]
Basis Of Presentation [Line Items]
Number of financial centers	3
Mineral Wells [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Hereford [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Sweetwater [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Sweetwater [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Eastland [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Ranger [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Rising Star [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Cisco [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Southlake [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Grapevine [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Aledo [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Willow Park [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Brock [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Alvarado [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Burleson [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Keller [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Trophy Club [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Boyd [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Bridgeport [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Decatur [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Roby [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Trent [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Merkel [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Clyde [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Moran [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Albany [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Midlothian [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Glen Rose [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Odessa [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Odessa [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Waxahachie [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Acton [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Fort Worth [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Fort Worth [Member] | Subsidiary of Common Parent [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Orange [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Newton [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Port Arthur [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Vidor [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Mauriceville [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1
Huntsville [Member]
Basis Of Presentation [Line Items]
Number of financial centers	1

Earnings_Per_Share_Additional_

Earnings Per Share - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Weighted average common shares outstanding, basic	31,970,405	31,484,375	31,722,272	31,476,715
Weighted average common shares outstanding, diluted	32,121,771	31,502,172	31,853,294	31,486,707

Interestbearing_Time_Deposits_2

Interest-bearing Time Deposits in Banks and Securities - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Interest Bearing Time Deposits In Banks And Securities [Line Items]
INTEREST-BEARING TIME DEPOSITS IN BANKS	$34,352,000	$67,506,000	$34,352,000	$67,506,000	$49,005,000
Time deposits with balances greater than $100,000	31,437,000		31,437,000		44,776,000
Time deposits balances			100,000		100,000
Number of investment positions	528		528
Securities pledged as collateral	1,061,307,000		1,061,307,000
Sales of investment securities available-for-sale	50,065,000	45,129,000	121,420,000	114,090,000
Gross realized gains from securities sales and calls	1,114,000	1,522,000	1,371,000	2,250,000
Gross realized losses from securities sales and calls	$1,222,000	$43,000	$1,224,000	$44,000
Minimum [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Interesting-bearing time deposits, maturity period, years			one
Maximum [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Interesting-bearing time deposits, maturity period, years			two

Interestbearing_Time_Deposits_3

Interest-bearing Time Deposits in Banks and Securities - Summary of Available-for-Sale and Held-to-Maturity Securities (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
In Thousands, unless otherwise specified
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Securities available-for-sale, Amortized Cost Basis	$1,955,442	$1,727,237
Securities available-for-sale, Gross Unrealized Holding Gains	46,543	92,693
Securities available-for-sale, Gross Unrealized Holding Losses	-26,682	-895
Securities available-for-sale, Estimated Fair Value	1,975,303	1,819,035	1,882,617
Securities held-to-maturity, Amortized Cost Basis	798	1,061	1,247
Securities held-to-maturity, Gross Unrealized Holding Gains	12	19
Securities held-to-maturity, Gross Unrealized Holding Losses
Securities held-to-maturity, Estimated Fair Value	810	1,080	1,271
U.S. Treasury Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Securities available-for-sale, Amortized Cost Basis		6,042
Securities available-for-sale, Gross Unrealized Holding Gains		48
Securities available-for-sale, Gross Unrealized Holding Losses
Securities available-for-sale, Estimated Fair Value		6,090
Obligations of U.S. Government Sponsored-Enterprises and Agencies [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Securities available-for-sale, Amortized Cost Basis	142,944	219,420
Securities available-for-sale, Gross Unrealized Holding Gains	1,684	4,060
Securities available-for-sale, Gross Unrealized Holding Losses	-14
Securities available-for-sale, Estimated Fair Value	144,614	223,480
Obligations of States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Securities available-for-sale, Amortized Cost Basis	960,624	786,278
Securities available-for-sale, Gross Unrealized Holding Gains	26,321	57,541
Securities available-for-sale, Gross Unrealized Holding Losses	-14,767	-129
Securities available-for-sale, Estimated Fair Value	972,178	843,690
Securities held-to-maturity, Amortized Cost Basis	525	735
Securities held-to-maturity, Gross Unrealized Holding Gains	3	7
Securities held-to-maturity, Gross Unrealized Holding Losses
Securities held-to-maturity, Estimated Fair Value	528	742
Corporate Bonds and Other [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Securities available-for-sale, Amortized Cost Basis	106,551	117,244
Securities available-for-sale, Gross Unrealized Holding Gains	3,578	6,020
Securities available-for-sale, Gross Unrealized Holding Losses		-73
Securities available-for-sale, Estimated Fair Value	110,129	123,191
Residential Mortgage-Backed Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Securities available-for-sale, Amortized Cost Basis	632,621	564,434
Securities available-for-sale, Gross Unrealized Holding Gains	14,960	23,285
Securities available-for-sale, Gross Unrealized Holding Losses	-7,492	-443
Securities available-for-sale, Estimated Fair Value	640,089	587,276
Securities held-to-maturity, Amortized Cost Basis	273	294
Securities held-to-maturity, Gross Unrealized Holding Gains	9	11
Securities held-to-maturity, Gross Unrealized Holding Losses
Securities held-to-maturity, Estimated Fair Value	282	305
Commercial Mortgage-Backed Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items]
Securities available-for-sale, Amortized Cost Basis	112,702	33,819
Securities available-for-sale, Gross Unrealized Holding Gains		1,739
Securities available-for-sale, Gross Unrealized Holding Losses	-4,409	-250
Securities available-for-sale, Estimated Fair Value	108,293	35,308
Securities held-to-maturity, Amortized Cost Basis		32
Securities held-to-maturity, Gross Unrealized Holding Gains		1
Securities held-to-maturity, Gross Unrealized Holding Losses
Securities held-to-maturity, Estimated Fair Value		$33

Interestbearing_Time_Deposits_4

Interest-bearing Time Deposits in Banks and Securities - Amortized Cost and Estimated Fair Value of Debt Securities (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
In Thousands, unless otherwise specified
Investments Debt And Equity Securities [Abstract]
Available-for-Sale, Amortized Cost Basis, Due within one year	$82,447
Available-for-Sale, Amortized Cost Basis, Due after one year through five years	533,039
Available-for-Sale, Amortized Cost Basis, Due after five years through ten years	536,830
Available-for-Sale, Amortized Cost Basis, Due after ten years	57,803
Available-for-Sale, Amortized Cost Basis, Mortgage-backed securities	745,323
Available-for-Sale, Amortized Cost Basis, Total	1,955,442
Available-for-Sale, Estimated Fair Value, Due within one year	83,490
Available-for-Sale, Estimated Fair Value, Due after one year through five years	547,624
Available-for-Sale, Estimated Fair Value, Due after five years through ten years	539,843
Available-for-Sale, Estimated Fair Value, Due after ten years	55,964
Available-for-Sale, Estimated Fair Value, Mortgage-backed securities	748,382
Available-for-Sale, Estimated Fair Value, Total	1,975,303
Held-to-Maturity, Amortized Cost Basis, Due within one year	525
Held-to-Maturity, Amortized Cost Basis, Due after one year through five years
Held-to-Maturity, Amortized Cost Basis, Due after five years through ten years
Held-to-Maturity, Amortized Cost Basis, Due after ten years
Held-to-Maturity, Amortized Cost Basis, Mortgage-backed securities	273
Held-to-Maturity, Amortized Cost Basis, Total	798	1,061	1,247
Held-to-Maturity, Estimated Fair Value, Due within one year	528
Held-to-Maturity, Estimated Fair Value, Due after one year through five years
Held-to-Maturity, Estimated Fair Value, Due after five years through ten years
Held-to-Maturity, Estimated Fair Value, Due after ten years
Held-to-Maturity, Estimated Fair Value, Mortgage-backed securities	282
Securities held-to-maturity, Estimated Fair Value	$810	$1,080	$1,271

Interestbearing_Time_Deposits_5

Interest-bearing Time Deposits in Banks and Securities - Continuous Unrealized-Loss Position of Available-for-Sale and Held-to-Maturity Securities (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule Of Available For Sale And Held To Maturity Securities Continuous Unrealized Loss Position [Line Items]
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Fair Value	$666,240	$71,271
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	26,602	853
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Fair Value	8,220	3,574
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss	80	42
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Fair Value	674,460	74,845
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Unrealized Loss	26,682	895
Obligations of U.S. Government Sponsored-Enterprises and Agencies [Member]
Schedule Of Available For Sale And Held To Maturity Securities Continuous Unrealized Loss Position [Line Items]
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Fair Value	10,941
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	14
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Fair Value
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Fair Value	10,941
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Unrealized Loss	14
Obligations of States and Political Subdivisions [Member]
Schedule Of Available For Sale And Held To Maturity Securities Continuous Unrealized Loss Position [Line Items]
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Fair Value	382,840	36,480
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	14,767	129
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Fair Value
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Fair Value	382,840	36,480
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Unrealized Loss	14,767	129
Residential Mortgage-Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities Continuous Unrealized Loss Position [Line Items]
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Fair Value	164,166	17,344
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	7,412	401
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Fair Value	8,220	3,574
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss	80	42
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Fair Value	172,386	20,918
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Unrealized Loss	7,492	443
Commercial Mortgage-Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities Continuous Unrealized Loss Position [Line Items]
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Fair Value	108,293	12,453
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	4,409	250
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Fair Value
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Fair Value	108,293	12,453
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Unrealized Loss	4,409	250
Corporate Bonds and Other [Member]
Schedule Of Available For Sale And Held To Maturity Securities Continuous Unrealized Loss Position [Line Items]
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Fair Value		4,994
Available-for-sale and held-to-maturity securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss		73
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Fair Value
Available-for-sale and held-to-maturity securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Fair Value		4,994
Available-for-sale and held-to-maturity securities, continuous unrealized loss position, Unrealized Loss		$73

Loans_and_Allowance_for_Loan_L2

Loans and Allowance for Loan Losses - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
	Contract	Contract	Contract	Contract
Summary Of Allowance For Loan Losses On Impaired Loans [Line Items]
Minimum number of days to consider the loans as non-accrual			Greater than 90 days
Loans held for sale	$5,724,000	$10,034,000	$5,724,000	$10,034,000	$11,457,000
Carrying amount of purchased credit impaired loans	22,809,000	24,283,000	22,809,000	24,283,000	21,800,000
Contractual balance	4,218,000		4,218,000
Average recorded investment in impaired loans	23,768,000		22,530,000	26,279,000	24,025,000
Non-accrual loans still accruing, past due 90 days, restructured loans and foreclosed assets	28,535,000	30,725,000	28,535,000	30,725,000	25,462,000
Non-accrual loans	22,809,000	24,283,000	22,809,000	24,283,000	21,800,000
Interest income recognized on impaired loans					384,000
Carrying amount of purchased credit impaired loans			2,954,000
Number of loans	1	2	6	2
Troubled debt restructured loan	71,000	221,000	316,000	221,000
Default for purposes of this disclosure is a troubled debt restructured loan			90 days
Loans modified as troubled debt restructured	221,000		221,000
Loans held by subsidiaries subject to blanket liens	1,461,000,000		1,461,000,000
Letters of credit outstanding, amount	53,600,000		53,600,000
Short-term borrowings outstanding	161,146,000		161,146,000
Purchased Credit Impaired Loans [Member]
Summary Of Allowance For Loan Losses On Impaired Loans [Line Items]
Carrying amount of purchased credit impaired loans	$2,954,000		$2,954,000

Loans_and_Allowance_for_Loan_L3

Loans and Allowance for Loan Losses - Major Classifications of Loans Held for Investment (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
In Thousands, unless otherwise specified
Receivables [Abstract]
Commercial	$571,973	$509,609	$482,655
Agricultural	66,758	68,306	63,148
Real estate	1,640,308	1,226,823	1,191,088
Consumer	330,046	272,428	256,929
Total loans held for investment	$2,609,085	$2,077,166	$1,993,820

Loans_and_Allowance_for_Loan_L4

Loans and Allowance for Loan Losses - Non-Accrual Loans, Loans Still Accruing and Past Due 90 Days or More and Restructured Loans (Detail) (USD $)	9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Receivables [Abstract]
Non-accrual loans	$22,809,000	$24,283,000	$21,800,000
Loans still accruing and past due 90 days or more	54,000	69,000	97,000
Restructured loans
Total	$22,863,000	$24,352,000	$21,897,000

Loans_and_Allowance_for_Loan_L5

Loans and Allowance for Loan Losses - Non-Accrual Loans, Loans Still Accruing and Past Due 90 Days or More and Restructured Loans (Parenthetical) (Detail) (USD $)	9 Months Ended
	Sep. 30, 2013
Receivables [Abstract]
Carrying amount of purchased credit impaired loans	$2,954,000

Loans_and_Allowance_for_Loan_L6

Loans and Allowance for Loan Losses - Recorded Investment in Impaired Loans and Related Valuation Allowance (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Receivables [Abstract]
Recorded Investment	$22,809,000	$21,800,000	$24,283,000
Valuation Allowance	$4,605,000	$6,010,000	$6,093,000

Loans_and_Allowance_for_Loan_L7

Loans and Allowance for Loan Losses - Schedule of Non-Accrual Loans (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	$22,809,000	$21,800,000	$24,283,000
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	1,986,000	2,251,000	2,890,000
Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	97,000	372,000	401,000
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	20,036,000	18,698,000	20,673,000
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	$690,000	$479,000	$319,000

Loans_and_Allowance_for_Loan_L8

Loans and Allowance for Loan Losses - Schedule of Impaired Loans and Related Allowance (Detail) (USD $)	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Contractual Principal Balance	$28,559,000	$28,559,000	$29,205,000	$26,170,000
Recorded Investment With No Allowance	5,294,000	5,294,000	3,142,000	2,184,000
Recorded Investment With Allowance	17,515,000	17,515,000	21,141,000	19,616,000
Total Recorded Investment	22,809,000	22,809,000	24,283,000	21,800,000
Related Allowance	4,605,000	4,605,000	6,093,000	6,010,000
Year-to-Date Average Recorded Investment	23,768,000	22,530,000	26,279,000	24,025,000
Three- month Average Recorded Investment		23,768,000	25,150,000
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Contractual Principal Balance	2,545,000	2,545,000	3,568,000	2,677,000
Recorded Investment With No Allowance	701,000	701,000	63,000	20,000
Recorded Investment With Allowance	1,285,000	1,285,000	2,827,000	2,231,000
Total Recorded Investment	1,986,000	1,986,000	2,890,000	2,251,000
Related Allowance	710,000	710,000	1,488,000	1,350,000
Year-to-Date Average Recorded Investment		1,779,000	3,943,000	2,966,000
Three- month Average Recorded Investment		2,113,000	3,728,000
Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Contractual Principal Balance	105,000	105,000	408,000	381,000
Recorded Investment With No Allowance	91,000	91,000
Recorded Investment With Allowance	6,000	6,000	401,000	372,000
Total Recorded Investment	97,000	97,000	401,000	372,000
Related Allowance	6,000	6,000	130,000	131,000
Year-to-Date Average Recorded Investment		104,000	455,000	437,000
Three- month Average Recorded Investment		99,000	416,000
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Contractual Principal Balance	25,085,000	25,085,000	24,866,000	22,569,000
Recorded Investment With No Allowance	4,290,000	4,290,000	3,049,000	2,049,000
Recorded Investment With Allowance	15,746,000	15,746,000	17,624,000	16,649,000
Total Recorded Investment	20,036,000	20,036,000	20,673,000	18,698,000
Related Allowance	3,628,000	3,628,000	4,341,000	4,356,000
Year-to-Date Average Recorded Investment		19,985,000	21,537,000	20,164,000
Three- month Average Recorded Investment		20,757,000	20,686,000
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Unpaid Contractual Principal Balance	824,000	824,000	363,000	543,000
Recorded Investment With No Allowance	212,000	212,000	30,000	115,000
Recorded Investment With Allowance	478,000	478,000	289,000	364,000
Total Recorded Investment	690,000	690,000	319,000	479,000
Related Allowance	261,000	261,000	134,000	173,000
Year-to-Date Average Recorded Investment		662,000	344,000	458,000
Three- month Average Recorded Investment		$799,000	$320,000

Loans_and_Allowance_for_Loan_L9

Loans and Allowance for Loan Losses - Schedule of Internal Ratings of Loans Held for Investment (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	$2,609,085	$2,077,166
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	571,973	509,609
Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	66,758	68,306
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	1,640,308	1,226,823
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	330,046	272,428
Pass [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	2,527,417	2,010,029
Pass [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	558,196	498,188
Pass [Member] | Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	66,084	64,397
Pass [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	1,574,973	1,176,330
Pass [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	328,164	271,114
Special Mention [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	23,929	17,597
Special Mention [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	3,282	2,193
Special Mention [Member] | Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	259	342
Special Mention [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	19,715	14,680
Special Mention [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	673	382
Substandard [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	57,341	49,341
Substandard [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	10,279	9,198
Substandard [Member] | Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	411	3,559
Substandard [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	45,454	35,673
Substandard [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	1,197	911
Doubtful [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	398	199
Doubtful [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	216	30
Doubtful [Member] | Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	4	8
Doubtful [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	166	140
Doubtful [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Internal ratings of loan	$12	$21

Recovered_Sheet1

Loans and Allowance for Loan Losses - Schedule of Past Due Loans (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment, Past Due [Line Items]
15-59 Days Past Due	$20,423	$13,976
60-89 Days Past Due	1,909	3,563
Greater Than 90 Days	1,941	1,647
Total Past Due	24,273	19,186
Current	2,584,812	2,057,980
Total	2,609,085	2,077,166
90 Days Past Due Still Accruing	54	97	69
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
15-59 Days Past Due	5,016	1,708
60-89 Days Past Due	667	470
Greater Than 90 Days	372	247
Total Past Due	6,055	2,425
Current	565,918	507,184
Total	571,973	509,609
90 Days Past Due Still Accruing
Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
15-59 Days Past Due	332	467
60-89 Days Past Due	39	95
Greater Than 90 Days
Total Past Due	371	562
Current	66,387	67,744
Total	66,758	68,306
90 Days Past Due Still Accruing
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
15-59 Days Past Due	12,976	10,141
60-89 Days Past Due	676	2,711
Greater Than 90 Days	1,409	1,237
Total Past Due	15,061	14,089
Current	1,625,247	1,212,734
Total	1,640,308	1,226,823
90 Days Past Due Still Accruing	8	34
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
15-59 Days Past Due	2,099	1,660
60-89 Days Past Due	527	287
Greater Than 90 Days	160	163
Total Past Due	2,786	2,110
Current	327,260	270,318
Total	330,046	272,428
90 Days Past Due Still Accruing	$46	$63

Recovered_Sheet2

Loans and Allowance for Loan Losses - Allowance for Loan Losses by Estimating Probable Losses in Various Categories of Loan Portfolio (Detail) (USD $)	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Receivables [Abstract]
Loans specifically evaluated as impaired	$4,605		$6,010	$6,093
Remaining portfolio	30,195		28,829	28,839
Total allowance for loan losses	$34,800	$34,099	$34,839	$34,932	$34,747	$34,315

Recovered_Sheet3

Loans and Allowance for Loan Losses - Schedule of Allowance for Loan Losses by Portfolio Segment (Detail) (USD $)	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	$10,152		$12,329
Loans collectively evaluated for impairment	24,648		22,510
Total allowance for loan losses	34,800	34,099	34,839	34,932	34,747	34,315
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	2,698		3,253
Loans collectively evaluated for impairment	4,315		4,090
Total allowance for loan losses	7,013	6,736	7,343	7,450	8,556	9,664
Agricultural [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	131		388
Loans collectively evaluated for impairment	287		1,153
Total allowance for loan losses	418	1,493	1,541	1,758	1,253	1,482
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	6,932		8,380
Loans collectively evaluated for impairment	18,362		15,683
Total allowance for loan losses	25,294	23,902	24,063	23,974	23,294	21,533
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	391		308
Loans collectively evaluated for impairment	1,684		1,584
Total allowance for loan losses	$2,075	$1,968	$1,892	$1,750	$1,644	$1,636

Recovered_Sheet4

Loans and Allowance for Loan Losses - Changes in Allowance for Loan Losses (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$34,099	$34,747	$34,839	$34,315
Provision for loan losses	1,349	787	2,582	2,842
Recoveries	297	462	719	1,011
Charge-offs	-945	-1,064	-3,340	-3,236
Ending balance	34,800	34,932	34,800	34,932
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	6,736	8,556	7,343	9,664
Provision for loan losses	354	-1,088	-77	-1,935
Recoveries	141	42	329	195
Charge-offs	-218	-60	-582	-474
Ending balance	7,013	7,450	7,013	7,450
Agricultural [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,493	1,253	1,541	1,482
Provision for loan losses	-999	491	-1,056	294
Recoveries	10	14	29	35
Charge-offs	-86		-96	-53
Ending balance	418	1,758	418	1,758
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	23,902	23,294	24,063	21,533
Provision for loan losses	1,644	1,200	3,035	4,040
Recoveries	42	325	95	502
Charge-offs	-294	-845	-1,899	-2,101
Ending balance	25,294	23,974	25,294	23,974
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,968	1,644	1,892	1,636
Provision for loan losses	350	184	680	443
Recoveries	104	81	266	279
Charge-offs	-347	-159	-763	-608
Ending balance	$2,075	$1,750	$2,075	$1,750

Recovered_Sheet5

Loans and Allowance for Loan Losses - Schedule of Investment in Loans Related to Balance in Allowance for Loan Losses on Basis of Company's Impairment Methodology (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Loans individually evaluated for impairment	$81,668	$67,137
Loans collectively evaluated for impairment	2,527,417	2,010,029
Total	2,609,085	2,077,166
Commercial [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Loans individually evaluated for impairment	13,777	11,421
Loans collectively evaluated for impairment	558,196	498,188
Total	571,973	509,609
Agricultural [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Loans individually evaluated for impairment	674	3,909
Loans collectively evaluated for impairment	66,084	64,397
Total	66,758	68,306
Real Estate [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Loans individually evaluated for impairment	65,335	50,493
Loans collectively evaluated for impairment	1,574,973	1,176,330
Total	1,640,308	1,226,823
Consumer [Member]
Schedule Of Allowance For Credit Losses And Recorded Investment In Financing Receivables [Line Items]
Loans individually evaluated for impairment	1,882	1,314
Loans collectively evaluated for impairment	328,164	271,114
Total	$330,046	$272,428

Recovered_Sheet6

Loans and Allowance for Loan Losses - Schedule of Loans Modified and Considered Troubled Debt Restructuring (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
	SecurityLoan	SecurityLoan	SecurityLoan	SecurityLoan
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Number	4	6	17	48
Pre- Modification Recorded Investment	$86	$1,102	$4,144	$9,930
Post-Modification Recorded Investment	86	1,102	4,144	9,930
Commercial [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Number		2	3	11
Pre- Modification Recorded Investment		9	218	796
Post-Modification Recorded Investment		9	218	796
Agricultural [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Number			1	5
Pre- Modification Recorded Investment			24	354
Post-Modification Recorded Investment			24	354
Real Estate [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Number		4	8	31
Pre- Modification Recorded Investment		1,093	3,779	8,761
Post-Modification Recorded Investment		1,093	3,779	8,761
Consumer [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Number	4		5	1
Pre- Modification Recorded Investment	86		123	19
Post-Modification Recorded Investment	$86		$123	$19

Recovered_Sheet7

Loans and Allowance for Loan Losses - Schedule of How Loans Were Modified as Troubled Debt Restructured Loans (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Adjusted Interest Rate			$420	$1,686
Extended Maturity	82	717	711	1,979
Combined Rate and Maturity	4	385	3,013	6,265
Commercial [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Adjusted Interest Rate				508
Extended Maturity			218	120
Combined Rate and Maturity		9		168
Agricultural [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Adjusted Interest Rate				243
Extended Maturity			24	15
Combined Rate and Maturity				95
Real Estate [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Adjusted Interest Rate			420	935
Extended Maturity		717	350	1,825
Combined Rate and Maturity		376	3,009	6,002
Consumer [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Adjusted Interest Rate
Extended Maturity	82		119	19
Combined Rate and Maturity	$4		$4

Recovered_Sheet8

Loans and Allowance for Loan Losses - Schedule of Troubled Debt Restructuring (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
	Contract	Contract	Contract	Contract
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Number	1	2	6	2
Balance	$71,000	$221,000	$316,000	$221,000
Commercial [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Number	1	2	6	2
Balance	71,000	221,000	316,000	221,000
Agricultural [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Number
Balance
Real Estate [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Number
Balance
Consumer [Member]
Troubled Debt Restructured Loan Modifications by Class [Line Items]
Number
Balance

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]
Income tax expense	$6,121	$6,828	$18,723	$19,028
Effective tax rates on pre-tax income	23.83%	25.64%	24.52%	25.39%
Statutory federal tax rate			35.00%

Stock_Based_Compensation_Addit

Stock Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		1 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Oct. 22, 2013
					Subsequent Event [Member]
Stock Based Compensation [Line Items]
Stock option expense	$88,000	$78,000	$264,000	$251,000
Employees incentive stock option shares			0	0	197,500

Pension_Plan_Additional_Inform

Pension Plan - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Compensation And Retirement Disclosure [Abstract]
Contribution towards pension plan			$0	$2,000,000
Net periodic benefit costs, total	$208,000	$185,000	$623,000	$555,000

Fair_Value_Disclosures_Financi

Fair Value Disclosures - Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
In Thousands, unless otherwise specified
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	$1,975,303	$1,819,035	$1,882,617
Obligations of U.S. Government Sponsored-Enterprises and Agencies [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	144,614	223,480
Obligations of States and Political Subdivisions [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	972,178	843,690
Corporate Bonds [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	106,096
Residential Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	640,089	587,276
Commercial Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	108,293	35,308
Other Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	4,033
Level 1 Inputs [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	66,994
Level 1 Inputs [Member] | Obligations of U.S. Government Sponsored-Enterprises and Agencies [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value
Level 1 Inputs [Member] | Obligations of States and Political Subdivisions [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	18,025
Level 1 Inputs [Member] | Corporate Bonds [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value
Level 1 Inputs [Member] | Residential Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	44,936
Level 1 Inputs [Member] | Commercial Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value
Level 1 Inputs [Member] | Other Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	4,033
Level 2 Inputs [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	1,908,309
Level 2 Inputs [Member] | Obligations of U.S. Government Sponsored-Enterprises and Agencies [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	144,614
Level 2 Inputs [Member] | Obligations of States and Political Subdivisions [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	954,153
Level 2 Inputs [Member] | Corporate Bonds [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	106,096
Level 2 Inputs [Member] | Residential Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	595,153
Level 2 Inputs [Member] | Commercial Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	108,293
Level 2 Inputs [Member] | Other Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value
Level 3 Inputs [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value
Level 3 Inputs [Member] | Obligations of U.S. Government Sponsored-Enterprises and Agencies [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value
Level 3 Inputs [Member] | Obligations of States and Political Subdivisions [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value
Level 3 Inputs [Member] | Corporate Bonds [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value
Level 3 Inputs [Member] | Residential Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value
Level 3 Inputs [Member] | Commercial Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value
Level 3 Inputs [Member] | Other Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value

Fair_Value_Disclosures_Additio

Fair Value Disclosures - Additional Information (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2013
				Minimum [Member]	Maximum [Member]
Fair Value Inputs Assets And Liabilities Quantitative Information [Line Items]
Impaired loans carrying value	$22,809,000	$21,800,000	$24,283,000
Impaired loans valuation reserves	4,605,000
Impaired loans net fair value	18,204,000
Debt discounts, percentage				5.00%	25.00%
Other real estate owned, total	$5,490,000	$3,505,000	$6,300,000

Fair_Value_Disclosures_Other_R

Fair Value Disclosures - Other Real Estate Owned (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value Disclosures [Abstract]
Carrying value of other real estate owned prior to re-measurement	$238	$3,140	$2,065	$4,993
Write-downs included in gain (loss) on sale of other real estate owned	-65	-125	-369	-661
Fair value	$173	$3,015	$1,696	$4,332

Fair_Value_Disclosures_Schedul

Fair Value Disclosures - Schedule of Estimated Fair Values and Carrying Values of All Financial Instruments Under Current Authoritative Guidance (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CASH AND DUE FROM BANKS	$164,666	$207,018	$128,606
FEDERAL FUNDS SOLD	14,300	14,045	23,400
INTEREST-BEARING DEPOSITS IN BANKS	48,634	139,676	25,633
INTEREST-BEARING TIME DEPOSITS IN BANKS	34,352	49,005	67,506
Available-for-sale securities	1,975,303	1,819,035	1,882,617
Held-to-maturity securities	798	1,061	1,247
Loans	2,580,009	2,053,784	1,968,922
Short term borrowings	466,500	259,697	254,480
Level 1 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	66,994
Level 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	1,908,309
Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities
Carrying Value [Member] | Level 1 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CASH AND DUE FROM BANKS	164,666	207,018
FEDERAL FUNDS SOLD	14,300	14,045
INTEREST-BEARING DEPOSITS IN BANKS	48,634	139,676
Deposits with no stated maturities	3,319,321	2,995,544
Carrying Value [Member] | Level 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
INTEREST-BEARING TIME DEPOSITS IN BANKS	34,352	49,005
Held-to-maturity securities	798	1,061
Accrued interest receivable	22,421	23,122
Deposits with stated maturities	681,236	637,040
Short term borrowings	466,500	259,697
Accrued interest payable	314	287
Carrying Value [Member] | Level 1 and 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	1,975,303	1,819,035
Carrying Value [Member] | Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	2,580,009	2,053,784
Estimated Fair Value [Member] | Level 1 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CASH AND DUE FROM BANKS	164,666	207,018
FEDERAL FUNDS SOLD	14,300	14,045
INTEREST-BEARING DEPOSITS IN BANKS	48,634	139,676
Deposits with no stated maturities	3,319,321	2,995,544
Estimated Fair Value [Member] | Level 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
INTEREST-BEARING TIME DEPOSITS IN BANKS	34,526	49,288
Held-to-maturity securities	810	1,080
Accrued interest receivable	22,421	23,122
Deposits with stated maturities	683,548	638,227
Short term borrowings	466,500	259,697
Accrued interest payable	314	287
Estimated Fair Value [Member] | Level 1 and 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities	1,975,303	1,819,035
Estimated Fair Value [Member] | Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	$2,593,923	$2,081,091

Acquisition_Additional_Informa

Acquisition - Additional Information (Detail) (USD $)	1 Months Ended
	31-May-13	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Loans At Acquisition Date [Line Items]
Payment for all outstanding shares of acquired entity in cash	$39,200,000
Payment for all outstanding shares of acquired entity by shares	420,000
Date of acquisition agreement	9-Feb-13
Fair value of purchased credit impaired loans		22,809,000	21,800,000	24,283,000
Contractual amounts		4,218,000
Orange Savings Bank [Member]
Loans At Acquisition Date [Line Items]
Payment for all outstanding shares of acquired entity in cash	39,200,000
Fair value of total loans		293,288,000
Total loans of contractual amounts		299,252,000
Fair value of purchased credit impaired loans		4,475,000
Contractual amounts		$5,878,000

Acquisition_Schedule_of_Amount

Acquisition - Schedule of Amounts Recorded on the Consolidated Balance Sheet on the Acquisition date (Detail) (USD $)	1 Months Ended
	31-May-13
Loans At Acquisition Date [Line Items]
Cash	$39,200,000
Orange Savings Bank [Member]
Loans At Acquisition Date [Line Items]
Cash	39,200,000
Common stock issued (420,000 shares)	23,100,000
Total fair value of consideration paid	$62,300,000

Acquisition_Schedule_of_Amount1

Acquisition - Schedule of Amounts Recorded on the Consolidated Balance Sheet on the Acquisition date (Parenthetical) (Detail)	1 Months Ended
	31-May-13
Business Combinations [Abstract]
Common stock issued shares	420,000

Acquisition_Schedule_of_Prelim

Acquisition - Schedule of Preliminary Estimated Fair Value Amounts Assigned to Major Asset and Liability Categories at Acquisition Date (Detail) (Orange Savings Bank [Member], USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Orange Savings Bank [Member]
Loans At Acquisition Date [Line Items]
Cash and cash equivalents	$13,494
Securities available for sale	107,735
Loans	293,288
Identifiable intangible assets	2,300
Other assets	12,569
Total identifiable assets acquired	429,386
Deposits	385,950
Other liabilities	4,154
Total liabilities assumed	390,104
Fair value of net identifiable assets acquired	39,282
Goodwill resulting from acquisition	$23,018