First Financial Bankshares (FFIN) 10-K 17 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Feb. 17, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	FFIN
Entity Registrant Name	FIRST FINANCIAL BANKSHARES INC
Entity Central Index Key	36,029
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		66,125,622
Entity Public Float			$ 2,070

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
ASSETS
CASH AND DUE FROM BANKS	$ 204,782	$ 179,140
FEDERAL FUNDS SOLD	3,130	3,810
INTEREST-BEARING DEPOSITS IN BANKS	48,574	89,936
Total cash and cash equivalents	256,486	272,886
INTEREST-BEARING TIME DEPOSITS IN BANKS	1,707	3,495
SECURITIES AVAILABLE-FOR-SALE, at fair value	2,860,837	2,733,899
SECURITIES HELD-TO-MATURITY (fair value of $124 and $283 at December 31, 2016 and 2015, respectively)	121	278
LOANS:
Held for investment	3,357,307	3,317,050
Less - allowance for loan losses	(45,779)	(41,877)
Net loans held for investment	3,311,528	3,275,173
Held for sale	26,898	33,543
Net loans	3,338,426	3,308,716
BANK PREMISES AND EQUIPMENT, net	122,685	115,712
INTANGIBLE ASSETS	143,603	144,449
OTHER ASSETS	86,066	85,635
Total assets	6,809,931	6,665,070
LIABILITIES AND SHAREHOLDERS' EQUITY
NONINTEREST-BEARING DEPOSITS	1,717,722	1,745,952
INTEREST-BEARING DEPOSITS	3,760,817	3,444,217
Total deposits	5,478,539	5,190,169
DIVIDENDS PAYABLE	11,897	10,558
BORROWINGS	445,770	615,675
OTHER LIABILITIES	35,840	43,682
Total liabilities	5,972,046	5,860,084
COMMITMENTS AND CONTINGENCIES
SHAREHOLDERS' EQUITY:
Common stock - $0.01 par value; authorized 120,000,000 shares; 66,094,695 and 65,990,234 shares issued at December 31, 2016 and 2015, respectively	661	660
Capital surplus	372,245	368,925
Retained earnings	446,534	388,006
Treasury stock (shares at cost: 507,409 and 520,651 at December 31, 2016 and 2015, respectively)	(6,671)	(6,296)
Deferred Compensation	6,671	6,296
Accumulated other comprehensive earnings	18,445	47,395
Total shareholders' equity	837,885	804,986
Total liabilities and shareholders' equity	$ 6,809,931	$ 6,665,070

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
SECURITIES HELD-TO-MATURITY, fair value	$ 124	$ 283
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	66,094,695	65,990,234
Treasury stock, shares	507,409	520,651

Consolidated Statement of Earni

Consolidated Statement of Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
INTEREST INCOME:
Interest and fees on loans	$ 161,018	$ 151,662	$ 136,684
Interest on investment securities:
Taxable	27,626	29,673	28,402
Exempt from federal income tax	43,302	40,080	33,081
Interest on federal funds sold and interest-bearing deposits in banks	342	208	372
Total interest income	232,288	221,623	198,539
INTEREST EXPENSE:
Interest on deposits	4,503	3,642	3,883
Other	948	446	298
Total interest expense	5,451	4,088	4,181
Net interest income	226,837	217,535	194,358
PROVISION FOR LOAN LOSSES	10,212	9,685	4,465
Net interest income after provision for loan losses	216,625	207,850	189,893
NONINTEREST INCOME:
Trust fees	19,636	19,252	18,766
Service charges on deposit accounts	18,386	17,171	16,910
ATM, interchange and credit card fees	23,910	21,860	19,427
Real estate mortgage operations	16,086	10,409	6,511
Net gain (loss) on sale of available-for-sale securities (includes $1,270, $432 and ($4) for the years ended December 31, 2016, 2015 and 2014, respectively, related to accumulated comprehensive earnings reclassifications)	1,270	432	(4)
Net gain on sale of foreclosed assets	456	538	904
Net gain (loss) on sale of assets	168	(820)	10
Interest on loan recoveries	2,112	1,050	601
Other	3,108	3,540	3,499
Total noninterest income	85,132	73,432	66,624
NONINTEREST EXPENSE:
Salaries and employee benefits	90,739	80,999	70,456
Loss from partial settlement of pension plan	267		2,909
Net occupancy expense	10,420	10,314	9,100
Equipment expense	13,479	12,222	10,740
FDIC insurance premiums	2,680	3,153	2,725
ATM, interchange and credit card expenses	7,231	6,384	6,870
Professional and service fees	6,877	4,831	4,295
Printing, stationery and supplies	2,093	2,278	2,637
Amortization of intangible assets	738	561	275
Other	31,306	28,722	27,918
Total noninterest expense	165,830	149,464	137,925
EARNINGS BEFORE INCOME TAXES	135,927	131,818	118,592
INCOME TAX EXPENSE (includes $445, $151 and ($1) for the years ended December 31, 2016, 2015 and 2014, respectively, related to income tax expense from reclassification items)	31,153	31,437	29,033
NET EARNINGS	$ 104,774	$ 100,381	$ 89,559
NET EARNINGS PER SHARE, BASIC	$ 1.59	$ 1.55	$ 1.40
NET EARNINGS PER SHARE, ASSUMING DILUTION	$ 1.59	$ 1.54	$ 1.39

Consolidated Statement of Earn5

Consolidated Statement of Earnings (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Reclassifications adjustment for realized gains on investment securities included in net earnings (loss), before income tax	$ 1,270	$ 432	$ (4)
Income tax expense from reclassification items	$ 445	$ 151	$ (1)

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
NET EARNINGS	$ 104,774	$ 100,381	$ 89,559
OTHER ITEMS OF COMPREHENSIVE EARNINGS (LOSS):
Change in unrealized gain (loss) on investment securities available-for-sale, before income tax	(44,679)	2,273	54,571
Reclassification adjustment for realized losses (gains) on investment securities included in net earnings, before income tax	(1,270)	(432)	4
Minimum liability pension adjustment, before income tax	1,410	(1,986)	2,540
Total other items of comprehensive earnings (losses)	(44,539)	(145)	57,115
Income tax benefit (expense) related to:
Investment securities	16,082	(644)	(19,101)
Minimum liability pension adjustment	(493)	695	(889)
Total income tax benefit (expense)	15,589	51	(19,990)
COMPREHENSIVE EARNINGS	$ 75,824	$ 100,287	$ 126,684

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Deferred Compensation [Member]	Accumulated Other Comprehensive Earnings (Losses) [Member]
Beginning Balance at Dec. 31, 2013	$ 587,647	$ 320	$ 302,991	$ 273,972	$ (5,490)	$ 5,490	$ 10,364
Beginning Balance, Shares at Dec. 31, 2013		31,992,497
Treasury Stock, Beginning Balance, Shares at Dec. 31, 2013					(269,467)
NET EARNINGS	89,559			89,559
Stock option exercises	1,437	$ 1	1,436
Stock option exercises, Shares		74,664
Cash dividends declared	(35,233)			(35,233)
Minimum liability pension adjustment, net of related income taxes	1,651						1,651
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes	35,474						35,474
Additional tax benefit related to directors' deferred compensation plan	$ 293		293
Shares purchased in connection with directors' deferred compensation plan, net					$ (388)	388
Shares purchased in connection with directors' deferred compensation plan, net, Shares	0				8,038
Stock option expense	$ 709		709
Two-for-one stock split in the form of 100% stock dividend		$ 320		(320)
Two-for-one stock split in the form of a 100% stock dividend, Shares		32,022,760			(268,134)
Ending Balance at Dec. 31, 2014	681,537	$ 641	305,429	327,978	$ (5,878)	5,878	47,489
Ending Balance, Shares at Dec. 31, 2014		64,089,921
Treasury Stock, Ending Balance, Shares at Dec. 31, 2014					(529,563)
NET EARNINGS	100,381			100,381
Stock issued in acquisition of FBC Bancshares, Inc.	59,648	$ 18	59,630
Stock issued in acquisition of FBC Bancshares, Inc., Shares		1,755,374
Stock option exercises	1,545	$ 1	1,544
Stock option exercises, Shares		105,121
Restricted Stock grant	1,350		1,350
Restricted stock grant, Shares		39,818
Cash dividends declared	(40,353)			(40,353)
Minimum liability pension adjustment, net of related income taxes	(1,291)						(1,291)
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes	1,197						1,197
Additional tax benefit related to directors' deferred compensation plan	$ 328		328
Shares purchased in connection with directors' deferred compensation plan, net					$ (418)	418
Shares purchased in connection with directors' deferred compensation plan, net, Shares	0				8,912
Stock option expense	$ 644		644
Ending Balance at Dec. 31, 2015	$ 804,986	$ 660	368,925	388,006	$ (6,296)	6,296	47,395
Ending Balance, Shares at Dec. 31, 2015		65,990,234
Treasury Stock, Ending Balance, Shares at Dec. 31, 2015	(520,651)				(520,651)
NET EARNINGS	$ 104,774			104,774
Stock option exercises	1,260	$ 1	1,259
Stock option exercises, Shares		82,871
Restricted Stock grant	809		809
Restricted stock grant, Shares		21,590
Cash dividends declared	(46,246)			(46,246)
Minimum liability pension adjustment, net of related income taxes	917						917
Change in unrealized gain (loss) in investment securities available-for-sale, net of related income taxes	(29,867)						(29,867)
Additional tax benefit related to directors' deferred compensation plan	$ 370		370
Shares purchased in connection with directors' deferred compensation plan, net					$ (375)	375
Shares purchased in connection with directors' deferred compensation plan, net, Shares	0				13,242
Stock option expense	$ 882		882
Ending Balance at Dec. 31, 2016	$ 837,885	$ 661	$ 372,245	$ 446,534	$ (6,671)	$ 6,671	$ 18,445
Ending Balance, Shares at Dec. 31, 2016		66,094,695
Treasury Stock, Ending Balance, Shares at Dec. 31, 2016	(507,409)				(507,409)

Consolidated Statements of Sha8

Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash dividend per share	$ 0.70	$ 0.62	$ 0.55
Percentage of stock dividend			100.00%
Common Stock [Member]
Percentage of stock dividend			100.00%
Retained Earnings [Member]
Cash dividend per share	$ 0.70	$ 0.62	$ 0.55
Percentage of stock dividend			100.00%

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
NET EARNINGS	$ 104,774	$ 100,381	$ 89,559
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	11,573	11,145	9,262
PROVISION FOR LOAN LOSSES	10,212	9,685	4,465
Securities premium amortization (discount accretion), net	29,005	27,705	20,221
Gain on sale of assets, net	(1,894)	(150)	(910)
Deferred federal income tax expense (benefit)	673	320	(893)
Change in loans held for sale	6,645	(24,739)	(3,640)
Change in other assets	2,397	(16,919)	9,852
Change in other liabilities	(2,643)	1,664	3,486
Total adjustments	55,968	8,711	41,843
Net cash provided by operating activities	160,742	109,092	131,402
CASH FLOWS FROM INVESTING ACTIVITIES:
Cash paid for asset acquisition of 4Trust Mortgage, Inc., net		(1,931)
Cash received in acquisition of FBC Bancshares, Inc., net		65,197
Net decrease in interest-bearing time deposits in banks	1,788	13,507	14,915
Activity in available-for-sale securities:
Sales	40,510	35,580	1,619
Maturities	3,509,113	2,717,724	2,917,407
Purchases	(3,737,865)	(3,055,117)	(3,248,804)
Activity in held-to-maturity securities - maturities	157	163	243
Net increase in loans	(48,836)	(144,320)	(247,829)
Purchases of bank premises and equipment and other assets	(20,399)	(17,433)	(17,412)
Proceeds from sale of bank premises and equipment and other assets	3,572	2,405	4,656
Net cash used in (provided by) investing activities	(251,960)	(384,225)	(575,205)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase (decrease) in noninterest-bearing deposits	(28,230)	23,473	208,146
Net increase in interest-bearing deposits	316,600	72,857	407,035
Net increase (decrease) in borrowings	(169,905)	235,440	(96,778)
Common stock transactions:
Proceeds from stock issuances	1,260	1,545	1,437
Dividends paid	(44,907)	(38,767)	(34,578)
Net cash provided by financing activities	74,818	294,548	485,262
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(16,400)	19,415	41,459
CASH AND CASH EQUIVALENTS, beginning of year	272,886	253,471	212,012
CASH AND CASH EQUIVALENTS, end of year	$ 256,486	$ 272,886	$ 253,471

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES: Nature of Operations First Financial Bankshares, Inc. (a Texas corporation) (“Bankshares”, “Company”, “we” or “us”) is a financial holding company which owns all of the capital stock of one bank with 69 locations located in Texas as of December 31, 2016. The subsidiary bank is First Financial Bank, National Association, Abilene. The bank’s primary source of revenue is providing loans and banking services to consumers and commercial customers in the market area in which the subsidiary is located. In addition, the Company also owns First Financial Trust & Asset Management Company, National Association, First Financial Insurance Agency, Inc., and First Technology Services, Inc. A summary of significant accounting policies of Bankshares and its subsidiaries applied in the preparation of the accompanying consolidated financial statements follows. The accounting principles followed by the Company and the methods of applying them are in conformity with both U.S. GAAP and prevailing practices of the banking industry. The Company evaluated subsequent events for potential recognition through the date the consolidated financial statements were issued. Use of Estimates in Preparation of Financial Statements The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The Company’s significant estimates include its allowance for loan losses and its valuation of financial instruments. Consolidation The accompanying consolidated financial statements include the accounts of Bankshares and its subsidiaries, all of which are wholly-owned. All significant intercompany accounts and transactions have been eliminated. Stock Repurchase On October 28, 2014, the Company’s Board of Directors authorized the repurchase of up to 1,500,000 common shares through September 30, 2017. The stock buyback plan authorizes management to repurchase the stock at such time as repurchases are considered beneficial to stockholders. 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. For the years ended December 31, 2016, 2015 and 2014, no shares were repurchased under this or the prior authorization that expired September 30, 2014. Stock Split On April 22, 2014, the Company’s Board of Directors declared a two-for-one Acquisitions and Asset Purchase On July 31, 2015, the Company acquired 100% of the outstanding capital stock of FBC Bancshares, Inc. through the merger of a wholly-owned subsidiary with and into FBC Bancshares, Inc. Following such merger, FBC Bancshares, Inc. and its wholly-owned subsidiary, First Bank, N.A. were merged into the Company and First Financial Bank, National Association, respectively. The results of operations of FBC Bancshares, Inc. subsequent to the acquisition date, are included in the consolidated earnings of the Company. See Note 18 for additional information. On June 1, 2015, the Company completed the asset purchase of 4Trust Mortgage, Inc. The results of operation of 4Trust Mortgage Inc. subsequent to the asset purchase date, are included in the consolidated earnings of the Company. See Note 18 for additional information. Increase in Authorized Shares On April 28, 2015, 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 120,000,000. Investment Securities Management classifies debt and equity securities as held-to-maturity, available-for-sale, held-to-maturity held-to-maturity available-for-sale Available-for-sale The Company records its available-for-sale When the fair value of a security is below its amortized cost, and depending on the length of time the condition exists and the extent the fair value is below amortized cost, additional analysis is performed to determine whether an other-than-temporary impairment condition exists. Available-for-sale held-to-maturity The Company’s investment portfolio consists of U.S. Treasury securities, obligations of U.S. government sponsored enterprises and agencies, obligations of state and political subdivisions, mortgage pass-through securities, corporate bonds and general obligation or revenue based municipal bonds. Pricing for such securities is generally readily available and transparent in the market. The Company utilizes independent third party pricing services to value its investment securities, which the Company reviews as well as the underlying pricing methodologies for reasonableness and to ensure such prices are aligned with pricing matrices. The Company validates quarterly, on a sample basis, prices supplied by the independent pricing services by comparison to prices obtained from other third party sources. 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 allowance for loan losses is an amount which represents management’s best estimate of probable losses that are inherent in the Company’s loan portfolio as of the balance sheet date. The allowance for loan losses is comprised of three elements: (i) specific reserves determined based on probable losses on specific classified loans; (ii) a historical valuation reserve component that considers historical loss rates and estimated loss emergence periods; and (iii) qualitative reserves based upon general economic conditions and other qualitative risk factors both internal and external to the Company. The allowance for loan losses is increased by charges to income and decreased by charge-offs Although we believe we use the best information available to make loan loss allowance determinations, future adjustments could be necessary if circumstances or economic conditions differ substantially from the assumptions used in making our initial determinations. A decline in the economy and employment could result in increased levels of non-performing 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. charged-off charge-off Loans are considered impaired when, based on current information and events, management determines that it is probable we will be unable to collect all amounts due in accordance with the loan agreement, including scheduled principal and interest payments. If a loan is impaired, a specific valuation allowance is allocated, if necessary. Interest payments on impaired loans are typically applied to principal unless collectability of the principal amount is reasonably assured, in which case interest is recognized on a cash basis. Impaired loans, or portions thereof, are charged off when deemed uncollectable. The Company’s policy requires measurement of the allowance for an impaired, collateral dependent loan based on the fair value of the collateral. Other loan impairments for non-collateral From time to time, the Company modifies its loan agreement with a borrower. A modified loan is considered a troubled debt restructuring when two conditions are met: (i) the borrower is experiencing financial difficulty and (ii) concessions are made by the Company that would not otherwise be considered for a borrower with similar credit risk characteristics. Modifications to loan terms may include a lower interest rate, a reduction of principal, or a longer term to maturity. For all impaired loans, including the Company’s troubled debt restructurings, the Company performs a periodic, well-documented credit evaluation of the borrower’s financial condition and prospects for repayment to assess the likelihood that all principal and interest payments required under the terms of the agreement will be collected in full. When doubt exists about the ultimate collectability of principal and interest, the troubled debt restructuring remains on non-accrual non-accrual The Company originates certain mortgage loans for sale in the secondary market. Accordingly, these loans are classified as held-for-sale Loans acquired, including loans acquired in a business combination, are initially recorded at fair value with no valuation allowance. Acquired loans are segregated between those considered to be credit impaired and those deemed performing. To make this determination, management considers such factors as past due status, non-accrual Purchased credit impaired loans are those loans that showed evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all amounts contractually owed. Their acquisition fair value, which includes a credit component at the acquisition date, was based on the estimate of cash flows, both principal and interest, expected to be collected or estimated collateral values if cash flows are not estimable, discounted at prevailing market rates of interest. The difference between the discounted cash flows expected at acquisition and the investment in the loan is recognized as interest income on a level-yield method over the life of the loan, unless management was unable to reasonably forecast cash flows in which case the loans were placed on nonaccrual. Contractually required payments for interest and principal that exceed the cash flows expected at acquisition are not recognized as a yield adjustment. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows subsequent to acquisition are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition. The carrying amount of purchased credit impaired loans at December 31, 2016 and 2015 were $1,256,000 and $2,178,000, respectively, compared to a contractual balance of $1,865,000 and $2,936,000, respectively. Other purchased credit impaired loan disclosures were omitted due to immateriality. Other Real Estate Other real estate owned is foreclosed property held pending disposition and is initially recorded at fair value, less estimated costs to sell. At foreclosure, if the fair value of the real estate, less estimated costs to sell, is less than the Company’s recorded investment in the related loan, a write-down is recognized through a charge to the allowance for loan losses. Any subsequent reduction in value is recognized by a charge to income. Operating and holding expenses of such properties, net of related income, and gains and losses on their disposition are included in net gain (loss) on sale of foreclosed assets as incurred. Bank Premises and Equipment Bank premises and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization are computed principally on a straight-line basis over the estimated useful lives of the related assets. Leasehold improvements are amortized over the life of the respective lease or the estimated useful lives of the improvements, whichever is shorter. Business Combinations, Goodwill and Other Intangible Assets The Company accounts for all business combinations under the purchase method of accounting. Tangible and intangible assets and liabilities of the acquired entity are recorded at fair value. Intangible assets with finite useful lives represent the future benefit associated with the acquisition of the core deposits and are amortized over seven years, utilizing a method that approximates the expected attrition of the deposits. Goodwill with an indefinite life is not amortized, but rather tested annually for impairment as of June 30 each year and totaled $139,971,000 at both December 31, 2016 and 2015. There was no impairment recorded for the years ended December 31, 2016, 2015 and 2014. The carrying amount of goodwill arising from acquisitions that qualify as an asset purchase for federal income tax purposes was $74,376,000 both at December 31, 2016 and 2015, and is deductible for federal income tax purposes. Also included in other intangible assets are mortgage servicing rights totaling $1,795,000 and $1,902,000 at December 31, 2016 and 2015, respectively. Securities Sold Under Agreements To Repurchase Securities sold under agreements to repurchase, which are classified as borrowings, generally mature within one to four days from the transaction date. Securities sold under agreements to repurchase are reflected at the amount of the cash received in connection with the transaction. The Company may be required to provide additional collateral based on the estimated fair value of the underlying securities. Segment Reporting The Company has determined that its banking regions meet the aggregation criteria of the current authoritative accounting guidance since each of its banking regions offer similar products and services, operate in a similar manner, have similar customers and report to the same regulatory authority, and therefore operate one line of business (community banking) located in a single geographic area (Texas). Statements of Cash Flows For purposes of reporting cash flows, cash and cash equivalents includes cash on hand, amounts due from banks, including interest-bearing deposits in banks with original maturity of 90 days or less, and federal funds sold. Accumulated Other Comprehensive Income (Loss) Unrealized net gains on the Company’s available-for-sale Income Taxes The Company’s provision for income taxes is based on income before income taxes adjusted for permanent differences between financial reporting and taxable income. Deferred tax assets and liabilities are determined using the liability (or balance sheet) method. Under this method, the net deferred tax asset or liability is determined based on the tax effects of the temporary differences between the book and tax bases of the various balance sheet assets and liabilities and gives current recognition to changes in tax rates and laws. Stock Based Compensation The Company grants stock options for a fixed number of shares to employees with an exercise price equal to the fair value of the shares at the grant date. The Company recorded stock option expense totaling $882,000, $644,000 and $709,000 for the years ended December 31, 2016, 2015 and 2014, respectively. The Company also grants restricted stock for a fixed number of shares. The Company recorded expenses associated with its director and officer restricted stock grants totaling $278,000 and $381,000, respectively, for the year ended December 31, 2016 and $139,000 and $62,000, respectively, for the year ended December 31, 2015. As the restricted stock plan was approved by shareholders in April 2015, there were no such expenses in 2014. See Note 15 for further information. Advertising Costs Advertising costs are expensed as incurred. Per Share Data Net earnings per share (“EPS”) are computed by dividing net earnings by the weighted average number of common stock shares outstanding during the period. The Company calculates dilutive EPS assuming all outstanding stock options to purchase common stock have been exercised at the beginning of the year (or the time of issuance, if later.) The dilutive effect of the outstanding options and restricted stock is reflected by application of the treasury stock method, whereby the proceeds from the exercised options and restricted stock are assumed to be used to purchase common stock at the average market price during the respective year. The following table reconciles the computation of basic EPS to dilutive EPS: Net Weighted Per Share For the year ended December 31, 2016: Net earnings per share, basic $ 104,774 66,013,004 $ 1.59 Effect of stock options and stock grants — 89,882 — Net earnings per share, assuming dilution $ 104,774 66,102,886 $ 1.59 For the year ended December 31, 2015: Net earnings per share, basic $ 100,381 64,892,934 $ 1.55 Effect of stock options and stock grants — 175,096 (0.01 ) Net earnings per share, assuming dilution $ 100,381 65,068,030 $ 1.54 For the year ended December 31, 2014: Net earnings per share, basic $ 89,559 64,047,803 $ 1.40 Effect of stock options — 260,732 (0.01 ) Net earnings per share, assuming dilution $ 89,559 64,308,535 $ 1.39 Recently Issued Authoritative Accounting Guidance Accounting Standards Update ( “ ASU ” ) 2014-09, “ Revenue from Contracts with Customers. ” 2014-09 2015-4 2014-09 2014-09, non-interest 2014-09 2014-09 non-interest ASU 2014-11, “Transfers and Servicing.” 2014-11 repurchase-to-maturity repurchase-to-maturity repurchase-to-maturity ASU 2014-14, “Receivables – Troubled Debt Restructuring by Creditors.” 2014-14 ASU 2014-15, “Presentation of Financial Statements – Going Concern.” 2014-15 2014-15 ASU 2015-01, “Income Statement – Extraordinary and Unusual Items.” 2015-01 ASU 2015-05, “ Intangibles – Goodwill and Other – Internal-Use Software – Customer ’ s Accounting for Fees Paid in a Cloud Computing Arrangement. ” 2015-05 2015-05 2015-05 ASU 2015-16, “Business Combinations – Simplifying the Accounting Measurement Period Adjustments. 2015-16 ASU 2016-1, “Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities.” 2016-1, available-for-sale 2016-1 ASU 2016-02, “Leases.” 2016-02 right-of-use 2016-02 ASU 2016-09, “Compensation – Stock Compensation: Improvements to Employee Share-Based Payment Accounting.” 2016-09 2016-09 2016-09 ASU 2016-13, “ Financial Instruments – Credit Losses. ” 2016-13 held-to-maturity 2016-13 2016-13 ASU 2017-04, “Intangibles – Goodwill and Other.” 2017-04 2017-04

Interest-bearing Time Deposits

Interest-bearing Time Deposits in Banks and Securities	12 Months Ended
	Dec. 31, 2016
Cash and Cash Equivalents [Abstract]
Interest-bearing Time Deposits in Banks and Securities	2. INTEREST-BEARING TIME DEPOSITS IN BANKS AND SECURITIES: Interest-bearing time deposits in banks totaled $1,707,000 and $3,495,000 at December 31, 2016 and 2015, respectively, and have original maturities generally ranging from one to three years. A summary of the Company’s available-for-sale December 31, 2016 Amortized Gross Gross Estimated Securities available-for-sale: U.S. Treasury securities $ 10,649 $ 19 $ — $ 10,668 Obligations of U.S. government sponsored enterprises and agencies 113,450 253 — 113,703 Obligations of state and political subdivisions 1,534,095 40,194 (10,013 ) 1,564,276 Corporate bonds and other 51,920 476 (3 ) 52,393 Residential mortgage-backed securities 848,614 8,260 (5,513 ) 851,361 Commercial mortgage-backed securities 269,044 622 (1,230 ) 268,436 Total securities available-for-sale $ 2,827,772 $ 49,824 $ (16,759 ) $ 2,860,837 December 31, 2015 Amortized Gross Gross Estimated Securities available-for-sale: U.S. Treasury securities $ 10,792 $ 5 $ (2 ) $ 10,795 Obligations of U.S. government sponsored enterprises and agencies 148,393 268 (107 ) 148,554 Obligations of state and political subdivisions 1,379,879 71,382 (134 ) 1,451,127 Corporate bonds and other 86,182 1,778 (5 ) 87,955 Residential mortgage-backed securities 781,648 10,993 (3,759 ) 788,882 Commercial mortgage-backed securities 247,991 429 (1,834 ) 246,586 Total securities available-for-sale $ 2,654,885 $ 84,855 $ (5,841 ) $ 2,733,899 Disclosures related to the Company’s held-to-maturity 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 December 31, 2016, were computed by using scheduled amortization of balances and historical prepayment rates. At December 31, 2016 and 2015, the Company did not hold any CMOs that entail higher risks than standard mortgage-backed securities. The amortized cost and estimated fair value of available-for-sale Amortized Estimated Due within one year $ 206,182 $ 207,276 Due after one year through five years 664,151 684,849 Due after five years through ten years 836,421 845,257 Due after ten years 3,360 3,658 Mortgage-backed securities 1,117,658 1,119,797 Total $ 2,827,772 $ 2,860,837 The following tables disclose, as of December 31, 2016 and 2015, the Company’s investment securities that have been in a continuous unrealized-loss Less than 12 Months 12 Months or Longer Total December 31, 2016 Fair Unrealized Fair Unrealized Fair Unrealized Obligations of state and political subdivisions $ 446,052 $ 9,997 $ 1,209 $ 16 $ 447,261 $ 10,013 Corporate bonds and other 244 3 — — 244 3 Residential mortgage-backed securities 372,331 4,532 33,227 981 405,558 5,513 Commercial mortgage-backed securities 193,495 1,180 13,263 50 206,758 1,230 Total $ 1,012,122 $ 15,712 $ 47,699 $ 1,047 $ 1,059,821 $ 16,759 Less than 12 Months 12 Months or Longer Total December 31, 2015 Fair Unrealized Fair Unrealized Fair Unrealized U.S. Treasury securities $ 5,110 $ 2 $ — $ — $ 5,110 $ 2 Obligations of U.S. government sponsored enterprises and agencies 50,388 107 — — 50,388 107 Obligations of state and political subdivisions 32,929 127 1,513 7 34,442 134 Corporate bonds and other 7,004 5 — — 7,004 5 Residential mortgage-backed securities 231,481 1,765 63,919 1,994 295,400 3,759 Commercial mortgage-backed securities 196,163 1,752 9,345 82 205,508 1,834 Total $ 523,075 $ 3,758 $ 74,777 $ 2,083 $ 597,852 $ 5,841 The number of investments in an unrealized loss position totaled 466 at December 31, 2016. We do not believe these unrealized losses are “other-than-temporary” as (i) we do not have the intent to sell our securities prior to recovery and/or maturity and, (ii) it is more likely than not that we will not have to sell our securities prior to recovery and/or maturity. In making this determination, we also consider the length of time and extent to which fair value has been less than cost and the financial condition of the issuer. The unrealized losses noted are interest rate related due to the level of interest rates at December 31, 2016 compared to the time of purchase. We have reviewed the ratings of the issuers and have not identified any issues related to the ultimate repayment of principal as a result of credit concerns on these securities. Our mortgage related securities are backed by GNMA, FNMA and FHLMC or are collateralized by securities backed by these agencies. At December 31, 2016, 82.13% of our available-for-sale Securities, carried at approximately $1,940,460,000 and $1,759,570,000 at December 31, 2016 and 2015, respectively, were pledged as collateral for public or trust fund deposits, repurchase agreements and for other purposes required or permitted by law. During 2016, 2015, and 2014, sales of investment securities that were classified as available-for-sale

Loans and Allowance for Loan Lo

Loans and Allowance for Loan Losses	12 Months Ended
	Dec. 31, 2016
Receivables [Abstract]
Loans and Allowance for Loan Losses	3. LOANS AND ALLOWANCE FOR LOAN LOSSES: Loans held-for-investment December 31, 2016 2015 Commercial $ 674,410 $ 696,163 Agricultural 84,021 102,351 Real estate 2,189,844 2,136,233 Consumer 409,032 382,303 Total loans held-for-investment $ 3,357,307 $ 3,317,050 Loans held-for-sale The Company’s non-accrual December 31, 2016 2015 Non-accrual $ 27,371 $ 28,601 Loans still accruing and past due 90 days or more 284 341 Troubled debt restructured loans** 701 199 Total $ 28,356 $ 29,141 * Includes $1,256,000 and $2,178,000, respectively, of purchased credit impaired loans as of December 31, 2016 and 2015. ** Our troubled debt restructured loans of $6,863,000 and $6,113,000, whose interest collection, after considering economic and business conditions and collection efforts, is doubtful are included in non-accrual The Company’s recorded investment in impaired loans and the related valuation allowance are as follows (in thousands): December 31, 2016 December 31, 2015 Recorded Investment Valuation Allowance Recorded Investment Valuation Allowance $ 27,371 $ 5,012 $ 28,601 $ 5,071 The Company had $29,000,000 and $29,768,000 in non-accrual, Non-accrual December 31, 2016 2015 Commercial $ 7,284 $ 8,761 Agricultural 99 97 Real Estate 18,754 18,766 Consumer 1,234 977 Total $ 27,371 $ 28,601 No significant additional funds are committed to be advanced in connection with impaired loans as of December 31, 2016. The Company’s impaired loans and related allowance as of December 31, 2016 and 2015 are summarized in the following tables by class of financing receivables (in thousands). No interest income was recognized on impaired loans subsequent to their classification as impaired. December 31, 2016 Unpaid Recorded Recorded Total Related 12 Month Commercial $ 13,389 $ 1,148 $ 6,136 $ 7,284 $ 2,128 $ 4,921 Agricultural 103 — 99 99 25 50 Real Estate 23,466 6,229 12,525 18,754 2,428 16,170 Consumer 1,421 280 954 1,234 431 914 Total $ 38,379 $ 7,657 $ 19,714 $ 27,371 $ 5,012 $ 22,055 * Includes $1,256,000 of purchased credit impaired loans. December 31, 2015 Unpaid Recorded Recorded Total Related 12 Month Commercial $ 10,056 $ 608 $ 8,153 $ 8,761 $ 2,030 $ 5,812 Agricultural 97 — 97 97 70 48 Real Estate 23,710 5,314 13,452 18,766 2,827 15,211 Consumer 1,167 624 353 977 144 664 Total $ 35,030 $ 6,546 $ 22,055 $ 28,601 $ 5,071 $ 21,735 * Includes $2,178,000 of purchased credit impaired loans. The Company recognized interest income on impaired loans prior to being recognized as impaired of approximately $829,000, $922,000 and $162,000 during the years ended December 31, 2016, 2015, and 2014, respectively. From a credit risk standpoint, the Company rates its loans in one of four categories: (i) pass, (ii) special mention, (iii) substandard or (iv) doubtful. Loans rated as loss are charged-off. The ratings of loans reflect a judgment about the risks of default and loss associated with the loan. The Company reviews the ratings on our credits as part of our on-going Credits rated special mention show clear signs of financial weaknesses or deterioration in credit worthiness, however, such concerns are not so pronounced that the Company generally expects to experience significant loss within the short-term. Such credits typically maintain the ability to perform within standard credit terms and credit exposure is not as prominent as credits rated more harshly. Credits rated substandard are those in which the normal repayment of principal and interest may be, or has been, jeopardized by reason of adverse trends or developments of a financial, managerial, economic or political nature, or important weaknesses exist in collateral. A protracted workout on these credits is a distinct possibility. Prompt corrective action is therefore required to strengthen the Company’s position, and/or to reduce exposure and to assure that adequate remedial measures are taken by the borrower. Credit exposure becomes more likely in such credits and a serious evaluation of the secondary support to the credit is performed. Credits rated doubtful are those in which full collection of principal appears highly questionable, and which some degree of loss is anticipated, even though the ultimate amount of loss may not yet be certain and/or other factors exist which could affect collection of debt. Based upon available information, positive action by the Company is required to avert or minimize loss. Credits rated doubtful are generally also placed on non-accrual. The following summarizes the Company’s internal ratings of its loans held-for-investment December 31, 2016 Pass Special Substandard Doubtful Total Commercial $ 629,756 $ 5,769 $ 38,885 $ — $ 674,410 Agricultural 81,620 715 1,686 — 84,021 Real Estate 2,111,947 18,091 59,806 — 2,189,844 Consumer 406,182 212 2,638 — 409,032 Total $ 3,229,505 $ 24,787 $ 103,015 $ — $ 3,357,307 December 31, 2015 Pass Special Substandard Doubtful Total Commercial $ 633,083 $ 9,762 $ 53,318 $ — $ 696,163 Agricultural 99,862 1,398 1,091 — 102,351 Real Estate 2,054,738 29,000 52,458 37 2,136,233 Consumer 379,941 416 1,946 — 382,303 Total $ 3,167,624 $ 40,576 $ 108,813 $ 37 $ 3,317,050 At December 31, 2016 and 2015, the Company’s past due loans are as follows (in thousands): December 31, 2016 15-59 60-89 Greater Total Total Total Total 90 Commercial $ 3,908 $ 1,122 $ 2,220 $ 7,250 $ 667,160 $ 674,410 $ 10 Agricultural 185 — — 185 83,836 84,021 — Real Estate 13,172 1,301 5,268 19,741 2,170,103 2,189,844 272 Consumer 1,845 368 122 2,335 406,697 409,032 2 Total $ 19,110 $ 2,791 $ 7,610 $ 29,511 $ 3,327,796 $ 3,357,307 $ 284 December 31, 2015 15-59 60-89 Greater Total Total Total Total 90 Commercial $ 3,099 $ 3,652 $ 1,024 $ 7,775 $ 688,388 $ 696,163 $ 54 Agricultural 348 83 — 431 101,920 102,351 — Real Estate 12,247 2,226 2,874 17,347 2,118,886 2,136,233 217 Consumer 1,645 183 266 2,094 380,209 382,303 70 Total $ 17,339 $ 6,144 $ 4,164 $ 27,647 $ 3,289,403 $ 3,317,050 $ 341 * The Company monitors commercial, agricultural and real estate loans after such loans are 15 days past due. Consumer loans are monitored after such loans are 30 days past due. The following table details the allowance for loan losses at December 31, 2016 and 2015 by portfolio segment (in thousands). There were no allowances for purchased credit impaired loans at December 31, 2016 or 2015. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. December 31, 2016 Commercial Agricultural Real Estate Consumer Total Loans individually evaluated for impairment $ 2,128 $ 25 $ 2,428 $ 431 $ 5,012 Loan collectively evaluated for impairment 9,579 1,076 24,436 5,676 40,767 Total $ 11,707 $ 1,101 $ 26,864 $ 6,107 $ 45,779 December 31, 2015 Commercial Agricultural Real Estate Consumer Total Loans individually evaluated for impairment $ 2,030 $ 70 $ 2,827 $ 144 $ 5,071 Loan collectively evaluated for impairment 10,614 1,121 21,548 3,523 36,806 Total $ 12,644 $ 1,191 $ 24,375 $ 3,667 $ 41,877 Changes in the allowance for loan losses for the years ended December 31, 2016 and 2015 are summarized as follows (in thousands): December 31, 2016 Commercial Agricultural Real Estate Consumer Total Beginning balance $ 12,644 $ 1,191 $ 24,375 $ 3,667 $ 41,877 Provision for loan losses 5,101 104 1,150 3,857 10,212 Recoveries 952 25 2,021 508 3,506 Charge-offs (6,990 ) (219 ) (682 ) (1,925 ) (9,816 ) Ending balance $ 11,707 $ 1,101 $ 26,864 $ 6,107 $ 45,779 December 31, 2015 Commercial Agricultural Real Estate Consumer Total Beginning balance $ 7,990 $ 527 $ 26,657 $ 1,650 $ 36,824 Provision for loan losses 8,044 773 (2,399 ) 3,267 9,685 Recoveries 344 55 558 450 1,407 Charge-offs (3,734 ) (164 ) (441 ) (1,700 ) (6,039 ) Ending balance $ 12,644 $ 1,191 $ 24,375 $ 3,667 $ 41,877 The Company’s recorded investment in loans as of December 31, 2016 and 2015 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 $1,256,000 and $2,178,000, respectively, at December 31, 2016 and 2015 are included in loans individually evaluated for impairment. December 31, 2016 Commercial Agricultural Real Estate Consumer Total Loans individually evaluated for impairment $ 7,284 $ 99 $ 18,754 $ 1,234 $ 27,371 Loan collectively evaluated for impairment 667,126 83,922 2,171,090 407,798 3,329,936 Total $ 674,410 $ 84,021 $ 2,189,844 $ 409,032 $ 3,357,307 December 31, 2015 Commercial Agricultural Real Estate Consumer Total Loans individually evaluated for impairment $ 8,761 $ 97 $ 18,766 $ 977 $ 28,601 Loan collectively evaluated for impairment 687,402 102,254 2,117,467 381,326 3,288,449 Total $ 696,163 $ 102,351 $ 2,136,233 $ 382,303 $ 3,317,050 The Company’s loans that were modified in the years ended December 31, 2016 and 2015, and considered troubled debt restructurings are as follows (in thousands): Year Ended December 31, 2016 Year Ended December 31, 2015 Number Pre-Modification Post- Number Pre-Modification Post- Commercial 15 $ 3,208 $ 3,208 8 $ 447 $ 447 Agricultural — — — 3 128 128 Real Estate 6 1,460 1,460 5 598 598 Consumer 7 189 189 7 255 255 Total 28 $ 4,857 $ 4,857 23 $ 1,428 $ 1,428 The balances below provide information as to how the loans were modified as troubled debt restructured loans during the years ended December 31, 2016 and 2015 (in thousands): Year Ended December 31, 2016 Year Ended December 31, 2015 Adjusted Extended Combined Adjusted Extended Combined Commercial $ — $ 2,560 $ 648 $ — $ 182 $ 265 Agricultural — — — — 128 — Real Estate — 298 1,162 15 150 433 Consumer — 70 119 — 56 199 Total $ — $ 2,928 $ 1,929 $ 15 $ 516 $ 897 During the years ended December 31, 2016 and 2015, certain loans were modified as a troubled debt restructured loans within the previous 12 months and for which there was a payment default. A default for purposes of this disclosure is a troubled debt restructured loan in which the borrower is 90 days past or more due or results in the foreclosure and repossession of the applicable collateral. The loans with payment default are as follows (dollars in thousands): Year Ended December 31, 2016 Year Ended December 31, 2015 Number Balance Number Balance Commercial 4 $ 1,690 1 $ 66 Agriculture — — — — Real Estate 3 921 1 15 Consumer — — 2 32 Total 7 $ 2,611 4 $ 113 As of December 31, 2016, the Company has no commitments to lend additional funds to loan customers whose terms have been modified in troubled debt restructurings. An analysis of the changes in loans to officers, directors, principal shareholders, or associates of such persons for the year ended December 31, 2016 (determined as of each respective year-end) Beginning Additional Payments Ending Year ended December 31, 2016 $ 65,729 $ 49,674 $ 70,974 $ 44,429 In the opinion of management, those loans are on substantially the same terms, including interest rates and collateral requirements, as those prevailing at the time for comparable transactions with unaffiliated persons. Our subsidiary bank has established a line of credit with the Federal Home Loan Bank of Dallas (FHLB) to provide liquidity and meet pledging requirements for those customers eligible to have securities pledged to secure certain uninsured deposits. At December 31, 2016, $2,081,615,000 in loans held by our bank subsidiary were subject to blanket liens as security for this line of credit. At December 31, 2016, $75,000,000 in advances were outstanding under this line of credit.

Bank Premises and Equipment

Bank Premises and Equipment	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Bank Premises and Equipment	4. BANK PREMISES AND EQUIPMENT The following is a summary of bank premises and equipment (in thousands): Useful Life December 31, 2016 2015 Land — $ 28,266 $ 29,050 Buildings 20 to 40 years 115,566 106,515 Furniture and equipment 3 to 10 years 58,145 54,353 Leasehold improvements Lesser of lease term or 5 to 15 years 4,783 4,328 206,760 194,246 Less- accumulated depreciation and amortization (84,075 ) (78,534 ) Total Bank Premises and Equipment $ 122,685 $ 115,712 Depreciation expense for the years ended December 31, 2016, 2015 and 2014 amounted to $9,390,000, $9,125,000 and $7,833,000, respectively, and is included in the captions net occupancy expense and equipment expense in the accompanying consolidated statements of earnings. The Company is lessor for portions of its banking premises. Total rental income for all leases included in net occupancy expense is approximately $2,139,000, $1,949,000 and $1,923,000, for the years ended December 31, 2016, 2015, and 2014, respectively. During the years ended December 31, 2016, 2015 and 2014, the Company recorded gains (losses) on sale the of bank premises and equipment totaling $168,000, ($820,000) and $10,000. In 2016, the Company sold its Weatherford and Orange main region branch building for $1,385,000 and $2,000,000 and recorded a gain of $560,000 and a loss of $31,000, respectively. The Company recorded a write down of $1,000,000 in 2015 in anticipation of the Orange branch building sale.

Deposits and Borrowings

Deposits and Borrowings	12 Months Ended
	Dec. 31, 2016
Banking and Thrift [Abstract]
Deposits and Borrowings	5. DEPOSITS AND BORROWINGS: Time deposits of $250,000 or more totaled approximately $130,385,000 and $190,386,000 at December 31, 2016 and 2015, respectively. At December 31, 2016, the scheduled maturities of time deposits (in thousands) were, as follows: Year ending December 31, 2017 $ 419,326 2018 54,713 2019 17,893 2020 9,939 2021 7,093 Thereafter 32 $ 508,996 Deposits received from related parties at December 31, 2016 and 2015 totaled $114,513,000 and $89,006,000, respectively. Borrowings at December 31, 2016 and 2015 consisted of the following (dollars in thousands): December 31, 2016 2015 Securities sold under agreements with customers to repurchase $ 360,820 $ 310,330 Federal funds purchased 9,950 6,325 Advances from Federal Home Loan Bank of Dallas 75,000 299,020 Total $ 445,770 $ 615,675 Securities sold under repurchase agreements are generally with significant customers of the Company that require short-term liquidity for their funds for which the Company pledges certain securities that have a fair value equal to at least the amount of the borrowings. The agreements mature daily and therefore the risk arising from a decline in the fair value of the collateral pledged is minimal. The securities pledged are mortgage-backed securities. These agreements do not include “right of set-off” At December 31, 2016 and 2015, the Company had advances from the Federal Home Loan Bank of Dallas of $75,000,000 and $299,020,000, respectively, that are scheduled to mature in 2017 and 2018. The interest rate on these advances were 0.46% and 0.31%, respectively, at December 31, 2016 and 2015.

Line of Credit

Line of Credit	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Line of Credit	6. LINE OF CREDIT: The Company renewed its loan agreement, effective June 30, 2015, with Frost Bank. Under the loan agreement, as renewed and amended, we are permitted to draw up to $25,000,000 on a revolving line of credit. Prior to June 30, 2017, interest is paid quarterly at The Wall Street Journal The Wall Street Journal

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	7. INCOME TAXES: The Company files a consolidated federal income tax return. Income tax expense is comprised of the following (dollars in thousands): Year Ended December 31, 2016 2015 2014 Current federal income tax $ 30,381 $ 31,014 $ 29,832 Current state income tax 99 103 94 Deferred federal income tax expense (benefit) 673 320 (893 ) Income tax expense $ 31,153 $ 31,437 $ 29,033 Income tax expense, as a percentage of pretax earnings, differs from the statutory federal income tax rate as follows: As a Percent of Pretax Earnings 2016 2015 2014 Statutory federal income tax rate 35.0 % 35.0 % 35.0 % Reductions in tax rate resulting from interest income exempt from federal income tax (12.1 ) (11.4 ) (10.6 ) Effect of state income tax 0.1 0.1 0.1 ESOP tax deduction (0.2 ) (0.2 ) (0.2 ) Other 0.1 0.3 0.2 Effective income tax rate 22.9 % 23.8 % 24.5 % The approximate effects of each type of difference that gave rise to the Company’s deferred tax assets and liabilities at December 31, 2016 and 2015 are as follows (dollars in thousands): 2016 2015 Deferred tax assets: Tax basis of loans in excess of financial statement basis $ 17,006 $ 16,326 Minimum liability in defined benefit plan 1,641 2,135 Recognized for financial reporting purposes but not yet for tax purposes: Deferred compensation 2,807 2,602 Write-downs and adjustments to other real estate owned and repossessed assets 9 7 Other deferred tax assets 226 224 Total deferred tax assets 21,689 21,294 Deferred tax liabilities: Financial statement basis of fixed assets in excess of tax basis 5,870 5,644 Intangible asset amortization deductible for tax purposes, but not for financial reporting purposes 15,191 13,881 Recognized for financial reporting purposes but not yet for tax purposes: Accretion on investment securities 1,788 1,813 Pension plan contributions 1,799 1,761 Net unrealized gain on investment securities available-for-sale 11,573 27,655 Other deferred tax liabilities 83 71 Total deferred tax liabilities 36,304 50,825 Net deferred tax asset (liability) $ (14,615 ) $ (29,531 ) At December 31, 2016 and 2015, management believes that it is more likely than not that all of the deferred tax amounts shown above will be realized and therefore no valuation allowance was recorded. Current authoritative accounting guidance prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. Benefits from tax positions should be recognized in the financial statements only when it is more likely than not that the tax position will be sustained upon examination by the appropriate taxing authority that would have full knowledge of all relevant information. A tax position that meets the more-likely-than-not more-likely-than-not more-likely-than-not

Fair Value Disclosures

Fair Value Disclosures	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Disclosures	8. 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 There were no transfers between Level 2 and Level 3 during the year ended December 31, 2016, 2015 and 2014. The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of December 31, 2016, and 2015 segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (in thousands): December 31, 2016 Level 1 Level 2 Level 3 Total Fair Available-for-sale U.S. Treasury securities $ 10,668 $ — $ — $ 10,668 Obligations of U. S. government sponsored enterprises and agencies — 113,703 — 113,703 Obligations of state and political subdivisions — 1,564,276 — 1,564,276 Corporate bonds — 47,965 — 47,965 Residential mortgage-backed securities — 851,361 — 851,361 Commercial mortgage-backed securities — 268,436 — 268,436 Other securities 4,428 — — 4,428 Total $ 15,096 $ 2,845,741 $ — $ 2,860,837 December 31, 2015 Level 1 Level 2 Level 3 Total Fair Available-for-sale U.S. Treasury securities $ 10,795 $ — $ — $ 10,795 Obligations of U. S. government sponsored enterprises and agencies — 148,554 — 148,554 Obligations of state and political subdivisions — 1,451,127 — 1,451,127 Corporate bonds — 83,254 — 83,254 Residential mortgage-backed securities — 788,882 — 788,882 Commercial mortgage-backed securities — 246,586 — 246,586 Other securities 4,701 — — 4,701 Total $ 15,496 $ 2,718,403 $ — $ 2,733,899 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 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. At December 31, 2016, impaired loans with a carrying value of $27,371,000 were reduced by specific valuation reserves totaling $5,012,000 resulting in a net fair value of $22,359,000. Loans Held-for-Sale held-for-sale held-for-sale held-for-sale Certain non-financial non-financial non-recurring non-financial Non-financial non-recurring re-measured re-measured Year Ended 2016 2015 Carrying value of other real estate owned prior to re-measurement $ — $ 351 Write-downs included in gain (loss) on sale of other real estate owned — (95 ) Fair value $ — $ 256 At December 31, 2016 and 2015, other real estate owned totaled $413,000 and $153,000, respectively. The Company is required under current authoritative accounting guidance to disclose the estimated fair value of their financial instrument assets and liabilities including those subject to the requirements discussed above. For the Company, as for most financial institutions, substantially all of its assets and liabilities are considered financial instruments. Many of the Company’s financial instruments, however, lack an available trading market as characterized by a willing buyer and willing seller engaging in an exchange transaction. The estimated fair value amounts of financial instruments have been determined by the Company using available market information and appropriate valuation methodologies. However, considerable judgment is required to interpret data to develop the estimates of fair value. Accordingly, the estimates presented herein are not necessarily indicative of the amounts the Company could realize in a current market exchange. The use of different market assumptions and/or estimation methodologies may have a material effect on the estimated fair value amounts. In addition, reasonable comparability between financial institutions may not be likely due to the wide range of permitted valuation techniques and numerous estimates that must be made given the absence of active secondary markets for many of the financial instruments. This lack of uniform valuation methodologies also introduces a greater degree of subjectivity to these estimated fair values. Cash and due from banks, federal funds sold, interest-bearing deposits and time deposits in banks and accrued interest receivable and payable are liquid in nature and considered Levels 1 or 2 of the fair value hierarchy. Financial instruments with stated maturities have been valued using a present value discounted cash flow with a discount rate approximating current market for similar assets and liabilities and are considered Levels 2 and 3 of the fair value hierarchy. Financial instrument liabilities with no stated maturities have an estimated fair value equal to both the amount payable on demand and the carrying value and are considered Level 1 of the fair value hierarchy. The carrying value and the estimated fair value of the Company’s contractual off-balance-sheet The estimated fair values and carrying values of all financial instruments under current authoritative guidance at December 31, 2016 and 2015, were as follows (dollars in thousands): 2016 2015 Carrying Estimated Carrying Estimated Fair Value Cash and due from banks $ 204,782 $ 204,782 $ 179,140 $ 179,140 Level 1 Federal funds sold 3,130 3,130 3,810 3,810 Level 1 Interest-bearing deposits in banks 48,574 48,574 89,936 89,936 Level 1 Interest-bearing time deposits in banks 1,707 1,709 3,495 3,500 Level 2 Available-for-sale 2,860,837 2,860,837 2,733,899 2,733,899 Levels 1 and 2 Held-to-maturity 121 124 278 283 Level 2 Loans 3,338,426 3,361,735 3,308,716 3,316,243 Level 3 Accrued interest receivable 36,469 36,469 34,697 34,697 Level 2 Deposits with stated maturities 508,996 510,304 620,852 622,572 Level 2 Deposits with no stated maturities 4,969,543 4,969,543 4,569,317 4,569,317 Level 1 Borrowings 445,770 445,770 615,675 615,675 Level 2 Accrued interest payable 225 225 240 240 Level 2

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. COMMITMENTS AND CONTINGENCIES: The Company is engaged in legal actions arising from the normal course of business. In management’s opinion, the Company has adequate legal defenses with respect to these actions, and as of December 31, 2016 the resolution of these matters is not expected to have material adverse effects upon the results of operations or financial condition of the Company. The Company leases a portion of its bank premises and equipment under operating leases. At December 31, 2016, future minimum lease commitments were: 2017 - $774,000, 2018 - $369,000, 2019 - $268,000, 2020 - $140,000, and 2021 - $32,000.

Financial Instruments with Off-

Financial Instruments with Off-Balance-Sheet Risk	12 Months Ended
	Dec. 31, 2016
Text Block [Abstract]
Financial Instruments with Off-Balance-Sheet Risk	10. FINANCIAL INSTRUMENTS WITH OFF-BALANCE-SHEET We are a party to financial instruments with off-balance-sheet Our exposure to credit loss in the event of nonperformance by the counterparty to the financial instrument for unfunded lines of credit, commitments to extend credit and standby letters of credit is represented by the contractual notional amount of these instruments. We generally use the same credit policies in making commitments and conditional obligations as we do for on-balance-sheet Total Notional Financial instruments whose contract amounts represent credit risk: Unfunded lines of credit $ 549,000 Unfunded commitments to extend credit 199,235 Standby letters of credit 27,380 Total commercial commitments $ 775,615 Unfunded lines of credit and commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. These commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. We evaluate each customer’s creditworthiness on a case-by-case Standby letters of credit are conditional commitments we issue to guarantee the performance of a customer to a third party. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. The average collateral value held on letters of credit usually exceeds the contract amount. We believe we have no other off-balance

Concentration of Credit Risk

Concentration of Credit Risk	12 Months Ended
	Dec. 31, 2016
Risks and Uncertainties [Abstract]
Concentration of Credit Risk	11. CONCENTRATION OF CREDIT RISK: The Company grants commercial, retail, agriculture and residential real estate loans to customers primarily in North Central, Southeastern and West Texas. Although the Company has a diversified loan portfolio, a substantial portion of its borrowers’ ability to honor their commitments is dependent upon each local economic sector. In addition, the Company holds mortgage related securities which are guaranteed by GNMA, FNMA or FHLMC or are collateralized by loans backed by these agencies.

Pension and Profit Sharing Plan

Pension and Profit Sharing Plans	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Pension and Profit Sharing Plans	12. PENSION AND PROFIT SHARING PLANS: The Company’s defined benefit pension plan was frozen effective January 1, 2004, whereby no new participants will be added to the Plan and no additional years of service will accrue to participants, unless the pension plan is reinstated at a future date. The pension plan covered substantially all of the Company’s employees at the time. The benefits for each employee were based on years of service and a percentage of the employee’s qualifying compensation during the final years of employment. The Company’s funding policy was and is to contribute annually the amount necessary to satisfy the Internal Revenue Service’s funding standards. Contributions to the pension plan, prior to freezing the plan, were intended to provide not only for benefits attributed to service to date but also for those expected to be earned in the future. As a result of the Pension Protection Act of 2006 (the “Protection Act”), the Company will be required to contribute amounts in future years to fund any shortfalls. The Company has evaluated the provisions of the Protection Act as well as the Internal Revenue Service’s funding standards to develop a plan for funding in future years. As a result, the Company made a contribution totaling $500,000 in both 2016 and 2015, and is continuing to evaluate future funding amounts. During 2016 and 2014, as permitted by the Internal Revenue Service, the Company offered settlement of a portion of its pension obligations to those plan participants who no longer were employed by the Company. As a result of the partial settlement of the plan, the Company recognized $267,000 and $2,909,000 for the years ended December 31, 2016 and 2014, respectively, in additional pension expense, before income tax, a component of noninterest expense. The effect of this transaction was relatively neutral to shareholders’ equity since the recorded pension obligation associated with the plan participants who accepted the settlement closely approximated the amount offered to such plan participants and the amount recognized in pension expense had been previously recognized as unrealized losses in other comprehensive earnings. In connection with this partial settlement, the Company paid $649,000 and $10,626,000 out of pension plan assets and the number of participants was reduced by 38 and 335, in 2016 and 2014, respectively. The Company’s investment risk and administrative expense associated with the Company’s pension plan has been significantly reduced going forward. Using an actuarial measurement date of December 31, 2016 and 2015, benefit obligation activity and fair value of plan assets for the years ended December 31, 2016 and 2015, and a statement of the funded status as of December 31, 2016 and 2015, are as follows (dollars in thousands): 2016 2015 Reconciliation of benefit obligations: Benefit obligation at January 1 $ 16,002 $ 15,581 Interest cost on projected benefit obligation 665 622 Actuarial loss (gain) 139 635 Benefits paid, including partial settlement of certain participant balances (1,353 ) (836 ) Benefit obligation at December 31 $ 15,453 $ 16,002 Reconciliation of fair value of plan assets: Fair value of plan assets at January 1 $ 14,820 $ 15,458 Actual return on plan assets 1,820 (302 ) Employer contributions 500 500 Benefits paid, including partial settlement of certain participant balances (1,353 ) (836 ) Fair value of plan assets at December 31 15,787 14,820 Funded status $ 334 $ (1,182 ) Amounts recognized as a component of accumulated other comprehensive earnings as of year-end 2016 2015 Net actuarial loss $ (4,688 ) $ (6,098 ) Deferred tax benefit 1,641 2,134 Amounts included in accumulated other comprehensive earnings, net of tax $ (3,047 ) $ (3,964 ) Net periodic benefit cost for the years ended December 31, 2016, 2015, and 2014, are as follows (dollars in thousands): Year Ended December 31, 2016 2015 2014 Service cost - benefits earned during the period $ — $ — $ — Interest cost on projected benefit obligation 665 622 1,131 Expected return on plan assets (912 ) (948 ) (1,497 ) Amortization of unrecognized net loss 375 222 337 Recognized loss on partial settlement of certain participant balances 267 — 2,909 Net periodic pension benefit expense (benefit) $ 395 $ (104 ) $ 2,880 The following table sets forth the rates used in the actuarial calculations of the present value of benefit obligations and net periodic pension cost and the rate of return on plan assets: 2016 2015 2014 Weighted average discount rate 4.25 % 4.25 % 4.10 % Expected long-term rate of return on assets 6.25 % 6.25 % 6.25 % The weighted average discount rate is estimated based on setting a discount rate to establish an obligation for pension benefits equivalent to an amount that, if invested in high quality fixed income securities, would produce a return that matches the expected benefit payment stream. The expected long-term rate of return on plan assets is based on historical returns and expectations of future returns based on asset mix, after consultation with our investment advisors and actuaries. The major type of plan assets in the pension plan and the targeted allocation percentage as of December 31, 2016 and 2015 is as follows: December 31, 2016 December 31, 2015 Targeted Equity securities 77 % 74 % 75 % Debt securities 22 % 25 % 25 % Cash and equivalents 1 % 1 % — The range and weighted average final maturities of debt securities held in the pension plan as of December 31, 2016 are 2.52 to 11.34 years and approximately 5.08 years, respectively. Assets held in the pension plan are considered either Level 1 consisting of the money market funds, publicly traded common stocks and publically traded mutual funds or Level 2 consisting of obligations of state and political subdivisions, corporate bonds and mortgage-backed securities. There were no Level 3 securities. See note 8 for a discussion of the fair value hierarchy. The breakdown by level is as follows (dollars in thousands): Level 1 Level 2 Level 3 Total Fair Money market fund $ 100 $ — $ — $ 100 Obligations of state and political subdivisions — 659 — 659 Corporate bonds — 885 — 885 Mortgage-backed securities — 956 — 956 Corporate stocks and mutual funds 13,187 — — 13,187 Total $ 13,287 $ 2,500 $ — $ 15,787 First Financial Trust & Asset Management Company, National Association, a wholly owned subsidiary of the Company, manages the pension plan assets as well as the profit sharing plan assets (see below). The investment strategy and targeted allocations are based on similar strategies First Financial Trust & Asset Management Company, National Association employs for most of its managed accounts whereby appropriate diversification is achieved. First Financial Trust & Asset Management Company, National Association is prohibited from holding investments deemed to be high risk by the Office of the Comptroller of the Currency. An estimate of the undiscounted projected future payments to eligible participants for the next five years and the following five years in the aggregate is as follows (in thousands): Year Ending December 31, 2017 856 2018 872 2019 892 2020 913 2021 935 2022 forward 4,861 As of December 31, 2016 and 2015, the pension plan’s total assets included First Financial Bankshares, Inc. common stock valued at approximately $2,786,000 and $1,859,000, respectively. The Company also provides a profit sharing plan, which covers substantially all full-time employees. The profit sharing plan is a defined contribution plan and allows employees to contribute a percentage of their base annual salary. Employees are fully vested to the extent of their contributions and become fully vested in the Company’s contributions over a six-year In 2004, after freezing our pension plan, we added a safe harbor match to the 401(k) plan. We match a maximum of 4% on employee deferrals of 5% of their employee compensation. Total expense for this matching in 2016, 2015 and 2014 was $2,331,000, $2,043,000 and $1,699,000, respectively, and is included in salaries and employee benefits in the statements of earnings. The Company has a directors’ deferred compensation plan whereby the directors may elect to defer up to 100% of their directors’ fees. All deferred compensation is invested in the Company’s common stock held in a rabbi trust. The stock is held in nominee name of the trustee, and the principal and earnings of the trust are held separate and apart from other funds of the Company, and are used exclusively for the uses and purposes of the deferred compensation agreement. The accounts of the trust have been consolidated in the financial statements of the Company.

Dividends from Subsidiaries

Dividends from Subsidiaries	12 Months Ended
	Dec. 31, 2016
Text Block [Abstract]
Dividends from Subsidiaries	13. DIVIDENDS FROM SUBSIDIARIES: At December 31, 2016, approximately $170,730,000 was available for the declaration of dividends by the Company’s subsidiaries without the prior approval of regulatory agencies.

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2016
Banking and Thrift [Abstract]
Regulatory Matters	14. REGULATORY MATTERS: Banking regulators measure capital adequacy by means of the risk-based capital ratios and the leverage ratio under the Basel III regulatory capital framework and prompt corrective action regulations. The risk-based capital rules provide for the weighting of assets and off-balance-sheet quarter-to-date Beginning in January 2016, under the Basel III regulatory capital framework, the implementation of the capital conservation buffer was effective for the Company starting at the 0.625% level and increasing 0.625% each year thereafter, until it reaches 2.5% on January 1, 2019. The capital conservation buffer is designed to absorb losses during periods of economic stress and requires increased capital levels for the purpose of capital distributions and other payments. Failure to meet the amount of the buffer will result in restrictions on the Company’s ability to make capital distributions, including dividend payments and stock repurchases, and to pay discretionary bonuses to executive officers. As of December 31, 2016 and 2015, we had a total risk-based capital ratio of 18.45% and 16.97%, a Tier 1 capital to risk-weighted assets ratio of 17.30% and 15.90%; a common equity Tier 1 capital to risk-weighted assets ratio of 17.30% and 15.90%, and a Tier 1 leverage ratio of 10.71% and 9.96%, respectively. The regulatory capital ratios as of December 31, 2016 and 2015 were calculated under Basel III rules. There is no threshold for well-capitalized status for bank holding companies. As of December 31, 2016 and 2015, the regulatory capital ratios of the Company and Bank under the Basel III regulatory capital framework are as follows: Actual Minimum Capital Phase-In Minimum Capital Phased-In Required to be As of December 31, 2016: Amount Ratio Amount Ratio Amount Ratio Amount Ratio Total Capital to Risk-Weighted Assets: Consolidated $ 739,959 18.45 % $ 345,827 8.625 % $ 421,007 10.50 % — N/A First Financial Bank, N.A. $ 633,403 15.84 % $ 344,930 8.625 % $ 419,915 10.50 % $ 399,919 10.00 % Tier 1 Capital to Risk-Weighted Assets: Consolidated $ 693,584 17.30 % $ 265,635 6.625 % $ 340,815 8.50 % — N/A First Financial Bank, N.A. $ 587,028 14.68 % $ 264,946 6.625 % $ 339,931 8.50 % $ 319,935 8.00 % Common Equity Tier 1 Capital to Risk-Weighted Assets: Consolidated $ 693,584 17.30 % $ 205,491 5.125 % $ 280,671 7.00 % — N/A First Financial Bank, N.A. $ 587,028 14.68 % $ 204,959 5.125 % $ 279,943 7.00 % $ 259,947 6.50 % Leverage Ratio: Consolidated $ 693,584 10.71 % $ 258,978 4.00 % $ 258,978 4.00 % — N/A First Financial Bank, N.A. $ 587,028 9.10 % $ 257,941 4.00 % $ 257,941 4.00 % $ 322,426 5.00 % As of December 31, 2015: Total Capital to Risk-Weighted Assets: Consolidated $ 672,920 16.97 % $ 318,528 8.00 % $ 418,068 10.50 % — N/A First Financial Bank, N.A. $ 570,910 14.37 % $ 317,788 8.00 % $ 417,097 10.50 % $ 397,235 10.00 % Tier 1 Capital to Risk-Weighted Assets: Consolidated $ 630,413 15.90 % $ 238,896 6.00 % $ 338,436 8.50 % — N/A First Financial Bank, N.A. $ 528,403 13.30 % $ 238,341 6.00 % $ 337,650 8.50 % $ 317,788 8.00 % Common Equity Tier 1 Capital to Risk-Weighted Assets: Consolidated $ 630,413 15.90 % $ 179,172 4.50 % $ 278,712 7.00 % — N/A First Financial Bank, N.A. $ 528,403 13.30 % $ 178,756 4.50 % $ 278,065 7.00 % $ 258,203 6.50 % Leverage Ratio: Consolidated $ 630,413 9.96 % $ 256,368 4.00 % $ 256,368 4.00 % — N/A First Financial Bank, N.A. $ 528,403 8.37 % $ 252,419 4.00 % $ 252,419 4.00 % $ 315,524 5.00 % We have performed a preliminary assessment using the regulatory capital estimation tool made available by the OCC and believe the Company and Bank are prepared to meet the new requirements upon full adoption of Basel III that will be effective December 31, 2019. In connection with the adoption of the Basel III regulatory capital framework, our subsidiary bank made the election to continue to exclude most accumulated other comprehensive income (“AOCI”) from capital in connection with its March 31, 2015 quarterly financial filing and, in effect, to retain the AOCI treatment under the prior capital rules. In connection with the First Financial Trust & Asset Management Company, National Association’s (the “Trust Company”) application to obtain our trust charter, the Trust Company is required to maintain tangible net assets of $2,000,000 at all times. As of December 31, 2016, our Trust Company had tangible net assets totaling $14,300,000. Our subsidiary bank may be required at times to maintain reserve balances with the Federal Reserve Bank. At December 31, 2016 and 2015, the subsidiary bank’s reserve balances were $4,340,000 and $17,725,000, respectively.

Stock Option Plan and Restricte

Stock Option Plan and Restricted Stock Plan	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Option Plan and Restricted Stock Plan	15. STOCK OPTION PLAN AND RESTRICTED STOCK PLAN: The Company has an incentive stock plan to provide for the granting of options to employees of the Company at prices not less than market at the date of grant. At December 31, 2016, the Company had allocated 3,337,000 shares of stock for issuance under the plan. The plan provides that options granted are exercisable after two years from date of grant at a rate of 20% each year cumulatively during the 10-year Weighted- Shares Weighted- Remaining Aggregate Intrinsic Outstanding, beginning of year 1,231,346 $ 26.70 Granted — — Exercised (82,871 ) 15.69 Cancelled (54,440 ) (29.52 ) Outstanding, end of year 1,094,035 27.40 6.56 $ 19,475 Exercisable at end of year 422,945 $ 20.38 4.29 $ 10,498 The options outstanding at December 31, 2016, had exercise prices ranging between $13.66 and $33.89. Stock options have been adjusted retroactively for the effects of stock dividends and splits. The following table summarizes information concerning outstanding and vested stock options as of December 31, 2016: Exercise Price Number Remaining Number Vested $ 13.66 36,522 0.1 36,522 16.78 123,473 2.4 123,473 15.73 180,380 4.8 136,460 30.85 320,410 6.8 126,490 $ 33.89 433,250 8.8 — 1,094,035 422,945 The fair value of the options granted during 2015 were estimated using the Black-Scholes options pricing model with the following weighted-average assumptions: risk-free interest rate of 1.89%; expected dividend yield of 1.89%; expected life of 5.78 years; and expected volatility of 23.36%. The weighted-average grant-date fair value of options granted during 2015 was $6.72. There were no grants during 2014 and 2016. The total intrinsic value of options exercised during the years ended December 31, 2016, 2015, and 2014, was $1,226,000, $1,539,000 and $1,738,000, respectively. As of December 31, 2016, there was $3,058,000 of total unrecognized compensation cost related to nonvested share-based compensation arrangements granted under the Plan. That cost is expected to be recognized over a weighted-average period of 2.14 years. The total fair value of shares vested during the years ended December 31, 2016, 2015, and 2014 was $592,000, $810,000 and $382,000. The aggregate intrinsic value of vested stock options at December 31, 2016 totaled $10,498,000. On April 28, 2015, shareholders of the Company approved a restricted stock plan for selected employees, officers, non-employee On July 21, 2015, 7,070 shares were granted to the ten non-employee re-election non-employee On October 27, 2015, the Company granted 31,273 shares with a total value of $1,060,000 to certain officers that is being expensed over the vesting period of three years. On October 25, 2016, the Company granted 15,405 shares with a total value of $560,000 to certain officers that is being expensed over the vesting period of three years. The Company recorded restricted stock expense for officers of $381,000 and $62,000, respectively, for the year ended December 31, 2016 and 2015.

Condensed Financial Information

Condensed Financial Information - Parent Company	12 Months Ended
	Dec. 31, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Financial Information - Parent Company	16. CONDENSED FINANCIAL INFORMATION - PARENT COMPANY: Condensed Balance Sheets-December 31, 2016 and 2015 2016 2015 ASSETS Cash in subsidiary bank $ 15,070 $ 12,311 Cash in unaffiliated banks 2 2 Interest-bearing deposits in subsidiary bank 78,179 78,160 Total cash and cash equivalents 93,251 90,473 Securities available-for-sale, 11,593 12,062 Investment in and advances to subsidiaries, at equity 744,971 713,909 Intangible assets 723 723 Other assets 2,668 3,693 Total assets $ 853,206 $ 820,860 LIABILITIES AND SHAREHOLDERS’ EQUITY Total liabilities $ 15,321 $ 15,874 Shareholders’ equity: Common stock 661 660 Capital surplus 372,245 368,925 Retained earnings 446,534 388,006 Treasury stock (6,671 ) (6,296 ) Deferred compensation 6,671 6,296 Accumulated other comprehensive earnings 18,445 47,395 Total shareholders’ equity 837,885 804,986 Total liabilities and shareholders’ equity $ 853,206 $ 820,860 Condensed Statements of Earnings- For the Years Ended December 31, 2016, 2015 and 2014 2016 2015 2014 Income: Cash dividends from subsidiaries $ 48,800 $ 51,200 $ 34,000 Excess of earnings over dividends of subsidiaries 58,809 52,911 58,539 Other 4,184 4,185 3,717 Total Income 111,793 108,296 96,256 Expenses: Salaries and employee benefits 5,655 6,067 5,595 Other operating expenses 3,531 4,439 3,309 Total Expense 9,186 10,506 8,904 Earnings before income taxes 102,607 97,790 87,352 Income tax benefit 2,167 2,591 2,207 Net earnings $ 104,774 $ 100,381 $ 89,559 Condensed Statements of Cash Flows- For the Years Ended December 31, 2016, 2015, and 2014 2016 2015 2014 Cash flows from operating activities: Net earnings $ 104,774 $ 100,381 $ 89,559 Adjustments to reconcile net earnings to net cash provided by operating activities: Excess of earnings over dividends of subsidiary bank (58,809 ) (52,911 ) (58,539 ) Depreciation and amortization, net 208 197 200 Decrease (increase) in other assets 1,702 507 (150 ) Increase (decrease) in other liabilities (1,374 ) 3,743 (314 ) Other 8 — — Net cash provided by operating activities 46,509 51,917 30,756 Cash flows from investing activities: Cash received (paid) in connection with acquisition of banks — 13,125 — Net decrease in interest-bearing time deposits in unaffiliated banks — — 480 Purchases of bank premises and equipment (94 ) (107 ) (780 ) Repayment from (of advances to) investment in and advances to subsidiaries, net — 5,800 (3,300 ) Other 10 — — Net cash used in (provided by) investing activities (84 ) 18,818 (3,600 ) Cash flows from financing activities: Repayment of subordinated debt — (13,125 ) — Proceeds of stock issuances 1,260 1,545 1,437 Cash dividends paid (44,907 ) (38,767 ) (34,578 ) Net cash used in financing activities (43,647 ) (50,347 ) (33,141 ) Net increase (decrease) in cash and cash equivalents 2,778 20,388 (5,985 ) Cash and cash equivalents, beginning of year 90,473 70,085 76,070 Cash and cash equivalents, end of year $ 93,251 $ 90,473 $ 70,085

Cash Flow Information

Cash Flow Information	12 Months Ended
	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Cash Flow Information	17. CASH FLOW INFORMATION: Supplemental information on cash flows and noncash transactions is as follows (dollars in thousands): Year Ended December 31, 2016 2015 2014 Supplemental cash flow information: Interest paid $ 5,465 $ 4,085 $ 4,231 Federal income taxes paid 28,348 29,674 28,711 Schedule of noncash investing and financing activities: Assets acquired through foreclosure 2,269 203 1,385 Investment securities purchased but not settled 12,381 — 1,248

Acquisitions and Asset Purchase

Acquisitions and Asset Purchase	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Acquisitions and Asset Purchase	18. ACQUISITIONS AND ASSET PURCHASE: On April 1, 2015, we entered into an agreement and plan of reorganization to acquire FBC Bancshares, Inc. and its wholly owned bank subsidiary, First Bank, N.A., Conroe, Texas. On July 31, 2015, the transaction was completed. Pursuant to the agreement, we issued 1,755,374 shares of the Company’s common stock in exchange for all of the outstanding shares of FBC Bancshares, Inc. At closing, FBC Bancshares, Inc. was merged into the Company and First Bank, N.A., Conroe, Texas, was merged into First Financial Bank, National Association, 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 45 in southern Texas, north of Houston. Factors that contributed to a purchase price resulting in goodwill include First Bank, N.A.’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 August 1, 2015. The assets acquired and liabilities assumed were recorded on the consolidated balance sheet at estimated fair value on the acquisition date. 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 (dollars in thousands): Fair value of consideration paid: Common stock issued (1,755,374 shares) $ 59,648 Fair value of identifiable assets acquired: Cash and cash equivalents 65,197 Securities available-for-sale 42,903 Loans 248,380 Identifiable intangible assets 2,343 Other assets 15,262 Total identifiable assets acquired 374,085 Fair value of liabilities assumed: Deposits 343,583 Subordinated debt 13,125 Other liabilities 1,651 Total liabilities assumed 358,359 Fair value of net identifiable assets acquired 15,726 Goodwill resulting from acquisition $ 43,922 Goodwill recorded in the acquisition 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 not deductible for federal income tax purposes. The subordinated debt of $13,125,000 was paid off August 3, 2015, subsequent to closing. The fair value of total loans acquired was $248,380,000 at acquisition compared to contractual amounts of $252,458,000. The fair value of purchased credit impaired loans at acquisition was $1,398,000 compared to contractual amounts of $1,704,000. Additional purchased credit impaired loan disclosures were omitted due to immateriality. All other acquired loans were considered performing loans. First Bank, N.A. had branches in Conroe, Magnolia, Tomball, Willis, Cut and Shoot and Huntsville, all located north of Houston, Texas. In February 2016, the Company closed First Bank’s Huntsville location and consolidated the branch with the Company’s existing Huntsville location. On April 8, 2015, the Company announced that it had entered into an asset purchase agreement with 4Trust Mortgage, Inc. for a cash purchase price of $1,900,000. The asset purchase was finalized on June 1, 2015. The total asset purchase price exceeded the estimated fair value of assets purchased by approximately $1,750,000 and the Company recorded such excess as goodwill.

Summary of Significant Accoun28

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations First Financial Bankshares, Inc. (a Texas corporation) (“Bankshares”, “Company”, “we” or “us”) is a financial holding company which owns all of the capital stock of one bank with 69 locations located in Texas as of December 31, 2016. The subsidiary bank is First Financial Bank, National Association, Abilene. The bank’s primary source of revenue is providing loans and banking services to consumers and commercial customers in the market area in which the subsidiary is located. In addition, the Company also owns First Financial Trust & Asset Management Company, National Association, First Financial Insurance Agency, Inc., and First Technology Services, Inc. A summary of significant accounting policies of Bankshares and its subsidiaries applied in the preparation of the accompanying consolidated financial statements follows. The accounting principles followed by the Company and the methods of applying them are in conformity with both U.S. GAAP and prevailing practices of the banking industry. The Company evaluated subsequent events for potential recognition through the date the consolidated financial statements were issued.
Use of Estimates in Preparation of Financial Statements	Use of Estimates in Preparation of Financial Statements The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The Company’s significant estimates include its allowance for loan losses and its valuation of financial instruments.
Consolidation	Consolidation The accompanying consolidated financial statements include the accounts of Bankshares and its subsidiaries, all of which are wholly-owned. All significant intercompany accounts and transactions have been eliminated.
Stock Repurchase	Stock Repurchase On October 28, 2014, the Company’s Board of Directors authorized the repurchase of up to 1,500,000 common shares through September 30, 2017. The stock buyback plan authorizes management to repurchase the stock at such time as repurchases are considered beneficial to stockholders. 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. For the years ended December 31, 2016, 2015 and 2014, no shares were repurchased under this or the prior authorization that expired September 30, 2014.
Stock Split	Stock Split On April 22, 2014, the Company’s Board of Directors declared a two-for-one
Acquisitions and Asset Purchase	Acquisitions and Asset Purchase On July 31, 2015, the Company acquired 100% of the outstanding capital stock of FBC Bancshares, Inc. through the merger of a wholly-owned subsidiary with and into FBC Bancshares, Inc. Following such merger, FBC Bancshares, Inc. and its wholly-owned subsidiary, First Bank, N.A. were merged into the Company and First Financial Bank, National Association, respectively. The results of operations of FBC Bancshares, Inc. subsequent to the acquisition date, are included in the consolidated earnings of the Company. See Note 18 for additional information. On June 1, 2015, the Company completed the asset purchase of 4Trust Mortgage, Inc. The results of operation of 4Trust Mortgage Inc. subsequent to the asset purchase date, are included in the consolidated earnings of the Company. See Note 18 for additional information.
Increase in Authorized Shares	Increase in Authorized Shares On April 28, 2015, 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 120,000,000.
Investment Securities	Investment Securities Management classifies debt and equity securities as held-to-maturity, available-for-sale, held-to-maturity held-to-maturity available-for-sale Available-for-sale The Company records its available-for-sale When the fair value of a security is below its amortized cost, and depending on the length of time the condition exists and the extent the fair value is below amortized cost, additional analysis is performed to determine whether an other-than-temporary impairment condition exists. Available-for-sale held-to-maturity The Company’s investment portfolio consists of U.S. Treasury securities, obligations of U.S. government sponsored enterprises and agencies, obligations of state and political subdivisions, mortgage pass-through securities, corporate bonds and general obligation or revenue based municipal bonds. Pricing for such securities is generally readily available and transparent in the market. The Company utilizes independent third party pricing services to value its investment securities, which the Company reviews as well as the underlying pricing methodologies for reasonableness and to ensure such prices are aligned with pricing matrices. The Company validates quarterly, on a sample basis, prices supplied by the independent pricing services by comparison to prices obtained from other third party sources.
Loans and Allowance for Loan Losses	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 allowance for loan losses is an amount which represents management’s best estimate of probable losses that are inherent in the Company’s loan portfolio as of the balance sheet date. The allowance for loan losses is comprised of three elements: (i) specific reserves determined based on probable losses on specific classified loans; (ii) a historical valuation reserve component that considers historical loss rates and estimated loss emergence periods; and (iii) qualitative reserves based upon general economic conditions and other qualitative risk factors both internal and external to the Company. The allowance for loan losses is increased by charges to income and decreased by charge-offs Although we believe we use the best information available to make loan loss allowance determinations, future adjustments could be necessary if circumstances or economic conditions differ substantially from the assumptions used in making our initial determinations. A decline in the economy and employment could result in increased levels of non-performing 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. charged-off charge-off Loans are considered impaired when, based on current information and events, management determines that it is probable we will be unable to collect all amounts due in accordance with the loan agreement, including scheduled principal and interest payments. If a loan is impaired, a specific valuation allowance is allocated, if necessary. Interest payments on impaired loans are typically applied to principal unless collectability of the principal amount is reasonably assured, in which case interest is recognized on a cash basis. Impaired loans, or portions thereof, are charged off when deemed uncollectable. The Company’s policy requires measurement of the allowance for an impaired, collateral dependent loan based on the fair value of the collateral. Other loan impairments for non-collateral From time to time, the Company modifies its loan agreement with a borrower. A modified loan is considered a troubled debt restructuring when two conditions are met: (i) the borrower is experiencing financial difficulty and (ii) concessions are made by the Company that would not otherwise be considered for a borrower with similar credit risk characteristics. Modifications to loan terms may include a lower interest rate, a reduction of principal, or a longer term to maturity. For all impaired loans, including the Company’s troubled debt restructurings, the Company performs a periodic, well-documented credit evaluation of the borrower’s financial condition and prospects for repayment to assess the likelihood that all principal and interest payments required under the terms of the agreement will be collected in full. When doubt exists about the ultimate collectability of principal and interest, the troubled debt restructuring remains on non-accrual non-accrual The Company originates certain mortgage loans for sale in the secondary market. Accordingly, these loans are classified as held-for-sale Loans acquired, including loans acquired in a business combination, are initially recorded at fair value with no valuation allowance. Acquired loans are segregated between those considered to be credit impaired and those deemed performing. To make this determination, management considers such factors as past due status, non-accrual Purchased credit impaired loans are those loans that showed evidence of deterioration of credit quality since origination and for which it is probable, at acquisition, that the Company will be unable to collect all amounts contractually owed. Their acquisition fair value, which includes a credit component at the acquisition date, was based on the estimate of cash flows, both principal and interest, expected to be collected or estimated collateral values if cash flows are not estimable, discounted at prevailing market rates of interest. The difference between the discounted cash flows expected at acquisition and the investment in the loan is recognized as interest income on a level-yield method over the life of the loan, unless management was unable to reasonably forecast cash flows in which case the loans were placed on nonaccrual. Contractually required payments for interest and principal that exceed the cash flows expected at acquisition are not recognized as a yield adjustment. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows subsequent to acquisition are recognized as impairment. Valuation allowances on these impaired loans reflect only losses incurred after the acquisition. The carrying amount of purchased credit impaired loans at December 31, 2016 and 2015 were $1,256,000 and $2,178,000, respectively, compared to a contractual balance of $1,865,000 and $2,936,000, respectively. Other purchased credit impaired loan disclosures were omitted due to immateriality.
Other Real Estate	Other Real Estate Other real estate owned is foreclosed property held pending disposition and is initially recorded at fair value, less estimated costs to sell. At foreclosure, if the fair value of the real estate, less estimated costs to sell, is less than the Company’s recorded investment in the related loan, a write-down is recognized through a charge to the allowance for loan losses. Any subsequent reduction in value is recognized by a charge to income. Operating and holding expenses of such properties, net of related income, and gains and losses on their disposition are included in net gain (loss) on sale of foreclosed assets as incurred.
Bank Premises and Equipment	Bank Premises and Equipment Bank premises and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization are computed principally on a straight-line basis over the estimated useful lives of the related assets. Leasehold improvements are amortized over the life of the respective lease or the estimated useful lives of the improvements, whichever is shorter.
Business Combinations, Goodwill and Other Intangible Assets	Business Combinations, Goodwill and Other Intangible Assets The Company accounts for all business combinations under the purchase method of accounting. Tangible and intangible assets and liabilities of the acquired entity are recorded at fair value. Intangible assets with finite useful lives represent the future benefit associated with the acquisition of the core deposits and are amortized over seven years, utilizing a method that approximates the expected attrition of the deposits. Goodwill with an indefinite life is not amortized, but rather tested annually for impairment as of June 30 each year and totaled $139,971,000 at both December 31, 2016 and 2015. There was no impairment recorded for the years ended December 31, 2016, 2015 and 2014. The carrying amount of goodwill arising from acquisitions that qualify as an asset purchase for federal income tax purposes was $74,376,000 both at December 31, 2016 and 2015, and is deductible for federal income tax purposes. Also included in other intangible assets are mortgage servicing rights totaling $1,795,000 and $1,902,000 at December 31, 2016 and 2015, respectively.
Securities Sold Under Agreements To Repurchase	Securities Sold Under Agreements To Repurchase Securities sold under agreements to repurchase, which are classified as borrowings, generally mature within one to four days from the transaction date. Securities sold under agreements to repurchase are reflected at the amount of the cash received in connection with the transaction. The Company may be required to provide additional collateral based on the estimated fair value of the underlying securities.
Segment Reporting	Segment Reporting The Company has determined that its banking regions meet the aggregation criteria of the current authoritative accounting guidance since each of its banking regions offer similar products and services, operate in a similar manner, have similar customers and report to the same regulatory authority, and therefore operate one line of business (community banking) located in a single geographic area (Texas).
Statements of Cash Flows	Statements of Cash Flows For purposes of reporting cash flows, cash and cash equivalents includes cash on hand, amounts due from banks, including interest-bearing deposits in banks with original maturity of 90 days or less, and federal funds sold.
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Unrealized net gains on the Company’s available-for-sale
Income Taxes	Income Taxes The Company’s provision for income taxes is based on income before income taxes adjusted for permanent differences between financial reporting and taxable income. Deferred tax assets and liabilities are determined using the liability (or balance sheet) method. Under this method, the net deferred tax asset or liability is determined based on the tax effects of the temporary differences between the book and tax bases of the various balance sheet assets and liabilities and gives current recognition to changes in tax rates and laws.
Stock Based Compensation	Stock Based Compensation The Company grants stock options for a fixed number of shares to employees with an exercise price equal to the fair value of the shares at the grant date. The Company recorded stock option expense totaling $882,000, $644,000 and $709,000 for the years ended December 31, 2016, 2015 and 2014, respectively. The Company also grants restricted stock for a fixed number of shares. The Company recorded expenses associated with its director and officer restricted stock grants totaling $278,000 and $381,000, respectively, for the year ended December 31, 2016 and $139,000 and $62,000, respectively, for the year ended December 31, 2015. As the restricted stock plan was approved by shareholders in April 2015, there were no such expenses in 2014.
Advertising Costs	Advertising Costs Advertising costs are expensed as incurred.
Per Share Data	Per Share Data Net earnings per share (“EPS”) are computed by dividing net earnings by the weighted average number of common stock shares outstanding during the period. The Company calculates dilutive EPS assuming all outstanding stock options to purchase common stock have been exercised at the beginning of the year (or the time of issuance, if later.) The dilutive effect of the outstanding options and restricted stock is reflected by application of the treasury stock method, whereby the proceeds from the exercised options and restricted stock are assumed to be used to purchase common stock at the average market price during the respective year. The following table reconciles the computation of basic EPS to dilutive EPS: Net Weighted Per Share For the year ended December 31, 2016: Net earnings per share, basic $ 104,774 66,013,004 $ 1.59 Effect of stock options and stock grants — 89,882 — Net earnings per share, assuming dilution $ 104,774 66,102,886 $ 1.59 For the year ended December 31, 2015: Net earnings per share, basic $ 100,381 64,892,934 $ 1.55 Effect of stock options and stock grants — 175,096 (0.01 ) Net earnings per share, assuming dilution $ 100,381 65,068,030 $ 1.54 For the year ended December 31, 2014: Net earnings per share, basic $ 89,559 64,047,803 $ 1.40 Effect of stock options — 260,732 (0.01 ) Net earnings per share, assuming dilution $ 89,559 64,308,535 $ 1.39
Recently Issued Authoritative Accounting Guidance	Recently Issued Authoritative Accounting Guidance Accounting Standards Update ( “ ASU ” ) 2014-09, “ Revenue from Contracts with Customers. ” 2014-09 2015-4 2014-09 2014-09, non-interest 2014-09 2014-09 non-interest ASU 2014-11, “Transfers and Servicing.” 2014-11 repurchase-to-maturity repurchase-to-maturity repurchase-to-maturity ASU 2014-14, “Receivables – Troubled Debt Restructuring by Creditors.” 2014-14 ASU 2014-15, “Presentation of Financial Statements – Going Concern.” 2014-15 2014-15 ASU 2015-01, “Income Statement – Extraordinary and Unusual Items.” 2015-01 ASU 2015-05, “ Intangibles – Goodwill and Other – Internal-Use Software – Customer ’ s Accounting for Fees Paid in a Cloud Computing Arrangement. ” 2015-05 2015-05 2015-05 ASU 2015-16, “Business Combinations – Simplifying the Accounting Measurement Period Adjustments. 2015-16 ASU 2016-1, “Financial Instruments – Overall: Recognition and Measurement of Financial Assets and Financial Liabilities.” 2016-1, available-for-sale 2016-1 ASU 2016-02, “Leases.” 2016-02 right-of-use 2016-02 ASU 2016-09, “Compensation – Stock Compensation: Improvements to Employee Share-Based Payment Accounting.” 2016-09 2016-09 2016-09 ASU 2016-13, “ Financial Instruments – Credit Losses. ” 2016-13 held-to-maturity 2016-13 2016-13 ASU 2017-04, “Intangibles – Goodwill and Other.” 2017-04 2017-04

Summary of Significant Accoun29

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Computation of Basic EPS to Dilutive EPS	The following table reconciles the computation of basic EPS to dilutive EPS: Net Weighted Per Share For the year ended December 31, 2016: Net earnings per share, basic $ 104,774 66,013,004 $ 1.59 Effect of stock options and stock grants — 89,882 — Net earnings per share, assuming dilution $ 104,774 66,102,886 $ 1.59 For the year ended December 31, 2015: Net earnings per share, basic $ 100,381 64,892,934 $ 1.55 Effect of stock options and stock grants — 175,096 (0.01 ) Net earnings per share, assuming dilution $ 100,381 65,068,030 $ 1.54 For the year ended December 31, 2014: Net earnings per share, basic $ 89,559 64,047,803 $ 1.40 Effect of stock options — 260,732 (0.01 ) Net earnings per share, assuming dilution $ 89,559 64,308,535 $ 1.39

Interest-bearing Time Deposit30

Interest-bearing Time Deposits in Banks and Securities (Tables)	12 Months Ended
	Dec. 31, 2016
Cash and Cash Equivalents [Abstract]
Summary of Available-for-Sale Securities	A summary of the Company’s available-for-sale December 31, 2016 Amortized Gross Gross Estimated Securities available-for-sale: U.S. Treasury securities $ 10,649 $ 19 $ — $ 10,668 Obligations of U.S. government sponsored enterprises and agencies 113,450 253 — 113,703 Obligations of state and political subdivisions 1,534,095 40,194 (10,013 ) 1,564,276 Corporate bonds and other 51,920 476 (3 ) 52,393 Residential mortgage-backed securities 848,614 8,260 (5,513 ) 851,361 Commercial mortgage-backed securities 269,044 622 (1,230 ) 268,436 Total securities available-for-sale $ 2,827,772 $ 49,824 $ (16,759 ) $ 2,860,837 December 31, 2015 Amortized Gross Gross Estimated Securities available-for-sale: U.S. Treasury securities $ 10,792 $ 5 $ (2 ) $ 10,795 Obligations of U.S. government sponsored enterprises and agencies 148,393 268 (107 ) 148,554 Obligations of state and political subdivisions 1,379,879 71,382 (134 ) 1,451,127 Corporate bonds and other 86,182 1,778 (5 ) 87,955 Residential mortgage-backed securities 781,648 10,993 (3,759 ) 788,882 Commercial mortgage-backed securities 247,991 429 (1,834 ) 246,586 Total securities available-for-sale $ 2,654,885 $ 84,855 $ (5,841 ) $ 2,733,899
Amortized Cost and Estimated Fair Value of Available-for-Sale Securities	The amortized cost and estimated fair value of available-for-sale Amortized Estimated Due within one year $ 206,182 $ 207,276 Due after one year through five years 664,151 684,849 Due after five years through ten years 836,421 845,257 Due after ten years 3,360 3,658 Mortgage-backed securities 1,117,658 1,119,797 Total $ 2,827,772 $ 2,860,837
Continuous Unrealized-Loss Position of Available-for-Sale Securities	The following tables disclose, as of December 31, 2016 and 2015, the Company’s investment securities that have been in a continuous unrealized-loss Less than 12 Months 12 Months or Longer Total December 31, 2016 Fair Unrealized Fair Unrealized Fair Unrealized Obligations of state and political subdivisions $ 446,052 $ 9,997 $ 1,209 $ 16 $ 447,261 $ 10,013 Corporate bonds and other 244 3 — — 244 3 Residential mortgage-backed securities 372,331 4,532 33,227 981 405,558 5,513 Commercial mortgage-backed securities 193,495 1,180 13,263 50 206,758 1,230 Total $ 1,012,122 $ 15,712 $ 47,699 $ 1,047 $ 1,059,821 $ 16,759 Less than 12 Months 12 Months or Longer Total December 31, 2015 Fair Unrealized Fair Unrealized Fair Unrealized U.S. Treasury securities $ 5,110 $ 2 $ — $ — $ 5,110 $ 2 Obligations of U.S. government sponsored enterprises and agencies 50,388 107 — — 50,388 107 Obligations of state and political subdivisions 32,929 127 1,513 7 34,442 134 Corporate bonds and other 7,004 5 — — 7,004 5 Residential mortgage-backed securities 231,481 1,765 63,919 1,994 295,400 3,759 Commercial mortgage-backed securities 196,163 1,752 9,345 82 205,508 1,834 Total $ 523,075 $ 3,758 $ 74,777 $ 2,083 $ 597,852 $ 5,841

Loans and Allowance for Loan 31

Loans and Allowance for Loan Losses (Tables)	12 Months Ended
	Dec. 31, 2016
Receivables [Abstract]
Loans Held-for-Investment by Class of Financing Receivables	Loans held-for-investment December 31, 2016 2015 Commercial $ 674,410 $ 696,163 Agricultural 84,021 102,351 Real estate 2,189,844 2,136,233 Consumer 409,032 382,303 Total loans held-for-investment $ 3,357,307 $ 3,317,050
Non-Accrual Loans, Loans Still Accruing and Past Due 90 Days or More and Restructured Loans	The Company’s non-accrual December 31, 2016 2015 Non-accrual $ 27,371 $ 28,601 Loans still accruing and past due 90 days or more 284 341 Troubled debt restructured loans** 701 199 Total $ 28,356 $ 29,141 * Includes $1,256,000 and $2,178,000, respectively, of purchased credit impaired loans as of December 31, 2016 and 2015. ** Our troubled debt restructured loans of $6,863,000 and $6,113,000, whose interest collection, after considering economic and business conditions and collection efforts, is doubtful are included in non-accrual
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): December 31, 2016 December 31, 2015 Recorded Investment Valuation Allowance Recorded Investment Valuation Allowance $ 27,371 $ 5,012 $ 28,601 $ 5,071
Schedule of Non-Accrual Loans	Non-accrual December 31, 2016 2015 Commercial $ 7,284 $ 8,761 Agricultural 99 97 Real Estate 18,754 18,766 Consumer 1,234 977 Total $ 27,371 $ 28,601
Schedule of Impaired Loans and Related Allowance	The Company’s impaired loans and related allowance as of December 31, 2016 and 2015 are summarized in the following tables by class of financing receivables (in thousands). No interest income was recognized on impaired loans subsequent to their classification as impaired. December 31, 2016 Unpaid Recorded Recorded Total Related 12 Month Commercial $ 13,389 $ 1,148 $ 6,136 $ 7,284 $ 2,128 $ 4,921 Agricultural 103 — 99 99 25 50 Real Estate 23,466 6,229 12,525 18,754 2,428 16,170 Consumer 1,421 280 954 1,234 431 914 Total $ 38,379 $ 7,657 $ 19,714 $ 27,371 $ 5,012 $ 22,055 * Includes $1,256,000 of purchased credit impaired loans. December 31, 2015 Unpaid Recorded Recorded Total Related 12 Month Commercial $ 10,056 $ 608 $ 8,153 $ 8,761 $ 2,030 $ 5,812 Agricultural 97 — 97 97 70 48 Real Estate 23,710 5,314 13,452 18,766 2,827 15,211 Consumer 1,167 624 353 977 144 664 Total $ 35,030 $ 6,546 $ 22,055 $ 28,601 $ 5,071 $ 21,735 * Includes $2,178,000 of purchased credit impaired loans.
Schedule of Internal Ratings of Loans	The following summarizes the Company’s internal ratings of its loans held-for-investment December 31, 2016 Pass Special Substandard Doubtful Total Commercial $ 629,756 $ 5,769 $ 38,885 $ — $ 674,410 Agricultural 81,620 715 1,686 — 84,021 Real Estate 2,111,947 18,091 59,806 — 2,189,844 Consumer 406,182 212 2,638 — 409,032 Total $ 3,229,505 $ 24,787 $ 103,015 $ — $ 3,357,307 December 31, 2015 Pass Special Substandard Doubtful Total Commercial $ 633,083 $ 9,762 $ 53,318 $ — $ 696,163 Agricultural 99,862 1,398 1,091 — 102,351 Real Estate 2,054,738 29,000 52,458 37 2,136,233 Consumer 379,941 416 1,946 — 382,303 Total $ 3,167,624 $ 40,576 $ 108,813 $ 37 $ 3,317,050
Schedule of Past Due Loans	At December 31, 2016 and 2015, the Company’s past due loans are as follows (in thousands): December 31, 2016 15-59 60-89 Greater Total Total Total Total 90 Commercial $ 3,908 $ 1,122 $ 2,220 $ 7,250 $ 667,160 $ 674,410 $ 10 Agricultural 185 — — 185 83,836 84,021 — Real Estate 13,172 1,301 5,268 19,741 2,170,103 2,189,844 272 Consumer 1,845 368 122 2,335 406,697 409,032 2 Total $ 19,110 $ 2,791 $ 7,610 $ 29,511 $ 3,327,796 $ 3,357,307 $ 284 December 31, 2015 15-59 60-89 Greater Total Total Total Total 90 Commercial $ 3,099 $ 3,652 $ 1,024 $ 7,775 $ 688,388 $ 696,163 $ 54 Agricultural 348 83 — 431 101,920 102,351 — Real Estate 12,247 2,226 2,874 17,347 2,118,886 2,136,233 217 Consumer 1,645 183 266 2,094 380,209 382,303 70 Total $ 17,339 $ 6,144 $ 4,164 $ 27,647 $ 3,289,403 $ 3,317,050 $ 341 * The Company monitors commercial, agricultural and real estate loans after such loans are 15 days past due. Consumer loans are monitored after such loans are 30 days past due.
Schedule of Allowance for Loan Losses by Portfolio Segment	The following table details the allowance for loan losses at December 31, 2016 and 2015 by portfolio segment (in thousands). There were no allowances for purchased credit impaired loans at December 31, 2016 or 2015. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. December 31, 2016 Commercial Agricultural Real Estate Consumer Total Loans individually evaluated for impairment $ 2,128 $ 25 $ 2,428 $ 431 $ 5,012 Loan collectively evaluated for impairment 9,579 1,076 24,436 5,676 40,767 Total $ 11,707 $ 1,101 $ 26,864 $ 6,107 $ 45,779 December 31, 2015 Commercial Agricultural Real Estate Consumer Total Loans individually evaluated for impairment $ 2,030 $ 70 $ 2,827 $ 144 $ 5,071 Loan collectively evaluated for impairment 10,614 1,121 21,548 3,523 36,806 Total $ 12,644 $ 1,191 $ 24,375 $ 3,667 $ 41,877
Changes in Allowance for Loan Losses	Changes in the allowance for loan losses for the years ended December 31, 2016 and 2015 are summarized as follows (in thousands): December 31, 2016 Commercial Agricultural Real Estate Consumer Total Beginning balance $ 12,644 $ 1,191 $ 24,375 $ 3,667 $ 41,877 Provision for loan losses 5,101 104 1,150 3,857 10,212 Recoveries 952 25 2,021 508 3,506 Charge-offs (6,990 ) (219 ) (682 ) (1,925 ) (9,816 ) Ending balance $ 11,707 $ 1,101 $ 26,864 $ 6,107 $ 45,779 December 31, 2015 Commercial Agricultural Real Estate Consumer Total Beginning balance $ 7,990 $ 527 $ 26,657 $ 1,650 $ 36,824 Provision for loan losses 8,044 773 (2,399 ) 3,267 9,685 Recoveries 344 55 558 450 1,407 Charge-offs (3,734 ) (164 ) (441 ) (1,700 ) (6,039 ) Ending balance $ 12,644 $ 1,191 $ 24,375 $ 3,667 $ 41,877
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 December 31, 2016 and 2015 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 $1,256,000 and $2,178,000, respectively, at December 31, 2016 and 2015 are included in loans individually evaluated for impairment. December 31, 2016 Commercial Agricultural Real Estate Consumer Total Loans individually evaluated for impairment $ 7,284 $ 99 $ 18,754 $ 1,234 $ 27,371 Loan collectively evaluated for impairment 667,126 83,922 2,171,090 407,798 3,329,936 Total $ 674,410 $ 84,021 $ 2,189,844 $ 409,032 $ 3,357,307 December 31, 2015 Commercial Agricultural Real Estate Consumer Total Loans individually evaluated for impairment $ 8,761 $ 97 $ 18,766 $ 977 $ 28,601 Loan collectively evaluated for impairment 687,402 102,254 2,117,467 381,326 3,288,449 Total $ 696,163 $ 102,351 $ 2,136,233 $ 382,303 $ 3,317,050
Schedule of Loans Modified and Considered Troubled Debt Restructurings	The Company’s loans that were modified in the years ended December 31, 2016 and 2015, and considered troubled debt restructurings are as follows (in thousands): Year Ended December 31, 2016 Year Ended December 31, 2015 Number Pre-Modification Post- Number Pre-Modification Post- Commercial 15 $ 3,208 $ 3,208 8 $ 447 $ 447 Agricultural — — — 3 128 128 Real Estate 6 1,460 1,460 5 598 598 Consumer 7 189 189 7 255 255 Total 28 $ 4,857 $ 4,857 23 $ 1,428 $ 1,428
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 years ended December 31, 2016 and 2015 (in thousands): Year Ended December 31, 2016 Year Ended December 31, 2015 Adjusted Extended Combined Adjusted Extended Combined Commercial $ — $ 2,560 $ 648 $ — $ 182 $ 265 Agricultural — — — — 128 — Real Estate — 298 1,162 15 150 433 Consumer — 70 119 — 56 199 Total $ — $ 2,928 $ 1,929 $ 15 $ 516 $ 897
Schedule of Troubled Debt Restructurings	The loans with payment default are as follows (dollars in thousands): Year Ended December 31, 2016 Year Ended December 31, 2015 Number Balance Number Balance Commercial 4 $ 1,690 1 $ 66 Agriculture — — — — Real Estate 3 921 1 15 Consumer — — 2 32 Total 7 $ 2,611 4 $ 113
Analysis of Changes in Loans to Officers, Directors, Principal Shareholders, or Associates of Such Persons	An analysis of the changes in loans to officers, directors, principal shareholders, or associates of such persons for the year ended December 31, 2016 (determined as of each respective year-end) Beginning Additional Payments Ending Year ended December 31, 2016 $ 65,729 $ 49,674 $ 70,974 $ 44,429

Bank Premises and Equipment (Ta

Bank Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Summary of Bank Premises and Equipment	The following is a summary of bank premises and equipment (in thousands): Useful Life December 31, 2016 2015 Land — $ 28,266 $ 29,050 Buildings 20 to 40 years 115,566 106,515 Furniture and equipment 3 to 10 years 58,145 54,353 Leasehold improvements Lesser of lease term or 5 to 15 years 4,783 4,328 206,760 194,246 Less- accumulated depreciation and amortization (84,075 ) (78,534 ) Total Bank Premises and Equipment $ 122,685 $ 115,712

Deposits and Borrowings (Tables

Deposits and Borrowings (Tables)	12 Months Ended
	Dec. 31, 2016
Banking and Thrift [Abstract]
Scheduled Maturities of Time Deposits	At December 31, 2016, the scheduled maturities of time deposits (in thousands) were, as follows: Year ending December 31, 2017 $ 419,326 2018 54,713 2019 17,893 2020 9,939 2021 7,093 Thereafter 32 $ 508,996
Schedule of Borrowings	Borrowings at December 31, 2016 and 2015 consisted of the following (dollars in thousands): December 31, 2016 2015 Securities sold under agreements with customers to repurchase $ 360,820 $ 310,330 Federal funds purchased 9,950 6,325 Advances from Federal Home Loan Bank of Dallas 75,000 299,020 Total $ 445,770 $ 615,675

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Tax Expense	The Company files a consolidated federal income tax return. Income tax expense is comprised of the following (dollars in thousands): Year Ended December 31, 2016 2015 2014 Current federal income tax $ 30,381 $ 31,014 $ 29,832 Current state income tax 99 103 94 Deferred federal income tax expense (benefit) 673 320 (893 ) Income tax expense $ 31,153 $ 31,437 $ 29,033
Percentage of Pretax Earnings, Differs from Statutory Federal Income Tax Rate	Income tax expense, as a percentage of pretax earnings, differs from the statutory federal income tax rate as follows: As a Percent of Pretax Earnings 2016 2015 2014 Statutory federal income tax rate 35.0 % 35.0 % 35.0 % Reductions in tax rate resulting from interest income exempt from federal income tax (12.1 ) (11.4 ) (10.6 ) Effect of state income tax 0.1 0.1 0.1 ESOP tax deduction (0.2 ) (0.2 ) (0.2 ) Other 0.1 0.3 0.2 Effective income tax rate 22.9 % 23.8 % 24.5 %
Schedule of Deferred Tax Assets and Liabilities	The approximate effects of each type of difference that gave rise to the Company’s deferred tax assets and liabilities at December 31, 2016 and 2015 are as follows (dollars in thousands): 2016 2015 Deferred tax assets: Tax basis of loans in excess of financial statement basis $ 17,006 $ 16,326 Minimum liability in defined benefit plan 1,641 2,135 Recognized for financial reporting purposes but not yet for tax purposes: Deferred compensation 2,807 2,602 Write-downs and adjustments to other real estate owned and repossessed assets 9 7 Other deferred tax assets 226 224 Total deferred tax assets 21,689 21,294 Deferred tax liabilities: Financial statement basis of fixed assets in excess of tax basis 5,870 5,644 Intangible asset amortization deductible for tax purposes, but not for financial reporting purposes 15,191 13,881 Recognized for financial reporting purposes but not yet for tax purposes: Accretion on investment securities 1,788 1,813 Pension plan contributions 1,799 1,761 Net unrealized gain on investment securities available-for-sale 11,573 27,655 Other deferred tax liabilities 83 71 Total deferred tax liabilities 36,304 50,825 Net deferred tax asset (liability) $ (14,615 ) $ (29,531 )

Fair Value Disclosures (Tables)

Fair Value Disclosures (Tables)	12 Months Ended
	Dec. 31, 2016
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 December 31, 2016, and 2015 segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (in thousands): December 31, 2016 Level 1 Level 2 Level 3 Total Fair Available-for-sale U.S. Treasury securities $ 10,668 $ — $ — $ 10,668 Obligations of U. S. government sponsored enterprises and agencies — 113,703 — 113,703 Obligations of state and political subdivisions — 1,564,276 — 1,564,276 Corporate bonds — 47,965 — 47,965 Residential mortgage-backed securities — 851,361 — 851,361 Commercial mortgage-backed securities — 268,436 — 268,436 Other securities 4,428 — — 4,428 Total $ 15,096 $ 2,845,741 $ — $ 2,860,837 December 31, 2015 Level 1 Level 2 Level 3 Total Fair Available-for-sale U.S. Treasury securities $ 10,795 $ — $ — $ 10,795 Obligations of U. S. government sponsored enterprises and agencies — 148,554 — 148,554 Obligations of state and political subdivisions — 1,451,127 — 1,451,127 Corporate bonds — 83,254 — 83,254 Residential mortgage-backed securities — 788,882 — 788,882 Commercial mortgage-backed securities — 246,586 — 246,586 Other securities 4,701 — — 4,701 Total $ 15,496 $ 2,718,403 $ — $ 2,733,899
Other Real Estate Owned	The following table presents other real estate owned that were re-measured Year Ended 2016 2015 Carrying value of other real estate owned prior to re-measurement $ — $ 351 Write-downs included in gain (loss) on sale of other real estate owned — (95 ) Fair value $ — $ 256
Schedule of Estimated Fair Values and Carrying Values of All Financial Instruments	The estimated fair values and carrying values of all financial instruments under current authoritative guidance at December 31, 2016 and 2015, were as follows (dollars in thousands): 2016 2015 Carrying Estimated Carrying Estimated Fair Value Cash and due from banks $ 204,782 $ 204,782 $ 179,140 $ 179,140 Level 1 Federal funds sold 3,130 3,130 3,810 3,810 Level 1 Interest-bearing deposits in banks 48,574 48,574 89,936 89,936 Level 1 Interest-bearing time deposits in banks 1,707 1,709 3,495 3,500 Level 2 Available-for-sale 2,860,837 2,860,837 2,733,899 2,733,899 Levels 1 and 2 Held-to-maturity 121 124 278 283 Level 2 Loans 3,338,426 3,361,735 3,308,716 3,316,243 Level 3 Accrued interest receivable 36,469 36,469 34,697 34,697 Level 2 Deposits with stated maturities 508,996 510,304 620,852 622,572 Level 2 Deposits with no stated maturities 4,969,543 4,969,543 4,569,317 4,569,317 Level 1 Borrowings 445,770 445,770 615,675 615,675 Level 2 Accrued interest payable 225 225 240 240 Level 2

Financial Instruments with Of36

Financial Instruments with Off-Balance-Sheet Risk (Tables)	12 Months Ended
	Dec. 31, 2016
Text Block [Abstract]
Schedule of Financial Instruments with Off-Balance-Sheet Risk	We generally use the same credit policies in making commitments and conditional obligations as we do for on-balance-sheet Total Notional Financial instruments whose contract amounts represent credit risk: Unfunded lines of credit $ 549,000 Unfunded commitments to extend credit 199,235 Standby letters of credit 27,380 Total commercial commitments $ 775,615

Pension and Profit Sharing Pl37

Pension and Profit Sharing Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Benefit Obligation Activity and Fair Value of Plan Assets and Statement of Funded Status	Using an actuarial measurement date of December 31, 2016 and 2015, benefit obligation activity and fair value of plan assets for the years ended December 31, 2016 and 2015, and a statement of the funded status as of December 31, 2016 and 2015, are as follows (dollars in thousands): 2016 2015 Reconciliation of benefit obligations: Benefit obligation at January 1 $ 16,002 $ 15,581 Interest cost on projected benefit obligation 665 622 Actuarial loss (gain) 139 635 Benefits paid, including partial settlement of certain participant balances (1,353 ) (836 ) Benefit obligation at December 31 $ 15,453 $ 16,002 Reconciliation of fair value of plan assets: Fair value of plan assets at January 1 $ 14,820 $ 15,458 Actual return on plan assets 1,820 (302 ) Employer contributions 500 500 Benefits paid, including partial settlement of certain participant balances (1,353 ) (836 ) Fair value of plan assets at December 31 15,787 14,820 Funded status $ 334 $ (1,182 )
Component of Accumulated Other Comprehensive Earnings	Amounts recognized as a component of accumulated other comprehensive earnings as of year-end 2016 2015 Net actuarial loss $ (4,688 ) $ (6,098 ) Deferred tax benefit 1,641 2,134 Amounts included in accumulated other comprehensive earnings, net of tax $ (3,047 ) $ (3,964 )
Net Periodic Pension Cost	Net periodic benefit cost for the years ended December 31, 2016, 2015, and 2014, are as follows (dollars in thousands): Year Ended December 31, 2016 2015 2014 Service cost - benefits earned during the period $ — $ — $ — Interest cost on projected benefit obligation 665 622 1,131 Expected return on plan assets (912 ) (948 ) (1,497 ) Amortization of unrecognized net loss 375 222 337 Recognized loss on partial settlement of certain participant balances 267 — 2,909 Net periodic pension benefit expense (benefit) $ 395 $ (104 ) $ 2,880
Benefit Obligations and Net Periodic Pension Cost and Rate of Return on Plan Assets	The following table sets forth the rates used in the actuarial calculations of the present value of benefit obligations and net periodic pension cost and the rate of return on plan assets: 2016 2015 2014 Weighted average discount rate 4.25 % 4.25 % 4.10 % Expected long-term rate of return on assets 6.25 % 6.25 % 6.25 %
Pension Plan and Targeted Allocation Percentage	The major type of plan assets in the pension plan and the targeted allocation percentage as of December 31, 2016 and 2015 is as follows: December 31, 2016 December 31, 2015 Targeted Equity securities 77 % 74 % 75 % Debt securities 22 % 25 % 25 % Cash and equivalents 1 % 1 % —
Breakdown by Level	The breakdown by level is as follows (dollars in thousands): Level 1 Level 2 Level 3 Total Fair Money market fund $ 100 $ — $ — $ 100 Obligations of state and political subdivisions — 659 — 659 Corporate bonds — 885 — 885 Mortgage-backed securities — 956 — 956 Corporate stocks and mutual funds 13,187 — — 13,187 Total $ 13,287 $ 2,500 $ — $ 15,787
Estimate of Undiscounted Projected Future Payments	An estimate of the undiscounted projected future payments to eligible participants for the next five years and the following five years in the aggregate is as follows (in thousands): Year Ending December 31, 2017 856 2018 872 2019 892 2020 913 2021 935 2022 forward 4,861

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2016
Banking and Thrift [Abstract]
Schedule of Regulatory Capital Ratios Under the Basel III Regulatory Capital Framework	As of December 31, 2016 and 2015, the regulatory capital ratios of the Company and Bank under the Basel III regulatory capital framework are as follows: Actual Minimum Capital Phase-In Minimum Capital Phased-In Required to be As of December 31, 2016: Amount Ratio Amount Ratio Amount Ratio Amount Ratio Total Capital to Risk-Weighted Assets: Consolidated $ 739,959 18.45 % $ 345,827 8.625 % $ 421,007 10.50 % — N/A First Financial Bank, N.A. $ 633,403 15.84 % $ 344,930 8.625 % $ 419,915 10.50 % $ 399,919 10.00 % Tier 1 Capital to Risk-Weighted Assets: Consolidated $ 693,584 17.30 % $ 265,635 6.625 % $ 340,815 8.50 % — N/A First Financial Bank, N.A. $ 587,028 14.68 % $ 264,946 6.625 % $ 339,931 8.50 % $ 319,935 8.00 % Common Equity Tier 1 Capital to Risk-Weighted Assets: Consolidated $ 693,584 17.30 % $ 205,491 5.125 % $ 280,671 7.00 % — N/A First Financial Bank, N.A. $ 587,028 14.68 % $ 204,959 5.125 % $ 279,943 7.00 % $ 259,947 6.50 % Leverage Ratio: Consolidated $ 693,584 10.71 % $ 258,978 4.00 % $ 258,978 4.00 % — N/A First Financial Bank, N.A. $ 587,028 9.10 % $ 257,941 4.00 % $ 257,941 4.00 % $ 322,426 5.00 % As of December 31, 2015: Total Capital to Risk-Weighted Assets: Consolidated $ 672,920 16.97 % $ 318,528 8.00 % $ 418,068 10.50 % — N/A First Financial Bank, N.A. $ 570,910 14.37 % $ 317,788 8.00 % $ 417,097 10.50 % $ 397,235 10.00 % Tier 1 Capital to Risk-Weighted Assets: Consolidated $ 630,413 15.90 % $ 238,896 6.00 % $ 338,436 8.50 % — N/A First Financial Bank, N.A. $ 528,403 13.30 % $ 238,341 6.00 % $ 337,650 8.50 % $ 317,788 8.00 % Common Equity Tier 1 Capital to Risk-Weighted Assets: Consolidated $ 630,413 15.90 % $ 179,172 4.50 % $ 278,712 7.00 % — N/A First Financial Bank, N.A. $ 528,403 13.30 % $ 178,756 4.50 % $ 278,065 7.00 % $ 258,203 6.50 % Leverage Ratio: Consolidated $ 630,413 9.96 % $ 256,368 4.00 % $ 256,368 4.00 % — N/A First Financial Bank, N.A. $ 528,403 8.37 % $ 252,419 4.00 % $ 252,419 4.00 % $ 315,524 5.00 %

Stock Option Plan and Restric39

Stock Option Plan and Restricted Stock Plan (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Analysis of Stock Option Activity	An analysis of stock option activity for the year ended December 31, 2016 is presented in the table and narrative below: Weighted- Shares Weighted- Remaining Aggregate Intrinsic Outstanding, beginning of year 1,231,346 $ 26.70 Granted — — Exercised (82,871 ) 15.69 Cancelled (54,440 ) (29.52 ) Outstanding, end of year 1,094,035 27.40 6.56 $ 19,475 Exercisable at end of year 422,945 $ 20.38 4.29 $ 10,498
Schedule of Information Concerning Outstanding and Vested Stock Options	The following table summarizes information concerning outstanding and vested stock options as of December 31, 2016: Exercise Price Number Remaining Number Vested $ 13.66 36,522 0.1 36,522 16.78 123,473 2.4 123,473 15.73 180,380 4.8 136,460 30.85 320,410 6.8 126,490 $ 33.89 433,250 8.8 — 1,094,035 422,945

Condensed Financial Informati40

Condensed Financial Information - Parent Company (Tables)	12 Months Ended
	Dec. 31, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Balance Sheets	Condensed Balance Sheets-December 31, 2016 and 2015 2016 2015 ASSETS Cash in subsidiary bank $ 15,070 $ 12,311 Cash in unaffiliated banks 2 2 Interest-bearing deposits in subsidiary bank 78,179 78,160 Total cash and cash equivalents 93,251 90,473 Securities available-for-sale, 11,593 12,062 Investment in and advances to subsidiaries, at equity 744,971 713,909 Intangible assets 723 723 Other assets 2,668 3,693 Total assets $ 853,206 $ 820,860 LIABILITIES AND SHAREHOLDERS’ EQUITY Total liabilities $ 15,321 $ 15,874 Shareholders’ equity: Common stock 661 660 Capital surplus 372,245 368,925 Retained earnings 446,534 388,006 Treasury stock (6,671 ) (6,296 ) Deferred compensation 6,671 6,296 Accumulated other comprehensive earnings 18,445 47,395 Total shareholders’ equity 837,885 804,986 Total liabilities and shareholders’ equity $ 853,206 $ 820,860
Condensed Statements of Earnings	Condensed Statements of Earnings- For the Years Ended December 31, 2016, 2015 and 2014 2016 2015 2014 Income: Cash dividends from subsidiaries $ 48,800 $ 51,200 $ 34,000 Excess of earnings over dividends of subsidiaries 58,809 52,911 58,539 Other 4,184 4,185 3,717 Total Income 111,793 108,296 96,256 Expenses: Salaries and employee benefits 5,655 6,067 5,595 Other operating expenses 3,531 4,439 3,309 Total Expense 9,186 10,506 8,904 Earnings before income taxes 102,607 97,790 87,352 Income tax benefit 2,167 2,591 2,207 Net earnings $ 104,774 $ 100,381 $ 89,559
Condensed Statements of Cash Flows	Condensed Statements of Cash Flows- For the Years Ended December 31, 2016, 2015, and 2014 2016 2015 2014 Cash flows from operating activities: Net earnings $ 104,774 $ 100,381 $ 89,559 Adjustments to reconcile net earnings to net cash provided by operating activities: Excess of earnings over dividends of subsidiary bank (58,809 ) (52,911 ) (58,539 ) Depreciation and amortization, net 208 197 200 Decrease (increase) in other assets 1,702 507 (150 ) Increase (decrease) in other liabilities (1,374 ) 3,743 (314 ) Other 8 — — Net cash provided by operating activities 46,509 51,917 30,756 Cash flows from investing activities: Cash received (paid) in connection with acquisition of banks — 13,125 — Net decrease in interest-bearing time deposits in unaffiliated banks — — 480 Purchases of bank premises and equipment (94 ) (107 ) (780 ) Repayment from (of advances to) investment in and advances to subsidiaries, net — 5,800 (3,300 ) Other 10 — — Net cash used in (provided by) investing activities (84 ) 18,818 (3,600 ) Cash flows from financing activities: Repayment of subordinated debt — (13,125 ) — Proceeds of stock issuances 1,260 1,545 1,437 Cash dividends paid (44,907 ) (38,767 ) (34,578 ) Net cash used in financing activities (43,647 ) (50,347 ) (33,141 ) Net increase (decrease) in cash and cash equivalents 2,778 20,388 (5,985 ) Cash and cash equivalents, beginning of year 90,473 70,085 76,070 Cash and cash equivalents, end of year $ 93,251 $ 90,473 $ 70,085

Cash Flow Information (Tables)

Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Supplemental Information on Cash Flows and Noncash Transactions	Supplemental information on cash flows and noncash transactions is as follows (dollars in thousands): Year Ended December 31, 2016 2015 2014 Supplemental cash flow information: Interest paid $ 5,465 $ 4,085 $ 4,231 Federal income taxes paid 28,348 29,674 28,711 Schedule of noncash investing and financing activities: Assets acquired through foreclosure 2,269 203 1,385 Investment securities purchased but not settled 12,381 — 1,248

Acquisitions and Asset Purcha42

Acquisitions and Asset Purchase (Tables) - FBC Bancshares, Inc. and First Bank, N.A. [Member]	12 Months Ended
	Dec. 31, 2016
Schedule of Amounts Recorded on Consolidated Balance Sheet on Acquisition Date	The assets acquired and liabilities assumed were recorded on the consolidated balance sheet at estimated fair value on the acquisition date. 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 (dollars in thousands): Fair value of consideration paid: Common stock issued (1,755,374 shares) $ 59,648
Schedule of Preliminary Estimated Fair Value Amounts Assigned to Major Asset and Liability Categories at Acquisition Date	Fair value of consideration paid: Common stock issued (1,755,374 shares) $ 59,648 Fair value of identifiable assets acquired: Cash and cash equivalents 65,197 Securities available-for-sale 42,903 Loans 248,380 Identifiable intangible assets 2,343 Other assets 15,262 Total identifiable assets acquired 374,085 Fair value of liabilities assumed: Deposits 343,583 Subordinated debt 13,125 Other liabilities 1,651 Total liabilities assumed 358,359 Fair value of net identifiable assets acquired 15,726 Goodwill resulting from acquisition $ 43,922

Summary of Significant Accoun43

Summary of Significant Accounting Policies - Additional Information (Detail)	Apr. 22, 2014	Dec. 31, 2016USD ($)Locationshares	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)shares	Jul. 31, 2015	Apr. 28, 2015shares	Oct. 28, 2014shares
Summary Of Significant Accounting Policies [Line Items]
Number of locations | Location		69
Stock repurchase program expiration date		Sep. 30, 2017
Minimum number of shares that company is required to repurchase | shares		0
Stock repurchased under authorization | shares		0	0	0
Stock split conversion ratio		Two-for-one stock split
Percentage of stock dividend declared	100.00%
Dividend declared date		Apr. 22, 2014
Dividend record date		May 15, 2014
Dividend distribution date		Jun. 2, 2014
Common stock, shares authorized | shares		120,000,000	120,000,000			120,000,000
Minimum number of days to consider the loans as non-accrual		Greater than 90 days
Loans individually evaluated for impairment		$ 27,371,000	$ 28,601,000
Contractual balance		38,379,000	35,030,000
Impairment recorded		$ 0	0	$ 0
Other identifiable intangible assets, amortized period (years)		7 years
Goodwill and intangible assets with indefinite lives		$ 139,971,000	139,971,000
Carrying amount of goodwill arising from acquisitions, is deductible for federal income tax purposes		74,376,000	74,376,000
Other intangible assets mortgage servicing rights		$ 1,795,000	1,902,000
Securities sold under agreements to repurchase maturity range (in days)		One to four days
Interest-bearing time deposits, maturity period (in days)		90 days or less
Unrealized net gains in available-for-sale securities, included in accumulated other comprehensive income		$ 21,492,000	51,359,000
Minimum pension liability, included in accumulated other comprehensive income		(3,047,000)	(3,964,000)
Stock compensation expense		882,000	644,000	709,000
Restricted stock expense				$ 0
Purchased Credit Impaired Loans [Member]
Summary Of Significant Accounting Policies [Line Items]
Loans individually evaluated for impairment		1,256,000	2,178,000
Contractual balance		1,865,000	2,936,000
Director [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted stock expense		278,000	139,000
Officers [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted stock expense		381,000	$ 62,000
FBC Bancshares, Inc. and First Bank, N.A. [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of common stock acquired					100.00%
Goodwill and intangible assets with indefinite lives		43,922,000
FBC Bancshares, Inc. and First Bank, N.A. [Member] | Purchased Credit Impaired Loans [Member]
Summary Of Significant Accounting Policies [Line Items]
Contractual balance		$ 1,704,000
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Stock repurchase program, number of shares authorized to be repurchased | shares							1,500,000
Percentage of stock dividend declared		53.00%

Summary of Significant Accoun44

Summary of Significant Accounting Policies - Computation of Basic EPS to Dilutive EPS (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net earnings	$ 104,774	$ 100,381	$ 89,559
Effect of stock options and stock grants, Net Earnings	0	0	0
Net earnings per share, assuming dilution, Net Earnings	$ 104,774	$ 100,381	$ 89,559
Net earnings per share, basic, Weighted Average Shares	66,013,004	64,892,934	64,047,803
Effect of stock options and stock grants, Weighted Average Shares	89,882	175,096	260,732
Net earnings per share, assuming dilution, Weighted Average Shares	66,102,886	65,068,030	64,308,535
Net earnings per share, basic, Per Share Amount	$ 1.59	$ 1.55	$ 1.40
Effect of stock options and stock grants, Per Share Amount		(0.01)	(0.01)
Net earnings per share, assuming dilution, Per Share Amount	$ 1.59	$ 1.54	$ 1.39

Interest-bearing Time Deposit45

Interest-bearing Time Deposits in Banks and Securities - Additional Information (Detail) $ in Thousands	Dec. 31, 2016USD ($)Investment	Dec. 31, 2016USD ($)Investment	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Interest Bearing Time Deposits In Banks And Securities [Line Items]
INTEREST-BEARING TIME DEPOSITS IN BANKS	$ 1,707	$ 1,707	$ 3,495
Held-to-maturity securities	$ 121	$ 121	278
Number of investment positions | Investment	466	466
Securities pledged as collateral	$ 1,940,460	$ 1,940,460	1,759,570
Sales of investment securities available-for-sale		40,510	35,580	$ 1,619
Gross realized gains from security sales		1,579	443	2
Gross realized losses from security sales or calls		$ 309	$ 11	$ 6
Obligations of State and Political Subdivisions [Member] | Texas [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Percentage of securities guaranteed by Texas Permanent School Fund	33.91%
Obligations of State and Political Subdivisions [Member] | Texas [Member] | Available-for-Sale Securities [Member] | Geographic Concentration Risk [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Concentration risk, percentage	82.13%
Minimum [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Interest-bearing time deposits, maturity period, years		1 year
Maximum [Member]
Interest Bearing Time Deposits In Banks And Securities [Line Items]
Interest-bearing time deposits, maturity period, years		3 years

Interest-bearing Time Deposit46

Interest-bearing Time Deposits in Banks and Securities - Summary of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	$ 2,827,772	$ 2,654,885
Securities available-for-sale, Gross Unrealized Holding Gains	49,824	84,855
Securities available-for-sale, Gross Unrealized Holding Losses	(16,759)	(5,841)
Securities available-for-sale, Estimated Fair Value	2,860,837	2,733,899
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	10,649	10,792
Securities available-for-sale, Gross Unrealized Holding Gains	19	5
Securities available-for-sale, Gross Unrealized Holding Losses		(2)
Securities available-for-sale, Estimated Fair Value	10,668	10,795
Obligations of U.S. Government Sponsored Enterprises and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	113,450	148,393
Securities available-for-sale, Gross Unrealized Holding Gains	253	268
Securities available-for-sale, Gross Unrealized Holding Losses		(107)
Securities available-for-sale, Estimated Fair Value	113,703	148,554
Obligations of State and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	1,534,095	1,379,879
Securities available-for-sale, Gross Unrealized Holding Gains	40,194	71,382
Securities available-for-sale, Gross Unrealized Holding Losses	(10,013)	(134)
Securities available-for-sale, Estimated Fair Value	1,564,276	1,451,127
Corporate Bonds and Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	51,920	86,182
Securities available-for-sale, Gross Unrealized Holding Gains	476	1,778
Securities available-for-sale, Gross Unrealized Holding Losses	(3)	(5)
Securities available-for-sale, Estimated Fair Value	52,393	87,955
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	848,614	781,648
Securities available-for-sale, Gross Unrealized Holding Gains	8,260	10,993
Securities available-for-sale, Gross Unrealized Holding Losses	(5,513)	(3,759)
Securities available-for-sale, Estimated Fair Value	851,361	788,882
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-Sale, Amortized Cost Basis, Total	269,044	247,991
Securities available-for-sale, Gross Unrealized Holding Gains	622	429
Securities available-for-sale, Gross Unrealized Holding Losses	(1,230)	(1,834)
Securities available-for-sale, Estimated Fair Value	$ 268,436	$ 246,586

Interest-bearing Time Deposit47

Interest-bearing Time Deposits in Banks and Securities - Amortized Cost and Estimated Fair Value of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Available-for-Sale, Amortized Cost Basis, Due within one year	$ 206,182
Available-for-Sale, Amortized Cost Basis, Due after one year through five years	664,151
Available-for-Sale, Amortized Cost Basis, Due after five years through ten years	836,421
Available-for-Sale, Amortized Cost Basis, Due after ten years	3,360
Available-for-Sale, Amortized Cost Basis, Mortgage-backed securities	1,117,658
Available-for-Sale, Amortized Cost Basis, Total	2,827,772	$ 2,654,885
Available-for-Sale, Estimated Fair Value, Due within one year	207,276
Available-for-Sale, Estimated Fair Value, Due after one year through five years	684,849
Available-for-Sale, Estimated Fair Value, Due after five years through ten years	845,257
Available-for-Sale, Estimated Fair Value, Due after ten years	3,658
Available-for-Sale, Estimated Fair Value, Mortgage-backed securities	1,119,797
Securities available-for-sale, Estimated Fair Value, Total	$ 2,860,837	$ 2,733,899

Interest-bearing Time Deposit48

Interest-bearing Time Deposits in Banks and Securities - Continuous Unrealized-Loss Position of Available-for-Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value	$ 1,012,122	$ 523,075
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	15,712	3,758
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Fair Value	47,699	74,777
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss	1,047	2,083
Available-for-sale securities, continuous unrealized loss position, Fair Value	1,059,821	597,852
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss	16,759	5,841
Obligations of State and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value	446,052	32,929
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	9,997	127
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Fair Value	1,209	1,513
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss	16	7
Available-for-sale securities, continuous unrealized loss position, Fair Value	447,261	34,442
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss	10,013	134
Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value	372,331	231,481
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	4,532	1,765
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Fair Value	33,227	63,919
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss	981	1,994
Available-for-sale securities, continuous unrealized loss position, Fair Value	405,558	295,400
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss	5,513	3,759
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value	193,495	196,163
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	1,180	1,752
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Fair Value	13,263	9,345
Available-for-sale securities, continuous unrealized loss position 12 Months or Longer, Unrealized Loss	50	82
Available-for-sale securities, continuous unrealized loss position, Fair Value	206,758	205,508
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss	1,230	1,834
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value		5,110
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss		2
Available-for-sale securities, continuous unrealized loss position, Fair Value		5,110
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss		2
Obligations of U.S. Government Sponsored Enterprises and Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value		50,388
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss		107
Available-for-sale securities, continuous unrealized loss position, Fair Value		50,388
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss		107
Corporate Bonds and Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Fair Value	244	7,004
Available-for-sale securities, continuous unrealized loss position Less than 12 Months, Unrealized Loss	3	5
Available-for-sale securities, continuous unrealized loss position, Fair Value	244	7,004
Available-for-sale securities, continuous unrealized loss position, Unrealized Loss	$ 3	$ 5

Loans and Allowance for Loan 49

Loans and Allowance for Loan Losses - Loans Held-for-Investment by Class of Financing Receivables (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Loans and Leases Receivable Disclosure [Line Items]
Total	$ 3,357,307	$ 3,317,050
Commercial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total	674,410	696,163
Agriculture [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total	84,021	102,351
Real Estate [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total	2,189,844	2,136,233
Consumer [Member]
Loans and Leases Receivable Disclosure [Line Items]
Total	$ 409,032	$ 382,303

Loans and Allowance for Loan 50

Loans and Allowance for Loan Losses - Additional Information (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale	$ 26,898,000	$ 33,543,000	$ 26,898,000	$ 33,543,000
Nonaccrual, past due 90 days or more and still accruing, restructured loans and foreclosed assets	29,000,000	29,768,000	29,000,000	29,768,000
Non accrual loans	27,371,000	28,601,000	27,371,000	28,601,000
Additional funds advanced in connection with impaired loans	0		0
Interest income recognized on impaired loans	0	0
Interest income recognized on impaired loans			829,000	922,000	$ 162,000
Allowance for loan losses	45,779,000	41,877,000	45,779,000	41,877,000	$ 36,824,000
Loans individually evaluated for impairment	27,371,000	28,601,000	$ 27,371,000	28,601,000
Default for purposes of this disclosure is a troubled debt restructured loan			90 days
Commitments to lend additional funds to borrowers with loan that have been modified as TDRs	0		$ 0
Loans held by subsidiaries subject to blanket liens	2,081,615,000		2,081,615,000
Advances from Federal Home Loan Bank of Dallas	75,000,000	299,020,000	75,000,000	299,020,000
Purchased Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non accrual loans	1,256,000	2,178,000	1,256,000	2,178,000
Allowance for loan losses	0	0	0	0
Loans individually evaluated for impairment	$ 1,256,000	$ 2,178,000	$ 1,256,000	$ 2,178,000

Loans and Allowance for Loan 51

Loans and Allowance for Loan Losses - Non-Accrual Loans, Loans Still Accruing and Past Due 90 Days or More and Restructured Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Non-accrual loans	$ 27,371	$ 28,601
Loans still accruing and past due 90 days or more	284	341
Troubled debt restructured loans	701	199
Total	$ 28,356	$ 29,141

Loans and Allowance for Loan 52

Loans and Allowance for Loan Losses - Non-Accrual Loans, Loans Still Accruing and Past Due 90 Days or More and Restructured Loans (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	$ 27,371	$ 28,601
Troubled debt restructured loans	701	199
Purchased Credit Impaired Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	1,256	2,178
Doubtful [Member]
Loans and Leases Receivable Disclosure [Line Items]
Troubled debt restructured loans	$ 6,863	$ 6,113

Loans and Allowance for Loan 53

Loans and Allowance for Loan Losses - Recorded Investment in Impaired Loans and Related Valuation Allowance (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Recorded Investment	$ 27,371	$ 28,601
Valuation Allowance	$ 5,012	$ 5,071

Loans and Allowance for Loan 54

Loans and Allowance for Loan Losses - Schedule of Non-Accrual Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	$ 27,371	$ 28,601
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	7,284	8,761
Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	99	97
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	18,754	18,766
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	$ 1,234	$ 977

Loans and Allowance for Loan 55

Loans and Allowance for Loan Losses - Schedule of Impaired Loans and Related Allowance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	$ 38,379	$ 35,030
Recorded Investment With No Allowance	7,657	6,546
Recorded Investment With Allowance	19,714	22,055
Total Recorded Investment	27,371	28,601
Related Allowance	5,012	5,071
12 Month Average Recorded Investment	22,055	21,735
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	13,389	10,056
Recorded Investment With No Allowance	1,148	608
Recorded Investment With Allowance	6,136	8,153
Total Recorded Investment	7,284	8,761
Related Allowance	2,128	2,030
12 Month Average Recorded Investment	4,921	5,812
Agriculture [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	103	97
Recorded Investment With Allowance	99	97
Total Recorded Investment	99	97
Related Allowance	25	70
12 Month Average Recorded Investment	50	48
Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	23,466	23,710
Recorded Investment With No Allowance	6,229	5,314
Recorded Investment With Allowance	12,525	13,452
Total Recorded Investment	18,754	18,766
Related Allowance	2,428	2,827
12 Month Average Recorded Investment	16,170	15,211
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Unpaid Contractual Principal Balance	1,421	1,167
Recorded Investment With No Allowance	280	624
Recorded Investment With Allowance	954	353
Total Recorded Investment	1,234	977
Related Allowance	431	144
12 Month Average Recorded Investment	$ 914	$ 664

Loans and Allowance for Loan 56

Loans and Allowance for Loan Losses - Schedule of Impaired Loans and Related Allowance (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	$ 7,657	$ 6,546
Purchased Credit Impaired Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment With No Allowance	$ 1,256	$ 2,178

Loans and Allowance for Loan 57

Loans and Allowance for Loan Losses - Schedule of Internal Ratings of Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	$ 3,357,307	$ 3,317,050
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	674,410	696,163
Agriculture [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	84,021	102,351
Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	2,189,844	2,136,233
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	409,032	382,303
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	3,229,505	3,167,624
Pass [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	629,756	633,083
Pass [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	81,620	99,862
Pass [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	2,111,947	2,054,738
Pass [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	406,182	379,941
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	24,787	40,576
Special Mention [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	5,769	9,762
Special Mention [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	715	1,398
Special Mention [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	18,091	29,000
Special Mention [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	212	416
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	103,015	108,813
Substandard [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	38,885	53,318
Substandard [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	1,686	1,091
Substandard [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	59,806	52,458
Substandard [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan	$ 2,638	1,946
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan		37
Doubtful [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Internal ratings of loan		$ 37

Loans and Allowance for Loan 58

Loans and Allowance for Loan Losses - Schedule of Past Due Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 29,511	$ 27,647
Total Current	3,327,796	3,289,403
Total Loans	3,357,307	3,317,050
Total 90 Days Past Due Still Accruing	284	341
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,250	7,775
Total Current	667,160	688,388
Total Loans	674,410	696,163
Total 90 Days Past Due Still Accruing	10	54
Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	185	431
Total Current	83,836	101,920
Total Loans	84,021	102,351
Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	19,741	17,347
Total Current	2,170,103	2,118,886
Total Loans	2,189,844	2,136,233
Total 90 Days Past Due Still Accruing	272	217
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,335	2,094
Total Current	406,697	380,209
Total Loans	409,032	382,303
Total 90 Days Past Due Still Accruing	2	70
15-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	19,110	17,339
15-59 Days Past Due [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,908	3,099
15-59 Days Past Due [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	185	348
15-59 Days Past Due [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	13,172	12,247
15-59 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,845	1,645
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,791	6,144
60-89 Days Past Due [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,122	3,652
60-89 Days Past Due [Member] | Agriculture [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		83
60-89 Days Past Due [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,301	2,226
60-89 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	368	183
Greater than 90 Days [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,610	4,164
Greater than 90 Days [Member] | Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,220	1,024
Greater than 90 Days [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,268	2,874
Greater than 90 Days [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 122	$ 266

Loans and Allowance for Loan 59

Loans and Allowance for Loan Losses - Schedule of Allowance for Loan Losses by Portfolio Segment (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	$ 5,012	$ 5,071
Loan collectively evaluated for impairment	40,767	36,806
Total allowance for loan losses	45,779	41,877	$ 36,824
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	2,128	2,030
Loan collectively evaluated for impairment	9,579	10,614
Total allowance for loan losses	11,707	12,644	7,990
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	25	70
Loan collectively evaluated for impairment	1,076	1,121
Total allowance for loan losses	1,101	1,191	527
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	2,428	2,827
Loan collectively evaluated for impairment	24,436	21,548
Total allowance for loan losses	26,864	24,375	26,657
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	431	144
Loan collectively evaluated for impairment	5,676	3,523
Total allowance for loan losses	$ 6,107	$ 3,667	$ 1,650

Loans and Allowance for Loan 60

Loans and Allowance for Loan Losses - Changes in Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 41,877	$ 36,824
Provision for loan losses	10,212	9,685
Recoveries	3,506	1,407
Charge-offs	(9,816)	(6,039)
Ending balance	45,779	41,877
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	12,644	7,990
Provision for loan losses	5,101	8,044
Recoveries	952	344
Charge-offs	(6,990)	(3,734)
Ending balance	11,707	12,644
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	1,191	527
Provision for loan losses	104	773
Recoveries	25	55
Charge-offs	(219)	(164)
Ending balance	1,101	1,191
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	24,375	26,657
Provision for loan losses	1,150	(2,399)
Recoveries	2,021	558
Charge-offs	(682)	(441)
Ending balance	26,864	24,375
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	3,667	1,650
Provision for loan losses	3,857	3,267
Recoveries	508	450
Charge-offs	(1,925)	(1,700)
Ending balance	$ 6,107	$ 3,667

Loans and Allowance for Loan 61

Loans and Allowance for Loan Losses - Schedule of Investment in Loans Related to Balance in Allowance for Loan Losses on Basis of Company's Impairment Methodology (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	$ 27,371	$ 28,601
Loan collectively evaluated for impairment	3,329,936	3,288,449
Total	3,357,307	3,317,050
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	7,284	8,761
Loan collectively evaluated for impairment	667,126	687,402
Total	674,410	696,163
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	99	97
Loan collectively evaluated for impairment	83,922	102,254
Total	84,021	102,351
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	18,754	18,766
Loan collectively evaluated for impairment	2,171,090	2,117,467
Total	2,189,844	2,136,233
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment	1,234	977
Loan collectively evaluated for impairment	407,798	381,326
Total	$ 409,032	$ 382,303

Loans and Allowance for Loan 62

Loans and Allowance for Loan Losses - Schedule of Loans Modified and Considered Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)SecurityLoan	Dec. 31, 2015USD ($)SecurityLoan
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	28	23
Pre-Modification Recorded Investment	$ 4,857	$ 1,428
Post-Modification Recorded Investment	$ 4,857	$ 1,428
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	15	8
Pre-Modification Recorded Investment	$ 3,208	$ 447
Post-Modification Recorded Investment	$ 3,208	$ 447
Agriculture [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan		3
Pre-Modification Recorded Investment		$ 128
Post-Modification Recorded Investment		$ 128
Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	6	5
Pre-Modification Recorded Investment	$ 1,460	$ 598
Post-Modification Recorded Investment	$ 1,460	$ 598
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number | SecurityLoan	7	7
Pre-Modification Recorded Investment	$ 189	$ 255
Post-Modification Recorded Investment	$ 189	$ 255

Loans and Allowance for Loan 63

Loans and Allowance for Loan Losses - Schedule of How Loans Were Modified as Troubled Debt Restructured Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	$ 4,857	$ 1,428
Adjusted Interest Rate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		15
Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	2,928	516
Combined Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	1,929	897
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	3,208	447
Commercial [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	2,560	182
Commercial [Member] | Combined Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	648	265
Agriculture [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		128
Agriculture [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		128
Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	1,460	598
Real Estate [Member] | Adjusted Interest Rate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans		15
Real Estate [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	298	150
Real Estate [Member] | Combined Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	1,162	433
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	189	255
Consumer [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	70	56
Consumer [Member] | Combined Rate and Maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans	$ 119	$ 199

Loans and Allowance for Loan 64

Loans and Allowance for Loan Losses - Schedule of Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)Contract	Dec. 31, 2015USD ($)Contract
Financing Receivable, Modifications [Line Items]
Number | Contract	7	4
Balance | $	$ 2,611	$ 113
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number | Contract	4	1
Balance | $	$ 1,690	$ 66
Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number | Contract	3	1
Balance | $	$ 921	$ 15
Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number | Contract		2
Balance | $		$ 32

Loans and Allowance for Loan 65

Loans and Allowance for Loan Losses - Analysis of Changes in Loans to Officers, Directors, Principal Shareholders, or Associates of Such Persons (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Receivables [Abstract]
Beginning Balance	$ 65,729
Additional Loans	49,674
Payments	70,974
Ending Balance	$ 44,429

Bank Premises and Equipment - S

Bank Premises and Equipment - Summary of Bank Premises and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Land	$ 28,266	$ 29,050
Buildings	115,566	106,515
Furniture and equipment	58,145	54,353
Leasehold improvements	4,783	4,328
Gross	206,760	194,246
Less- accumulated depreciation and amortization	(84,075)	(78,534)
Total Bank Premises and Equipment	$ 122,685	$ 115,712
Minimum [Member] | Buildings [Member]
Property, Plant and Equipment [Line Items]
Useful Life in years	20 years
Minimum [Member] | Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful Life in years	3 years
Minimum [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Useful Life in years	5 years
Maximum [Member] | Buildings [Member]
Property, Plant and Equipment [Line Items]
Useful Life in years		40 years
Maximum [Member] | Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful Life in years		10 years
Maximum [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Useful Life in years		15 years

Bank Premises and Equipment - A

Bank Premises and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 9,390	$ 9,125	$ 7,833
Rental income for leases included in net occupancy expense	2,139	1,949	1,923
Gain (loss) on sale the of bank premises and equipment	168	(820)	10
Gain (loss) on sale of building	1,894	150	$ 910
Weatherford [Member]
Property, Plant and Equipment [Line Items]
Proceeds from Sale of Building	1,385
Gain (loss) on sale of building	560
Orange [Member]
Property, Plant and Equipment [Line Items]
Proceeds from Sale of Building	2,000
Gain (loss) on sale of building	$ (31)
Write down of anticipated building sale		$ 1,000

Deposits and Borrowing - Additi

Deposits and Borrowing - Additional Information (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Banking and Thrift [Abstract]
Time deposit threshold amount	$ 250,000
Time deposits of $250,000 or more totaled	130,385,000	$ 190,386,000
Deposits received from related parties	114,513,000	89,006,000
Advances from Federal Home Loan Bank of Dallas, maturing during 2017	$ 75,000,000	299,020,000
Advances from Federal Home Loan Bank of Dallas, maturing during 2018		$ 299,020,000
Interest rate on advance	0.46%	0.31%

Deposits and Borrowings - Sched

Deposits and Borrowings - Scheduled Maturities of Time Deposits (Detail) $ in Thousands	Dec. 31, 2016USD ($)
Banking and Thrift [Abstract]
2,017	$ 419,326
2,018	54,713
2,019	17,893
2,020	9,939
2,021	7,093
Thereafter	32
Time deposits	$ 508,996

Deposits and Borrowings - Sch70

Deposits and Borrowings - Schedule of Borrowings (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
Securities sold under agreements with customers to repurchase	$ 360,820	$ 310,330
Federal funds purchased	9,950	6,325
Advances from Federal Home Loan Bank of Dallas	75,000	299,020
Total	$ 445,770	$ 615,675

Line of Credit - Additional Inf

Line of Credit - Additional Information (Detail) - USD ($)	Apr. 22, 2014	Dec. 31, 2016	Dec. 31, 2015
Line of Credit Facility [Line Items]
Revolving line of credit, permitted		$ 25,000,000
Line of credit, maturity date		Jun. 30, 2017
Term facility payable (in years)		Five
Interest paid on basis points		Prime Rate plus 50 basis points or LIBOR plus 250 basis points.
Percentage of restricted dividend payments		55.00%
Line of credit		$ 0	$ 0
Percentage of stock dividend declared	100.00%
Prime Rate [Member]
Line of Credit Facility [Line Items]
Interest rate spread above benchmark rate		0.50%
LIBOR [Member]
Line of Credit Facility [Line Items]
Interest rate spread above benchmark rate		2.50%
Minimum [Member]
Line of Credit Facility [Line Items]
Percentage of stock dividend declared		37.00%
Maximum [Member]
Line of Credit Facility [Line Items]
Percentage of stock dividend declared		53.00%

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Current federal income tax	$ 30,381	$ 31,014	$ 29,832
Current state income tax	99	103	94
Deferred federal income tax expense (benefit)	673	320	(893)
Income tax expense	$ 31,153	$ 31,437	$ 29,033

Income Taxes - Percentage of Pr

Income Taxes - Percentage of Pretax Earnings, Differs from Statutory Federal Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Statutory federal income tax rate	35.00%	35.00%	35.00%
Reductions in tax rate resulting from interest income exempt from federal income tax	(12.10%)	(11.40%)	(10.60%)
Effect of state income tax	0.10%	0.10%	0.10%
ESOP tax deduction	(0.20%)	(0.20%)	(0.20%)
Other	0.10%	0.30%	0.20%
Effective income tax rate	22.90%	23.80%	24.50%

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Tax basis of loans in excess of financial statement basis	$ 17,006	$ 16,326
Minimum liability in defined benefit plan	1,641	2,135
Deferred compensation	2,807	2,602
Write-downs and adjustments to other real estate owned and repossessed assets	9	7
Other deferred tax assets	226	224
Total deferred tax assets	21,689	21,294
Deferred tax liabilities:
Financial statement basis of fixed assets in excess of tax basis	5,870	5,644
Intangible asset amortization deductible for tax purposes, but not for financial reporting purposes	15,191	13,881
Accretion on investment securities	1,788	1,813
Pension plan contributions	1,799	1,761
Net unrealized gain on investment securities available-for-sale	11,573	27,655
Other deferred tax liabilities	83	71
Total deferred tax liabilities	36,304	50,825
Net deferred tax asset (liability)	$ (14,615)	$ (29,531)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Deferred tax amounts, valuation allowance recorded	$ 0	$ 0
Uncertain tax positions	$ 0	$ 0
Minimum [Member]
Income Taxes [Line Items]
Tax position measured if more-likely-than-not threshold is exceeded, percentage	50.00%

Fair Value Disclosures - Additi

Fair Value Disclosures - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets transfer between Level 2 and Level 3	$ 0	$ 0	$ 0
Impaired loans carrying value	27,371,000	28,601,000
Impaired loans valuation reserves	5,012,000	5,071,000
Impaired loans net fair value	22,359,000
Other real estate owned, total	413,000	$ 153,000
Level 2 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loan held-for-sale, fair value	$ 26,702,000
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt discounts, percentage	5.00%
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt discounts, percentage	25.00%

Fair Value Disclosures - Financ

Fair Value Disclosures - Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	$ 2,860,837	$ 2,733,899
U.S. Treasury Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	10,668	10,795
Obligations of U.S. Government Sponsored Enterprises and Agencies [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	113,703	148,554
Obligations of State and Political Subdivisions [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	1,564,276	1,451,127
Residential Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	851,361	788,882
Commercial Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	268,436	246,586
Fair Value, Measurements, Recurring [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	2,860,837	2,733,899
Fair Value, Measurements, Recurring [Member] | Corporate Bonds [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	47,965	83,254
Fair Value, Measurements, Recurring [Member] | U.S. Treasury Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	10,668	10,795
Fair Value, Measurements, Recurring [Member] | Obligations of U.S. Government Sponsored Enterprises and Agencies [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	113,703	148,554
Fair Value, Measurements, Recurring [Member] | Obligations of State and Political Subdivisions [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	1,564,276	1,451,127
Fair Value, Measurements, Recurring [Member] | Residential Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	851,361	788,882
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	268,436	246,586
Fair Value, Measurements, Recurring [Member] | Other Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	4,428	4,701
Fair Value, Measurements, Recurring [Member] | Level 1 Inputs [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	15,096	15,496
Fair Value, Measurements, Recurring [Member] | Level 1 Inputs [Member] | U.S. Treasury Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	10,668	10,795
Fair Value, Measurements, Recurring [Member] | Level 1 Inputs [Member] | Other Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	4,428	4,701
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	2,845,741	2,718,403
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member] | Corporate Bonds [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	47,965	83,254
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member] | Obligations of U.S. Government Sponsored Enterprises and Agencies [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	113,703	148,554
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member] | Obligations of State and Political Subdivisions [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	1,564,276	1,451,127
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member] | Residential Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	851,361	788,882
Fair Value, Measurements, Recurring [Member] | Level 2 Inputs [Member] | Commercial Mortgage-Backed Securities [Member]
Available-for-sale investment securities:
Available-for-sale investment securities, Total Fair Value	$ 268,436	$ 246,586

Fair Value Disclosures - Other

Fair Value Disclosures - Other Real Estate Owned (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Fair Value Disclosures [Abstract]
Carrying value of other real estate owned prior to re-measurement	$ 351
Write-downs included in gain (loss) on sale of other real estate owned	(95)
Other real estate owned, fair value	$ 256

Fair Value Disclosures - Schedu

Fair Value Disclosures - Schedule of Estimated Fair Values and Carrying Values of All Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Carrying Value [Member] | Level 1 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CASH AND DUE FROM BANKS	$ 204,782	$ 179,140
FEDERAL FUNDS SOLD	3,130	3,810
INTEREST-BEARING DEPOSITS IN BANKS	48,574	89,936
Deposits with no stated maturities	4,969,543	4,569,317
Carrying Value [Member] | Level 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
INTEREST-BEARING TIME DEPOSITS IN BANKS	1,707	3,495
Held-to-maturity securities	121	278
Accrued interest receivable	36,469	34,697
Deposits with stated maturities	508,996	620,852
BORROWINGS	445,770	615,675
Accrued interest payable	225	240
Carrying Value [Member] | Levels 1 and 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities	2,860,837	2,733,899
Carrying Value [Member] | Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	3,338,426	3,308,716
Estimated Fair Value [Member] | Level 1 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CASH AND DUE FROM BANKS	204,782	179,140
FEDERAL FUNDS SOLD	3,130	3,810
INTEREST-BEARING DEPOSITS IN BANKS	48,574	89,936
Deposits with no stated maturities	4,969,543	4,569,317
Estimated Fair Value [Member] | Level 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
INTEREST-BEARING TIME DEPOSITS IN BANKS	1,709	3,500
Held-to-maturity securities	124	283
Accrued interest receivable	36,469	34,697
Deposits with stated maturities	510,304	622,572
BORROWINGS	445,770	615,675
Accrued interest payable	225	240
Estimated Fair Value [Member] | Levels 1 and 2 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale Securities	2,860,837	2,733,899
Estimated Fair Value [Member] | Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	$ 3,361,735	$ 3,316,243

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Dec. 31, 2016USD ($)
Commitments and Contingencies Disclosure [Abstract]
Future minimum lease commitments, 2017	$ 774,000
Future minimum lease commitments, 2018	369,000
Future minimum lease commitments, 2019	268,000
Future minimum lease commitments, 2020	140,000
Future minimum lease commitments, 2021	$ 32,000

Financial Instruments with Of81

Financial Instruments with Off-Balance-Sheet Risk - Schedule of Financial Instruments with Off-Balance-sheet Risk (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)
Concentration Risk [Line Items]
Financial instruments whose contract amounts represent credit risk	$ 775,615
Unfunded Lines of Credit [Member]
Concentration Risk [Line Items]
Financial instruments whose contract amounts represent credit risk	549,000
Unfunded Commitments to Extend Credit [Member]
Concentration Risk [Line Items]
Financial instruments whose contract amounts represent credit risk	199,235
Standby Letters of Credit [Member]
Concentration Risk [Line Items]
Financial instruments whose contract amounts represent credit risk	$ 27,380

Pension and Profit Sharing Pl82

Pension and Profit Sharing Plans - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016USD ($)Participantsshares	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)Participants
Defined Benefit Plan Disclosure [Line Items]
Contributions to the plan	$ 500,000	$ 500,000
Loss from partial settlement of pension plan	267,000		$ 2,909,000
Benefits paid out of pension plan assets to plan participants	$ 649,000		$ 10,626,000
Number of participants reduced | Participants	38		335
Weighted average final maturities of debt securities held in the pension plan, Years	5 years 29 days
Level 3 securities | shares	0
Common stock value	$ 661,000	660,000
Vesting period	6 years
Defined contribution plan cost	$ 3,221,000	5,455,000	$ 5,324,000
Employee deferrals	4.00%
Employee compensation	5.00%
Directors' fees	100.00%
Profit Sharing Plan's Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Common stock value	$ 60,270,000	41,599,000
Pension Plan's Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Common stock value	2,786,000	1,859,000
Safe Harbor 401(k) Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan cost	$ 2,331,000	$ 2,043,000	$ 1,699,000
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average final maturities of debt securities held in the pension plan, Years	2 years 6 months 7 days
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average final maturities of debt securities held in the pension plan, Years	11 years 4 months 2 days

Pension and Profit Sharing Pl83

Pension and Profit Sharing Plans - Benefit Obligation Activity and Fair Value of Plan Assets and Statement of Funded Status (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Interest cost on projected benefit obligation	$ 665,000	$ 622,000	$ 1,131,000
Actuarial loss (gain)	(4,688,000)	(6,098,000)
Employer contributions	500,000	500,000
Fair value of plan assets at December 31	15,787,000
Reconciliation of Benefit Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at January 1	16,002,000	15,581,000
Interest cost on projected benefit obligation	665,000	622,000
Actuarial loss (gain)	139,000	635,000
Benefits paid, including partial settlement of certain participant balances	(1,353,000)	(836,000)
Benefit obligation at December 31	15,453,000	16,002,000	15,581,000
Reconciliation of Fair Value of Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at January 1	14,820,000	15,458,000
Actual return on plan assets	1,820,000	(302,000)
Employer contributions	500,000	500,000
Benefits paid, including partial settlement of certain participant balances	(1,353,000)	(836,000)
Fair value of plan assets at December 31	15,787,000	14,820,000	$ 15,458,000
Funded status	$ 334,000	$ (1,182,000)

Pension and Profit Sharing Pl84

Pension and Profit Sharing Plans - Component of Accumulated other Comprehensive Earnings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Net actuarial loss	$ (4,688)	$ (6,098)
Deferred tax benefit	1,641	2,134
Amounts included in accumulated other comprehensive earnings, net of tax	$ (3,047)	$ (3,964)

Pension and Profit Sharing Pl85

Pension and Profit Sharing Plans - Net Periodic Pension Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Service cost - benefits earned during the period	$ 0	$ 0	$ 0
Interest cost on projected benefit obligation	665	622	1,131
Expected return on plan assets	(912)	(948)	(1,497)
Amortization of unrecognized net loss	375	222	337
Recognized loss on partial settlement of certain participant balances	267		2,909
Net periodic pension benefit expense (benefit)	$ 395	$ (104)	$ 2,880

Pension and Profit Sharing Pl86

Pension and Profit Sharing Plans - Benefit Obligations and Net Periodic Pension Cost and Rate of Return on Plan Assets (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
Weighted average discount rate	4.25%	4.25%	4.10%
Expected long-term rate of return on assets	6.25%	6.25%	6.25%

Pension and Profit Sharing Pl87

Pension and Profit Sharing Plans - Pension Plan and Targeted Allocation Percentage (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation	77.00%	74.00%
Targeted Allocation	75.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation	22.00%	25.00%
Targeted Allocation	25.00%
Cash and Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocation	1.00%	1.00%

Pension and Profit Sharing Pl88

Pension and Profit Sharing Plans - Breakdown by Level (Detail) $ in Thousands	Dec. 31, 2016USD ($)
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	$ 15,787
Money Market Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	100
Obligations of State and Political Subdivisions [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	659
Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	885
Mortgage-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	956
Corporate Stocks and Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	13,187
Level 1 Inputs [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	13,287
Level 1 Inputs [Member] | Money Market Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	100
Level 1 Inputs [Member] | Corporate Stocks and Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	13,187
Level 2 Inputs [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	2,500
Level 2 Inputs [Member] | Obligations of State and Political Subdivisions [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	659
Level 2 Inputs [Member] | Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	885
Level 2 Inputs [Member] | Mortgage-backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total Fair Value	$ 956

Pension and Profit Sharing Pl89

Pension and Profit Sharing Plans - Estimate of Undiscounted Projected Future Payments (Detail) $ in Thousands	Dec. 31, 2016USD ($)
Compensation and Retirement Disclosure [Abstract]
2,017	$ 856
2,018	872
2,019	892
2,020	913
2,021	935
2022 forward	$ 4,861

Dividends from Subsidiaries - A

Dividends from Subsidiaries - Additional Information (Detail)	Dec. 31, 2016USD ($)
Equity [Abstract]
Amount available for the declaration of dividends by subsidiary banks without prior approval of regulatory agencies	$ 170,730,000

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Periodic increase of capital conservation buffer	0.625%
Total risk-based capital ratio, Actual Ratio	18.45%	16.97%
Tier1 Capital (to Risk-Weighted Assets), Actual Ratio	17.30%	15.90%
Common Tier1 Capital (to Risk-Weighted Assets), Actual Ratio	17.30%	15.90%
Tier1 Leverage ratio, Actual Ratio	10.71%	9.96%
Required tangible net assets	$ 2,000,000
Tangible net assets, total	14,300,000
Subsidiary bank's reserve balance	$ 4,340,000	$ 17,725,000
Minimum [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital conservation buffer	0.625%
Maximum [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital conservation buffer	2.50%

Regulatory Matters - Schedule o

Regulatory Matters - Schedule of Regulatory Capital Ratios Under the Basel III Regulatory Capital Framework (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk-Weighted Assets, Actual Ratio	18.45%	16.97%
Tier1 Capital to Risk-Weighted Assets, Actual Ratio	17.30%	15.90%
Common Equity Tier1 Capital to Risk-Weighted Assets, Actual Ratio	17.30%	15.90%
Leverage Ratio, Actual Ratio	10.71%	9.96%
Consolidated [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk-Weighted Assets, Actual Amount	$ 739,959	$ 672,920
Tier1 Capital to Risk-Weighted Assets, Actual Amount	693,584	630,413
Common Equity Tier1 Capital to Risk-Weighted Assets, Actual Amount	693,584	630,413
Leverage Ratio, Actual Amount	$ 693,584	$ 630,413
Total Capital to Risk-Weighted Assets, Actual Ratio	18.45%	16.97%
Tier1 Capital to Risk-Weighted Assets, Actual Ratio	17.30%	15.90%
Common Equity Tier1 Capital to Risk-Weighted Assets, Actual Ratio	17.30%	15.90%
Leverage Ratio, Actual Ratio	10.71%	9.96%
Consolidated [Member] | Minimum [Member] | Basel III Fully Phased-In [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk-Weighted Assets, Minimum Capital Required	$ 421,007	$ 418,068
Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	340,815	338,436
Common Equity Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	280,671	278,712
Leverage Ratio, Minimum Capital Required	$ 258,978	$ 256,368
Total Capital to Risk-Weighted Assets, Minimum Capital Required	10.50%	10.50%
Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	8.50%	8.50%
Common Equity Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required, Ratio	7.00%	7.00%
Leverage Ratio, Minimum Capital Required, Ratio	4.00%	4.00%
Consolidated [Member] | Minimum [Member] | Basel III Phase-In [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk-Weighted Assets, Minimum Capital Required	$ 345,827	$ 318,528
Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	265,635	238,896
Common Equity Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	205,491	179,172
Leverage Ratio, Minimum Capital Required	$ 258,978	$ 256,368
Total Capital to Risk-Weighted Assets, Minimum Capital Required	8.625%	8.00%
Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	6.625%	6.00%
Common Equity Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required, Ratio	5.125%	4.50%
Leverage Ratio, Minimum Capital Required, Ratio	4.00%	4.00%
Parent Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk-Weighted Assets, Actual Amount	$ 633,403	$ 570,910
Tier1 Capital to Risk-Weighted Assets, Actual Amount	587,028	528,403
Common Equity Tier1 Capital to Risk-Weighted Assets, Actual Amount	587,028	528,403
Leverage Ratio, Actual Amount	$ 587,028	$ 528,403
Total Capital to Risk-Weighted Assets, Actual Ratio	15.84%	14.37%
Tier1 Capital to Risk-Weighted Assets, Actual Ratio	14.68%	13.30%
Common Equity Tier1 Capital to Risk-Weighted Assets, Actual Ratio	14.68%	13.30%
Leverage Ratio, Actual Ratio	9.10%	8.37%
Parent Company [Member] | Minimum [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk-Weighted Assets, Required To Be Considered Well Capitalized , Ratio	10.00%	10.00%
Total Capital to Risk-Weighted Assets, Required To Be Considered Well Capitalized, Amount	$ 399,919	$ 397,235
Tier1 Capital to Risk-Weighted Assets, Required To Be Considered Well Capitalized , Ratio	8.00%	8.00%
Tier1 Capital to Risk-Weighted Assets, Required To Be Considered Well Capitalized, Amount	$ 319,935	$ 317,788
Common Equity Tier1 Capital to Risk-Weighted Assets, Required To Be Considered Well Capitalized , Ratio	6.50%	6.50%
Common Equity Tier1 Capital to Risk-Weighted Assets, Required To Be Considered Well Capitalized, Amount	$ 259,947	$ 258,203
Leverage Ratio, Required To Be Considered Well Capitalized , Ratio	5.00%	5.00%
Leverage Ratio, Required To Be Considered Well Capitalized, Amount	$ 322,426	$ 315,524
Parent Company [Member] | Minimum [Member] | Basel III Fully Phased-In [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk-Weighted Assets, Minimum Capital Required	419,915	417,097
Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	339,931	337,650
Common Equity Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	279,943	278,065
Leverage Ratio, Minimum Capital Required	$ 257,941	$ 252,419
Total Capital to Risk-Weighted Assets, Minimum Capital Required	10.50%	10.50%
Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	8.50%	8.50%
Common Equity Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required, Ratio	7.00%	7.00%
Leverage Ratio, Minimum Capital Required, Ratio	4.00%	4.00%
Parent Company [Member] | Minimum [Member] | Basel III Phase-In [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk-Weighted Assets, Minimum Capital Required	$ 344,930	$ 317,788
Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	264,946	238,341
Common Equity Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	204,959	178,756
Leverage Ratio, Minimum Capital Required	$ 257,941	$ 252,419
Total Capital to Risk-Weighted Assets, Minimum Capital Required	8.625%	8.00%
Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required	6.625%	6.00%
Common Equity Tier1 Capital to Risk-Weighted Assets, Minimum Capital Required, Ratio	5.125%	4.50%
Leverage Ratio, Minimum Capital Required, Ratio	4.00%	4.00%

Stock Option Plan and Restric93

Stock Option Plan and Restricted Stock Plan - Additional Information (Detail)	Oct. 25, 2016USD ($)shares	Apr. 26, 2016USD ($)Non_Employee_Directorsshares	Oct. 27, 2015USD ($)shares	Jul. 21, 2015USD ($)Non_Employee_Directorsshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)$ / shares	Dec. 31, 2014USD ($)$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of stock for issuance under the plan | shares					3,337,000
Restricted shares vesting period					6 years
Percentage of options granted					20.00%
Duration of options granted, years					10 years
Stock options outstanding, exercise price range, lower | $ / shares					$ 13.66
Stock options outstanding, exercise price range, upper | $ / shares					33.89
Weighted-average assumptions, risk-free interest rate						1.89%
Expected dividend yield						1.89%
Expected life						5 years 9 months 11 days
Expected volatility						23.36%
Weighted-average grant-date fair value of options granted | $ / shares					$ 0	$ 6.72	$ 0
Total intrinsic value of options exercised					$ 1,226,000	$ 1,539,000	$ 1,738,000
Total unrecognized compensation cost related to nonvested share-based compensation arrangements granted under the Plan					$ 3,058,000
Weighted-average period of unrecognized compensation cost recognition, years					2 years 1 month 21 days
Total fair value of shares vested					$ 592,000	810,000	382,000
Aggregate intrinsic value of vested stock options					10,498,000
Stock compensation expense					$ 882,000	644,000	$ 709,000
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares vesting period					2 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of stock for issuance under the plan | shares					439,000
Number of non employee directors | Non_Employee_Directors		10		10
Restricted Stock [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares granted | shares		7,660		7,070
Restricted shares value		$ 250,000		$ 250,000
Stock compensation expense					$ 278,000	139,000
Restricted Stock [Member] | Officers [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares vesting period	3 years		3 years
Restricted shares granted | shares	15,405		31,273
Restricted shares value	$ 560,000		$ 1,060,000
Stock compensation expense					$ 381,000	$ 62,000

Stock Option Plan and Restric94

Stock Option Plan and Restricted Stock Plan - Schedule of Analysis of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)$ / sharesshares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding, beginning of year, Shares | shares	1,231,346
Granted, Shares | shares	0
Exercised, Shares | shares	(82,871)
Cancelled, Shares | shares	(54,440)
Outstanding, end of year, Shares | shares	1,094,035
Exercisable at end of year, Shares | shares	422,945
Outstanding, beginning of year, Weighted-Average Ex. Price | $ / shares	$ 26.70
Granted, Weighted-Average Ex. Price | $ / shares	0
Exercised, Weighted-Average Ex. Price | $ / shares	15.69
Cancelled, Weighted-Average Ex. Price | $ / shares	(29.52)
Outstanding, end of year, Weighted-Average Ex. Price | $ / shares	27.40
Exercisable at end of year, Weighted-Average Ex. Price | $ / shares	$ 20.38
Outstanding, end of year, Weighted-Average Remaining Contractual Term (Years)	6 years 6 months 22 days
Exercisable at end of year, Weighted-Average Remaining Contractual Term (Years)	4 years 3 months 15 days
Outstanding, end of year, Aggregate Intrinsic Value | $	$ 19,475
Exercisable at end of year, Aggregate Intrinsic Value | $	$ 10,498

Stock Option Plan and Restric95

Stock Option Plan and Restricted Stock Plan - Schedule of Information Concerning Outstanding and Vested Stock Options (Detail)	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Outstanding	1,094,035
Number Vested	422,945
Exercise Price $13.66 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price | $ / shares	$ 13.66
Number Outstanding	36,522
Number Vested	36,522
Remaining Contracted Life (Years)	1 month 6 days
Exercise Price $16.78 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price | $ / shares	$ 16.78
Number Outstanding	123,473
Number Vested	123,473
Remaining Contracted Life (Years)	2 years 4 months 24 days
Exercise Price $15.73 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price | $ / shares	$ 15.73
Number Outstanding	180,380
Number Vested	136,460
Remaining Contracted Life (Years)	4 years 9 months 18 days
Exercise Price $30.85 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price | $ / shares	$ 30.85
Number Outstanding	320,410
Number Vested	126,490
Remaining Contracted Life (Years)	6 years 9 months 18 days
Exercise Price $33.89 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price | $ / shares	$ 33.89
Number Outstanding	433,250
Remaining Contracted Life (Years)	8 years 9 months 18 days

Condensed Financial Informati96

Condensed Financial Information - Parent Company - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
ASSETS
Interest-bearing deposits in subsidiary bank	$ 48,574	$ 89,936
Total cash and cash equivalents	256,486	272,886	$ 253,471	$ 212,012
OTHER ASSETS	86,066	85,635
Total assets	6,809,931	6,665,070
LIABILITIES AND SHAREHOLDERS' EQUITY
Total liabilities	5,972,046	5,860,084
SHAREHOLDERS' EQUITY:
Common stock	661	660
Capital surplus	372,245	368,925
Retained earnings	446,534	388,006
Treasury stock	(6,671)	(6,296)
Deferred Compensation	6,671	6,296
Accumulated other comprehensive earnings	18,445	47,395
Total shareholders' equity	837,885	804,986	681,537	587,647
Total liabilities and shareholders' equity	6,809,931	6,665,070
Subsidiary Bank [Member]
ASSETS
Cash in banks	15,070	12,311
Interest-bearing deposits in subsidiary bank	78,179	78,160
Unaffiliated Banks [Member]
ASSETS
Cash in banks	2	2
Parent Company [Member]
ASSETS
Total cash and cash equivalents	93,251	90,473	$ 70,085	$ 76,070
SECURITIES AVAILABLE-FOR-SALE, at fair value	11,593	12,062
Investment in and advances to subsidiaries, at equity	744,971	713,909
INTANGIBLE ASSETS	723	723
OTHER ASSETS	2,668	3,693
Total assets	853,206	820,860
LIABILITIES AND SHAREHOLDERS' EQUITY
Total liabilities	15,321	15,874
SHAREHOLDERS' EQUITY:
Common stock	661	660
Capital surplus	372,245	368,925
Retained earnings	446,534	388,006
Treasury stock	(6,671)	(6,296)
Deferred Compensation	6,671	6,296
Accumulated other comprehensive earnings	18,445	47,395
Total shareholders' equity	837,885	804,986
Total liabilities and shareholders' equity	$ 853,206	$ 820,860

Condensed Financial Informati97

Condensed Financial Information - Parent Company - Condensed Statements of Earnings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income:
Total interest income	$ 232,288	$ 221,623	$ 198,539
Expenses:
Salaries and employee benefits	90,739	80,999	70,456
EARNINGS BEFORE INCOME TAXES	135,927	131,818	118,592
Income tax benefit	(31,153)	(31,437)	(29,033)
NET EARNINGS	104,774	100,381	89,559
Parent Company [Member]
Income:
Cash dividends from subsidiaries	48,800	51,200	34,000
Excess of earnings over dividends of subsidiaries	58,809	52,911	58,539
Other	4,184	4,185	3,717
Total interest income	111,793	108,296	96,256
Expenses:
Salaries and employee benefits	5,655	6,067	5,595
Other operating expenses	3,531	4,439	3,309
Total Expense	9,186	10,506	8,904
EARNINGS BEFORE INCOME TAXES	102,607	97,790	87,352
Income tax benefit	2,167	2,591	2,207
NET EARNINGS	$ 104,774	$ 100,381	$ 89,559

Condensed Financial Informati98

Condensed Financial Information - Parent Company - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
NET EARNINGS	$ 104,774	$ 100,381	$ 89,559
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization, net	11,573	11,145	9,262
Decrease (increase) in other assets	2,397	(16,919)	9,852
Increase (decrease) in other liabilities	(2,643)	1,664	3,486
Net cash provided by operating activities	160,742	109,092	131,402
CASH FLOWS FROM INVESTING ACTIVITIES:
Net decrease in interest-bearing time deposits in unaffiliated banks	1,788	13,507	14,915
Purchases of bank premises and equipment	(20,399)	(17,433)	(17,412)
Net cash used in (provided by) investing activities	(251,960)	(384,225)	(575,205)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds of stock issuances	1,260	1,545	1,437
Cash dividends paid	(44,907)	(38,767)	(34,578)
Net cash provided by financing activities	74,818	294,548	485,262
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(16,400)	19,415	41,459
CASH AND CASH EQUIVALENTS, beginning of year	272,886	253,471	212,012
CASH AND CASH EQUIVALENTS, end of year	256,486	272,886	253,471
Parent Company [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
NET EARNINGS	104,774	100,381	89,559
Adjustments to reconcile net earnings to net cash provided by operating activities:
Excess of earnings over dividends of subsidiary bank	(58,809)	(52,911)	(58,539)
Depreciation and amortization, net	208	197	200
Decrease (increase) in other assets	1,702	507	(150)
Increase (decrease) in other liabilities	(1,374)	3,743	(314)
Other	8
Net cash provided by operating activities	46,509	51,917	30,756
CASH FLOWS FROM INVESTING ACTIVITIES:
Cash received (paid) in connection with acquisition of banks		13,125
Net decrease in interest-bearing time deposits in unaffiliated banks			480
Purchases of bank premises and equipment	(94)	(107)	(780)
Repayment from (of advances to) investment in and advances to subsidiaries, net		5,800	(3,300)
Other	10
Net cash used in (provided by) investing activities	(84)	18,818	(3,600)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayment of subordinated debt		(13,125)
Proceeds of stock issuances	1,260	1,545	1,437
Cash dividends paid	(44,907)	(38,767)	(34,578)
Net cash provided by financing activities	(43,647)	(50,347)	(33,141)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	2,778	20,388	(5,985)
CASH AND CASH EQUIVALENTS, beginning of year	90,473	70,085	76,070
CASH AND CASH EQUIVALENTS, end of year	$ 93,251	$ 90,473	$ 70,085

Cash Flow Information - Supplem

Cash Flow Information - Supplemental Information on Cash Flows and Noncash Transactions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Supplemental cash flow information:
Interest paid	$ 5,465	$ 4,085	$ 4,231
Federal income taxes paid	28,348	29,674	28,711
Schedule of noncash investing and financing activities:
Assets acquired through foreclosure	2,269	$ 203	1,385
Investment securities purchased but not settled	$ 12,381		$ 1,248

Acquisitions and Asset Purch100

Acquisitions and Asset Purchase - Additional Information (Detail) - USD ($)	Aug. 03, 2015	Jul. 31, 2015	Apr. 08, 2015	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Fair value of purchased credit impaired loans				$ 27,371,000	$ 28,601,000
Contractual amounts				38,379,000	35,030,000
Business acquisition, cash purchase price					1,931,000
Goodwill resulting from acquisition				139,971,000	139,971,000
Purchased Credit Impaired Loans [Member]
Business Acquisition [Line Items]
Contractual amounts				$ 1,865,000	$ 2,936,000
FBC Bancshares, Inc. and First Bank, N.A. [Member]
Business Acquisition [Line Items]
Business acquisition, agreement date				Apr. 1, 2015
Payment for all outstanding shares of acquired entity by shares		1,755,374
Subordinated debt, paid off	$ 13,125,000
Fair value of total loans				$ 248,380,000
Total loans of contractual amounts				252,458,000
Goodwill resulting from acquisition				43,922,000
FBC Bancshares, Inc. and First Bank, N.A. [Member] | Purchased Credit Impaired Loans [Member]
Business Acquisition [Line Items]
Fair value of purchased credit impaired loans				1,398,000
Contractual amounts				$ 1,704,000
4Trust Mortgage, Inc. [Member]
Business Acquisition [Line Items]
Business acquisition, agreement date				Apr. 8, 2015
Business acquisition, cash purchase price			$ 1,900,000
Goodwill resulting from acquisition				$ 1,750,000

Acquisitions and Asset Purch101

Acquisitions and Asset Purchase - Schedule of Amounts Recorded on Consolidated Balance Sheet on Acquisition Date (Detail) $ in Thousands	Jul. 31, 2015USD ($)
FBC Bancshares, Inc. and First Bank, N.A. [Member]
Business Acquisition [Line Items]
Common stock issued (1,755,374 shares)	$ 59,648

Acquisitions and Asset Purch102

Acquisitions and Asset Purchase - Schedule of Amounts Recorded on Consolidated Balance Sheet on Acquisition Date (Parenthetical) (Detail)	Jul. 31, 2015shares
FBC Bancshares, Inc. and First Bank, N.A. [Member]
Business Acquisition [Line Items]
Common stock issued shares	1,755,374

Acquisitions and Asset Purch103

Acquisitions and Asset Purchase - Schedule of Preliminary Estimated Fair Value Amounts Assigned to Major Asset and Liability Categories at Acquisition Date (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill resulting from acquisition	$ 139,971,000	$ 139,971,000
FBC Bancshares, Inc. and First Bank, N.A. [Member]
Business Acquisition [Line Items]
Cash and cash equivalents	65,197,000
Securities available-for-sale	42,903,000
Loans	248,380,000
Identifiable intangible assets	2,343,000
Other assets	15,262,000
Total identifiable assets acquired	374,085,000
Deposits	343,583,000
Subordinated debt	13,125,000
Other liabilities	1,651,000
Total liabilities assumed	358,359,000
Fair value of net identifiable assets acquired	15,726,000
Goodwill resulting from acquisition	$ 43,922,000