BancFirst (BANF) 10-K 13 Mar 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Jan. 30, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	BANF
Entity Registrant Name	BANCFIRST CORP /OK/
Entity Central Index Key	760498
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		15,504,513
Entity Public Float			$476,942,909

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
ASSETS
Cash and due from banks	$203,545	$196,547
Interest-bearing deposits with banks	1,710,350	1,660,988
Securities (fair value: $524,861 and $527,735, respectively)	524,783	527,627
Loans:
Total loans (net of unearned interest)	3,860,831	3,387,146
Allowance for loan losses	-40,889	-39,034
Loans, net	3,819,942	3,348,112
Premises and equipment, net	121,341	117,862
Other real estate owned	7,859	8,149
Intangible assets, net	10,635	10,273
Goodwill	44,962	44,545
Accrued interest receivable and other assets	131,555	124,871
Total assets	6,574,972	6,038,974
Deposits:
Noninterest-bearing	2,411,066	2,085,753
Interest-bearing	3,493,638	3,333,766
Total deposits	5,904,704	5,419,519
Short-term borrowings	3,982	4,590
Long-term borrowings		6,938
Accrued interest payable and other liabilities	30,168	24,126
Junior subordinated debentures	26,804	26,804
Total liabilities	5,965,658	5,481,977
Commitments and contingent liabilities (Note 19)
Stockholders’ equity:
Common stock, $1.00 par; 20,000,000 shares authorized; shares issued and outstanding: 15,504,513 and 15,333,622, respectively	15,504	15,334
Capital surplus	96,841	88,803
Retained earnings	492,776	448,953
Accumulated other comprehensive income, net of income tax of $2,644 and $2,103, respectively	4,193	3,907
Total stockholders’ equity	609,314	556,997
Total liabilities and stockholders’ equity	6,574,972	6,038,974
Senior Preferred Stock [Member]
Stockholders’ equity:
Preferred stock, value
Cumulative Preferred Stock [Member]
Stockholders’ equity:
Preferred stock, value

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Securities, fair value	$524,861	$527,735
Common stock, par value	$1	$1
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares issued	15,504,513	15,333,622
Common stock, shares outstanding	15,504,513	15,333,622
Accumulated other comprehensive income, tax	$2,644	$2,103
Senior Preferred Stock [Member]
Preferred stock, par value	$1	$1
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Cumulative Preferred Stock [Member]
Preferred stock, par value	$5	$5
Preferred stock, shares authorized	900,000	900,000
Preferred stock, shares issued	0	0

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
INTEREST INCOME
Loans, including fees	$182,972	$167,051	$169,143
Securities:
Taxable	5,727	4,947	7,686
Tax-exempt	1,061	1,222	1,555
Federal funds sold	2	2	2
Interest-bearing deposits with banks	4,391	4,064	4,201
Total interest income	194,153	177,286	182,587
INTEREST EXPENSE
Deposits	10,795	11,579	15,250
Short-term borrowings	16	6	28
Long-term borrowings	25	216	360
Junior subordinated debentures	1,966	1,966	2,134
Total interest expense	12,802	13,767	17,772
Net interest income	181,351	163,519	164,815
Provision for loan losses	3,072	1,258	3,100
Net interest income after provision for loan losses	178,279	162,261	161,715
NONINTEREST INCOME
Trust revenue	9,180	8,072	7,315
Service charges on deposits	56,389	52,450	46,492
Securities transactions	1,641	420	4,915
Income from sales of loans	1,813	2,306	2,773
Insurance commissions	14,642	14,094	12,626
Cash management	6,741	6,250	7,504
Gain on sale of other assets	335	293	374
Other	5,672	6,270	5,718
Total noninterest income	96,413	90,155	87,717
NONINTEREST EXPENSE
Salaries and employee benefits	108,640	102,165	99,535
Occupancy and fixed assets expense, net	11,610	10,635	10,576
Depreciation	9,595	9,412	9,013
Amortization of intangible assets	1,754	1,665	1,827
Data processing services	4,689	4,785	4,822
Net expense from other real estate owned	511	434	1,547
Marketing and business promotion	7,024	6,652	7,327
Deposit insurance	3,291	3,003	2,949
Other	36,407	32,823	32,832
Total noninterest expense	183,521	171,574	170,428
Income before taxes	91,171	80,842	79,004
Income tax expense	27,284	26,525	27,104
Net income	63,887	54,317	51,900
NET INCOME PER COMMON SHARE
Basic	$4.14	$3.56	$3.42
Diluted	$4.04	$3.49	$3.36
OTHER COMPREHENSIVE INCOME
Unrealized gains (losses) on securities, net of tax of $(747), $1,249 and $719, respectively	613	-2,321	-1,334
Reclassification adjustment for gains included in net income, net of tax of $206, $48 and $965, respectively	-327	-89	-1,793
Other comprehensive income (loss), net of tax of $(541), $1,297 and $1,684, respectively	286	-2,410	-3,127
Comprehensive income	$64,173	$51,907	$48,773

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Net of tax on unrealized gains (losses) on securities	($747)	$1,249	$719
Net of tax on reclassification adjustment for gains included in net income	206	48	965
Net of tax on other comprehensive income (loss)	($541)	$1,297	$1,684

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (USD $)	Total	COMMON STOCK [Member]	CAPITAL SURPLUS [Member]	RETAINED EARNINGS [Member]	ACCUMULATED OTHER COMPREHENSIVE INCOME [Member]
In Thousands, except Share data
Balance at beginning of period at Dec. 31, 2011		$15,118	$77,462	$381,017	$9,444
Balance at beginning of period, Shares at Dec. 31, 2011		15,117,430
Shares issued, Value		131	2,139
Shares issued, Shares		131,665
Net income	51,900			51,900
Net change	-3,127				-3,127
Tax effect of stock options			1,270
Dividends on common stock				-17,061
Stock-based compensation arrangements			1,530
Shares acquired and canceled, Value		-7		-249
Shares acquired and canceled, Shares		-6,787
Balance at end of period at Dec. 31, 2012	519,567	15,242	82,401	415,607	6,317
Balance at end of period, Shares at Dec. 31, 2012	15,242,308	15,242,308
Shares issued, Value		158	3,590
Shares issued, Shares		157,155
Net income	54,317			54,317
Net change	-2,410				-2,410
Tax effect of stock options			1,452
Dividends on common stock				-18,327
Stock-based compensation arrangements			1,360
Shares acquired and canceled, Value		-66		-2,644
Shares acquired and canceled, Shares		-65,841
Balance at end of period at Dec. 31, 2013	556,997	15,334	88,803	448,953	3,907
Balance at end of period, Shares at Dec. 31, 2013	15,333,622	15,333,622
Shares issued, Value		170	4,742
Shares issued, Shares		170,891
Net income	63,887			63,887
Net change	286				286
Tax effect of stock options			1,620
Dividends on common stock				-20,064
Stock-based compensation arrangements			1,676
Balance at end of period at Dec. 31, 2014	$609,314	$15,504	$96,841	$492,776	$4,193
Balance at end of period, Shares at Dec. 31, 2014	15,504,513	15,504,513

Consolidated_Statements_of_Sto1

Consolidated Statements of Stockholders' Equity (Parenthetical) (RETAINED EARNINGS [Member], USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
RETAINED EARNINGS [Member]
Dividend on common stock	$1.30	$1.20	$1.12

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flow (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$63,887	$54,317	$51,900
Adjustments to reconcile to net cash provided by operating activities:
Provision for loan losses	3,072	1,258	3,100
Depreciation and amortization	11,349	11,077	10,840
Net amortization of securities premiums and discounts	910	1,563	1,401
Realized securities gains	-1,641	-420	-4,915
Gain on sales of loans	-1,813	-2,306	-2,773
Cash receipts from the sale of loans originated for sale	152,440	200,946	231,802
Cash disbursements for loans originated for sale	-153,592	-193,853	-230,666
Deferred income tax benefit	-3,683	-483	-689
Gain on other assets	-760	-790	-232
(Increase)/decrease in interest receivable	-309	284	2,686
Decrease in interest payable	-333	-375	-540
Amortization of stock-based compensation arrangements	1,676	1,360	1,530
Other, net	5,719	5,512	-3,148
Net cash provided by operating activities	76,922	78,090	60,296
INVESTING ACTIVITIES
Net cash and due from banks provided by acquisitions	174,283
Net decrease/(increase) in federal funds sold	4,619	700	-300
Purchases of held for investment securities	-708	-902	-2,525
Purchases of available for sale securities	-224,217	-157,139	-106,759
Proceeds from maturities, calls and paydowns of held for investment securities	4,101	5,816	8,616
Proceeds from maturities, calls and paydowns of available for sale securities	225,394	181,769	145,740
Proceeds from sales of available for sale securities	4,855	521	6,025
Purchases of loans	-76,315	-66,587	-29,380
Proceeds from sales of loans	30,201	88,166	49,385
Net other increase in loans	-319,950	-174,915	-252,905
Purchases of premises, equipment and computer software	-11,490	-13,896	-13,438
Proceeds from the sale of other assets	5,851	5,389	9,651
Net cash used in investing activities	-183,376	-131,078	-185,890
FINANCING ACTIVITIES
Net increase in demand, transaction and savings deposits	305,940	47,914	467,688
Net decrease in time deposits	-122,569	-69,225	-64,593
Net (decrease)/increase in short-term borrowings	-608	19	-3,703
Pay down of long-term borrowings	-6,938	-2,240	-9,298
Issuance of common stock	6,532	5,200	3,540
Common stock acquired		-2,710	-256
Redemption of junior subordinated debentures			-9,279
Cash dividends paid	-19,543	-13,583	-21,090
Net cash provided by (used in) financing activities	162,814	-34,625	363,009
Net increase /(decrease) in cash, due from banks and interest-bearing deposits	56,360	-87,613	237,415
Cash, due from banks and interest-bearing deposits at the beginning of the period	1,857,535	1,945,148	1,707,733
Cash, due from banks and interest-bearing deposits at the end of the period	1,913,895	1,857,535	1,945,148
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid during the year for interest	13,135	14,142	18,312
Cash paid during the year for income taxes	26,178	20,946	25,975
Noncash investing and financing activities:
Unpaid common stock dividends declared	$5,265	$4,744

Description_of_Business_and_Su

Description of Business and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Description of Business and Summary of Significant Accounting Policies	(1) DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	The accounting and reporting policies of BancFirst Corporation and its subsidiaries (the “Company”) conform to accounting principles generally accepted in the United States of America (U.S. GAAP) and general practice within the banking industry. A summary of the significant accounting policies follows.
	Nature of Operations
	BancFirst Corporation is an Oklahoma business corporation and a financial holding company under federal law. It conducts virtually all of its operating activities through its principal wholly-owned subsidiary, BancFirst (the “Bank” or “BancFirst”), a state-chartered bank headquartered in Oklahoma City, Oklahoma. The Bank provides a wide range of retail and commercial banking services, including: commercial, real estate, agricultural and consumer lending; depository and funds transfer services; collections; safe deposit boxes; cash management services; retail brokerage services; and other services tailored for both individual and corporate customers. The Bank also offers trust services and acts as executor, administrator, trustee, transfer agent and in various other fiduciary capacities. Through its Technology and Operations Center, the Bank provides item processing, research and other correspondent banking services to financial institutions and governmental units. The Company’s wholly-owned subsidiary, BancFirst Insurance Services, Inc., an independent insurance agency, offers a variety of commercial and personal insurance products. In addition, the Company’s wholly-owned subsidiary, Council Oak Partners, LLC, an Oklahoma limited liability company engages in investing activities.
	Basis of Presentation
	The accompanying consolidated financial statements include the accounts of BancFirst Corporation, Council Oak Partners, LLC, BancFirst Insurance Services, Inc., and BancFirst and its subsidiaries. The principal operating subsidiaries of BancFirst are Council Oak Investment Corporation, Council Oak Real Estate Inc. and BancFirst Agency, Inc. BancFirst Community Development Corporation was dissolved in September 2014. All significant intercompany accounts and transactions have been eliminated. Assets held in a fiduciary or agency capacity are not assets of the Company and, accordingly, are not included in the consolidated financial statements. Certain amounts from 2013 and 2012 have been reclassified to conform to the 2014 presentation. These reclassifications were not material to the Company’s financial statements.
	Use of Estimates in the Preparation of Financial Statements
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States inherently involves the use of estimates and assumptions that affect the amounts reported in the financial statements and the related disclosures. These estimates relate principally to the determination of the allowance for loan losses, income taxes, the fair value of financial instruments and the valuation of intangibles. Such estimates and assumptions may change over time and actual amounts realized may differ from those reported.
	Securities
	The Company does not engage in securities trading activities. Any sales of securities are for the purpose of executing the Company’s asset/liability management strategy, eliminating a perceived credit risk in a specific security, or providing liquidity. Securities that are being held for indefinite periods of time, or that may be sold as part of the Company’s asset/liability management strategy, to provide liquidity or for other reasons, are classified as available for sale and are stated at estimated fair value. Unrealized gains or losses on securities available for sale are reported as a component of stockholders’ equity, net of income tax. Gains or losses from sales of securities are based upon the book values of the specific securities sold. Securities for which the Company has the intent and ability to hold to maturity are classified as held for investment and are stated at cost, adjusted for amortization of premiums and accretion of discounts computed under the interest method. The Company reviews its portfolio of securities for impairment at least quarterly. Impairment is considered to be other-than-temporary if it is likely that all amounts contractually due will not be received for debt securities and when there is no positive evidence indicating that an investment’s carrying amount is recoverable in the near term for equity securities. When impairment is considered other-than-temporary, the cost basis of the security is written down to fair value, with the impairment charge included in earnings. In evaluating whether the impairment is temporary or other-than-temporary, the Company considers, among other things, the time period the security has been in an unrealized loss position, and whether the Company has the intent and ability to hold a security for a period of time sufficient to allow for any anticipated recovery in fair value.
	Loans
	The lending function is governed by written policies and procedures, as determined by senior management and approved by the Board of Directors. The policies and procedures set the standards for lending in each major loan category by collateral type and use of loan proceeds. The objectives of these policies and procedures are to identify profitable markets, determine appropriate risk tolerance levels for each type of loan, establish limits for loan officer approval, set concentration limits, establish loan-to-value thresholds, set repayment terms and loan structure guidelines and adhere to documentation requirements. Interest rate risk is controlled by the use of variable rate provisions, the vast majority of which have a rate floor, limits on fixing rates for longer periods, and strict adherence to the original amortization terms in a rising interest rate environment.
	One to four family residential real estate loans are made in accordance with underwriting policies and are fully documented. Credit worthiness is assessed based on significant credit characteristics including credit history, residential and employment stability. These loans include first liens, junior liens and home equity lines of credit. The composition of this portfolio is primarily first liens, which comprise more than 80% of the portfolio, with junior liens comprising less than 15%, and home equity lines of credit comprising less than 5%. The Company does not engage in any hybrid loan programs. In addition, the Company does not have any exposure to loans with negative amortization, interest rate carryover or discounting of the initial rates (teaser rates).
	Loans originated within the Company are stated at the principal amount outstanding, net of unearned interest, loan fees and allowance for loan losses. Interest on all performing loans is recognized, on a simple interest basis, based upon the principal amount outstanding. A loan is placed on nonaccrual status when, in the opinion of management, the future collectability of interest and/or principal is not probable. When interest accrual is discontinued, all unpaid accrued interest is reversed. Interest income is recognized on certain of these loans on a cash basis if the full collection of the remaining principal balance is reasonably expected. Otherwise, interest income is not recognized until the principal balance is fully collected. See Note (5) for loan disclosures.
	Acquired Loans
	Loans acquired through business combinations since December 2009 are required to be carried at fair value as of the date of the combination. Loans that would have a general allowance for loan losses or have specific evidence of deterioration of credit quality since origination are adjusted to fair value and any allowance for loan losses is eliminated. The difference between the fair value of loans which do not have specific evidence of deterioration of credit quality since origination and their principal balance is recognized in interest income on a level-yield method over the life of the loans. For loans which it is probable, at acquisition, that the Company will be unable to collect all contractually required payments (as determined by the present value of expected future cash flows), the difference between the undiscounted cash flows expected at acquisition and the investment in the loan, or the “accretable yield,” is recognized in interest income on a level-yield method over the life of the loan. Contractually required payments for interest and principal that exceed the undiscounted cash flows expected at acquisition, or the “nonaccretable difference,” are not recognized as yield adjustments or as loss accruals or valuation allowances. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows are recognized as impairments. Any probable loss due to subsequent credit deterioration of the loans since acquisition is provided for in the allowance for loan losses.
	Loans Held For Sale
	The Company originates mortgage loans to be sold. At the time of origination, the acquiring bank has already been determined and the terms of the loan, including the interest rate, have already been set by the acquiring bank allowing the Company to originate the loan at fair value. Mortgage loans are generally sold within 30 days of origination. Loans held for sale are carried at the lower of cost or market. Gains or losses recognized upon the sale of the loans are determined on a specific identification basis. The Company does not sell residential mortgage loans with recourse other than obligations under standard representations and warranties or for fraud. These obligations relate to loan performance for the life of the loan. The amount of loans repurchased since the inception of the program is not considered to be material, and therefore, no reserve has been required.
	Allowance for Loan Losses
	The allowance for loan losses is an estimate of probable credit losses related to specifically identified loans and for losses inherent in the portfolio that have been incurred as of the balance sheet date. The allowance for loan losses is increased by provisions charged to operating expense and is reduced by net loan charge-offs. The amount of the allowance for loan losses is based on past loan loss experience, evaluations of known impaired loans, levels of adversely graded loans, general economic conditions and other environmental factors. Loans are considered impaired when, based on current information and events, it is probable the Company will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreement, including scheduled principal and interest payments. Impairment is evaluated in aggregate for smaller-balance loans of a similar nature and on an individual loan basis for other loans. If a loan is impaired, a specific allowance is provided, if necessary, so that the loan is reported net, at the present value of estimated future cash flows using the loan’s existing rate or at the fair value of collateral if repayment is expected primarily from the collateral. Interest payments on impaired loans are typically applied to principal unless collectability of the principal amount is reasonably assured, in which case interest is recognized on a cash basis. Impaired loans, or portions thereof, are charged off when deemed uncollectible.
	Appraisal Policy
	An updated appraisal of the collateral is obtained when a loan is first identified as a problem loan. Appraisals are reviewed annually and are updated as needed, or are updated more frequently if significant changes are believed to have occurred in the collateral or market conditions. Appraisals of other real estate owned are also reviewed and updated consistent with this policy.
	Nonaccrual Policy
	The Company does not accrue interest on (1) any loan upon which a default of principal or interest has existed for a period of 90 days or over unless the collateral margin or guarantor support are such that full collection of principal and interest are not in doubt, and an orderly plan for collection is in process; and (2) any other loan for which it is expected full collection of principal and interest is not probable.
	A nonaccrual loan may be restored to an accrual status when none of its principal and interest are past due and unpaid or otherwise becomes well secured and in the process of collection and when prospects for collection of future contractual payments are no longer in doubt. With the exception of a formal debt forgiveness agreement, no loan which has had principal charged-off shall be restored to accrual status unless the charged-off principal has been recovered.
	Charge-off Policy
	When a loan deteriorates to the point that the account officer or the Loan Committee concludes it no longer represents a viable asset, it will be charged off. Similarly, any portion of a loan that is deemed to no longer be a viable asset will be charged off. A loan will not be charged off unless such action has been approved by the branch President.
	Premises and Equipment
	Premises and equipment are stated at cost, less accumulated depreciation. Depreciation is charged to operating expense and is computed using the straight-line method over the estimated useful lives of the assets. Maintenance and repairs are charged to expense as incurred while improvements are capitalized. Premises and equipment is tested for impairment if events or changes in circumstances occur that indicate that the carrying amount of any premises and equipment may not be recoverable. Impairment losses are measured by comparing the fair values of the premises and equipment with their recorded amounts. Premises that are identified to be sold are transferred to other real estate owned at the lower of their carrying amounts or their fair values less estimated costs to sell. Any losses on premises identified to be sold are charged to operating expense. When premises and equipment are transferred to other real estate owned, sold, or otherwise retired, the cost and applicable accumulated depreciation are removed from the respective accounts and any resulting gains or losses are reported in the statement of comprehensive income.
	Other Real Estate Owned
	Other real estate owned consists of properties acquired through foreclosure proceedings or acceptance of a deed in lieu of foreclosure, and premises held for sale. These properties are carried at the lower of the book values of the related loans or fair values based upon appraisals, less estimated costs to sell. Losses arising at the time of reclassification of such properties from loans to other real estate owned are charged directly to the allowance for loan losses. Any losses on premises identified to be sold are charged to operating expense at the time of transfer from premises to other real estate owned. Losses from declines in value of the properties subsequent to classification as other real estate owned are charged to operating expense.
	Intangible Assets and Goodwill
	Core deposit intangibles are amortized on a straight-line basis over the estimated useful lives of seven to ten years and customer relationship intangibles are amortized on a straight-line basis over the estimated useful life of three to eighteen years. Mortgage servicing rights are amortized based on current prepayment assumptions. Goodwill is not amortized, but is evaluated at a reporting unit level at least annually for impairment, or more frequently if other indicators of impairment are present. At least annually in the fourth quarter, intangible assets, excluding mortgage servicing rights, are evaluated for possible impairment. Impairment losses are measured by comparing the fair values of the intangible assets with their recorded amounts. Any impairment losses are reported in the statement of comprehensive income. Mortgage servicing rights are adjusted to fair value semi-annually, if impaired.
	Derivatives
	The Company recognizes all of its derivative instruments as assets or liabilities in the balance sheet at fair value and recognizes the realized and unrealized change in fair value in the statement of comprehensive income. Income is derived from a fixed pricing spread when customer hedge contracts are immediately offset with counterparty contracts as compensation for administrative costs and credit risk and recognized in other noninterest income.
	Insurance Commissions and Fees
	Commission revenue is recognized at the later of the billing date or the effective date of the related insurance policies for those accounts billed by the Agency. Commission revenue, for accounts that are directly billed by the insurance company to the insured, is recognized when determinable by the Agency, which is generally when such commissions are received.
	The Agency also receives contingent commissions from insurance companies as additional incentive for achieving specified premium volume goals and/or loss experience parameters relating to the insurance placed by the Agency. Contingent commissions from insurance companies are recognized when determinable, which is generally when such commissions are received.
	Stock-based Compensation
	The Company recognizes stock-based compensation as compensation expense in the statement of comprehensive income based on the fair value of the Company’s stock options on the measurement date, which, for the Company, is the date of the grant. The fair value of each option grant is estimated on the date of grant using the Black-Scholes option-pricing model and is based on certain assumptions including risk-free rate of return, dividend yield, stock price volatility and the expected term. The fair value of each option is expensed over its vesting period.
	Income Taxes
	The Company files a consolidated income tax return with its subsidiaries. Federal and state income tax expense or benefit has been allocated to subsidiaries on a separate return basis. Deferred taxes are recognized under the liability method based upon the future tax consequences of temporary differences between the carrying amounts and tax basis of assets and liabilities, using the tax rates expected to apply to taxable income in the periods when the related temporary differences are expected to be realized. Realization of deferred tax assets is dependent upon the generation of a sufficient level of future taxable income and recoverable taxes paid in prior years. Although realization is not assured, management believes it is more likely than not that all of the deferred tax assets will be realized.
	Earnings Per Common Share
	Basic earnings per common share is computed by dividing net income, less any preferred dividends requirement, by the weighted average of common shares outstanding. Diluted earnings per common share reflects the potential dilution that could occur if options, convertible securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in the earnings of the Company.
	Comprehensive Income
	Comprehensive income includes all changes in stockholders’ equity during a period, except those resulting from transactions with stockholders. Besides net income, other components of the Company’s comprehensive income includes the after tax effect of changes in the net unrealized gain/loss on securities available for sale.
	Statement of Cash Flows
	For purposes of the statement of cash flows, the Company considers cash and due from banks, and interest-bearing deposits with banks as cash equivalents.
	Recent Accounting Pronouncements
	In August 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-15, “Presentation of Financial Statements – Going Concern (Topic 205-40).” ASU 2014-15 provides guidance on management’s responsibility in evaluating whether there is substantial doubt about the Company’s ability to continue as a going concern and related footnote disclosures. For each reporting period, management will be required to evaluate whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year from the date the financial statements are issued. The amendments are effective for annual periods, and interim reporting periods within those annual periods, beginning after December 15, 2016. Early adoption is permitted. Adoption of ASU 2014-15 is not expected to have a significant effect on the Company’s financial statements.
	In January 2014, the FASB issued Accounting Standards Update ASU No. 2014-04, “Receivables: Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure (Topic 310-40).” ASU 2014-04 clarifies that an in-substance repossession or foreclosure occurs upon either the creditor obtaining legal title to the residential real estate property or the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. The amendments are effective for annual periods, and interim reporting periods within those annual periods, beginning after December 15, 2014. The amendments may be adopted using either a modified retrospective transition method or a prospective transition method. Early adoption is permitted. Adoption of ASU 2014-04 is not expected to have a significant effect on the Company’s financial statements.
	In January 2014, the FASB issued ASU No. 2014-01, “Accounting for Investments in Affordable Housing Projects (Topic 323).” ASU 2014-01 revises the necessary criteria that need to be met in order for an entity to account for investments in affordable housing projects net of the provision for income taxes. It also changes the method of recognition from an effective amortization approach to a proportional amortization approach. Additional disclosures were also set forth in this update. The amendments are effective for annual periods, and interim reporting periods within those annual periods, beginning after December 15, 2014. The amendments are required to be applied retrospectively to all periods presented. Early adoption is permitted and adoption of the standard is optional. Adoption of ASU 2014-01 may affect income statement presentation, but otherwise is not expected to have a material impact on the Company’s financial statements.

Recent_Developments_Including_

Recent Developments, Including Mergers and Acquisitions	12 Months Ended
	Dec. 31, 2014
Recent Developments Including Mergers And Acquisitions [Abstract]
Recent Developments, Including Mergers and Acquisitions	(2) RECENT DEVELOPMENTS, INCLUDING MERGERS AND ACQUISITIONS
	On January 24, 2014, BancFirst assumed all of the deposits and purchased certain assets of The Bank of Union, El Reno, Oklahoma (“The Bank of Union”). The Bank of Union was closed on that day by the Oklahoma State Banking Department.
	At the time of the closing, The Bank of Union had total deposits of approximately $302 million that were assumed by BancFirst. BancFirst initially purchased approximately $121 million of loans, the majority of which were classified as performing, $4.8 million of securities, and $10,000 of other real estate. Its bid included a discount for the loans purchased. BancFirst had bid on, but was generally not awarded, loans that were classified as nonperforming. As a result of the acquisition, the Company recorded a core deposit intangible of approximately $2.2 million and goodwill of $417,000. The effect of this acquisition was included in the consolidated financial statements of the Company from the date of acquisition forward. The acquisition did not have a material effect on the Company’s consolidated financial statements.
	At December 31, 2014, the balance of acquired loans from the former Bank of Union was approximately $74.8 million, the majority of which were classified as performing, and deposits in acquired branches were approximately $174.4 million.
	On January 19, 2012, Council Oak Investment Corporation, a wholly-owned subsidiary of BancFirst, completed the sale of one of its investments that resulted in a pretax gain of approximately $4.5 million. After related expenses and income taxes, the increase in net income approximated $2.6 million.

Cash_Due_from_Banks_InterestBe

Cash, Due from Banks, Interest-Bearing Deposits and Federal Funds Sold	12 Months Ended
	Dec. 31, 2014
Cash And Cash Equivalents [Abstract]
Cash, Due from Banks, Interest-Bearing Deposits and Federal Funds Sold	(3) CASH, DUE FROM BANKS, INTEREST-BEARING DEPOSITS AND FEDERAL FUNDS SOLD
	The Company maintains accounts with the Federal Reserve Bank and various other financial institutions primarily for the purpose of holding excess liquidity and clearing cash items. It may also sell federal funds to certain of these institutions on an overnight basis. At December 31, 2014 and 2013, the Company had no significant concentrations of credit risk with other financial institutions. The Company maintained vault cash and funds on deposit with the Federal Reserve Bank, which is included in the table below.
	The Company is required, as a matter of law, to maintain a reserve balance in the form of vault cash or cash on deposit with the Federal Reserve Bank. The average amount of required reserves for each of the years ended December 31, 2014 and 2013 is included in the following table:
		December 31,
		2014		2013
		(Dollars in thousands)
	Vault cash and funds on deposit with the Federal Reserve Bank	$	1,804,028	$	1,758,908
	Average required reserves		44,711		37,456

Securities

Securities	12 Months Ended
	Dec. 31, 2014
Investments Debt And Equity Securities [Abstract]
Securities	(4) SECURITIES
	The following table summarizes securities held for investment and securities available for sale:
			December 31,
			2014		2013
			(Dollars in thousands)
	Held for investment at cost (fair value: $8,671 and $12,094, respectively)		$	8,593	$	11,986
	Available for sale, at fair value			516,190		515,641
	Total		$	524,783	$	527,627
	The following table summarizes the amortized cost and estimated fair values of securities held for investment:
			Amortized		Gross		Gross			Estimated
			Cost		Unrealized		Unrealized			Fair
					Gains		Losses			Value
			(Dollars in thousands)
	December 31, 2014
	Mortgage backed securities (1)		$	471	$	34	$	—		$	505
	States and political subdivisions			8,122		44		—			8,166
	Total		$	8,593	$	78	$	—		$	8,671
	December 31, 2013
	Mortgage backed securities (1)		$	607	$	48	$	—		$	655
	States and political subdivisions			11,379		67		(7	)		11,439
	Total		$	11,986	$	115	$	(7	)	$	12,094
	The following table summarizes the amortized cost and estimated fair values of securities available for sale:
			Amortized		Gross		Gross			Estimated
			Cost		Unrealized		Unrealized			Fair
					Gains		Losses			Value
			(Dollars in thousands)
	December 31, 2014
	U.S. treasuries		$	248,767	$	404	$	(178	)	$	248,993
	U.S. federal agencies			171,641		983		(175	)		172,449
	Mortgage backed securities (1)			26,441		602		(586	)		26,457
	States and political subdivisions			51,706		1,716		(49	)		53,373
	Other securities (2)			10,798		4,252		(132	)		14,918
	Total		$	509,353	$	7,957	$	(1,120	)	$	516,190
	December 31, 2013
	U.S. treasuries		$	29,946	$	—	$	(85	)	$	29,861
	U.S. federal agencies			386,391		1,399		(505	)		387,285
	Mortgage backed securities (1)			32,057		625		(4	)		32,678
	States and political subdivisions			49,116		1,290		(72	)		50,334
	Other securities (2)			12,121		3,503		(141	)		15,483
	Total		$	509,631	$	6,817	$	(807	)	$	515,641
	-1	Primarily consists of FHLMC, FNMA, GNMA and mortgage backed securities through U.S. agencies.
	-2	Primarily consists of equity securities.
	The maturities of securities held for investment and available for sale are summarized in the following table using contractual maturities. Actual maturities may differ from contractual maturities due to obligations that are called or prepaid. For purposes of the maturity table, mortgage-backed securities, which are not due at a single maturity date, have been presented at their contractual maturity.
			December 31,
			2014				2013
			Amortized		Estimated		Amortized			Estimated
			Cost		Fair		Cost			Fair
					Value					Value
			(Dollars in thousands)
	Held for Investment
	Contractual maturity of debt securities:
	Within one year		$	1,451	$	1,456	$	3,640		$	3,649
	After one year but within five years			6,603		6,642		7,277			7,321
	After five years but within ten years			380		396		837			865
	After ten years			159		177		232			259
	Total		$	8,593	$	8,671	$	11,986		$	12,094
	Available for Sale
	Contractual maturity of debt securities:
	Within one year		$	41,772	$	41,870	$	208,625		$	209,065
	After one year but within five years			350,975		352,044		167,554			168,210
	After five years but within ten years			21,990		22,717		27,195			27,797
	After ten years			87,252		88,132		97,542			98,551
	Total debt securities			501,989		504,763		500,916			503,623
	Equity securities			7,364		11,427		8,715			12,018
Total		$	509,353	$	516,190	$	509,631		$	515,641
The following is a detail of proceeds from sales and realized securities gains and losses, on available for sale securities:
		Year Ended December 31,
		2014		2013		2012
		(Dollars in thousands)
Proceeds		$	4,855	$	521	$	6,025
Gross gains realized			1,641		456		5,575
Gross losses realized			—		36		660
The following table is a summary of the Company’s book value of securities that were pledged as collateral for public funds on deposit, repurchase agreements and for other purposes as required or permitted by law:
		Year Ended December 31,
		2014		2013
		(Dollars in thousands)
Book value of pledged securities		$	522,190	$	443,835
The following table summarizes securities with unrealized losses, segregated by the duration of the unrealized loss, at December 31, 2014 and 2013 respectively:
		Less than 12 Months				More than 12 Months					Total
		Estimated		Unrealized		Estimated			Unrealized		Estimated		Unrealized
		Fair Value		Losses		Fair Value			Losses		Fair Value		Losses
		(Dollars in thousands)
December 31, 2014
Held for Investment
Mortgage backed securities		$	—	$	—	$	—		$	—	$	—	$	—
States and political subdivisions			—		—		—			—		—		—
Total		$	—	$	—	$	—		$	—	$	—	$	—
Available for Sale
U.S. treasuries		$	149,589	$	178	$	—		$	—	$	149,589	$	178
U.S. federal agencies			40,551		113		13,653			62		54,204		175
Mortgage backed securities			17,041		585		26			1		17,067		586
States and political subdivisions			3,093		26		977			23		4,070		49
Other securities			—		—		300			132		300		132
Total		$	210,274	$	902	$	14,956		$	218	$	225,230	$	1,120
December 31, 2013
Held for Investment
Mortgage backed securities		$	1	$	—	$	1		$	—	$	2	$	—
States and political subdivisions			—		—		1,328			7		1,328		7
Total		$	1	$	—	$	1,329		$	7	$	1,330	$	7
Available for Sale
U.S. treasuries		$	29,861	$	85	$	—		$	—	$	29,861	$	85
U.S. federal agencies			79,411		246		150,188			259		229,599		505
Mortgage backed securities			66		4		—			—		66		4
States and political subdivisions			2,459		72		—			—		2,459		72
Other securities			160		141		—			—		160		141
Total		$	111,957	$	548	$	150,188		$	259	$	262,145	$	807
Declines in the fair value of held for investment and available-for-sale securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses. In estimating other-than-temporary impairment losses, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer and (iii) the intent and ability of the Company to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in fair value.
Management has the ability and intent to hold the securities classified as held for investment until they mature, at which time the Company will receive full value for the securities. Furthermore, as of December 31, 2014 and 2013, the Company also had the ability and intent to hold the securities classified as available for sale for a period of time sufficient for a recovery of cost. The unrealized losses are largely due to increases in market interest rates over the yields available at the time the underlying debt securities were purchased. The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline. Management does not believe any of the securities are impaired due to reasons of credit quality, and has no intent or requirement to sell before the recovery of the unrealized loss; therefore, the Company has not recognized any impairment in the Company’s consolidated statement of comprehensive income.

Loans_and_Allowance_for_Loan_L

Loans and Allowance for Loan Losses	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Loans and Allowance for Loan Losses	(5) LOANS AND ALLOWANCE FOR LOAN LOSSES
	The following is a schedule of loans outstanding by category:
		December 31,
		2014						2013
		Amount			Percent			Amount				Percent
		(Dollars in thousands)
	Commercial and financial:
	Commercial and industrial	$	745,106			19.3	%	$	605,672				17.88	%
	Oil & gas production and equipment		104,940			2.72			96,907				2.86
	Agriculture		132,830			3.44			111,323				3.29
	State and political subdivisions:
	Taxable		20,431			0.53			10,217				0.3
	Tax-exempt		20,952			0.54			11,073				0.33
	Real estate:
	Construction		356,621			9.24			284,808				8.41
	Farmland		149,507			3.87			132,512				3.91
	One to four family residences		775,795			20.09			703,903				20.78
	Multifamily residential properties		66,766			1.73			60,080				1.77
	Commercial		1,191,477			30.86			1,097,484				32.4
	Consumer		267,179			6.92			250,588				7.4
	Other (not classified above)		29,227			0.76			22,579				0.67
	Total loans	$	3,860,831			100	%	$	3,387,146				100	%
	Loans held for sale (included above)	$	9,433					$	6,469
	The Company’s loans are mostly to customers within Oklahoma and over 65% of the loans are secured by real estate. Credit risk on loans is managed through limits on amounts loaned to individual borrowers, underwriting standards and loan monitoring procedures. The amounts and types of collateral obtained, if any, to secure loans are based upon the Company’s underwriting standards and management’s credit evaluation. Collateral varies, but may include real estate, equipment, accounts receivable, inventory, livestock and securities. The Company’s interest in collateral is secured through filing mortgages and liens, and in some cases, by possession of the collateral.
	There are inherent risks associated with the Company’s lending activities. These risks include, among other things, the impact of changes in interest rates and changes in the economic conditions in the markets where the Company operates. Increases in interest rates and/or weakening economic conditions could adversely impact the ability of borrowers to repay outstanding loans or the value of the collateral securing these loans. The Company is also subject to various laws and regulations that affect its lending activities. Failure to comply with applicable laws and regulations could subject the Company to regulatory enforcement action that could result in the assessment of significant civil money penalties against the Company. As a lender, the Company faces the risk that a significant number of its borrowers will fail to pay their loans when due. If borrower defaults cause losses in excess of the Company’s allowance for loan losses, it could have an adverse effect on the Company’s business, profitability, and financial condition.
	Loans secured by real estate, including farmland, multifamily, commercial, one to four family residential and construction and development loans, have been a large portion of the Company’s loan portfolio. The Company is subject to risk of future market fluctuations in property values relating to these loans. In addition, multi-family and commercial real estate (“CRE”) loans represent the majority of the Company’s real estate loans outstanding, a decline in tenant occupancy due to such factors or for other reasons could adversely impact the ability of the Company’s borrowers to repay their loans on a timely basis, which could have a negative impact on the Company’s financial condition and results of operation. The Company attempts to manage this risk through rigorous loan underwriting standards.
	During the ordinary course of business, the Company may foreclose on and take title to properties securing certain loans. In doing so, there is a risk that hazardous or toxic substances could be found on these properties. If hazardous or toxic substances are found, the Company may be liable for remediation costs, as well as for personal injury and property damage.
	Nonperforming and Restructured Assets
	The following is a summary of nonperforming and restructured assets:
		December 31,
		2014			2013
		(Dollars in thousands)
	Past due 90 days or more and still accruing	$	1,135		$	1,179
	Nonaccrual		16,410			14,390
	Restructured		16,515			17,624
	Total nonperforming and restructured loans		34,060			33,193
	Other real estate owned and repossessed assets		8,079			8,386
	Total nonperforming and restructured assets	$	42,139		$	41,579
	Nonperforming and restructured loans to total loans		0.88	%		0.98	%
	Nonperforming and restructured assets to total assets		0.64	%		0.69	%
	Nonaccrual loans, accruing loans past due 90 days or more, and restructured loans are shown in the table above. Had nonaccrual loans performed in accordance with their original contractual terms, the Company would have recognized additional interest income of approximately $1.2 million in 2014, $1.5 million in 2013 and $1.3 million in 2012.
	Restructured loans consisted primarily of one loan restructured to defer principal payments. The loan was evaluated by management and determined to be well collateralized. Additionally, none of the concessions granted involved a principal reduction or a change from the current market rate of interest. The collateral value will be monitored periodically to evaluate possible impairment. The Company charges interest on principal balances outstanding during deferral periods. As a result, the current and future financial effects of the recorded balance of loans considered to be restructured were not considered to be material.
	Loans are segregated into classes based upon the nature of the collateral and the borrower. These classes are used to estimate the allowance for loan losses. The following table is a summary of amounts included in nonaccrual loans, segregated by class of loans. Residential real estate refers to one to four family real estate.
		December 31,
		2014			2013
		(Dollars in thousands)
	Real estate:
	Non-residential real estate owner occupied	$	296		$	595
	Non-residential real estate other		5,126			6,270
	Residential real estate permanent mortgage		681			718
	Residential real estate all other		1,796			1,521
	Commercial and financial:
	Non-consumer non-real estate		1,556			1,192
	Consumer non-real estate		250			176
	Other loans		1,659			1,407
	Acquired loans		5,046			2,511
	Total	$	16,410		$	14,390
	The following table presents an age analysis of past due loans, segregated by class of loans:
		Age Analysis of Past Due Loans
		30-59			60-89			90 Days				Total			Current			Total Loans		Accruing
		Days			Days			and				Past Due			Loans					Loans 90
		Past Due			Past Due			Greater				Loans								Days or
																				More
																				Past Due
	(Dollars in thousands)
As of December 31, 2014
Real estate:
Non-residential real estate owner occupied	$	635		$	—		$	269			$	904		$	482,731		$	483,635	$	70
Non-residential real estate other		377			317			825				1,519			952,484			954,003		—
Residential real estate permanent mortgage		2,010			758			544				3,312			304,267			307,579		172
Residential real estate all other		1,820			194			1,488				3,502			633,586			637,088		387
Commercial and financial:
Non-consumer non-real estate		841			71			793				1,705			965,002			966,707		24
Consumer non-real estate		1,914			711			330				2,955			244,810			247,765		215
Other loans		1,858			916			741				3,515			158,902			162,417		—
Acquired loans		1,815			997			1,304				4,116			97,521			101,637		267
Total	$	11,270		$	3,964		$	6,294			$	21,528		$	3,839,303		$	3,860,831	$	1,135
As of December 31, 2013
Real estate:
Non-residential real estate owner occupied	$	411		$	—		$	316			$	727		$	454,305		$	455,032	$	96
Non-residential real estate other		5,391			269			1,543				7,203			856,179			863,382		2
Residential real estate permanent mortgage		2,000			566			789				3,355			262,625			265,980		275
Residential real estate all other		2,159			211			1,272				3,642			564,231			567,873		184
Commercial and financial:
Non-consumer non-real estate		1,122			118			1,047				2,287			793,028			795,315		125
Consumer non-real estate		1,761			667			392				2,820			225,515			228,335		279
Other loans		1,799			763			1,244				3,806			141,550			145,356		—
Acquired loans		1,491			310			593				2,394			63,479			65,873		218
Total	$	16,134		$	2,904		$	7,196			$	26,234		$	3,360,912		$	3,387,146	$	1,179
Impaired Loans
Loans are considered impaired when, based on current information and events, it is probable the Company will be unable to collect the full amount of scheduled principal and interest payments in accordance with the original contractual terms of the loan agreement. If a loan is impaired, a specific valuation allowance may be allocated if necessary so that the loan is reported, net of allowance for loss, at the present value of future cash flows using the loan’s existing rate, or the fair value of collateral if repayment is expected solely from the collateral.
The following table presents impaired loans, segregated by class of loans. No material amount of interest income was recognized on impaired loans subsequent to their classification as impaired.
	Impaired Loans
	Unpaid			Recorded			Related				Average
	Principal			Investment			Allowance				Recorded
	Balance			with							Investment
				Allowance
	(Dollars in thousands)
As of December 31, 2014
Real estate:
Non-residential real estate owner occupied	$	521		$	448		$	15			$	453
Non-residential real estate other		23,154			21,164			1,364				21,522
Residential real estate permanent mortgage		1,095			880			85				1,042
Residential real estate all other		2,480			2,270			299				2,273
Commercial and financial:
Non-consumer non-real estate		1,895			1,580			431				1,646
Consumer non-real estate		664			648			138				602
Other loans		2,101			1,659			228				1,512
Acquired loans		10,933			7,708			—				8,082
Total	$	42,843		$	36,357		$	2,560			$	37,132
As of December 31, 2013
Real estate:
Non-residential real estate owner occupied	$	877		$	752		$	28			$	881
Non-residential real estate other		24,964			23,351			2,161				23,816
Residential real estate permanent mortgage		1,253			1,025			58				1,170
Residential real estate all other		2,214			1,803			361				1,857
Commercial and financial:
Non-consumer non-real estate		1,801			1,459			388				1,553
Consumer non-real estate		628			611			139				455
Other loans		1,545			1,464			219				1,602
Acquired loans		9,848			7,861			124				7,928
Total	$	43,130		$	38,326		$	3,478			$	39,262
Credit Risk Monitoring and Loan Grading
The Company considers various factors to monitor the credit risk in the loan portfolio including volume and severity of loan delinquencies, nonaccrual loans, internal grading of loans, historical loan loss experience and economic conditions.
An internal risk grading system is used to indicate the credit risk of loans. The loan grades used by the Company are for internal risk identification purposes and do not directly correlate to regulatory classification categories or any financial reporting definitions.
The general characteristics of the risk grades are as follows:
Grade 1 – Acceptable - Loans graded 1 represent reasonable and satisfactory credit risk which requires normal attention and supervision. Capacity to repay through primary and/or secondary sources is not questioned.
Grade 2 – Acceptable - Increased Attention - This category consists of loans that have credit characteristics deserving management’s close attention. These potential weaknesses could result in deterioration of the repayment prospects for the loan or the Bank’s credit position at some future date. Such credit characteristics include loans to highly leveraged borrowers in cyclical industries, adverse financial trends which could potentially weaken repayment capacity, loans that have fundamental structure deficiencies, loans lacking secondary sources of repayment where prudent, and loans with deficiencies in essential documentation, including financial information.
Grade 3 – Loans with Problem Potential - This category consists of performing loans which are considered to exhibit problem potential. Loans in this category would generally include, but not be limited to, borrowers with a weakened financial condition or poor performance history, past dues, loans restructured to reduce payments to an amount that is below market standards and/or loans with severe documentation problems. In general, these loans have no identifiable loss potential in the near future, however; the possibility of a loss developing is heightened.
Grade 4 - Problem Loans/Assets – Nonperforming - This category consists of nonperforming loans/assets which are considered to be problems. Nonperforming loans are described as being 90 days and over past due and still accruing, and loans that are nonaccrual. The government guaranteed portion of Small Business Administration (“SBA”) loans is excluded.
Grade 5 - Loss Potential - This category consists of loans/assets which are considered to possess loss potential. While the loss may not occur in the current year, management expects that loans/assets in this category will ultimately result in a loss, unless substantial improvement occurs.
Grade 6 - Charge Off - This category consists of loans that are considered uncollectible and other assets with little or no value.
The following table presents internal loan grading by class of loans:
	Internal Loan Grading
	Grade
	1			2			3				4			5			Total
	(Dollars in thousands)
As of December 31, 2014
Real estate:
Non-residential real estate owner occupied	$	402,706		$	75,555		$	5,008			$	366		$	—		$	483,635
Non-residential real estate other		795,209			133,542			20,126				5,126			—			954,003
Residential real estate permanent mortgage		272,411			27,855			6,369				944			—			307,579
Residential real estate all other		529,555			99,214			6,146				2,173			—			637,088
Commercial and financial:
Non-consumer non-real estate		821,094			117,457			26,550				1,606			—			966,707
Consumer non-real estate		233,424			12,229			1,548				564			—			247,765
Other loans		157,191			4,261			601				173			191			162,417
Acquired loans		46,465			36,951			12,651				5,206			364			101,637
Total	$	3,258,055		$	507,064		$	78,999			$	16,158		$	555		$	3,860,831
As of December 31, 2013
Real estate:
Non-residential real estate owner occupied	$	382,798		$	66,139		$	5,446			$	649		$	—		$	455,032
Non-residential real estate other		711,081			125,617			20,309				6,375			—			863,382
Residential real estate permanent mortgage		233,924			24,882			6,081				1,093			—			265,980
Residential real estate all other		475,421			82,571			8,238				1,643			—			567,873
Commercial and financial:
Non-consumer non-real estate		691,772			97,812			4,462				1,269			—			795,315
Consumer non-real estate		214,153			11,819			1,931				431			1			228,335
Other loans		141,787			2,558			772				239			—			145,356
Acquired loans		47,220			11,980			3,766				2,907			—			65,873
Total	$	2,898,156		$	423,378		$	51,005			$	14,606		$	1		$	3,387,146
Allowance for Loan Losses Methodology
The allowance for loan losses (“ALL”) is determined by a calculation based on segmenting the loans into the following categories: (1) adversely graded loans [Grades 3, 4 and 5] that have a specific reserve allocation; (2) loans without a specific reserve segmented by loans secured by real estate other than 1-4 family residential property, loans secured by 1-4 family residential property, commercial, industrial and agricultural loans not secured by real estate, consumer purpose loans not secured by real estate, and loans over 60 days past due that are not otherwise Grade 3, 4, or 5; (3) Grade 2 loans; (4) Grade 1 loans and (5) loans held for sale which are excluded.
The ALL is calculated as the sum of the following: (1) the total dollar amount of specific reserve allocations; (2) the dollar amount derived by multiplying each segment of adversely graded loans without a specific reserve allocation times its respective reserve factor; (3) the dollar amount derived by multiplying Grade 2 loans and Grade 1 loans (less certain exclusions) times the respective reserve factor; and (4) other adjustments as deemed appropriate and documented by the Senior Loan Committee or Board of Directors.
The amount of the ALL is an estimate based upon factors which are subject to rapid change due to changing economic conditions and the economic prospects of borrowers. It is reasonably possible that a material change could occur in the estimated ALL in the near term.
The following table details activity in the ALL by class of loans for the period presented. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.
	ALL
	Balance at			Charge-			Recoveries				Net			Provisions			Balance
	beginning			offs							charge-			charged to			at end of
	of period										offs			operations			period
	(Dollars in thousands)
As of December 31, 2014
Real estate:
Non-residential real estate owner occupied	$	4,827		$	(42	)	$	102			$	60		$	(481	)	$	4,406
Non-residential real estate other		11,026			(29	)		49				20			(1,430	)		9,616
Residential real estate permanent mortgage		2,825			(207	)		78				(129	)		252			2,948
Residential real estate all other		6,708			(171	)		32				(139	)		(300	)		6,269
Commercial and financial:
Non-consumer non-real estate		8,977			(564	)		70				(494	)		4,288			12,771
Consumer non-real estate		2,556			(687	)		203				(484	)		332			2,404
Other loans		1,991			(351	)		149				(202	)		570			2,359
Acquired loans		124			(568	)		719				151			(159	)		116
Total	$	39,034		$	(2,619	)	$	1,402			$	(1,217	)	$	3,072		$	40,889
As of December 31, 2013
Real estate:
Non-residential real estate owner occupied	$	5,104		$	(3	)	$	20			$	17		$	(294	)	$	4,827
Non-residential real estate other		9,865			(19	)		12				(7	)		1,168			11,026
Residential real estate permanent mortgage		2,781			(162	)		32				(130	)		174			2,825
Residential real estate all other		7,034			(209	)		33				(176	)		(150	)		6,708
Commercial and financial:
Non-consumer non-real estate		9,385			(217	)		175				(42	)		(366	)		8,977
Consumer non-real estate		2,451			(597	)		225				(372	)		477			2,556
Other loans		1,885			(300	)		75				(225	)		331			1,991
Acquired loans		220			(53	)		39				(14	)		(82	)		124
Total	$	38,725		$	(1,560	)	$	611			$	(949	)	$	1,258		$	39,034
The following table details the amount of ALL by class of loans for the period presented, on the basis of the impairment methodology used by the Company.
	December 31, 2014						December 31, 2013
	(Dollars in thousands)
	Individually			Collectively			Individually				Collectively
	evaluated for			evaluated for			evaluated for				evaluated for
	impairment			impairment			impairment				impairment
Real estate:
Non-residential real estate owner occupied	$	202		$	4,204		$	231			$	4,596
Non-residential real estate other		1,518			8,098			2,449				8,577
Residential real estate permanent mortgage		407			2,541			243				2,582
Residential real estate all other		743			5,526			994				5,714
Commercial and financial:
Non-consumer non-real estate		4,671			8,100			966				8,011
Consumer non-real estate		372			2,032			334				2,222
Other loans		214			2,145			252				1,739
Acquired loans		—			116			—				124
Total	$	8,127		$	32,762		$	5,469			$	33,565
The following table details the loans outstanding by class of loans for the period presented, on the basis of the impairment methodology used by the Company.
	Loans
	December 31, 2014										December 31, 2013
	(Dollars in thousands)
	Individually			Collectively			Loans				Individually			Collectively			Loans
	evaluated			evaluated			acquired				evaluated			evaluated			acquired
	for			for			with				for			for			with
	impairment			impairment			deteriorated				impairment			impairment			deteriorated
							credit										credit
							quality										quality
Real estate:
Non-residential real estate owner occupied	$	5,374		$	478,261		$	—			$	6,095		$	448,937		$	—
Non-residential real estate other		25,251			928,752			—				26,684			836,698			—
Residential real estate permanent mortgage		7,313			300,266			—				7,174			258,806			—
Residential real estate all other		8,319			628,769			—				9,881			557,992			—
Commercial and financial:
Non-consumer non-real estate		28,156			938,551			—				5,731			789,584			—
Consumer non-real estate		2,112			245,653			—				2,362			225,972			—
Other loans		233			162,184			—				317			145,039			—
Acquired loans		—			83,416			18,221				—			59,200			6,674
Total	$	76,758		$	3,765,852		$	18,221			$	58,244		$	3,322,228		$	6,674
The following table is a summary of amounts included in the ALL for impaired loans with specific reserves and the recorded balance of the related loans. No material amounts of interest income were collected on impaired loans with specific reserves for 2014, 2013 or 2012.
	Year Ended December 31,
	2014			2013			2012
	(Dollars in thousands)
Allowance for loss on impaired loans	$	1,559		$	1,578		$	2,170
Recorded balance of impaired loans		3,673			5,283			6,185
Average recorded investment		4,478			5,734			8,416
Transfers from Loans
Transfers from loans to other real estate owned and repossessed assets are non-cash transactions, and are not included in the statements of cash flow.
Transfers from loans to other real estate owned and repossessed assets during the periods presented are summarized as follows:
	Year Ended December 31,
	2014			2013			2012
	(Dollars in thousands)
Other real estate owned	$	3,573		$	1,710		$	2,543
Repossessed assets		1,209			1,171			1,034
Total	$	4,782		$	2,881		$	3,577
Related Party Loans
The Company has made loans in the ordinary course of business to the executive officers and directors of the Company and to certain affiliates of these executive officers and directors. Management believes that all such loans were made on substantially the same terms as those prevailing at the time for comparable transactions with other persons and do not represent more than a normal risk of collectability or present other unfavorable features. A summary of these loans is as follows:
Year Ended December 31,	Balance				Additions			Collections/				Balance
	Beginning							Terminations				End of the
	of the Period											Period
			(Dollars in thousands)
2014	$	27,134			$	22,521		$	(24,636	)		$	25,019
2013		29,030				11,979			(13,875	)			27,134
2012		25,264				24,706			(20,940	)			29,030

Premises_and_Equipment_Net

Premises and Equipment, Net	12 Months Ended
	Dec. 31, 2014
Property Plant And Equipment [Abstract]
Premises and Equipment, Net	(6) PREMISES AND EQUIPMENT, NET
	The following is a summary of premises and equipment by classification:
		Estimated		December 31,
		Useful Lives		2014			2013
				(Dollars in thousands)
	Land			$	29,658		$	29,055
	Buildings		10 to 40 years		127,250			120,784
	Furniture, fixtures and equipment		3 to 15 years		64,734			61,641
	Accumulated depreciation				(100,301	)		(93,618	)
	Premises and equipment, net			$	121,341		$	117,862

Intangible_Assets_and_goodwill

Intangible Assets and goodwill	12 Months Ended
	Dec. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets and Goodwill	(7) INTANGIBLE ASSETS AND GOODWILL
	The following is a summary of intangible assets:
		Gross		Accumulated			Net
		Carrying		Amortization			Carrying
		Amount					Amount
		(Dollars in thousands)
	As of December 31, 2014
	Core deposit intangibles	$	13,198	$	(6,013	)	$	7,185
	Customer relationship intangibles		5,699		(2,699	)		3,000
	Mortgage servicing intangibles		643		(193	)		450
	Total	$	19,540	$	(8,905	)	$	10,635
	As of December 31, 2013
	Core deposit intangibles	$	10,963	$	(4,620	)	$	6,343
	Customer relationship intangibles		5,699		(2,337	)		3,362
	Mortgage servicing intangibles		718		(150	)		568
	Total	$	17,380	$	(7,107	)	$	10,273
	Estimated amortization of intangible assets for the next five years, as of December 31, 2014, is as follows (dollars in thousands):
	Estimated Amortization
	2015	$	1,855
	2016		1,631
	2017		1,540
	2018		1,531
	2019		1,524
	At December 31, 2014, the weighted-average remaining life of all intangible assets was approximately 6.5 years which consisted of customer relationship intangibles with a weighted-average life of 8.8 years, core deposit intangibles with a weighted-average life of 5.9 years and mortgage servicing intangibles with a weighted-average life of 2.3 years based on current prepayment assumptions.
	The following is a summary of goodwill by business segment:
		Metropolitan		Community			Other		Executive,		Consolidated
		Banks		Banks			Financial		Operations
							Services		& Support
		(Dollars in thousands)
	Balance at December 31, 2013	$	8,078	$	30,553		$	5,464	$	450	$	44,545
	Acquisitions		—		417			—		—		417
	Balance at December 31, 2014	$	8,078	$	30,970		$	5,464	$	450	$	44,962
		Metropolitan		Community			Other		Executive,		Consolidated
		Banks		Banks			Financial		Operations
							Services		& Support
		(Dollars in thousands)
	Year Ended December 31, 2013
	Balance at beginning and end of period	$	8,078	$	30,553		$	5,464	$	450	$	44,545

Time_Deposits

Time Deposits	12 Months Ended
	Dec. 31, 2014
Banking And Thrift [Abstract]
Time Deposits	(8) TIME DEPOSITS
	Time deposits include certificates of deposit and individual retirement accounts.
	At December 31, 2014, the scheduled maturities of all time deposits are as follows (Dollars in thousands):
	2015	$	478,610
	2016		121,816
	2017		51,816
	2018		47,463
	2019		51,410
	Thereafter		164
	Total	$	751,279
	The following table is a summary of large time deposits for the periods presented:
		December 31,
		2014		2013
		(Dollars in thousands)
	Time deposits of $100,000 or more	$	347,563	$	355,054

ShortTerm_Borrowings

Short-Term Borrowings	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Short-Term Borrowings	(9) SHORT-TERM BORROWINGS
	The following is a summary of short-term borrowings:
		December 31,
		2014			2013
		(Dollars in thousands)
	Federal funds purchased	$	1,000		$	700
	Repurchase agreements		2,982			3,890
	Total	$	3,982		$	4,590
	Weighted average interest rate		0.18	%		0.13	%
	End of period interest rate		0.14	%		0.15	%
	Federal funds purchased represent borrowings of overnight funds from other financial institutions.
	The Company enters into sales of securities to certain of its customers with simultaneous agreements to repurchase. These agreements represent an overnight borrowing of funds.

LongTerm_Borrowings

Long-Term Borrowings	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Long-Term Borrowings	(10) LONG-TERM BORROWINGS
	The Company has a line of credit from the Federal Home Loan Bank (“FHLB”) of Topeka, Kansas to use for liquidity or to match-fund certain long-term fixed rate loans. The Company’s assets, including residential first mortgages of $619.6 million, are pledged as collateral for the borrowings under the line of credit. As of December 31, 2014, the Company had the ability to draw up to $22.7 million on the FHLB line of credit based on FHLB stock holdings of $551,900 with no advances outstanding.

Junior_Subordinated_Debentures

Junior Subordinated Debentures	12 Months Ended
	Dec. 31, 2014
Offsetting [Abstract]
Junior Subordinated Debentures	(11) JUNIOR SUBORDINATED DEBENTURES
	In January 2004, BancFirst Corporation established BFC Capital Trust II (“BFC II”), a trust formed under the Delaware Business Trust Act. BancFirst Corporation owns all of the common securities of BFC II. In February 2004, BFC II issued $25 million of aggregate liquidation amount of 7.20% Cumulative Trust Preferred Securities (the “Cumulative Trust Preferred Securities”) to other investors. In March 2004, BFC II issued an additional $1 million in Cumulative Trust Preferred Securities through the execution of an over-allotment option. The proceeds from the sale of the Cumulative Trust Preferred Securities and the common securities of BFC II were invested in $26.8 million of 7.20% Junior Subordinated Debentures of BancFirst Corporation. Interest payments on the $26.8 million of 7.20% Junior Subordinated Debentures are payable January 15, April 15, July 15 and October 15 of each year. Such interest payments may be deferred for up to twenty consecutive quarters. The stated maturity date of the $26.8 million of 7.20% Junior Subordinated Debentures is March 31, 2034, but they are subject to mandatory redemption pursuant to optional prepayment terms. The Cumulative Trust Preferred Securities represent an undivided interest in the $26.8 million of 7.20% Junior Subordinated Debentures and are guaranteed by BancFirst Corporation. During any deferral period or during any event of default, BancFirst Corporation may not declare or pay any dividends on any of its capital stock. The Cumulative Trust Preferred Securities were callable at par, in whole or in part, after March 31, 2009.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	(12) INCOME TAXES
	The components of the Company’s income tax expense (benefit) are as follows:
		Year Ended December 31,
		2014			2013			2012
		(Dollars in thousands)
	Current taxes:
	Federal	$	28,258		$	23,326		$	24,928
	State		2,709			3,682			2,865
	Deferred taxes		(3,683	)		(483	)		(689	)
	Total income taxes	$	27,284		$	26,525		$	27,104
	Income tax expense applicable to securities transactions approximated $574,000, $147,000and $1,720,000 for the years ended December 31, 2014, 2013 and 2012, respectively.
	A reconciliation of tax expense at the federal statutory tax rate applied to income before taxes is presented in the following table:
		Year Ended December 31,
		2014			2013			2012
		(Dollars in thousands)
	Tax expense at the federal statutory tax rate	$	31,910		$	28,295		$	27,651
	Increase (decrease) in tax expense from:
	Tax-exempt income, net		(571	)		(621	)		(783	)
	Modified endowment life contracts		(755	)		(812	)		(870	)
	State tax expense, net of federal tax benefit		1,469			2,303			2,374
	Federal tax credits		(6,479	)		(4,132	)		(2,455	)
	Other, net		1,710			1,492			1,187
	Total tax expense	$	27,284		$	26,525		$	27,104
	The net deferred tax asset consisted of the following and is reported in other assets:
		December 31,
		2014			2013
		(Dollars in thousands)
	Provision for loan losses	$	15,814		$	13,662
	Write-downs of other real estate owned		1,297			962
	Deferred compensation		2,652			2,237
	Stock-based compensation		3,190			2,934
	Investments in partnership interests		1,966			1,170
	Other		306			1,479
	Gross deferred tax assets		25,225			22,444
	Unrealized net gains on securities		(2,644	)		(2,103	)
	Premium on securities of banks acquired		(715	)		(800	)
	Intangibles		(2,917	)		(2,561	)
	Basis difference related to tax credits		(1,977	)		(1,620	)
	Depreciation		(5,504	)		(5,975	)
	Leveraged lease		(1,964	)		(2,282	)
	Other		(89	)		(257	)
	Gross deferred tax liabilities		(15,810	)		(15,598	)
	Net deferred tax asset	$	9,415		$	6,846
	The Company recognizes accrued interest and penalties related to unrecognized tax benefits, if applicable, in income tax expense. During the years ended December 31, 2014, 2013 and 2012, the Company did not recognize or accrue any interest and penalties related to unrecognized tax benefits. Federal and various state income tax statutes dictate that tax returns filed in any of the previous three reporting periods remain open to examination which includes the years 2012 to 2014. The Company has no open examinations with either the Internal Revenue Service or any state agency.
	Management performs an analysis of the Company’s tax position annually and believes it is more likely than not that all of its tax positions will be utilized in future years.

StockBased_Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	(13) STOCK-BASED COMPENSATION
	The Company adopted a nonqualified incentive stock option plan (the “BancFirst ISOP”) in May 1986. The Company amended the BancFirst ISOP to increase the number of shares to be issued under the plan to 3,000,000 shares in May 2013. At December 31, 2014, 114,985 shares were available for future grants. The BancFirst ISOP will terminate on December 31, 2019. The options vest and are exercisable beginning four years from the date of grant at the rate of 25% per year for four years. Options expire at the end of fifteen years from the date of grant. Options outstanding as of December 31, 2014 will become exercisable through the year 2021. The option price must be no less than 100% of the fair value of the stock relating to such option at the date of grant.
	In June 1999, the Company adopted the BancFirst Corporation Non-Employee Directors’ Stock Option Plan (the “BancFirst Directors’ Stock Option Plan”). Each non-employee director is granted an option for 10,000 shares. The Company amended the BancFirst Directors’ Stock Option Plan to increase the number of shares to be issued under the plan to 230,000 shares in May 2014. At December 31, 2014, 20,000 shares were available for future grants. The options vest and are exercisable beginning one year from the date of grant at the rate of 25% per year for four years, and expire at the end of fifteen years from the date of grant. Options outstanding as of December 31, 2014 will become exercisable through the year 2018. The option price must be no less than 100% of the fair value of the stock relating to such option at the date of grant.
	The Company currently uses newly issued shares for stock option exercises, but reserves the right to use shares purchased under the Company’s Stock Repurchase Program (the “SRP”) in the future.
	The following table is a summary of the activity under both the BancFirst ISOP and the BancFirst Directors’ Stock Option Plan:
		Options			Wgtd. Avg.		Wgtd. Avg.			Aggregate
					Exercise		Remaining			Intrinsic
					Price		Contractual			Value
							Term
		(Dollars in thousands, except per share data)
	Year Ended December 31, 2014
	Outstanding at December 31, 2013		1,158,317		$	34.45
	Options granted		44,000			61.78
	Options exercised		(169,535	)		28.73
	Options canceled, forfeited, or expired		(3,125	)		36.73
	Outstanding at December 31, 2014		1,029,657			36.55		8.59	Yrs	$	27,638
	Exercisable at December 31, 2014		492,557			29.84		5.15	Yrs	$	16,525
	Year Ended December 31, 2013
	Outstanding at December 31, 2012		1,216,981		$	31.98
	Options granted		115,000			49.13
	Options exercised		(153,664	)		25.03
	Options canceled, forfeited, or expired		(20,000	)		40.83
	Outstanding at December 31, 2013		1,158,317			34.45		8.84	Yrs	$	25,034
	Exercisable at December 31, 2013		561,167			27.95		6.7	Yrs	$	15,774
	The following table has additional information regarding options granted and options exercised under both the BancFirst ISOP and the BancFirst Directors’ Stock Option Plan:
		Year Ended December 31,
		2014			2013		2012
		(Dollars in thousands, except per share data)
	Weighted average grant-date fair value per share of options granted	$	12.27		$	10.88	$	8.82
	Total intrinsic value of options exercised		5,597			3,723		3,297
	Cash received from options exercised		4,870			3,846		2,227
	Tax benefit realized from options exercised		2,165			1,440		1,275
	The fair value of each option grant is estimated on the date of grant using the Black-Scholes option-pricing model and is based on certain assumptions including risk-free rate of return, dividend yield, stock price volatility and the expected term. The fair value of each option is expensed over its vesting period.
	The following table is a summary of the Company’s recorded stock-based compensation expense:
		Year Ended December 31,
		2014			2013		2012
		(Dollars in thousands)
	Stock-based compensation expense	$	1,676		$	1,360	$	1,530
	Tax benefit		648			526		592
	Stock-based compensation expense, net of tax	$	1,028		$	834	$	938
	The Company will continue to amortize the remaining fair value of stock options over the remaining vesting period of approximately seven years. The following table shows the remaining fair value of stock options:
		December 31, 2014
		(Dollars in thousands)
	Fair value of stock options	$	4,215
	The following table shows the assumptions used for computing stock-based compensation expense under the fair value method:
		Year Ended December 31,
		2014			2013		2012
	Risk-free interest rate		2.10 % to 2.54%			1.95% to 3.15%		1.74% to 1.95%
	Dividend yield		2.00%			2.00%		2.00%
	Stock price volatility		18.03% to 18.98%			18.35% to 20.21%		21.71% to 38.75%
	Expected term		10Yrs			10Yrs		10Yrs
	The risk-free interest rate is determined by reference to the spot zero-coupon rate for the U.S. Treasury security with a maturity similar to the expected term of the options. The dividend yield is the expected yield for the expected term. The stock price volatility is estimated from the recent historical volatility of the Company’s stock. The expected term is estimated from the historical option exercise experience.
	In May 1999, the Company adopted the BancFirst Corporation Directors’ Deferred Stock Compensation Plan (the “BancFirst Deferred Stock Compensation Plan”). The Company amended the BancFirst Deferred Stock Compensation Plan to increase the number of shares to be issued under the plan to 91,110 shares in May 2014. Under the plan, directors and members of the community advisory boards of the Company and its subsidiaries may defer up to 100% of their board fees. They are credited for each deferral with a number of stock units based on the current market price of the Company’s stock, which accumulate in an account until such time as the director or community board member terminates serving as a board member. Shares of common stock of the Company are then distributed to the terminating director or community board member based upon the number of stock units accumulated in his or her account. A summary of the accumulated stock units is as follows:
		December 31,
		2014			2013
	Accumulated stock units		60,859			56,380
	Average price	$	37.41		$	35.31

Retirement_Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2014
Compensation And Retirement Disclosure [Abstract]
Retirement Plans	(14) RETIREMENT PLANS
	In May 1986, the Company adopted the BancFirst Corporation Employee Stock Ownership (“ESOP”) and Thrift Plan (“401(k)”) effective January 1, 1985. The plan was separated into two individual plans effective January 1, 2009. The 401(k) and ESOP plans cover all eligible employees, as defined in the plans, of the Company and its subsidiaries. The 401(k) plan allows employees to defer up to the maximum legal limit of their compensation, of which the Company may match up to 3% of their compensation. In addition, the Company may make discretionary contributions based on employee contributions or eligible compensation to the ESOP plan, as determined by the Company’s Board of Directors. The aggregate amounts of contributions by the Company to the 401(k) and ESOP plans are shown in the following table:
		December 31,
		2014		2013		2012
		(Dollars in thousands)
	401(k) contributions	$	1,870	$	1,738	$	1,690
	ESOP contributions		1,928		1,820		1,703
	Total contributions	$	3,798	$	3,558	$	3,393

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Stockholders' Equity	(15) STOCKHOLDERS’ EQUITY
	As of December 31, 2014, 2013 and 2012 the Company’s authorized and outstanding preferred and common stock was as follows:
		No. of Shares		No. of Shares Outstanding at December 31,								Par		Dividends			Voting
		Authorized at										Value					Rights
												Per
	Class of Stock	December 31,		2014			2013		2012			Share
		2014
	Senior Preferred		10,000,000		—			—		—		$	1		As declared			Voting
	10% Cumulative Preferred		900,000		—			—		—		$	5		As declared			Non-voting
	Common		20,000,000		15,504,513			15,333,622		15,242,308		$	1		As declared			Voting
	The following is a description of the capital stock of the Company:
	(a) Senior Preferred Stock: No shares issued or outstanding. Shares may be issued with such voting, dividend, redemption, sinking fund, conversion, exchange, liquidation and other rights as shall be determined by the Company’s Board of Directors, without approval of the stockholders. The Senior Preferred Stock would have a preference over common stock as to payment of dividends, as to the right to distribution of assets upon redemption of such shares or upon liquidation of the Company.
	(b) 10% Cumulative Preferred Stock: Redeemable at the Company’s option at $5.00 per share plus accumulated dividends; non-voting; cumulative dividends at the rate of 10% payable semi-annually on January 15 and July 15; no shares issued or outstanding.
	(c) Common stock: At December 31, 2014, 2013 and 2012 the shares issued equaled shares outstanding.
	In November 1999, the Company adopted a Stock Repurchase Program (the “SRP”). The SRP may be used as a means to increase earnings per share and return on equity, to purchase treasury stock for the exercise of stock options or for distributions under the Deferred Stock Compensation Plan, to provide liquidity for optionees to dispose of stock from exercises of their stock options, and to provide liquidity for stockholders wishing to sell their stock. All shares repurchased under the SRP have been retired and not held as treasury stock. The timing, price and amount of stock repurchases under the SRP may be determined by management and approved by the Company’s Executive Committee.
	The following table is a summary of the shares under the program:
		Year Ended December 31,
		2014		2013			2012
	Number of shares repurchased		—		40,241			6,787
	Average price of shares repurchased	$	—	$	40.88		$	37.7
	Shares remaining to be repurchased		194,723		194,723			234,964
	The Company’s ability to pay dividends is dependent upon dividend payments received from BancFirst. Banking regulations limit bank dividends based upon net earnings retained and minimum capital requirements. Dividends in excess of these requirements require regulatory approval. At January 1, 2015, approximately $73.4 million of the equity of BancFirst was available for dividend payments to the Company.
	During any deferral period or any event of default on the Junior Subordinated Debentures, the Company may not declare or pay any dividends on any of its capital stock.
	The Company and BancFirst are subject to risk-based capital guidelines issued by the Board of Governors of the Federal Reserve System and the Federal Deposit Insurance Corporation (“FDIC”). These guidelines are used to evaluate capital adequacy and involve both quantitative and qualitative evaluations of the Company’s and BancFirst’s assets, liabilities, and certain off-balance-sheet items calculated under regulatory practices. Failure to meet the minimum capital requirements can initiate certain mandatory or discretionary actions by the regulatory agencies that could have a direct material effect on the Company’s financial statements. Management believes that as of December 31, 2014, the Company and BancFirst met all capital adequacy requirements to which they are subject. The actual and required capital amounts and ratios are shown in the following table:
		Actual					For Capital					To Be Well
							Adequacy					Capitalized Under
							Purposes					Prompt Corrective
												Action Provisions
		Amount		Ratio			Amount		Ratio			Amount		Ratio
		(Dollars in thousands)
	As of December 31, 2014:
	Total Capital
	(to Risk Weighted Assets)-
	BancFirst Corporation	$	616,862		14.75	%	$	334,531		8	%		N/A		N/A
	BancFirst		571,495		13.68	%		334,092		8	%	$	417,615		10	%
	Tier I Capital
	(to Risk Weighted Assets)-
	BancFirst Corporation		575,973		13.77	%		167,265		4	%		N/A		N/A
	BancFirst		530,606		12.71	%		167,046		4	%		250,569		6	%
	Tier I Capital
	(to Total Assets)-
	BancFirst Corporation		575,973		8.83	%		197,249		3	%		N/A		N/A
	BancFirst		530,606		8.15	%		196,716		3	%		327,859		5	%
	As of December 31, 2013:
	Total Capital
	(to Risk Weighted Assets)-
	BancFirst Corporation	$	563,873		14.85	%	$	303,700		8	%		N/A		N/A
	BancFirst		529,200		13.96	%		303,190		8	%	$	378,988		10	%
	Tier I Capital
	(to Risk Weighted Assets)-
	BancFirst Corporation		524,839		13.83	%		151,850		4	%		N/A		N/A
	BancFirst		490,166		12.93	%		151,595		4	%		227,393		6	%
	Tier I Capital
	(to Total Assets)-
	BancFirst Corporation		524,839		8.77	%		181,174		3	%		N/A		N/A
	BancFirst		490,166		8.2	%		180,606		3	%		301,011		5	%
	As of December 31, 2014, the most recent notification from the Federal Reserve Bank of Kansas City and the FDIC categorized BancFirst as “well capitalized” under the regulatory framework for prompt corrective action. To be well capitalized under federal bank regulatory agency definitions, a depository institution must have a Tier 1 Ratio of at least 6%, a combined Tier 1 and Tier 2 Ratio of at least 10%, and a Leverage Ratio of at least 5%. The Company’s trust preferred securities have continued to be included in Tier 1 capital as the Company’s total assets do not exceed $10 billion. There are no conditions or events since the most recent notification of BancFirst’s capital category that management believes would materially change its category under capital requirements existing as of the report date.
	Basel III Capital Rules
	In July 2013, the three federal bank regulatory agencies jointly published interim final rules (the “Basel III Capital Rules”) establishing a new comprehensive capital framework for U.S. banking organizations. The rules implement the Basel Committee’s December 2010 framework known as “Basel III” for strengthening international capital standards as well as certain provisions of the Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Dodd-Frank Act”). These Rules substantially revise the risk-based capital requirements applicable to bank holding companies and depository institutions, compared to the current U.S. risk-based capital rules. The Basel III Capital Rules define the components of capital and address other issues affecting the numerator in banking institutions’ regulatory capital ratios. These Rules also address risk weights and other issues affecting the denominator in banking institutions’ regulatory capital ratios and replace the existing risk-weighting approach with a more risk-sensitive approach. The Basel III Capital Rules also implement the requirements of Section 939A of the Dodd-Frank Act to remove references to credit ratings from the federal banking agencies’ rules. The Basel III Capital Rules are effective for the Company and BancFirst on January 1, 2015 (subject to a 4-year phase-in period).
	The Basel III Capital Rules, among other things, (i) introduce a new capital measure called “Common Equity Tier 1” (“CET1”), (ii) specify that Tier 1 capital consist of CET1 and “Additional Tier 1 capital” instruments meeting specified requirements, (iii) define CET1 narrowly by requiring that most deductions/adjustments to regulatory capital measures be made to CET1 and not to the other components of capital and (iv) expand the scope of the deductions/adjustments as compared to existing regulations.
	Under the Basel III Capital Rules, the initial minimum capital ratios as of January 1, 2015 will be as follows:
	4.5% CET1 to risk-weighted assets.
	6.0% Tier 1 capital to risk-weighted assets.
	8.0% Total capital to risk-weighted assets.
4.0% Minimum leverage ratio
Implementation of the deductions and other adjustments to CET1 will begin on January 1, 2015 and will be phased-in over a 4-year period (beginning at 40% on January 1, 2015 and an additional 20% per year thereafter). Under the new rule, in order to avoid limitations on capital distributions, including dividend payments and certain discretionary bonus payments to executive officers, a banking organization must hold a capital conservation buffer composed of CET1 capital above its minimum risk-based capital requirements. The implementation of the capital conservation buffer will begin on January 1, 2016 at the 0.625% level and be phased in over a four-year period (increasing by that amount on each subsequent January 1, until it reaches 2.5% on January 1, 2019).
Management believes that, as of December 31, 2014, the Company and BancFirst would meet all capital adequacy requirements under the Basel III Capital Rules on a fully phased-in basis as if such requirements were currently in effect.

Net_Income_Per_Common_Share

Net Income Per Common Share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Net Income Per Common Share	-16	NET INCOME PER COMMON SHARE
	Basic and diluted net income per common share are calculated as follows:
			Income		Shares		Per
			(Numerator)		(Denominator)		Share
							Amount
			(Dollars in thousands, except per share data)
	Year Ended December 31, 2014
	Basic
	Income available to common stockholders		$	63,887		15,430,773	$	4.14
	Effect of stock options			—		363,630
	Diluted
	Income available to common stockholders plus assumed exercises of stock options		$	63,887		15,794,403	$	4.04
	Year Ended December 31, 2013
	Basic
	Income available to common stockholders		$	54,317		15,268,843	$	3.56
	Effect of stock options			—		279,979
	Diluted
	Income available to common stockholders plus assumed exercises of stock options		$	54,317		15,548,822	$	3.49
	Year Ended December 31, 2012
	Basic
	Income available to common stockholders		$	51,900		15,172,457	$	3.42
	Effect of stock options			—		271,188
	Diluted
	Income available to common stockholders plus assumed exercises of stock options		$	51,900		15,443,645	$	3.36
	The following table shows the number and average exercise price of options that were excluded from the computation of diluted net income per common share for each year because the options’ exercise prices were greater than the average market price of the common shares.
			Shares		Average
					Exercise
					Price
	December 31, 2014			69,405	$	55.87
	December 31, 2013			118,603		42.79
	December 31, 2012			604,429		38.69

Condensed_Parent_Company_Finan

Condensed Parent Company Financial Statements	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Condensed Parent Company Financial Statements	(17) CONDENSED PARENT COMPANY FINANCIAL STATEMENTS
	BALANCE SHEETS
		December 31,
		2014			2013
		(Dollars in thousands)
	ASSETS
	Cash	$	36,700		$	27,592
	Securities		103			115
	Investments in subsidiaries		598,413			555,761
	Goodwill		450			450
	Dividends receivable		6,434			5,927
	Other assets		983			913
	Total assets	$	643,083		$	590,758
	LIABILITIES AND STOCKHOLDERS’ EQUITY
	Other liabilities	$	6,965		$	6,957
	Junior subordinated debentures		26,804			26,804
	Stockholders’ equity		609,314			556,997
	Total liabilities and stockholders’ equity	$	643,083		$	590,758
	STATEMENTS OF INCOME
		Year Ended December 31,
		2014			2013			2012
		(Dollars in thousands)
	OPERATING INCOME
	Dividends from subsidiaries	$	24,851		$	22,612		$	20,784
	Interest on interest-bearing deposits		62			47			57
	Other		14			92			—
	Total operating income		24,927			22,751			20,841
	OPERATING EXPENSE
	Interest		1,965			1,965			2,134
	Other		667			661			942
	Total operating expense		2,632			2,626			3,076
	Income before taxes and equity in undistributed earnings of subsidiaries		22,295			20,125			17,765
	Allocated income tax benefit		472			978			1,371
	Income before equity in undistributed earnings of subsidiaries		22,767			21,103			19,136
	Equity in undistributed earnings of subsidiaries		42,196			34,351			34,281
	Amortization of stock-based compensation arrangements of subsidiaries		(1,076	)		(1,137	)		(1,517	)
	Net income	$	63,887		$	54,317		$	51,900
	STATEMENTS OF CASH FLOW
		Year Ended December 31,
		2014			2013			2012
		(Dollars in thousands)
	CASH FLOWS FROM OPERATING ACTIVITIES
	Net income	$	63,887		$	54,317		$	51,900
	Adjustments to reconcile to net cash provided by operating activities:
	Equity in undistributed earnings of subsidiaries		(42,196	)		(34,351	)		(34,281	)
	Amortization of stock-based compensation arrangements		1,076			1,137			1,517
	Other, net		(656	)		(2,116	)		2,944
	Net cash provided by operating activities		22,111			18,987			22,080
	INVESTING ACTIVITIES
	Net cash provided by acquisitions		—			—			19,866
	Sales and maturities of held for investment and available for sale securities		8			63			—
	Net cash provided by investing activities		8			63			19,866
	FINANCING ACTIVITIES
	Issuance of common stock		6,532			5,200			3,540
	Common stock acquired		—			(2,710	)		(256	)
	Cash dividends paid		(19,543	)		(13,583	)		(21,090	)
	Redemption of Junior Subordinated Debentures		—			—			(9,279	)
	Net cash used for financing activities		(13,011	)		(11,093	)		(27,085	)
	Net increase in cash		9,108			7,957			14,861
	Cash and due from banks at the beginning of the period		27,592			19,635			4,774
	Cash and due from banks at the end of the period	$	36,700		$	27,592		$	19,635
	SUPPLEMENTAL DISCLOSURE
	Cash paid during the period for interest	$	1,965		$	1,965		$	2,128
	Cash received during the period for income taxes, net	$	1,822		$	4,449		$	1,884

Related_Party_Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related Party Transactions
	(18) RELATED PARTY TRANSACTIONS
	Refer to Note (5) for information regarding loan transactions with related parties.

Commitments_and_Contingent_Lia

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	(19) COMMITMENTS AND CONTINGENT LIABILITIES
	The Company is a party to financial instruments with off balance sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include loan commitments and standby letters of credit which involve elements of credit and interest-rate risk to varying degrees. The Company’s exposure to credit loss in the event of nonperformance by the other party to the instrument is represented by the instrument’s contractual amount. To control this credit risk, the Company uses the same underwriting standards as it uses for loans recorded on the balance sheet. The amounts of financial instruments with off-balance-sheet risk are as follows:
		December 31,
		2014		2013
		(Dollars in thousands)
	Loan commitments	$	937,221	$	945,270
	Stand-by letters of credit		63,734		61,262
	Loan commitments are agreements to lend to a customer, as long as there is no violation of any condition established in the contract. Stand-by letters of credit are conditional commitments issued by the Company to guarantee the performance of a customer to a third party. These instruments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Since many of the instruments are expected to expire without being drawn upon, the total amounts do not necessarily represent commitments that will be funded in the future.
	The Company leases two parcels of land on which it owns buildings, nineteen ATM locations, two storage facilities, three parking lots and office space in thirteen buildings. These leases expire at various dates through 2064.
	The future minimum rental payments under these leases at December 31, 2014, were as follows (Dollars in thousands):
	2015	$	1,060
	2016		981
	2017		699
	2018		186
	2019		128
	Later years		624
	Total	$	3,678
	Rental expense on all property and equipment rented, including those rented on a monthly or temporary basis were as follows (Dollars in thousands):
	Year Ending December 31:
	2014	$	1,255
	2013		1,175
	2012		1,159
	The Company is a defendant in legal actions arising from normal business activities. Management believes that all legal actions against the Company are without merit or that the ultimate liability, if any, resulting from them will not materially affect the Company’s financial statements.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements	(20) FAIR VALUE MEASUREMENTS
	Accounting standards define fair value as the price that would be received to sell an asset or the price paid to transfer a liability in the principal or most advantageous market available to the entity in an orderly transaction between market participants on the measurement date.
	FASB Accounting Standards Codification Topic 820 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 to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities in active markets.
	—	Level 2 Inputs to the valuation methodology include quoted prices for similar assets and liabilities in active markets, and inputs that are observable for the asset and liability, either directly or indirectly, for substantially the full term of the financial instrument.
	—	Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 3 assets and liabilities include financial instruments whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. This category includes certain impaired loans, foreclosed assets, other real estate owned, goodwill and other intangible assets.
	Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring Basis
	A description of the valuation methodologies and key inputs used to measure financial assets and financial liabilities at fair value on a recurring basis, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below. These valuation methodologies were applied to the following categories of the Company’s financial assets and financial liabilities.
	Securities Available for Sale
	Securities classified as available for sale are reported at fair value. U.S. Treasuries are valued using Level 1 inputs. Other securities available for sale including U.S. federal agencies, mortgage backed securities and state and political subdivisions are valued using prices from an independent pricing service utilizing Level 2 data. The fair value measurements consider observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the bond’s terms and conditions, among other things. The Company also invests in securities classified as available for sale for which observable information is not readily available. These securities are reported at fair value utilizing Level 3 inputs. For these securities, management determines the fair value based on the income approach or information provided by outside consultants or lead investors.
	The Company reviews the prices for Level 1 and Level 2 securities supplied by the independent pricing service for reasonableness and to ensure such prices are aligned with traditional pricing matrices. In general, the Company does not purchase investment portfolio securities that are esoteric or that have complicated structures. The Company’s entire portfolio consists of traditional investments including U.S. Treasury obligations, federal agency mortgage pass-through securities, general obligation municipal bonds and a small amount of municipal revenue bonds. Pricing for such instruments is fairly generic and is easily obtained. For in-state bond issues that have relatively low issue sizes and liquidity, the Company utilizes the same parameters adjusted for the specific issue. From time to time, the Company will validate, on a sample basis, prices supplied by the independent pricing service by comparison to prices obtained from third party sources.
	Derivatives
	Derivatives are reported at fair value utilizing Level 2 inputs. The Company obtains dealer and market quotations to value its oil and gas swaps and options. The Company utilizes dealer quotes and observable market data inputs to substantiate internal valuation models.
	Loans Held For Sale
	The Company originates mortgage loans to be sold. At the time of origination, the acquiring bank has already been determined and the terms of the loan, including interest rate, have already been set by the acquiring bank allowing the Company to originate the loan at fair value. Mortgage loans are generally sold within 30 days of origination. Loans held for sale are valued using Level 2 inputs. Gains or losses recognized upon the sale of the loans are determined on a specific identification basis.
	Mortgage Servicing Intangibles
	The Company acquired mortgage servicing intangibles with the acquisition of 1st Bank Oklahoma on July 12, 2011. Mortgage servicing intangibles are amortized based on current prepayment assumptions and are adjusted to fair value semi-annually, if impaired. Fair value is estimated based on the present value of future cash flows over several interest rate scenarios, which are then discounted at risk-adjusted rates. The Company considers portfolio characteristics, contractually specified servicing fees, prepayment assumptions, delinquency rates, late charges, other ancillary revenue, costs to service and other economic factors. When available, fair value estimates and assumptions are compared to observable market data and the recent market activity and actual portfolio experience.
	The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of December 31, 2014 and 2013, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value:
			Level 1			Level 2			Level 3		Total Fair
			Inputs			Inputs			Inputs		Value
			(Dollars in thousands)
	December 31, 2014
	Securities available for sale:
	U.S. Treasury		$	248,993		$	—		$	—	$	248,993
	U.S. federal agencies			—			172,449			—		172,449
	Mortgage-backed securities			—			9,425			17,032		26,457
	States and political subdivisions			—			53,373			—		53,373
	Other securities			—			3,491			11,427		14,918
	Derivative assets			—			6,124			—		6,124
	Derivative liabilities			—			4,756			—		4,756
	Loans held for sale			—			9,433			—		9,433
	Mortgage servicing intangibles			—			—			450		450
	December 31, 2013
	Securities available for sale:
	U.S. Treasury		$	29,861		$	—		$	—	$	29,861
	U.S. federal agencies			—			387,285			—		387,285
	Mortgage-backed securities			—			13,262			19,416		32,678
	States and political subdivisions			—			50,334			—		50,334
	Other securities			—			3,465			12,018		15,483
	Derivative assets			—			2,211			—		2,211
	Derivative liabilities			—			1,029			—		1,029
	Loans held for sale			—			6,469			—		6,469
	Mortgage servicing intangibles			—			—			568		568
	The changes in Level 3 assets measured at estimated fair value on a recurring basis during the years ended December 31, 2014 and 2013 were as follows:
			Twelve Months Ended
			December 31,
			2014			2013
			(Dollars in thousands)
	Balance at the beginning of the year		$	32,002		$	10,779
	Purchases, issuances and settlements			(1,314	)		20,499
	Sales			(3,433	)		(251	)
	Gains included in earnings			1,469			234
	Total unrealized gains/(losses)			185			741
	Balance at the end of the year		$	28,909		$	32,002
	The Company’s policy is to recognize transfers in and transfers out of Levels 1, 2 and 3 as of the end of the reporting period. During the years ended December 31, 2014 and 2013, the Company did not transfer any securities between levels in the fair value hierarchy.
	Financial Assets and Financial Liabilities Measured at Fair Value on a Nonrecurring Basis
	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). These financial assets and financial liabilities are reported at fair value utilizing Level 3 inputs.
	Impaired loans are reported at the fair value of the underlying collateral if repayment is dependent on liquidation of the collateral. In no case does the fair value of an impaired loan exceed the fair value of the underlying collateral. The impaired loans are adjusted to fair value through a specific allocation of the allowance for loan losses or a direct charge-down of the loan.
	Foreclosed assets, upon initial recognition, are measured and adjusted to fair value through a charge-off to the allowance for possible loan losses based upon the fair value of the foreclosed asset.
	Other real estate owned is revalued at fair value subsequent to initial recognition, with any losses recognized in net expense from other real estate owned.
	The following table summarizes assets measured at fair value on a nonrecurring basis and the related gains or losses recognized during the year:
			Level 1			Level 2			Level 3		Total Fair		Gains
											Value		(Losses)
			(Dollars in thousands)
Year Ended December 31, 2014
Impaired loans (less specific allowance)			—			—		$	33,797	$	33,797	$	—
Foreclosed assets			—			—			220		220		(18	)
Other real estate owned			—			—			7,859		7,859		(304	)
Year Ended December 31, 2013
Impaired loans (less specific allowance)			—			—		$	34,848	$	34,848	$	—
Foreclosed assets			—			—			237		237		(35	)
Other real estate owned			—			—			8,149		8,149		(170	)
Estimated Fair Value of Financial Instruments
The Company is required under current authoritative accounting guidance to disclose the estimated fair value of their financial instruments that are not recorded at fair value. For the Company, as for most financial institutions, substantially all of its assets and liabilities are considered financial instruments. A financial instrument is defined as cash, evidence of an ownership interest in an entity or a contract that creates a contractual obligation or right to deliver or receive cash or another financial instrument from a second entity. The following methods and assumptions were used to estimate the fair value of each class of financial instruments:
Cash and Cash Equivalents Include: Cash and Due from Banks and Interest-Bearing Deposits
The carrying amount of these short-term instruments is a reasonable estimate of fair value.
Securities Held for Investment
For securities held for investment, which are generally traded in secondary markets, fair values are based on quoted market prices or dealer quotes, if available. If a quoted market price is not available, fair value is estimated using quoted market prices for similar securities making adjustments for credit or liquidity if applicable.
Loans
For certain homogeneous categories of loans, such as some residential mortgages, fair values are estimated using the quoted market prices for securities backed by similar loans, adjusted for differences in loan characteristics. The fair values of other types of loans are estimated by discounting the future cash flows using the current rates at which similar loans would be made to borrowers with similar credit ratings and for the same remaining maturities.
Deposits
The fair values of transaction and savings accounts are the amounts payable on demand at the reporting date. The fair values of fixed-maturity certificates of deposit are estimated using the rates currently offered for deposits of similar remaining maturities.
Short-term Borrowings
The amounts payable on these short-term instruments are reasonable estimates of fair value.
Long-term Borrowings
The fair values of fixed-rate long-term borrowings are estimated using the rates that would be charged for borrowings of similar remaining maturities.
Junior Subordinated Debentures
The fair values of junior subordinated debentures are estimated using the rates that would be charged for junior subordinated debentures of similar remaining maturities.
Loan Commitments and Letters of Credit
The fair values of commitments are estimated using the fees currently charged to enter into similar agreements, taking into account the terms of the agreements. The fair values of letters of credit are based on fees currently charged for similar agreements.
The estimated fair values of the Company’s financial instruments that are reported at amortized cost in the Company’s consolidated balance sheets, segregated by the level of valuation inputs within the fair value hierarchy utilized to measure fair value, are as follows:
		December 31,
		2014						2013
		Carrying			Fair Value			Carrying		Fair Value
		Amount						Amount
		(Dollars in thousands)
FINANCIAL ASSETS
Level 2 inputs:
Cash and cash equivalents		$	1,913,895		$	1,913,895		$	1,857,535	$	1,857,535
Securities held for investment			8,593			8,671			11,986		12,094
Level 3 inputs:
Loans, net			3,819,942			3,857,224			3,348,112		3,364,940
FINANCIAL LIABILITIES
Level 2 inputs:
Deposits			5,904,704			5,945,502			5,419,519		5,451,114
Short-term borrowings			3,982			3,982			4,590		4,590
Long-term borrowings			—			—			6,938		6,908
Junior subordinated debentures			26,804			31,200			26,804		29,259
OFF-BALANCE SHEET FINANCIAL INSTRUMENTS
Loan commitments						1,640					1,654
Letters of credit						478					459
Non-financial Assets and Non-financial Liabilities Measured at Fair Value
The Company has no non-financial assets or non-financial liabilities measured at fair value on a recurring basis. Certain non-financial assets and non-financial liabilities measured at fair value on a nonrecurring basis include intangible assets (excluding mortgage service rights, which are valued quarterly) and other non-financial long-lived assets measured at fair value and adjusted for impairment. These items are evaluated at least annually for impairment, of which there were none as of December 31, 2014 or 2013. The overall levels of non-financial assets and non-financial liabilities measured at fair value on a nonrecurring basis were not considered to be significant to the Company at December 31, 2014 or 2013.

Derivative_Financial_Instrumen

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2014
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	(21) DERIVATIVE FINANCIAL INSTRUMENTS
	The Company enters into oil and gas swaps and options contracts to accommodate the business needs of its customers. Upon the origination of an oil or gas swap or option contract with a customer, to mitigate the exposure to fluctuations in oil and gas prices, the Company simultaneously enters into an offsetting contract with a counterparty. These derivatives are not designated as hedged instruments and are recorded on the Company’s consolidated balance sheet at fair value.
	The Company utilizes dealer quotations and observable market data inputs to substantiate internal valuation models. The notional amounts and estimated fair values of oil and gas derivative positions outstanding are presented in the following table:
				December 31,
				2014								2013
	Oil and Natural Gas	Notional Unit		Notional				Estimated				Notional			Estimated
	Swaps and Options			Amount				Fair Value				Amount			Fair Value
		(Notional amounts and dollars in thousands)
	Oil
	Derivative assets	Barrels			312			$	4,629				335		$	827
	Derivative liabilities	Barrels			(312	)			(4,271	)			(335	)		(378	)
	Natural Gas
	Derivative assets	MMBTUs			2,010				1,495				5,128			1,384
	Derivative liabilities	MMBTUs			(2,010	)			(485	)			(5,128	)		(651	)
	Total Fair Value	Included in
	Derivative assets	Other assets							6,124							2,211
	Derivative liabilities	Other liabilities							(4,756	)						(1,029	)
	The following table is a summary of the Company’s recognized income related to the activity, which was included in other noninterest income:
		Year Ended December 31,
		2014				2013				2012
		(Dollars in thousands)
	Derivative income	$	500			$	521			$	599
	The Company’s credit exposure on oil and gas swaps and options varies based on the current market prices of oil and natural gas. Other than credit risk, changes in the fair value of customer positions will be offset by equal and opposite changes in the counterparty positions. The net positive fair value of the contracts represents the profit derived from the activity and is unaffected by market price movements. The Company’s share of total profit is approximately 35%.
	Customer credit exposure is managed by strict position limits and is primarily offset by first liens on production while the remainder is offset by cash. Counterparty credit exposure is managed by selecting highly rated counterparties (rated A- or better by Standard and Poor’s) and monitoring market information.
	The following table is a summary of the Company’s net credit exposure relating to oil and gas swaps and options with bank counterparties:
		December 31,
		2014				2013
		(Dollars in thousands)
	Credit exposure	$	4,028			$	9
	Balance Sheet Offsetting
	Derivatives may be eligible for offset in the consolidated balance sheet and/or subject to master netting arrangements. The Company’s derivative transactions with upstream financial institution counterparties and bank customers are generally executed under International Swaps and Derivative Association (“ISDA”) master agreements which include “right of set-off” provisions. In such cases there is generally a legally enforceable right to offset recognized amounts and there may be an intention to settle such amounts on a net basis. Nonetheless, the Company does not generally offset such financial instruments for financial reporting purposes.

Segment_Information

Segment Information	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Segment Information	(22) SEGMENT INFORMATION
	The Company evaluates its performance with an internal profitability measurement system that measures the profitability of its business units on a pre-tax basis. The four principal business units are metropolitan banks, community banks, other financial services and executive, operations and support. Metropolitan and community banks offer traditional banking products such as commercial and retail lending, and a full line of deposit accounts. Metropolitan banks consist of banking locations in the metropolitan Oklahoma City and Tulsa areas. Community banks consist of banking locations in communities throughout Oklahoma. Other financial services are specialty product business units including guaranteed small business lending, residential mortgage lending, trust services, securities brokerage, electronic banking and insurance. The executive, operations and support groups represent executive management, operational support and corporate functions that are not allocated to the other business units.
	The results of operations and selected financial information for the four business units are as follows:
		Metropolitan			Community			Other		Executive,			Eliminations			Consolidated
		Banks			Banks			Financial		Operations
								Services		& Support
		(Dollars in thousands)
	December 31, 2014
	Net interest income (expense)	$	59,923		$	116,935		$	6,155	$	(1,662	)	$	—		$	181,351
	Provision for loan losses		3,077			(488	)		481		2			—			3,072
	Noninterest income		13,752			51,415			28,079		69,442			(66,275	)		96,413
	Depreciation and amortization		2,216			7,277			522		1,334			—			11,349
	Other expenses		32,300			89,888			22,304		27,998			(318	)		172,172
	Income before taxes	$	36,082		$	71,673		$	10,927	$	38,446		$	(65,957	)	$	91,171
	Total assets	$	2,298,828		$	4,113,783		$	145,814	$	679,194		$	(662,647	)	$	6,574,972
	Capital expenditures	$	1,948		$	7,972		$	121	$	1,449		$	—		$	11,490
	December 31, 2013
	Net interest income (expense)	$	56,346		$	102,705		$	6,239	$	(1,771	)	$	—		$	163,519
	Provision for loan losses		(154	)		1,205			121		86			—			1,258
	Noninterest income		12,881			48,418			25,659		59,298			(56,101	)		90,155
	Depreciation and amortization		2,178			7,011			521		1,367			—			11,077
	Other expenses		31,396			84,011			21,604		23,818			(332	)		160,497
	Income before taxes	$	35,807		$	58,896		$	9,652	$	32,256		$	(55,769	)	$	80,842
	Total assets	$	2,079,444		$	3,764,429		$	103,656	$	703,294		$	(611,849	)	$	6,038,974
	Capital expenditures	$	5,534		$	6,445		$	219	$	1,698		$	—		$	13,896
	December 31, 2012
	Net interest income (expense)	$	54,062		$	105,966		$	7,055	$	(2,268	)	$	—		$	164,815
	Provision for loan losses		1,202			1,607			182		109			—			3,100
	Noninterest income		11,222			43,809			29,624		56,848			(53,786	)		87,717
	Depreciation and amortization		1,956			6,898			485		1,501			—			10,840
	Other expenses		29,511			80,535			22,056		27,783			(297	)		159,588
	Income before taxes	$	32,615		$	60,735		$	13,956	$	25,187		$	(53,489	)	$	79,004
	Total assets	$	1,996,539		$	3,801,653		$	186,473	$	602,342		$	(564,757	)	$	6,022,250
	Capital expenditures	$	4,099		$	8,045		$	398	$	896		$	—		$	13,438
	The financial information for each business unit is presented on the basis used internally by management to evaluate performance and allocate resources. The Company utilizes a transfer pricing system to allocate the benefit or cost of funds provided or used by the various business units. Certain services provided by the support group to other business units, such as item processing, are allocated at rates approximating the cost of providing the services. Eliminations are adjustments to consolidate the business units and companies. Capital expenditures are generally charged to the business unit using the asset.

Selected_Quarterly_Financial_D

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	(23) SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)
	A summary of the unaudited quarterly results of operations for the years ended December 31, 2014 and 2013 is as follows:
		Quarter
		Fourth		Third			Second		First
		(Dollars in thousands, except per share data)
	2014
	Net interest income	$	47,319	$	46,514		$	45,489	$	42,029
	Provision for loan losses		1,840		(3,115	)		3,129		1,218
	Securities transactions		822		284			85		450
	Noninterest income		24,302		24,938			23,611		23,562
	Noninterest expense		46,886		46,942			45,857		43,836
	Net income		15,749		18,793			14,688		14,657
	Net income per common share:
	Basic		1.02		1.22			0.94		0.96
	Diluted		0.99		1.19			0.92		0.94
	2013
	Net interest income	$	41,921	$	40,712		$	40,630	$	40,256
	Provision for loan losses		454		(12	)		516		300
	Securities transactions		79		90			129		122
	Noninterest income		22,235		23,652			21,733		22,535
	Noninterest expense		43,854		43,321			42,455		41,944
	Net income		13,861		14,491			12,593		13,372
	Net income per common share:
	Basic		0.91		0.94			0.83		0.88
	Diluted		0.88		0.93			0.82		0.86

Subsequent_Event

Subsequent Event	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Event

Description_of_Business_and_Su1

Description of Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations
	BancFirst Corporation is an Oklahoma business corporation and a financial holding company under federal law. It conducts virtually all of its operating activities through its principal wholly-owned subsidiary, BancFirst (the “Bank” or “BancFirst”), a state-chartered bank headquartered in Oklahoma City, Oklahoma. The Bank provides a wide range of retail and commercial banking services, including: commercial, real estate, agricultural and consumer lending; depository and funds transfer services; collections; safe deposit boxes; cash management services; retail brokerage services; and other services tailored for both individual and corporate customers. The Bank also offers trust services and acts as executor, administrator, trustee, transfer agent and in various other fiduciary capacities. Through its Technology and Operations Center, the Bank provides item processing, research and other correspondent banking services to financial institutions and governmental units. The Company’s wholly-owned subsidiary, BancFirst Insurance Services, Inc., an independent insurance agency, offers a variety of commercial and personal insurance products. In addition, the Company’s wholly-owned subsidiary, Council Oak Partners, LLC, an Oklahoma limited liability company engages in investing activities.
Basis of Presentation	Basis of Presentation
	The accompanying consolidated financial statements include the accounts of BancFirst Corporation, Council Oak Partners, LLC, BancFirst Insurance Services, Inc., and BancFirst and its subsidiaries. The principal operating subsidiaries of BancFirst are Council Oak Investment Corporation, Council Oak Real Estate Inc. and BancFirst Agency, Inc. BancFirst Community Development Corporation was dissolved in September 2014. All significant intercompany accounts and transactions have been eliminated. Assets held in a fiduciary or agency capacity are not assets of the Company and, accordingly, are not included in the consolidated financial statements. Certain amounts from 2013 and 2012 have been reclassified to conform to the 2014 presentation. These reclassifications were not material to the Company’s financial statements.
Use of Estimates in the Preparation of Financial Statements	Use of Estimates in the Preparation of Financial Statements
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States inherently involves the use of estimates and assumptions that affect the amounts reported in the financial statements and the related disclosures. These estimates relate principally to the determination of the allowance for loan losses, income taxes, the fair value of financial instruments and the valuation of intangibles. Such estimates and assumptions may change over time and actual amounts realized may differ from those reported.
Securities	Securities
	The Company does not engage in securities trading activities. Any sales of securities are for the purpose of executing the Company’s asset/liability management strategy, eliminating a perceived credit risk in a specific security, or providing liquidity. Securities that are being held for indefinite periods of time, or that may be sold as part of the Company’s asset/liability management strategy, to provide liquidity or for other reasons, are classified as available for sale and are stated at estimated fair value. Unrealized gains or losses on securities available for sale are reported as a component of stockholders’ equity, net of income tax. Gains or losses from sales of securities are based upon the book values of the specific securities sold. Securities for which the Company has the intent and ability to hold to maturity are classified as held for investment and are stated at cost, adjusted for amortization of premiums and accretion of discounts computed under the interest method. The Company reviews its portfolio of securities for impairment at least quarterly. Impairment is considered to be other-than-temporary if it is likely that all amounts contractually due will not be received for debt securities and when there is no positive evidence indicating that an investment’s carrying amount is recoverable in the near term for equity securities. When impairment is considered other-than-temporary, the cost basis of the security is written down to fair value, with the impairment charge included in earnings. In evaluating whether the impairment is temporary or other-than-temporary, the Company considers, among other things, the time period the security has been in an unrealized loss position, and whether the Company has the intent and ability to hold a security for a period of time sufficient to allow for any anticipated recovery in fair value.
Loans	Loans
	The lending function is governed by written policies and procedures, as determined by senior management and approved by the Board of Directors. The policies and procedures set the standards for lending in each major loan category by collateral type and use of loan proceeds. The objectives of these policies and procedures are to identify profitable markets, determine appropriate risk tolerance levels for each type of loan, establish limits for loan officer approval, set concentration limits, establish loan-to-value thresholds, set repayment terms and loan structure guidelines and adhere to documentation requirements. Interest rate risk is controlled by the use of variable rate provisions, the vast majority of which have a rate floor, limits on fixing rates for longer periods, and strict adherence to the original amortization terms in a rising interest rate environment.
	One to four family residential real estate loans are made in accordance with underwriting policies and are fully documented. Credit worthiness is assessed based on significant credit characteristics including credit history, residential and employment stability. These loans include first liens, junior liens and home equity lines of credit. The composition of this portfolio is primarily first liens, which comprise more than 80% of the portfolio, with junior liens comprising less than 15%, and home equity lines of credit comprising less than 5%. The Company does not engage in any hybrid loan programs. In addition, the Company does not have any exposure to loans with negative amortization, interest rate carryover or discounting of the initial rates (teaser rates).
	Loans originated within the Company are stated at the principal amount outstanding, net of unearned interest, loan fees and allowance for loan losses. Interest on all performing loans is recognized, on a simple interest basis, based upon the principal amount outstanding. A loan is placed on nonaccrual status when, in the opinion of management, the future collectability of interest and/or principal is not probable. When interest accrual is discontinued, all unpaid accrued interest is reversed. Interest income is recognized on certain of these loans on a cash basis if the full collection of the remaining principal balance is reasonably expected. Otherwise, interest income is not recognized until the principal balance is fully collected. See Note (5) for loan disclosures.
Acquired Loans	Acquired Loans
	Loans acquired through business combinations since December 2009 are required to be carried at fair value as of the date of the combination. Loans that would have a general allowance for loan losses or have specific evidence of deterioration of credit quality since origination are adjusted to fair value and any allowance for loan losses is eliminated. The difference between the fair value of loans which do not have specific evidence of deterioration of credit quality since origination and their principal balance is recognized in interest income on a level-yield method over the life of the loans. For loans which it is probable, at acquisition, that the Company will be unable to collect all contractually required payments (as determined by the present value of expected future cash flows), the difference between the undiscounted cash flows expected at acquisition and the investment in the loan, or the “accretable yield,” is recognized in interest income on a level-yield method over the life of the loan. Contractually required payments for interest and principal that exceed the undiscounted cash flows expected at acquisition, or the “nonaccretable difference,” are not recognized as yield adjustments or as loss accruals or valuation allowances. Increases in expected cash flows subsequent to the initial investment are recognized prospectively through adjustment of the yield on the loan over its remaining life. Decreases in expected cash flows are recognized as impairments. Any probable loss due to subsequent credit deterioration of the loans since acquisition is provided for in the allowance for loan losses.
Loans Held For Sale	Loans Held For Sale
	The Company originates mortgage loans to be sold. At the time of origination, the acquiring bank has already been determined and the terms of the loan, including the interest rate, have already been set by the acquiring bank allowing the Company to originate the loan at fair value. Mortgage loans are generally sold within 30 days of origination. Loans held for sale are carried at the lower of cost or market. Gains or losses recognized upon the sale of the loans are determined on a specific identification basis. The Company does not sell residential mortgage loans with recourse other than obligations under standard representations and warranties or for fraud. These obligations relate to loan performance for the life of the loan. The amount of loans repurchased since the inception of the program is not considered to be material, and therefore, no reserve has been required.
Allowance for Loan Losses	Allowance for Loan Losses
	The allowance for loan losses is an estimate of probable credit losses related to specifically identified loans and for losses inherent in the portfolio that have been incurred as of the balance sheet date. The allowance for loan losses is increased by provisions charged to operating expense and is reduced by net loan charge-offs. The amount of the allowance for loan losses is based on past loan loss experience, evaluations of known impaired loans, levels of adversely graded loans, general economic conditions and other environmental factors. Loans are considered impaired when, based on current information and events, it is probable the Company will be unable to collect all amounts due in accordance with the original contractual terms of the loan agreement, including scheduled principal and interest payments. Impairment is evaluated in aggregate for smaller-balance loans of a similar nature and on an individual loan basis for other loans. If a loan is impaired, a specific allowance is provided, if necessary, so that the loan is reported net, at the present value of estimated future cash flows using the loan’s existing rate or at the fair value of collateral if repayment is expected primarily from the collateral. Interest payments on impaired loans are typically applied to principal unless collectability of the principal amount is reasonably assured, in which case interest is recognized on a cash basis. Impaired loans, or portions thereof, are charged off when deemed uncollectible.
Appraisal Policy	Appraisal Policy
	An updated appraisal of the collateral is obtained when a loan is first identified as a problem loan. Appraisals are reviewed annually and are updated as needed, or are updated more frequently if significant changes are believed to have occurred in the collateral or market conditions. Appraisals of other real estate owned are also reviewed and updated consistent with this policy.
Nonaccrual Policy	Nonaccrual Policy
	The Company does not accrue interest on (1) any loan upon which a default of principal or interest has existed for a period of 90 days or over unless the collateral margin or guarantor support are such that full collection of principal and interest are not in doubt, and an orderly plan for collection is in process; and (2) any other loan for which it is expected full collection of principal and interest is not probable.
	A nonaccrual loan may be restored to an accrual status when none of its principal and interest are past due and unpaid or otherwise becomes well secured and in the process of collection and when prospects for collection of future contractual payments are no longer in doubt. With the exception of a formal debt forgiveness agreement, no loan which has had principal charged-off shall be restored to accrual status unless the charged-off principal has been recovered.
Charge-off Policy	Charge-off Policy
	When a loan deteriorates to the point that the account officer or the Loan Committee concludes it no longer represents a viable asset, it will be charged off. Similarly, any portion of a loan that is deemed to no longer be a viable asset will be charged off. A loan will not be charged off unless such action has been approved by the branch President.
Premises and Equipment	Premises and Equipment
	Premises and equipment are stated at cost, less accumulated depreciation. Depreciation is charged to operating expense and is computed using the straight-line method over the estimated useful lives of the assets. Maintenance and repairs are charged to expense as incurred while improvements are capitalized. Premises and equipment is tested for impairment if events or changes in circumstances occur that indicate that the carrying amount of any premises and equipment may not be recoverable. Impairment losses are measured by comparing the fair values of the premises and equipment with their recorded amounts. Premises that are identified to be sold are transferred to other real estate owned at the lower of their carrying amounts or their fair values less estimated costs to sell. Any losses on premises identified to be sold are charged to operating expense. When premises and equipment are transferred to other real estate owned, sold, or otherwise retired, the cost and applicable accumulated depreciation are removed from the respective accounts and any resulting gains or losses are reported in the statement of comprehensive income.
Other Real Estate Owned	Other Real Estate Owned
	Other real estate owned consists of properties acquired through foreclosure proceedings or acceptance of a deed in lieu of foreclosure, and premises held for sale. These properties are carried at the lower of the book values of the related loans or fair values based upon appraisals, less estimated costs to sell. Losses arising at the time of reclassification of such properties from loans to other real estate owned are charged directly to the allowance for loan losses. Any losses on premises identified to be sold are charged to operating expense at the time of transfer from premises to other real estate owned. Losses from declines in value of the properties subsequent to classification as other real estate owned are charged to operating expense.
Intangible Assets and Goodwill	Intangible Assets and Goodwill
	Core deposit intangibles are amortized on a straight-line basis over the estimated useful lives of seven to ten years and customer relationship intangibles are amortized on a straight-line basis over the estimated useful life of three to eighteen years. Mortgage servicing rights are amortized based on current prepayment assumptions. Goodwill is not amortized, but is evaluated at a reporting unit level at least annually for impairment, or more frequently if other indicators of impairment are present. At least annually in the fourth quarter, intangible assets, excluding mortgage servicing rights, are evaluated for possible impairment. Impairment losses are measured by comparing the fair values of the intangible assets with their recorded amounts. Any impairment losses are reported in the statement of comprehensive income. Mortgage servicing rights are adjusted to fair value semi-annually, if impaired.
Derivatives	Derivatives
	The Company recognizes all of its derivative instruments as assets or liabilities in the balance sheet at fair value and recognizes the realized and unrealized change in fair value in the statement of comprehensive income. Income is derived from a fixed pricing spread when customer hedge contracts are immediately offset with counterparty contracts as compensation for administrative costs and credit risk and recognized in other noninterest income.
Insurance Commissions and Fees	Insurance Commissions and Fees
	Commission revenue is recognized at the later of the billing date or the effective date of the related insurance policies for those accounts billed by the Agency. Commission revenue, for accounts that are directly billed by the insurance company to the insured, is recognized when determinable by the Agency, which is generally when such commissions are received.
	The Agency also receives contingent commissions from insurance companies as additional incentive for achieving specified premium volume goals and/or loss experience parameters relating to the insurance placed by the Agency. Contingent commissions from insurance companies are recognized when determinable, which is generally when such commissions are received.
Stock-based Compensation	Stock-based Compensation
	The Company recognizes stock-based compensation as compensation expense in the statement of comprehensive income based on the fair value of the Company’s stock options on the measurement date, which, for the Company, is the date of the grant. The fair value of each option grant is estimated on the date of grant using the Black-Scholes option-pricing model and is based on certain assumptions including risk-free rate of return, dividend yield, stock price volatility and the expected term. The fair value of each option is expensed over its vesting period.
Income Taxes	Income Taxes
	The Company files a consolidated income tax return with its subsidiaries. Federal and state income tax expense or benefit has been allocated to subsidiaries on a separate return basis. Deferred taxes are recognized under the liability method based upon the future tax consequences of temporary differences between the carrying amounts and tax basis of assets and liabilities, using the tax rates expected to apply to taxable income in the periods when the related temporary differences are expected to be realized. Realization of deferred tax assets is dependent upon the generation of a sufficient level of future taxable income and recoverable taxes paid in prior years. Although realization is not assured, management believes it is more likely than not that all of the deferred tax assets will be realized.
Earnings Per Common Share	Earnings Per Common Share
	Basic earnings per common share is computed by dividing net income, less any preferred dividends requirement, by the weighted average of common shares outstanding. Diluted earnings per common share reflects the potential dilution that could occur if options, convertible securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in the earnings of the Company.
Comprehensive Income	Comprehensive Income
	Comprehensive income includes all changes in stockholders’ equity during a period, except those resulting from transactions with stockholders. Besides net income, other components of the Company’s comprehensive income includes the after tax effect of changes in the net unrealized gain/loss on securities available for sale.
Statement of Cash Flows	Statement of Cash Flows
	For purposes of the statement of cash flows, the Company considers cash and due from banks, and interest-bearing deposits with banks as cash equivalents.
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	In August 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-15, “Presentation of Financial Statements – Going Concern (Topic 205-40).” ASU 2014-15 provides guidance on management’s responsibility in evaluating whether there is substantial doubt about the Company’s ability to continue as a going concern and related footnote disclosures. For each reporting period, management will be required to evaluate whether there are conditions or events that raise substantial doubt about the Company’s ability to continue as a going concern within one year from the date the financial statements are issued. The amendments are effective for annual periods, and interim reporting periods within those annual periods, beginning after December 15, 2016. Early adoption is permitted. Adoption of ASU 2014-15 is not expected to have a significant effect on the Company’s financial statements.
	In January 2014, the FASB issued Accounting Standards Update ASU No. 2014-04, “Receivables: Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure (Topic 310-40).” ASU 2014-04 clarifies that an in-substance repossession or foreclosure occurs upon either the creditor obtaining legal title to the residential real estate property or the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. The amendments are effective for annual periods, and interim reporting periods within those annual periods, beginning after December 15, 2014. The amendments may be adopted using either a modified retrospective transition method or a prospective transition method. Early adoption is permitted. Adoption of ASU 2014-04 is not expected to have a significant effect on the Company’s financial statements.
	In January 2014, the FASB issued ASU No. 2014-01, “Accounting for Investments in Affordable Housing Projects (Topic 323).” ASU 2014-01 revises the necessary criteria that need to be met in order for an entity to account for investments in affordable housing projects net of the provision for income taxes. It also changes the method of recognition from an effective amortization approach to a proportional amortization approach. Additional disclosures were also set forth in this update. The amendments are effective for annual periods, and interim reporting periods within those annual periods, beginning after December 15, 2014. The amendments are required to be applied retrospectively to all periods presented. Early adoption is permitted and adoption of the standard is optional. Adoption of ASU 2014-01 may affect income statement presentation, but otherwise is not expected to have a material impact on the Company’s financial statements.

Cash_Due_from_Banks_InterestBe1

Cash, Due from Banks, Interest-Bearing Deposits and Federal Funds Sold (Tables)	12 Months Ended
	Dec. 31, 2014
Cash And Cash Equivalents [Abstract]
Summary of Average Amount of Required Reserves	The average amount of required reserves for each of the years ended December 31, 2014 and 2013 is included in the following table:
		December 31,
		2014		2013
		(Dollars in thousands)
	Vault cash and funds on deposit with the Federal Reserve Bank	$	1,804,028	$	1,758,908
	Average required reserves		44,711		37,456

Securities_Tables

Securities (Tables)	12 Months Ended
	Dec. 31, 2014
Investments Debt And Equity Securities [Abstract]
Summary of Securities Held for Investment and Securities Available for Sale	The following table summarizes securities held for investment and securities available for sale:
			December 31,
			2014		2013
			(Dollars in thousands)
	Held for investment at cost (fair value: $8,671 and $12,094, respectively)		$	8,593	$	11,986
	Available for sale, at fair value			516,190		515,641
	Total		$	524,783	$	527,627
Summary of Amortized Cost and Estimated Fair Values of Securities Held for Investment	The following table summarizes the amortized cost and estimated fair values of securities held for investment:
			Amortized		Gross		Gross			Estimated
			Cost		Unrealized		Unrealized			Fair
					Gains		Losses			Value
			(Dollars in thousands)
	December 31, 2014
	Mortgage backed securities (1)		$	471	$	34	$	—		$	505
	States and political subdivisions			8,122		44		—			8,166
	Total		$	8,593	$	78	$	—		$	8,671
	December 31, 2013
	Mortgage backed securities (1)		$	607	$	48	$	—		$	655
	States and political subdivisions			11,379		67		(7	)		11,439
	Total		$	11,986	$	115	$	(7	)	$	12,094
Summary of Amortized Cost and Estimated Fair Values of Securities Available for Sale	The following table summarizes the amortized cost and estimated fair values of securities available for sale:
			Amortized		Gross		Gross			Estimated
			Cost		Unrealized		Unrealized			Fair
					Gains		Losses			Value
			(Dollars in thousands)
	December 31, 2014
	U.S. treasuries		$	248,767	$	404	$	(178	)	$	248,993
	U.S. federal agencies			171,641		983		(175	)		172,449
	Mortgage backed securities (1)			26,441		602		(586	)		26,457
	States and political subdivisions			51,706		1,716		(49	)		53,373
	Other securities (2)			10,798		4,252		(132	)		14,918
	Total		$	509,353	$	7,957	$	(1,120	)	$	516,190
	December 31, 2013
	U.S. treasuries		$	29,946	$	—	$	(85	)	$	29,861
	U.S. federal agencies			386,391		1,399		(505	)		387,285
	Mortgage backed securities (1)			32,057		625		(4	)		32,678
	States and political subdivisions			49,116		1,290		(72	)		50,334
	Other securities (2)			12,121		3,503		(141	)		15,483
	Total		$	509,631	$	6,817	$	(807	)	$	515,641
	-1	Primarily consists of FHLMC, FNMA, GNMA and mortgage backed securities through U.S. agencies.
	-2	Primarily consists of equity securities.
Maturity of Securities	The maturities of securities held for investment and available for sale are summarized in the following table using contractual maturities. Actual maturities may differ from contractual maturities due to obligations that are called or prepaid. For purposes of the maturity table, mortgage-backed securities, which are not due at a single maturity date, have been presented at their contractual maturity.
			December 31,
			2014				2013
			Amortized		Estimated		Amortized			Estimated
			Cost		Fair		Cost			Fair
					Value					Value
			(Dollars in thousands)
	Held for Investment
	Contractual maturity of debt securities:
	Within one year		$	1,451	$	1,456	$	3,640		$	3,649
	After one year but within five years			6,603		6,642		7,277			7,321
	After five years but within ten years			380		396		837			865
	After ten years			159		177		232			259
	Total		$	8,593	$	8,671	$	11,986		$	12,094
	Available for Sale
	Contractual maturity of debt securities:
	Within one year		$	41,772	$	41,870	$	208,625		$	209,065
	After one year but within five years			350,975		352,044		167,554			168,210
	After five years but within ten years			21,990		22,717		27,195			27,797
	After ten years			87,252		88,132		97,542			98,551
	Total debt securities			501,989		504,763		500,916			503,623
	Equity securities			7,364		11,427		8,715			12,018
	Total		$	509,353	$	516,190	$	509,631		$	515,641
Proceeds from Sales and Realized Securities Gains and Losses, on Available for Sale Securities	The following is a detail of proceeds from sales and realized securities gains and losses, on available for sale securities:
			Year Ended December 31,
			2014		2013		2012
			(Dollars in thousands)
	Proceeds		$	4,855	$	521	$	6,025
	Gross gains realized			1,641		456		5,575
	Gross losses realized			—		36		660
Company's Book Value of Pledged Securities	The following table is a summary of the Company’s book value of securities that were pledged as collateral for public funds on deposit, repurchase agreements and for other purposes as required or permitted by law:
			Year Ended December 31,
			2014		2013
			(Dollars in thousands)
	Book value of pledged securities		$	522,190	$	443,835
Summary of Securities with Unrealized Losses, Segregated by Duration of Unrealized Loss	The following table summarizes securities with unrealized losses, segregated by the duration of the unrealized loss, at December 31, 2014 and 2013 respectively:
			Less than 12 Months				More than 12 Months					Total
			Estimated		Unrealized		Estimated			Unrealized		Estimated		Unrealized
			Fair Value		Losses		Fair Value			Losses		Fair Value		Losses
			(Dollars in thousands)
	December 31, 2014
	Held for Investment
	Mortgage backed securities		$	—	$	—	$	—		$	—	$	—	$	—
	States and political subdivisions			—		—		—			—		—		—
	Total		$	—	$	—	$	—		$	—	$	—	$	—
	Available for Sale
	U.S. treasuries		$	149,589	$	178	$	—		$	—	$	149,589	$	178
	U.S. federal agencies			40,551		113		13,653			62		54,204		175
	Mortgage backed securities			17,041		585		26			1		17,067		586
	States and political subdivisions			3,093		26		977			23		4,070		49
	Other securities			—		—		300			132		300		132
	Total		$	210,274	$	902	$	14,956		$	218	$	225,230	$	1,120
	December 31, 2013
	Held for Investment
	Mortgage backed securities		$	1	$	—	$	1		$	—	$	2	$	—
	States and political subdivisions			—		—		1,328			7		1,328		7
	Total		$	1	$	—	$	1,329		$	7	$	1,330	$	7
	Available for Sale
	U.S. treasuries		$	29,861	$	85	$	—		$	—	$	29,861	$	85
	U.S. federal agencies			79,411		246		150,188			259		229,599		505
	Mortgage backed securities			66		4		—			—		66		4
	States and political subdivisions			2,459		72		—			—		2,459		72
	Other securities			160		141		—			—		160		141
	Total		$	111,957	$	548	$	150,188		$	259	$	262,145	$	807

Loans_and_Allowance_for_Loan_L1

Loans and Allowance for Loan Losses (Tables)	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Schedule of Loans Outstanding by Category	The following is a schedule of loans outstanding by category:
		December 31,
		2014						2013
		Amount			Percent			Amount				Percent
		(Dollars in thousands)
	Commercial and financial:
	Commercial and industrial	$	745,106			19.3	%	$	605,672				17.88	%
	Oil & gas production and equipment		104,940			2.72			96,907				2.86
	Agriculture		132,830			3.44			111,323				3.29
	State and political subdivisions:
	Taxable		20,431			0.53			10,217				0.3
	Tax-exempt		20,952			0.54			11,073				0.33
	Real estate:
	Construction		356,621			9.24			284,808				8.41
	Farmland		149,507			3.87			132,512				3.91
	One to four family residences		775,795			20.09			703,903				20.78
	Multifamily residential properties		66,766			1.73			60,080				1.77
	Commercial		1,191,477			30.86			1,097,484				32.4
	Consumer		267,179			6.92			250,588				7.4
	Other (not classified above)		29,227			0.76			22,579				0.67
	Total loans	$	3,860,831			100	%	$	3,387,146				100	%
	Loans held for sale (included above)	$	9,433					$	6,469
Summary of Nonperforming and Restructured Assets	The following is a summary of nonperforming and restructured assets:
		December 31,
		2014			2013
		(Dollars in thousands)
	Past due 90 days or more and still accruing	$	1,135		$	1,179
	Nonaccrual		16,410			14,390
	Restructured		16,515			17,624
	Total nonperforming and restructured loans		34,060			33,193
	Other real estate owned and repossessed assets		8,079			8,386
	Total nonperforming and restructured assets	$	42,139		$	41,579
	Nonperforming and restructured loans to total loans		0.88	%		0.98	%
	Nonperforming and restructured assets to total assets		0.64	%		0.69	%
Summary of Amounts Included in Nonaccrual Loans Segregated by Class of Loans	Loans are segregated into classes based upon the nature of the collateral and the borrower. These classes are used to estimate the allowance for loan losses. The following table is a summary of amounts included in nonaccrual loans, segregated by class of loans. Residential real estate refers to one to four family real estate.
		December 31,
		2014			2013
		(Dollars in thousands)
	Real estate:
	Non-residential real estate owner occupied	$	296		$	595
	Non-residential real estate other		5,126			6,270
	Residential real estate permanent mortgage		681			718
	Residential real estate all other		1,796			1,521
	Commercial and financial:
	Non-consumer non-real estate		1,556			1,192
	Consumer non-real estate		250			176
	Other loans		1,659			1,407
	Acquired loans		5,046			2,511
	Total	$	16,410		$	14,390
Age Analysis of Past Due Loans Segregated by Class of Loans	The following table presents an age analysis of past due loans, segregated by class of loans:
		Age Analysis of Past Due Loans
		30-59			60-89			90 Days				Total			Current			Total Loans		Accruing
		Days			Days			and				Past Due			Loans					Loans 90
		Past Due			Past Due			Greater				Loans								Days or
																				More
																				Past Due
		(Dollars in thousands)
	As of December 31, 2014
	Real estate:
	Non-residential real estate owner occupied	$	635		$	—		$	269			$	904		$	482,731		$	483,635	$	70
	Non-residential real estate other		377			317			825				1,519			952,484			954,003		—
	Residential real estate permanent mortgage		2,010			758			544				3,312			304,267			307,579		172
	Residential real estate all other		1,820			194			1,488				3,502			633,586			637,088		387
	Commercial and financial:
	Non-consumer non-real estate		841			71			793				1,705			965,002			966,707		24
	Consumer non-real estate		1,914			711			330				2,955			244,810			247,765		215
	Other loans		1,858			916			741				3,515			158,902			162,417		—
	Acquired loans		1,815			997			1,304				4,116			97,521			101,637		267
	Total	$	11,270		$	3,964		$	6,294			$	21,528		$	3,839,303		$	3,860,831	$	1,135
	As of December 31, 2013
	Real estate:
	Non-residential real estate owner occupied	$	411		$	—		$	316			$	727		$	454,305		$	455,032	$	96
	Non-residential real estate other		5,391			269			1,543				7,203			856,179			863,382		2
	Residential real estate permanent mortgage		2,000			566			789				3,355			262,625			265,980		275
	Residential real estate all other		2,159			211			1,272				3,642			564,231			567,873		184
	Commercial and financial:
	Non-consumer non-real estate		1,122			118			1,047				2,287			793,028			795,315		125
	Consumer non-real estate		1,761			667			392				2,820			225,515			228,335		279
	Other loans		1,799			763			1,244				3,806			141,550			145,356		—
	Acquired loans		1,491			310			593				2,394			63,479			65,873		218
	Total	$	16,134		$	2,904		$	7,196			$	26,234		$	3,360,912		$	3,387,146	$	1,179
Impaired Loans Segregated by Class of Loans	The following table presents impaired loans, segregated by class of loans. No material amount of interest income was recognized on impaired loans subsequent to their classification as impaired.
		Impaired Loans
		Unpaid			Recorded			Related				Average
		Principal			Investment			Allowance				Recorded
		Balance			with							Investment
					Allowance
		(Dollars in thousands)
	As of December 31, 2014
	Real estate:
	Non-residential real estate owner occupied	$	521		$	448		$	15			$	453
	Non-residential real estate other		23,154			21,164			1,364				21,522
	Residential real estate permanent mortgage		1,095			880			85				1,042
	Residential real estate all other		2,480			2,270			299				2,273
	Commercial and financial:
	Non-consumer non-real estate		1,895			1,580			431				1,646
	Consumer non-real estate		664			648			138				602
	Other loans		2,101			1,659			228				1,512
	Acquired loans		10,933			7,708			—				8,082
	Total	$	42,843		$	36,357		$	2,560			$	37,132
	As of December 31, 2013
	Real estate:
	Non-residential real estate owner occupied	$	877		$	752		$	28			$	881
	Non-residential real estate other		24,964			23,351			2,161				23,816
	Residential real estate permanent mortgage		1,253			1,025			58				1,170
	Residential real estate all other		2,214			1,803			361				1,857
	Commercial and financial:
	Non-consumer non-real estate		1,801			1,459			388				1,553
	Consumer non-real estate		628			611			139				455
	Other loans		1,545			1,464			219				1,602
	Acquired loans		9,848			7,861			124				7,928
	Total	$	43,130		$	38,326		$	3,478			$	39,262
Internal Loan Grading by Class of Loans	The following table presents internal loan grading by class of loans:
		Internal Loan Grading
		Grade
		1			2			3				4			5			Total
		(Dollars in thousands)
	As of December 31, 2014
	Real estate:
	Non-residential real estate owner occupied	$	402,706		$	75,555		$	5,008			$	366		$	—		$	483,635
	Non-residential real estate other		795,209			133,542			20,126				5,126			—			954,003
	Residential real estate permanent mortgage		272,411			27,855			6,369				944			—			307,579
	Residential real estate all other		529,555			99,214			6,146				2,173			—			637,088
	Commercial and financial:
	Non-consumer non-real estate		821,094			117,457			26,550				1,606			—			966,707
	Consumer non-real estate		233,424			12,229			1,548				564			—			247,765
	Other loans		157,191			4,261			601				173			191			162,417
	Acquired loans		46,465			36,951			12,651				5,206			364			101,637
	Total	$	3,258,055		$	507,064		$	78,999			$	16,158		$	555		$	3,860,831
	As of December 31, 2013
	Real estate:
	Non-residential real estate owner occupied	$	382,798		$	66,139		$	5,446			$	649		$	—		$	455,032
	Non-residential real estate other		711,081			125,617			20,309				6,375			—			863,382
	Residential real estate permanent mortgage		233,924			24,882			6,081				1,093			—			265,980
	Residential real estate all other		475,421			82,571			8,238				1,643			—			567,873
	Commercial and financial:
	Non-consumer non-real estate		691,772			97,812			4,462				1,269			—			795,315
	Consumer non-real estate		214,153			11,819			1,931				431			1			228,335
	Other loans		141,787			2,558			772				239			—			145,356
	Acquired loans		47,220			11,980			3,766				2,907			—			65,873
	Total	$	2,898,156		$	423,378		$	51,005			$	14,606		$	1		$	3,387,146
Activity in All by Class of Loans	The following table details activity in the ALL by class of loans for the period presented. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories.
		ALL
		Balance at			Charge-			Recoveries				Net			Provisions			Balance
		beginning			offs							charge-			charged to			at end of
		of period										offs			operations			period
		(Dollars in thousands)
	As of December 31, 2014
	Real estate:
	Non-residential real estate owner occupied	$	4,827		$	(42	)	$	102			$	60		$	(481	)	$	4,406
	Non-residential real estate other		11,026			(29	)		49				20			(1,430	)		9,616
	Residential real estate permanent mortgage		2,825			(207	)		78				(129	)		252			2,948
	Residential real estate all other		6,708			(171	)		32				(139	)		(300	)		6,269
	Commercial and financial:
	Non-consumer non-real estate		8,977			(564	)		70				(494	)		4,288			12,771
	Consumer non-real estate		2,556			(687	)		203				(484	)		332			2,404
	Other loans		1,991			(351	)		149				(202	)		570			2,359
	Acquired loans		124			(568	)		719				151			(159	)		116
	Total	$	39,034		$	(2,619	)	$	1,402			$	(1,217	)	$	3,072		$	40,889
	As of December 31, 2013
	Real estate:
	Non-residential real estate owner occupied	$	5,104		$	(3	)	$	20			$	17		$	(294	)	$	4,827
	Non-residential real estate other		9,865			(19	)		12				(7	)		1,168			11,026
	Residential real estate permanent mortgage		2,781			(162	)		32				(130	)		174			2,825
	Residential real estate all other		7,034			(209	)		33				(176	)		(150	)		6,708
	Commercial and financial:
	Non-consumer non-real estate		9,385			(217	)		175				(42	)		(366	)		8,977
	Consumer non-real estate		2,451			(597	)		225				(372	)		477			2,556
	Other loans		1,885			(300	)		75				(225	)		331			1,991
	Acquired loans		220			(53	)		39				(14	)		(82	)		124
	Total	$	38,725		$	(1,560	)	$	611			$	(949	)	$	1,258		$	39,034
Allowance for Loan Losses Outstanding by Impairment Methodology	The following table details the amount of ALL by class of loans for the period presented, on the basis of the impairment methodology used by the Company.
		December 31, 2014						December 31, 2013
		(Dollars in thousands)
		Individually			Collectively			Individually				Collectively
		evaluated for			evaluated for			evaluated for				evaluated for
		impairment			impairment			impairment				impairment
	Real estate:
	Non-residential real estate owner occupied	$	202		$	4,204		$	231			$	4,596
	Non-residential real estate other		1,518			8,098			2,449				8,577
	Residential real estate permanent mortgage		407			2,541			243				2,582
	Residential real estate all other		743			5,526			994				5,714
	Commercial and financial:
	Non-consumer non-real estate		4,671			8,100			966				8,011
	Consumer non-real estate		372			2,032			334				2,222
	Other loans		214			2,145			252				1,739
	Acquired loans		—			116			—				124
	Total	$	8,127		$	32,762		$	5,469			$	33,565
Loans Outstanding by Impairment Methodology	The following table details the loans outstanding by class of loans for the period presented, on the basis of the impairment methodology used by the Company.
		Loans
		December 31, 2014										December 31, 2013
		(Dollars in thousands)
		Individually			Collectively			Loans				Individually			Collectively			Loans
		evaluated			evaluated			acquired				evaluated			evaluated			acquired
		for			for			with				for			for			with
		impairment			impairment			deteriorated				impairment			impairment			deteriorated
								credit										credit
								quality										quality
	Real estate:
	Non-residential real estate owner occupied	$	5,374		$	478,261		$	—			$	6,095		$	448,937		$	—
	Non-residential real estate other		25,251			928,752			—				26,684			836,698			—
	Residential real estate permanent mortgage		7,313			300,266			—				7,174			258,806			—
	Residential real estate all other		8,319			628,769			—				9,881			557,992			—
	Commercial and financial:
	Non-consumer non-real estate		28,156			938,551			—				5,731			789,584			—
	Consumer non-real estate		2,112			245,653			—				2,362			225,972			—
	Other loans		233			162,184			—				317			145,039			—
	Acquired loans		—			83,416			18,221				—			59,200			6,674
	Total	$	76,758		$	3,765,852		$	18,221			$	58,244		$	3,322,228		$	6,674
Summary of Amounts Included in ALL for Impaired Loans with Specific Reserves and Recorded Balance of Related Loans	The following table is a summary of amounts included in the ALL for impaired loans with specific reserves and the recorded balance of the related loans. No material amounts of interest income were collected on impaired loans with specific reserves for 2014, 2013 or 2012.
		Year Ended December 31,
		2014			2013			2012
		(Dollars in thousands)
	Allowance for loss on impaired loans	$	1,559		$	1,578		$	2,170
	Recorded balance of impaired loans		3,673			5,283			6,185
	Average recorded investment		4,478			5,734			8,416
Transfers from Loans to Other Real Estate Owned and Repossessed Assets	Transfers from loans to other real estate owned and repossessed assets during the periods presented are summarized as follows:
		Year Ended December 31,
		2014			2013			2012
		(Dollars in thousands)
	Other real estate owned	$	3,573		$	1,710		$	2,543
	Repossessed assets		1,209			1,171			1,034
	Total	$	4,782		$	2,881		$	3,577
Related Party Loans	A summary of these loans is as follows:
	Year Ended December 31,	Balance				Additions			Collections/				Balance
		Beginning							Terminations				End of the
		of the Period											Period
				(Dollars in thousands)
	2014	$	27,134			$	22,521		$	(24,636	)		$	25,019
	2013		29,030				11,979			(13,875	)			27,134
	2012		25,264				24,706			(20,940	)			29,030

Premises_and_Equipment_Net_Tab

Premises and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2014
Property Plant And Equipment [Abstract]
Summary of Premises and Equipment by Classification	The following is a summary of premises and equipment by classification:
		Estimated		December 31,
		Useful Lives		2014			2013
				(Dollars in thousands)
	Land			$	29,658		$	29,055
	Buildings		10 to 40 years		127,250			120,784
	Furniture, fixtures and equipment		3 to 15 years		64,734			61,641
	Accumulated depreciation				(100,301	)		(93,618	)
	Premises and equipment, net			$	121,341		$	117,862

Recovered_Sheet1

Intangible Assets and Goodwill (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets	The following is a summary of intangible assets:
		Gross		Accumulated			Net
		Carrying		Amortization			Carrying
		Amount					Amount
		(Dollars in thousands)
	As of December 31, 2014
	Core deposit intangibles	$	13,198	$	(6,013	)	$	7,185
	Customer relationship intangibles		5,699		(2,699	)		3,000
	Mortgage servicing intangibles		643		(193	)		450
	Total	$	19,540	$	(8,905	)	$	10,635
	As of December 31, 2013
	Core deposit intangibles	$	10,963	$	(4,620	)	$	6,343
	Customer relationship intangibles		5,699		(2,337	)		3,362
	Mortgage servicing intangibles		718		(150	)		568
	Total	$	17,380	$	(7,107	)	$	10,273
Estimated Amortization of Intangible Assets	Estimated amortization of intangible assets for the next five years, as of December 31, 2014, is as follows (dollars in thousands):
	Estimated Amortization
	2015	$	1,855
	2016		1,631
	2017		1,540
	2018		1,531
	2019		1,524
Summary of Goodwill by Business Segment	The following is a summary of goodwill by business segment:
		Metropolitan		Community			Other		Executive,		Consolidated
		Banks		Banks			Financial		Operations
							Services		& Support
		(Dollars in thousands)
	Balance at December 31, 2013	$	8,078	$	30,553		$	5,464	$	450	$	44,545
	Acquisitions		—		417			—		—		417
	Balance at December 31, 2014	$	8,078	$	30,970		$	5,464	$	450	$	44,962
		Metropolitan		Community			Other		Executive,		Consolidated
		Banks		Banks			Financial		Operations
							Services		& Support
		(Dollars in thousands)
	Year Ended December 31, 2013
	Balance at beginning and end of period	$	8,078	$	30,553		$	5,464	$	450	$	44,545

Time_Deposits_Tables

Time Deposits (Tables)	12 Months Ended
	Dec. 31, 2014
Banking And Thrift [Abstract]
Schedule of Maturities of Time Deposits	At December 31, 2014, the scheduled maturities of all time deposits are as follows (Dollars in thousands):
	2015	$	478,610
	2016		121,816
	2017		51,816
	2018		47,463
	2019		51,410
	Thereafter		164
	Total	$	751,279
Summary of Large Time Deposits for Periods Presented	The following table is a summary of large time deposits for the periods presented:
		December 31,
		2014		2013
		(Dollars in thousands)
	Time deposits of $100,000 or more	$	347,563	$	355,054

ShortTerm_Borrowings_Tables

Short-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Summary of Short- Term Borrowings	The following is a summary of short-term borrowings:
		December 31,
		2014			2013
		(Dollars in thousands)
	Federal funds purchased	$	1,000		$	700
	Repurchase agreements		2,982			3,890
	Total	$	3,982		$	4,590
	Weighted average interest rate		0.18	%		0.13	%
	End of period interest rate		0.14	%		0.15	%

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Components of the Company's Income Tax Expense (Benefit)	The components of the Company’s income tax expense (benefit) are as follows:
		Year Ended December 31,
		2014			2013			2012
		(Dollars in thousands)
	Current taxes:
	Federal	$	28,258		$	23,326		$	24,928
	State		2,709			3,682			2,865
	Deferred taxes		(3,683	)		(483	)		(689	)
	Total income taxes	$	27,284		$	26,525		$	27,104
Reconciliation of Tax Expense at the Federal Statutory Tax Rate	A reconciliation of tax expense at the federal statutory tax rate applied to income before taxes is presented in the following table:
		Year Ended December 31,
		2014			2013			2012
		(Dollars in thousands)
	Tax expense at the federal statutory tax rate	$	31,910		$	28,295		$	27,651
	Increase (decrease) in tax expense from:
	Tax-exempt income, net		(571	)		(621	)		(783	)
	Modified endowment life contracts		(755	)		(812	)		(870	)
	State tax expense, net of federal tax benefit		1,469			2,303			2,374
	Federal tax credits		(6,479	)		(4,132	)		(2,455	)
	Other, net		1,710			1,492			1,187
	Total tax expense	$	27,284		$	26,525		$	27,104
Summary of Net Deferred Tax Asset Reported in Other Assets	The net deferred tax asset consisted of the following and is reported in other assets:
		December 31,
		2014			2013
		(Dollars in thousands)
	Provision for loan losses	$	15,814		$	13,662
	Write-downs of other real estate owned		1,297			962
	Deferred compensation		2,652			2,237
	Stock-based compensation		3,190			2,934
	Investments in partnership interests		1,966			1,170
	Other		306			1,479
	Gross deferred tax assets		25,225			22,444
	Unrealized net gains on securities		(2,644	)		(2,103	)
	Premium on securities of banks acquired		(715	)		(800	)
	Intangibles		(2,917	)		(2,561	)
	Basis difference related to tax credits		(1,977	)		(1,620	)
	Depreciation		(5,504	)		(5,975	)
	Leveraged lease		(1,964	)		(2,282	)
	Other		(89	)		(257	)
	Gross deferred tax liabilities		(15,810	)		(15,598	)
	Net deferred tax asset	$	9,415		$	6,846

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Activity Under Stock Option Plan	The following table is a summary of the activity under both the BancFirst ISOP and the BancFirst Directors’ Stock Option Plan:
		Options			Wgtd. Avg.		Wgtd. Avg.			Aggregate
					Exercise		Remaining			Intrinsic
					Price		Contractual			Value
							Term
		(Dollars in thousands, except per share data)
	Year Ended December 31, 2014
	Outstanding at December 31, 2013		1,158,317		$	34.45
	Options granted		44,000			61.78
	Options exercised		(169,535	)		28.73
	Options canceled, forfeited, or expired		(3,125	)		36.73
	Outstanding at December 31, 2014		1,029,657			36.55		8.59	Yrs	$	27,638
	Exercisable at December 31, 2014		492,557			29.84		5.15	Yrs	$	16,525
	Year Ended December 31, 2013
	Outstanding at December 31, 2012		1,216,981		$	31.98
	Options granted		115,000			49.13
	Options exercised		(153,664	)		25.03
	Options canceled, forfeited, or expired		(20,000	)		40.83
	Outstanding at December 31, 2013		1,158,317			34.45		8.84	Yrs	$	25,034
	Exercisable at December 31, 2013		561,167			27.95		6.7	Yrs	$	15,774
Options Granted and Options Exercised Under Stock Option Plan	The following table has additional information regarding options granted and options exercised under both the BancFirst ISOP and the BancFirst Directors’ Stock Option Plan:
		Year Ended December 31,
		2014			2013		2012
		(Dollars in thousands, except per share data)
	Weighted average grant-date fair value per share of options granted	$	12.27		$	10.88	$	8.82
	Total intrinsic value of options exercised		5,597			3,723		3,297
	Cash received from options exercised		4,870			3,846		2,227
	Tax benefit realized from options exercised		2,165			1,440		1,275
Stock-based Employee Compensation Expense	The following table is a summary of the Company’s recorded stock-based compensation expense:
		Year Ended December 31,
		2014			2013		2012
		(Dollars in thousands)
	Stock-based compensation expense	$	1,676		$	1,360	$	1,530
	Tax benefit		648			526		592
	Stock-based compensation expense, net of tax	$	1,028		$	834	$	938
Remaining Fair Value of Stock Options	The Company will continue to amortize the remaining fair value of stock options over the remaining vesting period of approximately seven years. The following table shows the remaining fair value of stock options:
		December 31, 2014
		(Dollars in thousands)
	Fair value of stock options	$	4,215
Assumptions Used for Computing Stock-Based Compensation Expense	The following table shows the assumptions used for computing stock-based compensation expense under the fair value method:
		Year Ended December 31,
		2014			2013		2012
	Risk-free interest rate		2.10 % to 2.54%			1.95% to 3.15%		1.74% to 1.95%
	Dividend yield		2.00%			2.00%		2.00%
	Stock price volatility		18.03% to 18.98%			18.35% to 20.21%		21.71% to 38.75%
	Expected term		10Yrs			10Yrs		10Yrs
Summary of Accumulated Stock Units	A summary of the accumulated stock units is as follows:
		December 31,
		2014			2013
	Accumulated stock units		60,859			56,380
	Average price	$	37.41		$	35.31

Retirement_Plans_Tables

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2014
Compensation And Retirement Disclosure [Abstract]
Aggregate Amounts of Contributions to the 401(k) and ESOP Plans	The aggregate amounts of contributions by the Company to the 401(k) and ESOP plans are shown in the following table:
		December 31,
		2014		2013		2012
		(Dollars in thousands)
	401(k) contributions	$	1,870	$	1,738	$	1,690
	ESOP contributions		1,928		1,820		1,703
	Total contributions	$	3,798	$	3,558	$	3,393

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Summary of Authorized Outstanding Preferred and Common Stock	As of December 31, 2014, 2013 and 2012 the Company’s authorized and outstanding preferred and common stock was as follows:
		No. of Shares		No. of Shares Outstanding at December 31,								Par		Dividends			Voting
		Authorized at										Value					Rights
												Per
	Class of Stock	December 31,		2014			2013		2012			Share
		2014
	Senior Preferred		10,000,000		—			—		—		$	1		As declared			Voting
	10% Cumulative Preferred		900,000		—			—		—		$	5		As declared			Non-voting
	Common		20,000,000		15,504,513			15,333,622		15,242,308		$	1		As declared			Voting
Summary of Shares Repurchased Under Stock Purchase Program	The following table is a summary of the shares under the program:
		Year Ended December 31,
		2014		2013			2012
	Number of shares repurchased		—		40,241			6,787
	Average price of shares repurchased	$	—	$	40.88		$	37.7
	Shares remaining to be repurchased		194,723		194,723			234,964
Required Capital Amounts and Company's Respective Ratios	The actual and required capital amounts and ratios are shown in the following table:
		Actual					For Capital					To Be Well
							Adequacy					Capitalized Under
							Purposes					Prompt Corrective
												Action Provisions
		Amount		Ratio			Amount		Ratio			Amount		Ratio
		(Dollars in thousands)
	As of December 31, 2014:
	Total Capital
	(to Risk Weighted Assets)-
	BancFirst Corporation	$	616,862		14.75	%	$	334,531		8	%		N/A		N/A
	BancFirst		571,495		13.68	%		334,092		8	%	$	417,615		10	%
	Tier I Capital
	(to Risk Weighted Assets)-
	BancFirst Corporation		575,973		13.77	%		167,265		4	%		N/A		N/A
	BancFirst		530,606		12.71	%		167,046		4	%		250,569		6	%
	Tier I Capital
	(to Total Assets)-
	BancFirst Corporation		575,973		8.83	%		197,249		3	%		N/A		N/A
	BancFirst		530,606		8.15	%		196,716		3	%		327,859		5	%
	As of December 31, 2013:
	Total Capital
	(to Risk Weighted Assets)-
	BancFirst Corporation	$	563,873		14.85	%	$	303,700		8	%		N/A		N/A
	BancFirst		529,200		13.96	%		303,190		8	%	$	378,988		10	%
	Tier I Capital
	(to Risk Weighted Assets)-
	BancFirst Corporation		524,839		13.83	%		151,850		4	%		N/A		N/A
	BancFirst		490,166		12.93	%		151,595		4	%		227,393		6	%
	Tier I Capital
	(to Total Assets)-
	BancFirst Corporation		524,839		8.77	%		181,174		3	%		N/A		N/A
	BancFirst		490,166		8.2	%		180,606		3	%		301,011		5	%

Net_Income_Per_Common_Share_Ta

Net Income Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Basic and Diluted Net Income Per Common Share	Basic and diluted net income per common share are calculated as follows:
		Income		Shares		Per
		(Numerator)		(Denominator)		Share
						Amount
		(Dollars in thousands, except per share data)
	Year Ended December 31, 2014
	Basic
	Income available to common stockholders	$	63,887		15,430,773	$	4.14
	Effect of stock options		—		363,630
	Diluted
	Income available to common stockholders plus assumed exercises of stock options	$	63,887		15,794,403	$	4.04
	Year Ended December 31, 2013
	Basic
	Income available to common stockholders	$	54,317		15,268,843	$	3.56
	Effect of stock options		—		279,979
	Diluted
	Income available to common stockholders plus assumed exercises of stock options	$	54,317		15,548,822	$	3.49
	Year Ended December 31, 2012
	Basic
	Income available to common stockholders	$	51,900		15,172,457	$	3.42
	Effect of stock options		—		271,188
	Diluted
	Income available to common stockholders plus assumed exercises of stock options	$	51,900		15,443,645	$	3.36
Average Exercise Price of Options Excluded from Computation of Diluted Net Income Per Common Share	The following table shows the number and average exercise price of options that were excluded from the computation of diluted net income per common share for each year because the options’ exercise prices were greater than the average market price of the common shares.
		Shares		Average
				Exercise
				Price
	December 31, 2014		69,405	$	55.87
	December 31, 2013		118,603		42.79
	December 31, 2012		604,429		38.69

Condensed_Parent_Company_Finan1

Condensed Parent Company Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Summary of Balance Sheet of Parent Company	BALANCE SHEETS
		December 31,
		2014			2013
		(Dollars in thousands)
	ASSETS
	Cash	$	36,700		$	27,592
	Securities		103			115
	Investments in subsidiaries		598,413			555,761
	Goodwill		450			450
	Dividends receivable		6,434			5,927
	Other assets		983			913
	Total assets	$	643,083		$	590,758
	LIABILITIES AND STOCKHOLDERS’ EQUITY
	Other liabilities	$	6,965		$	6,957
	Junior subordinated debentures		26,804			26,804
	Stockholders’ equity		609,314			556,997
	Total liabilities and stockholders’ equity	$	643,083		$	590,758
Summary of Income Statement of Parent Company	STATEMENTS OF INCOME
		Year Ended December 31,
		2014			2013			2012
		(Dollars in thousands)
	OPERATING INCOME
	Dividends from subsidiaries	$	24,851		$	22,612		$	20,784
	Interest on interest-bearing deposits		62			47			57
	Other		14			92			—
	Total operating income		24,927			22,751			20,841
	OPERATING EXPENSE
	Interest		1,965			1,965			2,134
	Other		667			661			942
	Total operating expense		2,632			2,626			3,076
	Income before taxes and equity in undistributed earnings of subsidiaries		22,295			20,125			17,765
	Allocated income tax benefit		472			978			1,371
	Income before equity in undistributed earnings of subsidiaries		22,767			21,103			19,136
	Equity in undistributed earnings of subsidiaries		42,196			34,351			34,281
	Amortization of stock-based compensation arrangements of subsidiaries		(1,076	)		(1,137	)		(1,517	)
	Net income	$	63,887		$	54,317		$	51,900
Summary of Cash Flow of Parent Company	STATEMENTS OF CASH FLOW
		Year Ended December 31,
		2014			2013			2012
		(Dollars in thousands)
	CASH FLOWS FROM OPERATING ACTIVITIES
	Net income	$	63,887		$	54,317		$	51,900
	Adjustments to reconcile to net cash provided by operating activities:
	Equity in undistributed earnings of subsidiaries		(42,196	)		(34,351	)		(34,281	)
	Amortization of stock-based compensation arrangements		1,076			1,137			1,517
	Other, net		(656	)		(2,116	)		2,944
	Net cash provided by operating activities		22,111			18,987			22,080
	INVESTING ACTIVITIES
	Net cash provided by acquisitions		—			—			19,866
	Sales and maturities of held for investment and available for sale securities		8			63			—
	Net cash provided by investing activities		8			63			19,866
	FINANCING ACTIVITIES
	Issuance of common stock		6,532			5,200			3,540
	Common stock acquired		—			(2,710	)		(256	)
	Cash dividends paid		(19,543	)		(13,583	)		(21,090	)
	Redemption of Junior Subordinated Debentures		—			—			(9,279	)
	Net cash used for financing activities		(13,011	)		(11,093	)		(27,085	)
	Net increase in cash		9,108			7,957			14,861
	Cash and due from banks at the beginning of the period		27,592			19,635			4,774
	Cash and due from banks at the end of the period	$	36,700		$	27,592		$	19,635
	SUPPLEMENTAL DISCLOSURE
	Cash paid during the period for interest	$	1,965		$	1,965		$	2,128
	Cash received during the period for income taxes, net	$	1,822		$	4,449		$	1,884

Commitments_and_Contingent_Lia1

Commitments and Contingent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Summary of Financial Instruments with Off-Balance-Sheet Risks	The amounts of financial instruments with off-balance-sheet risk are as follows:
		December 31,
		2014		2013
		(Dollars in thousands)
	Loan commitments	$	937,221	$	945,270
	Stand-by letters of credit		63,734		61,262
Summary of Future Minimum Rental Payments Under Lease	The future minimum rental payments under these leases at December 31, 2014, were as follows (Dollars in thousands):
	2015	$	1,060
	2016		981
	2017		699
	2018		186
	2019		128
	Later years		624
	Total	$	3,678
Summary of Rental Expense	Rental expense on all property and equipment rented, including those rented on a monthly or temporary basis were as follows (Dollars in thousands):
	Year Ending December 31:
	2014	$	1,255
	2013		1,175
	2012		1,159

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities Measured on Recurring Basis	The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of December 31, 2014 and 2013, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value:
		Level 1			Level 2			Level 3		Total Fair
		Inputs			Inputs			Inputs		Value
		(Dollars in thousands)
	December 31, 2014
	Securities available for sale:
	U.S. Treasury	$	248,993		$	—		$	—	$	248,993
	U.S. federal agencies		—			172,449			—		172,449
	Mortgage-backed securities		—			9,425			17,032		26,457
	States and political subdivisions		—			53,373			—		53,373
	Other securities		—			3,491			11,427		14,918
	Derivative assets		—			6,124			—		6,124
	Derivative liabilities		—			4,756			—		4,756
	Loans held for sale		—			9,433			—		9,433
	Mortgage servicing intangibles		—			—			450		450
	December 31, 2013
	Securities available for sale:
	U.S. Treasury	$	29,861		$	—		$	—	$	29,861
	U.S. federal agencies		—			387,285			—		387,285
	Mortgage-backed securities		—			13,262			19,416		32,678
	States and political subdivisions		—			50,334			—		50,334
	Other securities		—			3,465			12,018		15,483
	Derivative assets		—			2,211			—		2,211
	Derivative liabilities		—			1,029			—		1,029
	Loans held for sale		—			6,469			—		6,469
	Mortgage servicing intangibles		—			—			568		568
Changes in Level 3 Assets Measured at Estimated Fair Value on Recurring Basis	The changes in Level 3 assets measured at estimated fair value on a recurring basis during the years ended December 31, 2014 and 2013 were as follows:
		Twelve Months Ended
		December 31,
		2014			2013
		(Dollars in thousands)
	Balance at the beginning of the year	$	32,002		$	10,779
	Purchases, issuances and settlements		(1,314	)		20,499
	Sales		(3,433	)		(251	)
	Gains included in earnings		1,469			234
	Total unrealized gains/(losses)		185			741
	Balance at the end of the year	$	28,909		$	32,002
Assets Measured at Fair Value on Nonrecurring Basis	The following table summarizes assets measured at fair value on a nonrecurring basis and the related gains or losses recognized during the year:
		Level 1			Level 2			Level 3		Total Fair		Gains
										Value		(Losses)
		(Dollars in thousands)
	Year Ended December 31, 2014
	Impaired loans (less specific allowance)		—			—		$	33,797	$	33,797	$	—
	Foreclosed assets		—			—			220		220		(18	)
	Other real estate owned		—			—			7,859		7,859		(304	)
	Year Ended December 31, 2013
	Impaired loans (less specific allowance)		—			—		$	34,848	$	34,848	$	—
	Foreclosed assets		—			—			237		237		(35	)
	Other real estate owned		—			—			8,149		8,149		(170	)
Estimated Fair Values of Financial Instruments	The estimated fair values of the Company’s financial instruments that are reported at amortized cost in the Company’s consolidated balance sheets, segregated by the level of valuation inputs within the fair value hierarchy utilized to measure fair value, are as follows:
		December 31,
		2014						2013
		Carrying			Fair Value			Carrying		Fair Value
		Amount						Amount
		(Dollars in thousands)
	FINANCIAL ASSETS
	Level 2 inputs:
	Cash and cash equivalents	$	1,913,895		$	1,913,895		$	1,857,535	$	1,857,535
	Securities held for investment		8,593			8,671			11,986		12,094
	Level 3 inputs:
	Loans, net		3,819,942			3,857,224			3,348,112		3,364,940
	FINANCIAL LIABILITIES
	Level 2 inputs:
	Deposits		5,904,704			5,945,502			5,419,519		5,451,114
	Short-term borrowings		3,982			3,982			4,590		4,590
	Long-term borrowings		—			—			6,938		6,908
	Junior subordinated debentures		26,804			31,200			26,804		29,259
	OFF-BALANCE SHEET FINANCIAL INSTRUMENTS
	Loan commitments					1,640					1,654
	Letters of credit					478					459

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Notional Amounts and Estimated Fair Values of Outstanding Derivative Positions	The notional amounts and estimated fair values of oil and gas derivative positions outstanding are presented in the following table:
				December 31,
				2014								2013
	Oil and Natural Gas	Notional Unit		Notional				Estimated				Notional			Estimated
	Swaps and Options			Amount				Fair Value				Amount			Fair Value
		(Notional amounts and dollars in thousands)
	Oil
	Derivative assets	Barrels			312			$	4,629				335		$	827
	Derivative liabilities	Barrels			(312	)			(4,271	)			(335	)		(378	)
	Natural Gas
	Derivative assets	MMBTUs			2,010				1,495				5,128			1,384
	Derivative liabilities	MMBTUs			(2,010	)			(485	)			(5,128	)		(651	)
	Total Fair Value	Included in
	Derivative assets	Other assets							6,124							2,211
	Derivative liabilities	Other liabilities							(4,756	)						(1,029	)
Recognized Derivative Income Included in Other Noninterest Income	The following table is a summary of the Company’s recognized income related to the activity, which was included in other noninterest income:
		Year Ended December 31,
		2014				2013				2012
		(Dollars in thousands)
	Derivative income	$	500			$	521			$	599
Summary of Company's Net Credit Exposure Relating to Oil and Gas Swaps and Options with Bank Counterparties	The following table is a summary of the Company’s net credit exposure relating to oil and gas swaps and options with bank counterparties:
		December 31,
		2014				2013
		(Dollars in thousands)
	Credit exposure	$	4,028			$	9

Segment_Information_Tables

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Results of Operations and Selected Financial Information	The results of operations and selected financial information for the four business units are as follows:
		Metropolitan			Community			Other		Executive,			Eliminations			Consolidated
		Banks			Banks			Financial		Operations
								Services		& Support
		(Dollars in thousands)
	December 31, 2014
	Net interest income (expense)	$	59,923		$	116,935		$	6,155	$	(1,662	)	$	—		$	181,351
	Provision for loan losses		3,077			(488	)		481		2			—			3,072
	Noninterest income		13,752			51,415			28,079		69,442			(66,275	)		96,413
	Depreciation and amortization		2,216			7,277			522		1,334			—			11,349
	Other expenses		32,300			89,888			22,304		27,998			(318	)		172,172
	Income before taxes	$	36,082		$	71,673		$	10,927	$	38,446		$	(65,957	)	$	91,171
	Total assets	$	2,298,828		$	4,113,783		$	145,814	$	679,194		$	(662,647	)	$	6,574,972
	Capital expenditures	$	1,948		$	7,972		$	121	$	1,449		$	—		$	11,490
	December 31, 2013
	Net interest income (expense)	$	56,346		$	102,705		$	6,239	$	(1,771	)	$	—		$	163,519
	Provision for loan losses		(154	)		1,205			121		86			—			1,258
	Noninterest income		12,881			48,418			25,659		59,298			(56,101	)		90,155
	Depreciation and amortization		2,178			7,011			521		1,367			—			11,077
	Other expenses		31,396			84,011			21,604		23,818			(332	)		160,497
	Income before taxes	$	35,807		$	58,896		$	9,652	$	32,256		$	(55,769	)	$	80,842
	Total assets	$	2,079,444		$	3,764,429		$	103,656	$	703,294		$	(611,849	)	$	6,038,974
	Capital expenditures	$	5,534		$	6,445		$	219	$	1,698		$	—		$	13,896
	December 31, 2012
	Net interest income (expense)	$	54,062		$	105,966		$	7,055	$	(2,268	)	$	—		$	164,815
	Provision for loan losses		1,202			1,607			182		109			—			3,100
	Noninterest income		11,222			43,809			29,624		56,848			(53,786	)		87,717
	Depreciation and amortization		1,956			6,898			485		1,501			—			10,840
	Other expenses		29,511			80,535			22,056		27,783			(297	)		159,588
	Income before taxes	$	32,615		$	60,735		$	13,956	$	25,187		$	(53,489	)	$	79,004
	Total assets	$	1,996,539		$	3,801,653		$	186,473	$	602,342		$	(564,757	)	$	6,022,250
	Capital expenditures	$	4,099		$	8,045		$	398	$	896		$	—		$	13,438

Selected_Quarterly_Financial_D1

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Summary of the Unaudited Quarterly Results of Operations	A summary of the unaudited quarterly results of operations for the years ended December 31, 2014 and 2013 is as follows:
		Quarter
		Fourth		Third			Second		First
		(Dollars in thousands, except per share data)
	2014
	Net interest income	$	47,319	$	46,514		$	45,489	$	42,029
	Provision for loan losses		1,840		(3,115	)		3,129		1,218
	Securities transactions		822		284			85		450
	Noninterest income		24,302		24,938			23,611		23,562
	Noninterest expense		46,886		46,942			45,857		43,836
	Net income		15,749		18,793			14,688		14,657
	Net income per common share:
	Basic		1.02		1.22			0.94		0.96
	Diluted		0.99		1.19			0.92		0.94
	2013
	Net interest income	$	41,921	$	40,712		$	40,630	$	40,256
	Provision for loan losses		454		(12	)		516		300
	Securities transactions		79		90			129		122
	Noninterest income		22,235		23,652			21,733		22,535
	Noninterest expense		43,854		43,321			42,455		41,944
	Net income		13,861		14,491			12,593		13,372
	Net income per common share:
	Basic		0.91		0.94			0.83		0.88
	Diluted		0.88		0.93			0.82		0.86

Description_of_Business_and_Su2

Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Days from origination after which mortgage loan are sold	30 days
Loan upon which a default of principal or interest has existed for a period	90 days
Intangible assets, Estimated useful lives	6 years 6 months
Core Deposit Intangibles [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, Estimated useful lives	5 years 10 months 24 days
Minimum [Member] | Core Deposit Intangibles [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, Estimated useful lives	7 years
Minimum [Member] | Customer Relationship Intangibles [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, Estimated useful lives	3 years
Maximum [Member] | Core Deposit Intangibles [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, Estimated useful lives	10 years
Maximum [Member] | Customer Relationship Intangibles [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, Estimated useful lives	18 years
First Liens [Member] | Minimum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Loans and finance receivables portfolio percentage	80.00%
Junior Liens [Member] | Maximum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Loans and finance receivables portfolio percentage	15.00%
Home Equity Lines of Credit [Member] | Maximum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Loans and finance receivables portfolio percentage	5.00%

Recent_Developments_Including_1

Recent Developments Including Mergers and Acquisitions - Additional Information (Detail) (USD $)	0 Months Ended
	Jan. 19, 2012	Dec. 31, 2014	Dec. 31, 2013	Jan. 24, 2014
Business Combination, Separately Recognized Transactions [Line Items]
Goodwill		$44,962,000	$44,545,000
Pretax gain on sale of investments	4,500,000
Gain on sale of investments, Net of tax	2,600,000
BancFirst [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Deposits assumed		174,400,000		302,000,000
Loans				121,000,000
Securities				4,800,000
Other real estate				10,000
Intangibles assets, net				2,200,000
Goodwill				417,000
BancFirst [Member] | Performing [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Loans		$74,800,000

Cash_Due_from_Banks_InterestBe2

Cash Due from Banks Interest-Bearing Deposits and Federal Funds Sold - Summary of Average Amount of Required Reserves (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Average Amount Of Required Reserves [Abstract]
Vault cash and funds on deposit with the Federal Reserve Bank	$1,804,028	$1,758,908
Average required reserves	$44,711	$37,456

Securities_Summary_of_Securiti

Securities - Summary of Securities Held for Investment and Securities Available for Sale (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Marketable Securities [Abstract]
Held for investment at cost (fair value: $8,671 and $12,094, respectively)	$8,593	$11,986
Available for sale, at fair value	516,190	515,641
Total	$524,783	$527,627

Securities_Summary_of_Securiti1

Securities - Summary of Securities Held for Investment and Securities Available for Sale (Parenthetical) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Marketable Securities [Abstract]
Held for investment at fair value	$8,671	$12,094

Securities_Summary_of_Amortize

Securities - Summary of Amortized Cost and Estimated Fair Values of Securities Held for Investment (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$8,593	$11,986
Gross Unrealized Gains	78	115
Gross Unrealized Losses		-7
Estimated Fair Value	8,671	12,094
Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	471	607
Gross Unrealized Gains	34	48
Estimated Fair Value	505	655
States and Political Subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	8,122	11,379
Gross Unrealized Gains	44	67
Gross Unrealized Losses		-7
Estimated Fair Value	$8,166	$11,439

Securities_Summary_of_Amortize1

Securities - Summary of Amortized Cost and Estimated Fair Values of Securities Available for Sale (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$509,353	$509,631
Gross Unrealized Gains	7,957	6,817
Gross Unrealized Losses	-1,120	-807
Estimated Fair Value, Total	516,190	515,641
U.S. Treasuries [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	248,767	29,946
Gross Unrealized Gains	404
Gross Unrealized Losses	-178	-85
Estimated Fair Value, Total	248,993	29,861
U.S. Federal Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	171,641	386,391
Gross Unrealized Gains	983	1,399
Gross Unrealized Losses	-175	-505
Estimated Fair Value, Total	172,449	387,285
Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	26,441	32,057
Gross Unrealized Gains	602	625
Gross Unrealized Losses	-586	-4
Estimated Fair Value, Total	26,457	32,678
States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	51,706	49,116
Gross Unrealized Gains	1,716	1,290
Gross Unrealized Losses	-49	-72
Estimated Fair Value, Total	53,373	50,334
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,798	12,121
Gross Unrealized Gains	4,252	3,503
Gross Unrealized Losses	-132	-141
Estimated Fair Value, Total	$14,918	$15,483

Securities_Maturity_of_Securit

Securities - Maturity of Securities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Held for Investment, Contractual maturity of debt securities, Amortized Cost
Amortized cost, Within one year	$1,451	$3,640
Amortized cost, After one year but within five years	6,603	7,277
Amortized cost, After five years but within ten years	380	837
Amortized cost, After ten years	159	232
Amortized Cost	8,593	11,986
Available for sale, Contractual maturity of debt securities, Amortized Cost
Amortized Cost, Within one year	41,772	208,625
Amortized Cost, After one year but within five years	350,975	167,554
Amortized Cost, After five years but within ten years	21,990	27,195
Amortized Cost, After ten years	87,252	97,542
Total debt securities	501,989	500,916
Amortized Cost, Equity securities	7,364	8,715
Amortized Cost, Total	509,353	509,631
Held for Investment, Contractual maturity of debt securities, Estimated Fair Value
Estimated Fair Value, Within one year	1,456	3,649
Estimated Fair Value, After one year but within five years	6,642	7,321
Estimated Fair Value, After five years but within ten years	396	865
Estimated Fair Value, After ten years	177	259
Estimated Fair Value	8,671	12,094
Available for sale, Contractual maturity of debt securities, Estimated Fair Value
Estimated Fair Value, Within one year	41,870	209,065
Estimated Fair Value, After one year but within five years	352,044	168,210
Estimated Fair Value, After five years but within ten years	22,717	27,797
Estimated Fair Value, After ten years	88,132	98,551
Total debt securities	504,763	503,623
Estimated Fair Value, Equity securities	11,427	12,018
Estimated Fair Value, Total	$516,190	$515,641

Securities_Proceeds_from_Sales

Securities - Proceeds from Sales and Realized Securities Gains and Losses, on Available for Sale Securities (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Available For Sale Securities Gross Realized Gain Loss [Abstract]
Proceeds	$4,855	$521	$6,025
Gross gains realized	1,641	456	5,575
Gross losses realized		$36	$660

Securities_Companys_Book_Value

Securities - Company's Book Value of Pledged Securities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Pledged Financial Instruments Not Separately Reported Securities Pledged By Type Of Security [Abstract]
Book value of pledged securities	$522,190	$443,835

Securities_Summary_of_Securiti2

Securities - Summary of Securities with Unrealized Losses, Segregated by Duration of Unrealized Loss (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014
Held for Investment
Held-to-maturity Securities, Less than 12 Months, Fair Value	$1
Held-to-maturity Securities, 12 Months or Longer, Fair Value	1,329
Held-to-maturity Securities, 12 Months or Longer, Unrealized Losses	7
Held-to-maturity Securities, Fair Value, Total	1,330
Held-to-maturity Securities, Unrealized Losses, Total	7
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value	111,957	210,274
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	548	902
Available-for-sale Securities, 12 Months or Longer, Fair Value	150,188	14,956
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	259	218
Available-for-sale Securities, Fair Value, Total	262,145	225,230
Available-for-sale Securities, Unrealized Losses, Total	807	1,120
Mortgage Backed Securities [Member]
Held for Investment
Held-to-maturity Securities, Less than 12 Months, Fair Value	1
Held-to-maturity Securities, 12 Months or Longer, Fair Value	1
Held-to-maturity Securities, Fair Value, Total	2
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value	66	17,041
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	4	585
Available-for-sale Securities, 12 Months or Longer, Fair Value		26
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses		1
Available-for-sale Securities, Fair Value, Total	66	17,067
Available-for-sale Securities, Unrealized Losses, Total	4	586
States and Political Subdivisions [Member]
Held for Investment
Held-to-maturity Securities, 12 Months or Longer, Fair Value	1,328
Held-to-maturity Securities, 12 Months or Longer, Unrealized Losses	7
Held-to-maturity Securities, Fair Value, Total	1,328
Held-to-maturity Securities, Unrealized Losses, Total	7
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value	2,459	3,093
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	72	26
Available-for-sale Securities, 12 Months or Longer, Fair Value		977
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses		23
Available-for-sale Securities, Fair Value, Total	2,459	4,070
Available-for-sale Securities, Unrealized Losses, Total	72	49
U.S. Treasuries [Member]
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value	29,861	149,589
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	85	178
Available-for-sale Securities, Fair Value, Total	29,861	149,589
Available-for-sale Securities, Unrealized Losses, Total	85	178
U.S. Federal Agencies [Member]
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value	79,411	40,551
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	246	113
Available-for-sale Securities, 12 Months or Longer, Fair Value	150,188	13,653
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	259	62
Available-for-sale Securities, Fair Value, Total	229,599	54,204
Available-for-sale Securities, Unrealized Losses, Total	505	175
Other Securities [Member]
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value	160
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	141
Available-for-sale Securities, 12 Months or Longer, Fair Value		300
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses		132
Available-for-sale Securities, Fair Value, Total	160	300
Available-for-sale Securities, Unrealized Losses, Total	$141	$132

Loans_and_Allowance_for_Loan_L2

Loans and Allowance for Loan Losses - Schedule of Loans Outstanding by Category (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$3,860,831	$3,387,146
Loans held for sale (included above)	9,433	6,469
Percent	100.00%	100.00%
Taxable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	20,431	10,217
Percent	0.53%	0.30%
Tax-exempt [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	20,952	11,073
Percent	0.54%	0.33%
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	745,106	605,672
Percent	19.30%	17.88%
Oil & Gas Production And Equipment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	104,940	96,907
Percent	2.72%	2.86%
Agriculture [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	132,830	111,323
Percent	3.44%	3.29%
Construction [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	356,621	284,808
Percent	9.24%	8.41%
Farmland [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	149,507	132,512
Percent	3.87%	3.91%
One to Four Family Residences [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	775,795	703,903
Percent	20.09%	20.78%
Multifamily Residential Properties [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	66,766	60,080
Percent	1.73%	1.77%
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,191,477	1,097,484
Percent	30.86%	32.40%
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	267,179	250,588
Percent	6.92%	7.40%
Other (Not Classified Above) [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$29,227	$22,579
Percent	0.76%	0.67%

Loans_and_Allowance_for_Loan_L3

Loans and Allowance for Loan Losses - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	SecurityLoan
Receivables [Abstract]
Percentage of loans secured by real estate	65.00%
Interest income recognized	$1.20	$1.50	$1.30
Troubled debt restructuring principal deferral	1

Loans_and_Allowance_for_Loan_L4

Loans and Allowance for Loan Losses - Summary of Nonperforming and Restructured Assets (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Summary Of Nonperforming And Restructured Assets [Abstract]
Past due 90 days or more and still accruing	$1,135	$1,179
Nonaccrual	16,410	14,390
Restructured	16,515	17,624
Total nonperforming and restructured loans	34,060	33,193
Other real estate owned and repossessed assets	8,079	8,386
Total nonperforming and restructured assets	$42,139	$41,579
Nonperforming and restructured loans to total loans	0.88%	0.98%
Nonperforming and restructured assets to total assets	0.64%	0.69%

Loans_and_Allowance_for_Loan_L5

Loans and Allowance for Loan Losses - Summary of Amounts Included in Nonaccrual Loans Segregated by Class of Loans (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans, Total	$16,410	$14,390
Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans, Total	296	595
Non-residential Real Estate Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans, Total	5,126	6,270
Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans, Total	681	718
Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans, Total	1,796	1,521
Non-consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans, Total	1,556	1,192
Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans, Total	250	176
Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans, Total	1,659	1,407
Acquired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual loans, Total	$5,046	$2,511

Loans_and_Allowance_for_Loan_L6

Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans Segregated by Class of Loans (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	$11,270	$16,134
60-89 Days Past Due	3,964	2,904
90 Days and Greater	6,294	7,196
Total Past Due Loans	21,528	26,234
Current Loans	3,839,303	3,360,912
Total Loans	3,860,831	3,387,146
Accruing Loans 90 Days or More Past Due	1,135	1,179
Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	635	411
90 Days and Greater	269	316
Total Past Due Loans	904	727
Current Loans	482,731	454,305
Total Loans	483,635	455,032
Accruing Loans 90 Days or More Past Due	70	96
Non-residential Real Estate Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	377	5,391
60-89 Days Past Due	317	269
90 Days and Greater	825	1,543
Total Past Due Loans	1,519	7,203
Current Loans	952,484	856,179
Total Loans	954,003	863,382
Accruing Loans 90 Days or More Past Due		2
Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	2,010	2,000
60-89 Days Past Due	758	566
90 Days and Greater	544	789
Total Past Due Loans	3,312	3,355
Current Loans	304,267	262,625
Total Loans	307,579	265,980
Accruing Loans 90 Days or More Past Due	172	275
Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	1,820	2,159
60-89 Days Past Due	194	211
90 Days and Greater	1,488	1,272
Total Past Due Loans	3,502	3,642
Current Loans	633,586	564,231
Total Loans	637,088	567,873
Accruing Loans 90 Days or More Past Due	387	184
Non-consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	841	1,122
60-89 Days Past Due	71	118
90 Days and Greater	793	1,047
Total Past Due Loans	1,705	2,287
Current Loans	965,002	793,028
Total Loans	966,707	795,315
Accruing Loans 90 Days or More Past Due	24	125
Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	1,914	1,761
60-89 Days Past Due	711	667
90 Days and Greater	330	392
Total Past Due Loans	2,955	2,820
Current Loans	244,810	225,515
Total Loans	247,765	228,335
Accruing Loans 90 Days or More Past Due	215	279
Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	1,858	1,799
60-89 Days Past Due	916	763
90 Days and Greater	741	1,244
Total Past Due Loans	3,515	3,806
Current Loans	158,902	141,550
Total Loans	162,417	145,356
Acquired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59 Days Past Due	1,815	1,491
60-89 Days Past Due	997	310
90 Days and Greater	1,304	593
Total Past Due Loans	4,116	2,394
Current Loans	97,521	63,479
Total Loans	101,637	65,873
Accruing Loans 90 Days or More Past Due	$267	$218

Loans_and_Allowance_for_Loan_L7

Loans and Allowance for Loan Losses - Impaired Loans Segregated by Class of Loans (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	$42,843	$43,130
Recorded Investment with Allowance	36,357	38,326
Related Allowance	2,560	3,478
Average Recorded Investment	37,132	39,262
Non-residential Real Estate Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	521	877
Recorded Investment with Allowance	448	752
Related Allowance	15	28
Average Recorded Investment	453	881
Non-residential Real Estate Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	23,154	24,964
Recorded Investment with Allowance	21,164	23,351
Related Allowance	1,364	2,161
Average Recorded Investment	21,522	23,816
Residential Real Estate Permanent Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	1,095	1,253
Recorded Investment with Allowance	880	1,025
Related Allowance	85	58
Average Recorded Investment	1,042	1,170
Residential Real Estate All Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	2,480	2,214
Recorded Investment with Allowance	2,270	1,803
Related Allowance	299	361
Average Recorded Investment	2,273	1,857
Non-consumer Non-real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	1,895	1,801
Recorded Investment with Allowance	1,580	1,459
Related Allowance	431	388
Average Recorded Investment	1,646	1,553
Consumer Non-real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	664	628
Recorded Investment with Allowance	648	611
Related Allowance	138	139
Average Recorded Investment	602	455
Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	2,101	1,545
Recorded Investment with Allowance	1,659	1,464
Related Allowance	228	219
Average Recorded Investment	1,512	1,602
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	10,933	9,848
Recorded Investment with Allowance	7,708	7,861
Related Allowance		124
Average Recorded Investment	$8,082	$7,928

Loans_and_Allowance_for_Loan_L8

Loans and Allowance for Loan Losses - Internal Loan Grading by Class of Loans (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$3,860,831	$3,387,146
Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	483,635	455,032
Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	954,003	863,382
Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	307,579	265,980
Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	637,088	567,873
Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	966,707	795,315
Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	247,765	228,335
Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	162,417	145,356
Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	101,637	65,873
Grade 1 [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	3,258,055	2,898,156
Grade 1 [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	402,706	382,798
Grade 1 [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	795,209	711,081
Grade 1 [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	272,411	233,924
Grade 1 [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	529,555	475,421
Grade 1 [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	821,094	691,772
Grade 1 [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	233,424	214,153
Grade 1 [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	157,191	141,787
Grade 1 [Member] | Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	46,465	47,220
Grade 2 [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	507,064	423,378
Grade 2 [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	75,555	66,139
Grade 2 [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	133,542	125,617
Grade 2 [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	27,855	24,882
Grade 2 [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	99,214	82,571
Grade 2 [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	117,457	97,812
Grade 2 [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	12,229	11,819
Grade 2 [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	4,261	2,558
Grade 2 [Member] | Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	36,951	11,980
Grade 3 [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	78,999	51,005
Grade 3 [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	5,008	5,446
Grade 3 [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	20,126	20,309
Grade 3 [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	6,369	6,081
Grade 3 [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	6,146	8,238
Grade 3 [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	26,550	4,462
Grade 3 [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,548	1,931
Grade 3 [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	601	772
Grade 3 [Member] | Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	12,651	3,766
Grade 4 [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	16,158	14,606
Grade 4 [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	366	649
Grade 4 [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	5,126	6,375
Grade 4 [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	944	1,093
Grade 4 [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	2,173	1,643
Grade 4 [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,606	1,269
Grade 4 [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	564	431
Grade 4 [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	173	239
Grade 4 [Member] | Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	5,206	2,907
Grade 5 [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	555	1
Grade 5 [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans		1
Grade 5 [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	191
Grade 5 [Member] | Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$364

Loans_and_Allowance_for_Loan_L9

Loans and Allowance for Loan Losses - Activity in All by Class of Loans (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				$39,034				$38,725	$39,034	$38,725
Charge- offs									-2,619	-1,560
Recoveries									1,402	611
Net charge- offs									-1,217	-949
Provisions charged to operations	1,840	-3,115	3,129	1,218	454	-12	516	300	3,072	1,258	3,100
Balance at end of period	40,889				39,034				40,889	39,034	38,725
Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				4,827				5,104	4,827	5,104
Charge- offs									-42	-3
Recoveries									102	20
Net charge- offs									60	17
Provisions charged to operations									-481	-294
Balance at end of period	4,406				4,827				4,406	4,827
Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				11,026				9,865	11,026	9,865
Charge- offs									-29	-19
Recoveries									49	12
Net charge- offs									20	-7
Provisions charged to operations									-1,430	1,168
Balance at end of period	9,616				11,026				9,616	11,026
Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				2,825				2,781	2,825	2,781
Charge- offs									-207	-162
Recoveries									78	32
Net charge- offs									-129	-130
Provisions charged to operations									252	174
Balance at end of period	2,948				2,825				2,948	2,825
Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				6,708				7,034	6,708	7,034
Charge- offs									-171	-209
Recoveries									32	33
Net charge- offs									-139	-176
Provisions charged to operations									-300	-150
Balance at end of period	6,269				6,708				6,269	6,708
Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				8,977				9,385	8,977	9,385
Charge- offs									-564	-217
Recoveries									70	175
Net charge- offs									-494	-42
Provisions charged to operations									4,288	-366
Balance at end of period	12,771				8,977				12,771	8,977
Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				2,556				2,451	2,556	2,451
Charge- offs									-687	-597
Recoveries									203	225
Net charge- offs									-484	-372
Provisions charged to operations									332	477
Balance at end of period	2,404				2,556				2,404	2,556
Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				1,991				1,885	1,991	1,885
Charge- offs									-351	-300
Recoveries									149	75
Net charge- offs									-202	-225
Provisions charged to operations									570	331
Balance at end of period	2,359				1,991				2,359	1,991
Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of period				124				220	124	220
Charge- offs									-568	-53
Recoveries									719	39
Net charge- offs									151	-14
Provisions charged to operations									-159	-82
Balance at end of period	$116				$124				$116	$124

Recovered_Sheet2

Loans and Allowance for Loan Losses - Allowance for Loan Losses Outstanding by Impairment Methodology (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	$8,127	$5,469
Collectively evaluated for impairment	32,762	33,565
Non-residential Real Estate Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	202	231
Collectively evaluated for impairment	4,204	4,596
Non-residential Real Estate Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	1,518	2,449
Collectively evaluated for impairment	8,098	8,577
Residential Real Estate Permanent Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	407	243
Collectively evaluated for impairment	2,541	2,582
Residential Real Estate All Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	743	994
Collectively evaluated for impairment	5,526	5,714
Non-consumer Non-real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	4,671	966
Collectively evaluated for impairment	8,100	8,011
Consumer Non-real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	372	334
Collectively evaluated for impairment	2,032	2,222
Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	214	252
Collectively evaluated for impairment	2,145	1,739
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment	$116	$124

Recovered_Sheet3

Loans and Allowance for Loan Losses - Loans Outstanding by Impairment Methodology (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	$76,758	$58,244
Collectively evaluated for impairment	3,765,852	3,322,228
Loans acquired with deteriorated credit quality	18,221	6,674
Non-residential Real Estate Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	5,374	6,095
Collectively evaluated for impairment	478,261	448,937
Non-residential Real Estate Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	25,251	26,684
Collectively evaluated for impairment	928,752	836,698
Residential Real Estate Permanent Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	7,313	7,174
Collectively evaluated for impairment	300,266	258,806
Residential Real Estate All Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	8,319	9,881
Collectively evaluated for impairment	628,769	557,992
Non-consumer Non-real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	28,156	5,731
Collectively evaluated for impairment	938,551	789,584
Consumer Non-real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	2,112	2,362
Collectively evaluated for impairment	245,653	225,972
Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	233	317
Collectively evaluated for impairment	162,184	145,039
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment	83,416	59,200
Loans acquired with deteriorated credit quality	$18,221	$6,674

Recovered_Sheet4

Loans and Allowance for Loan Losses - ALLL for Impaired Loans with Specific Reserves (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Receivables [Abstract]
Allowance for loss on impaired loans	$1,559	$1,578	$2,170
Recorded balance of impaired loans	3,673	5,283	6,185
Average recorded investment	$4,478	$5,734	$8,416

Recovered_Sheet5

Loans and Allowance for Loan Losses - Transfers from Loans to Other Real Estate Owned and Repossessed Assets (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable Allowance For Credit Loss Additional Information Transfer From Loans To Other Real Estate Owned And Repossessed Assets [Abstract]
Other real estate owned	$3,573	$1,710	$2,543
Repossessed assets	1,209	1,171	1,034
Total	$4,782	$2,881	$3,577

Recovered_Sheet6

Loans and Allowance for Loan Losses - Related Party Loans (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Receivables [Abstract]
Balance Beginning of the Period	$27,134	$29,030	$25,264
Additions	22,521	11,979	24,706
Collections/ Terminations	-24,636	-13,875	-20,940
Balance End of the Period	$25,019	$27,134	$29,030

Premises_and_Equipment_Net_Sum

Premises and Equipment, Net - Summary of premises and equipment by classification (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property Plant And Equipment [Line Items]
Accumulated depreciation	-100,301	-93,618
Premises and equipment, net	121,341	117,862
Building [Member]
Property Plant And Equipment [Line Items]
Premises and Equipment, gross	127,250	120,784
Building [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Lives	10 years	10 years
Building [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Lives	40 years	40 years
Furniture Fixtures And Equipment [Member]
Property Plant And Equipment [Line Items]
Premises and Equipment, gross	64,734	61,641
Furniture Fixtures And Equipment [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Lives	3 years	3 years
Furniture Fixtures And Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Lives	15 years	15 years
Land [Member]
Property Plant And Equipment [Line Items]
Premises and Equipment, gross	29,658	29,055

Intangible_Assets_and_Goodwill1

Intangible Assets and Goodwill - Summary of Intangible Assets (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$19,540	$17,380
Accumulated Amortization	-8,905	-7,107
Net Carrying Amount	10,635	10,273
Core Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	13,198	10,963
Accumulated Amortization	-6,013	-4,620
Net Carrying Amount	7,185	6,343
Customer Relationship Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,699	5,699
Accumulated Amortization	-2,699	-2,337
Net Carrying Amount	3,000	3,362
Mortgage Servicing Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	643	718
Accumulated Amortization	-193	-150
Net Carrying Amount	$450	$568

Intangible_Assets_and_Goodwill2

Intangible Assets and Goodwill - Estimated Amortization of Intangible Assets (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Goodwill And Intangible Assets Disclosure [Abstract]
2015	$1,855
2016	1,631
2017	1,540
2018	1,531
2019	$1,524

Intangible_Assets_and_Goodwill3

Intangible Assets and Goodwill - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Weighted-average life	6 years 6 months
Customer Related Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-average life	8 years 9 months 18 days
Core Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-average life	5 years 10 months 24 days
Mortgage Servicing Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-average life	2 years 3 months 18 days

Intangible_Assets_and_Goodwill4

Intangible Assets and Goodwill - Summary of Goodwill by Business Segment (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Goodwill [Line Items]
Balance at beginning of period	$44,545
Acquisitions	417
Balance at end of period	44,962
Metropolitan Banks [Member]
Goodwill [Line Items]
Balance at beginning of period		8,078
Balance at end of period	8,078	8,078
Community Banks [Member]
Goodwill [Line Items]
Balance at beginning of period	30,553
Acquisitions	417
Balance at end of period	30,970
Other Financial Services [Member]
Goodwill [Line Items]
Balance at beginning of period		5,464
Balance at end of period	5,464	5,464
Executive, Operations & Support [Member]
Goodwill [Line Items]
Balance at beginning of period		450
Balance at end of period	$450	$450

Time_Deposits_Summary_of_Sched

Time Deposits - Summary of Scheduled Maturities of all Time Deposits (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Investments Schedule [Abstract]
2015	$478,610
2016	121,816
2017	51,816
2018	47,463
2019	51,410
Thereafter	164
Total	$751,279

Time_Deposits_Summary_of_Large

Time Deposits - Summary of Large time Deposits for Periods Presented (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments Schedule [Abstract]
Time deposits of $100,000 or more	$347,563	$355,054

ShortTerm_Borrowings_Summary_o

Short-Term Borrowings - Summary of Short-Term Borrowings (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Short-term Debt [Line Items]
Total	$3,982	$4,590
Weighted average interest rate	0.18%	0.13%
Federal Funds Purchased [Member]
Short-term Debt [Line Items]
Total	1,000	700
Repurchase Agreements [Member]
Short-term Debt [Line Items]
Total	$2,982	$3,890
Short-term Debt [Member]
Short-term Debt [Line Items]
End of period interest rate	0.14%	0.15%

LongTerm_Borrowings_Additional

Long-Term Borrowings - Additional Information (Detail) (USD $)	Dec. 31, 2014
Long Term Debt And Other Financing Arrangement [Line Items]
Maximum drawing capacity	$22,700,000
FHLB stock holdings	551,900
Advances outstanding	0
Residential Mortgage [Member]
Long Term Debt And Other Financing Arrangement [Line Items]
Line of credit assets pledged as collateral	$619,600,000

Junior_Subordinated_Debentures1

Junior Subordinated Debentures - Additional Information (Detail) (USD $)	12 Months Ended	1 Months Ended
	Dec. 31, 2014	Mar. 31, 2004	Feb. 29, 2004	Dec. 31, 2013
Junior Subordinated Debentures [Line Items]
Junior subordinated notes assumed	26,804,000			$26,804,000
Bancfirst Capital Trust Two [Member]
Junior Subordinated Debentures [Line Items]
Debt instrument maturity date	31-Mar-34
Bancfirst Capital Trust Two [Member] | Subordinated Debentures Subject to Mandatory Redemption [Member]
Junior Subordinated Debentures [Line Items]
Interest rate of securities	7.20%
Frequency of payment	Payable January 15, April 15, July 15 and October 15 of each year
Junior subordinated notes assumed	26,800,000
Bancfirst Capital Trust Two [Member] | Cumulative Preferred Stock [Member]
Junior Subordinated Debentures [Line Items]
Issue of securities		$1,000,000	$25,000,000
Cumulative trust preferred securities interest rate	7.20%

Income_Taxes_Components_of_the

Income Taxes - Components of the Company's Income Tax Expense (Benefit) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current taxes:
Federal	$28,258	$23,326	$24,928
State	2,709	3,682	2,865
Deferred taxes	-3,683	-483	-689
Total income taxes	$27,284	$26,525	$27,104

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes [Line Items]
Securities transactions income tax expense	$574,000	$147,000	$1,720,000
Recognition of interest and penalties related to unrecognized tax benefits	$0	$0	$0
Earliest Tax Year [Member]
Income Taxes [Line Items]
Year under examination	2012
Latest Tax Year [Member]
Income Taxes [Line Items]
Year under examination	2014

Income_Taxes_Reconciliation_of

Income Taxes - Reconciliation of Tax Expense at the Federal Statutory Tax Rate (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Tax expense at the federal statutory tax rate	$31,910	$28,295	$27,651
Increase (decrease) in tax expense from:
Tax-exempt income, net	-571	-621	-783
Modified endowment life contracts	-755	-812	-870
State tax expense, net of federal tax benefit	1,469	2,303	2,374
Federal tax credits	-6,479	-4,132	-2,455
Other, net	1,710	1,492	1,187
Total income taxes	$27,284	$26,525	$27,104

Income_Taxes_Summary_of_Net_De

Income Taxes - Summary of Net Deferred Tax Asset Reported in Other Assets (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Income Tax Disclosure [Abstract]
Provision for loan losses	$15,814	$13,662
Write-downs of other real estate owned	1,297	962
Deferred compensation	2,652	2,237
Stock-based compensation	3,190	2,934
Investments in partnership interests	1,966	1,170
Other	306	1,479
Gross deferred tax assets	25,225	22,444
Unrealized net gains on securities	-2,644	-2,103
Premium on securities of banks acquired	-715	-800
Intangibles	-2,917	-2,561
Basis difference related to tax credits	-1,977	-1,620
Depreciation	-5,504	-5,975
Leveraged lease	-1,964	-2,282
Other	-89	-257
Gross deferred tax liabilities	-15,810	-15,598
Net deferred tax asset	$9,415	$6,846

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014	31-May-13	31-May-14
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of options granted for non-employee director	10,000
Deferred board fees percentage for stock units accumulation	100.00%
Nonqualified Incentive Stock Option Plan [Member] | Stock Option [ Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares to be issued under incentive stock option plan		3,000,000
Shares for future grants	114,985
Stock option plan termination date	31-Dec-19
Option exercisable rate	25.00%
Option exercisable period	4 years
Options expire period	15 years
Share based compensation options exercisable period	2021
Vesting period in years, start	4 years
Options vest and exercisable Description	The options vest and are exercisable beginning four years from the date of grant at the rate of 25% per year for four years. Options expire at the end of fifteen years from the date of grant
Vesting period in years	7 years
Nonqualified Incentive Stock Option Plan [Member] | Stock Option [ Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock price percentage to fair value at grant date	100.00%
Non-Employee Directors Stock Option Plan [ Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares to be issued under incentive stock option plan			230,000
Shares for future grants	20,000
Option exercisable rate	25.00%
Option exercisable period	1 year
Options expire period	15 years
Share based compensation options exercisable period	2018
Options vest and exercisable Description	The options vest and are exercisable beginning one year from the date of grant at the rate of 25% per year for four years
Vesting period in years	4 years
Non-Employee Directors Stock Option Plan [ Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock price percentage to fair value at grant date	100.00%
Banc First Deferred Stock Compensation Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized for issuance under deferred compensation plan			91,110

StockBased_Compensation_Summar

Stock-Based Compensation - Summary of Activity Under Stock Option Plan (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding at beginning period - Options	1,158,317	1,216,981
Options granted	44,000	115,000
Options exercised	-169,535	-153,664
Options canceled, forfeited or expired - Options	-3,125	-20,000
Outstanding at ending period - Options	1,029,657	1,158,317
Exercisable at ending period - Options	492,557	561,167
Outstanding at beginning period - Wgtd. Avg. Exercise Price	$34.45	$31.98
Options granted - Wgtd. Avg. Exercise Price	$61.78	$49.13
Options exercised - Wgtd. Avg. Exercise Price	$28.73	$25.03
Options cancelled, forfeited, or expired - Wgtd. Avg. Exercise Price	$36.73	$40.83
Outstanding at ending period - Wgtd. Avg. Exercise Price	$36.55	$34.45
Exercisable at ending period - Wgtd. Avg. Exercise Price	$29.84	$27.95
Outstanding at ending period - Wgtd. Avg. Remaining Contractual Term, years	8 years 7 months 2 days	8 years 10 months 2 days
Exercisable at ending period - Wgtd. Avg. Remaining Contractual Term, years	5 years 1 month 24 days	6 years 8 months 12 days
Outstanding at ending period - Aggregate Intrinsic Value	$27,638	$25,034
Exercisable at ending period - Aggregate Intrinsic Value	$16,525	$15,774

StockBased_Compensation_Option

Stock-Based Compensation - Options Granted and Options Exercised Under Stock Option Plan (Detail) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share Based Compensation Arrangement By Share Based Payment Award Options Additional Disclosures [Abstract]
Weighted average grant-date fair value per share of options granted	$12.27	$10.88	$8.82
Total intrinsic value of options exercised	$5,597	$3,723	$3,297
Cash received from options exercised	4,870	3,846	2,227
Tax benefit realized from options exercised	$2,165	$1,440	$1,275

StockBased_Compensation_StockB

Stock-Based Compensation - Stock-Based Employee Compensation Expense (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Labor And Related Expense [Abstract]
Stock-based compensation expense	$1,676	$1,360	$1,530
Tax benefit	648	526	592
Stock-based compensation expense, net of tax	$1,028	$834	$938

StockBased_Compensation_Remain

Stock-Based Compensation - Remaining Fair Value of Stock Options (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Remaining Fair Value Of Stock Options [Abstract]
Fair value of stock options	$4,215

StockBased_Compensation_Assump

Stock-Based Compensation - Assumptions Used for Computing Stock-Based Compensation Expense (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	2.00%	2.00%	2.00%
Expected term	10 years	10 years	10 years
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	2.10%	1.95%	1.74%
Stock price volatility	18.03%	18.35%	21.71%
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	2.54%	3.15%	1.95%
Stock price volatility	18.98%	20.21%	38.75%

Stock_Based_Compensation_Summa

Stock - Based Compensation - Summary of Accumulated Stock Units (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Accumulated stock units	60,859	56,380
Average price	$37.41	$35.31

Retirement_Plans_Additional_In

Retirement Plans - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014
	Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Number of retirement plans	2
Maximum [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Maximum legal limit of employer contribution to plan	3.00%

Retirement_Plans_Aggregate_Amo

Retirement Plans - Aggregate Amounts of Contributions to the 401(k) and ESOP Plans (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Contribution Plan Disclosure [Line Items]
Total contributions	$3,798	$3,558	$3,393
401(k) contributions [Member]
Defined Contribution Plan Disclosure [Line Items]
Aggregate amounts of contributions	1,870	1,738	1,690
ESOP contributions [Member]
Defined Contribution Plan Disclosure [Line Items]
Aggregate amounts of contributions	$1,928	$1,820	$1,703

Stockholders_Equity_Summary_of

Stockholders' Equity - Summary of Authorized Outstanding Preferred and Common Stock (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Class of Stock [Line Items]
Common stock, shares authorized	20,000,000	20,000,000
Common stock, shares outstanding	15,504,513	15,333,622	15,242,308
Common stock, par value	$1	$1
Common stock dividend payment terms	As declared
Common stock, voting rights	Voting
Senior Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares outstanding	0
Preferred stock, par value	$1	$1
Preferred stock, dividend payment terms	As declared
Preferred stock, voting rights	Voting
Cumulative Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized	900,000	900,000
Preferred stock, shares outstanding	0
Preferred stock, par value	$5	$5
Preferred stock, dividend payment terms	As declared
Preferred stock, voting rights	Non-voting

Stockholders_Equity_Additional

Stockholders' Equity - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Jan. 01, 2015	Dec. 31, 2013
Stockholders Equity [Line Items]
Minimum Tier 1 Ratio to be well capitalized	6.00%
Minimum combined Tier 1 and Tier 2 Ratio to be well capitalized	10.00%
Minimum Leverage Ratio to be well capitalized	5.00%
2015 [Member]
Stockholders Equity [Line Items]
Implementation of the deductions and other adjustments to CET1	4 years
Implementation of the deductions and other adjustments to CET1, Percentage	40.00%
After 2015 [Member]
Stockholders Equity [Line Items]
Implementation of the deductions and other adjustments to CET1, Additional Percentage	20.00%
2016 [Member]
Stockholders Equity [Line Items]
Implementation of the capital conservation buffer, Percentage	0.63%
Capital conservation buffer implementation phase-out period	4 years
2019 [Member]
Stockholders Equity [Line Items]
Capital Conservation Buffer Maximum Level	2.50%
Maximum [Member]
Stockholders Equity [Line Items]
Quantitative limit for trust preferred securities to be included in tier 1 capital	10,000,000,000
Minimum [Member] | 2015 [Member]
Stockholders Equity [Line Items]
Minimum ratio of CET1 to risk-weighted assets	4.50%
Tier 1 capital to risk-weighted assets	6.00%
Total capital to risk weighted assets	8.00%
Minimum leverage ratio	4.00%
Subsequent Event [Member]
Stockholders Equity [Line Items]
Available equity of BancFirst for dividend payments to the company		$73,400,000
Senior Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0
Cumulative Preferred Stock [Member]
Stockholders Equity [Line Items]
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0
Dividend payable at redemption, per share	5
Cumulative preferred stock dividend rate	10.00%

Stockholders_Equity_Summary_of1

Stockholders' Equity - Summary of Shares Repurchased Under Stock Purchase Program (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
Summary Of Shares Repurchased Under Stock Purchase Program [Abstract]
Number of shares repurchased	40,241	6,787
Average price of shares repurchased	$40.88	$37.70
Shares remaining to be repurchased	194,723	234,964	194,723

Stockholders_Equity_Required_C

Stockholders' Equity - Required Capital Amounts and Company's Respective Ratios (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	6.00%
Tier 1 Capital Required To Be Well Capitalized To Average assets Ratio	5.00%
Parent Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital To Risk Weighted Assets Actual Amount	$616,862	$563,873
Total Capital To Risk Weighted Assets Actual Ratio	14.75%	14.85%
Capital Required For Capital Adequacy Amount	334,531	303,700
Capital Required For Capital Adequacy to Risk Weighted Assets Ratio	8.00%	8.00%
Tier 1 Risk Based Capital Amount	575,973	524,839
Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	13.77%	13.83%
Tier 1 Risk Based Capital Required For Capital Adequacy Amount	167,265	151,850
Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	4.00%	4.00%
Tier 1 Capital Amount	575,973	524,839
Tier 1 Capital To Average Assets Ratio	8.83%	8.77%
Tier 1 Capital Required For Capital Adequacy Amount	197,249	181,174
Tier 1 Capital Required For Capital Adequacy To Average Assets Ratio	3.00%	3.00%
BancFirst [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital To Risk Weighted Assets Actual Amount	571,495	529,200
Total Capital To Risk Weighted Assets Actual Ratio	13.68%	13.96%
Capital Required For Capital Adequacy Amount	334,092	303,190
Capital Required For Capital Adequacy to Risk Weighted Assets Ratio	8.00%	8.00%
Capital Required To Be Well Capitalized Amount	417,615	378,988
Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	10.00%	10.00%
Tier 1 Risk Based Capital Amount	530,606	490,166
Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	12.71%	12.93%
Tier 1 Risk Based Capital Required For Capital Adequacy Amount	167,046	151,595
Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	4.00%	4.00%
Tier 1 Risk Based Capital Required To Be well Capitalized Amount	250,569	227,393
Tier 1 Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	6.00%	6.00%
Tier 1 Capital Amount	530,606	490,166
Tier 1 Capital To Average Assets Ratio	8.15%	8.20%
Tier 1 Capital Required For Capital Adequacy Amount	196,716	180,606
Tier 1 Capital Required For Capital Adequacy To Average Assets Ratio	3.00%	3.00%
Tier 1 Capital Required To Be Well Capitalized Amount	$327,859	$301,011
Tier 1 Capital Required To Be Well Capitalized To Average assets Ratio	5.00%	5.00%

Net_Income_Per_Common_Share_Ba

Net Income Per Common Share - Basic and Diluted Net Income Per Common Share (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share Reconciliation [Abstract]
Income available to common stockholders	$15,749	$18,793	$14,688	$14,657	$13,861	$14,491	$12,593	$13,372	$63,887	$54,317	$51,900
Income available to common stockholders plus assumed exercises of stock options									$63,887	$54,317	$51,900
Income available to common stockholders - Shares									15,430,773	15,268,843	15,172,457
Effect of stock options - Shares									363,630	279,979	271,188
Income available to common stockholders plus assumed exercises of stock options - Shares									15,794,403	15,548,822	15,443,645
Income available to common stockholders - Per Share Amount	$1.02	$1.22	$0.94	$0.96	$0.91	$0.94	$0.83	$0.88	$4.14	$3.56	$3.42
Income available to common stockholders plus assumed exercises of stock options - Per Share Amount	$0.99	$1.19	$0.92	$0.94	$0.88	$0.93	$0.82	$0.86	$4.04	$3.49	$3.36

Net_Income_Per_Common_Share_Av

Net Income Per Common Share - Average Exercise Prices of Options Excluded from Computation of Diluted Net Income Per Common Share (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Abstract]
Shares	69,405	118,603	604,429
Average Exercise Price	$55.87	$42.79	$38.69

Condensed_Parent_Company_Finan2

Condensed Parent Company Financial Statements - Summary of Balance Sheet of Parent Company (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
ASSETS
Cash	$203,545	$196,547
Securities	524,783	527,627
Goodwill	44,962	44,545
Total assets	6,574,972	6,038,974	6,022,250
LIABILITIES AND STOCKHOLDERS’ EQUITY
Other liabilities	30,168	24,126
Junior subordinated debentures	26,804	26,804
Stockholders’ equity	609,314	556,997	519,567
Total liabilities and stockholders’ equity	6,574,972	6,038,974
Parent Company [Member]
ASSETS
Cash	36,700	27,592
Securities	103	115
Investments in subsidiaries	598,413	555,761
Goodwill	450	450
Dividends receivable	6,434	5,927
Other assets	983	913
Total assets	643,083	590,758
LIABILITIES AND STOCKHOLDERS’ EQUITY
Other liabilities	6,965	6,957
Junior subordinated debentures	26,804	26,804
Stockholders’ equity	609,314	556,997
Total liabilities and stockholders’ equity	$643,083	$590,758

Condensed_Parent_Company_Finan3

Condensed Parent Company Financial Statements- Summary of Income Statement of Parent Company (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
OPERATING INCOME
Interest on interest-bearing deposits									$4,391	$4,064	$4,201
OPERATING EXPENSE
Other									36,407	32,823	32,832
Income before taxes									91,171	80,842	79,004
Allocated income tax benefit									-27,284	-26,525	-27,104
Amortization of stock-based compensation arrangements of subsidiaries									-1,676	-1,360	-1,530
Net income	15,749	18,793	14,688	14,657	13,861	14,491	12,593	13,372	63,887	54,317	51,900
Parent Company [Member]
OPERATING INCOME
Dividends from subsidiaries									24,851	22,612	20,784
Interest on interest-bearing deposits									62	47	57
Other									14	92
Total operating income									24,927	22,751	20,841
OPERATING EXPENSE
Interest									1,965	1,965	2,134
Other									667	661	942
Total operating expense									2,632	2,626	3,076
Income before taxes									22,295	20,125	17,765
Allocated income tax benefit									472	978	1,371
Income before equity in undistributed earnings of subsidiaries									22,767	21,103	19,136
Equity in undistributed earnings of subsidiaries									42,196	34,351	34,281
Amortization of stock-based compensation arrangements of subsidiaries									-1,076	-1,137	-1,517
Net income									$63,887	$54,317	$51,900

Condensed_Parent_Company_Finan4

Condensed Parent Company Financial Statements - Summary of Cash Flow of Parent Company (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$63,887	$54,317	$51,900
Adjustments to reconcile to net cash provided by operating activities:
Amortization of stock-based compensation arrangements	1,676	1,360	1,530
Other, net	5,719	5,512	-3,148
Net cash provided by operating activities	76,922	78,090	60,296
INVESTING ACTIVITIES
Net cash and due from banks provided by acquisitions	174,283
Net cash used in investing activities	-183,376	-131,078	-185,890
FINANCING ACTIVITIES
Issuance of common stock	6,532	5,200	3,540
Common stock acquired		-2,710	-256
Cash dividends paid	-19,543	-13,583	-21,090
Redemption of junior subordinated debentures			-9,279
Net cash provided by (used in) financing activities	162,814	-34,625	363,009
Net increase /(decrease) in cash, due from banks and interest-bearing deposits	56,360	-87,613	237,415
Cash, due from banks and interest-bearing deposits at the beginning of the period	1,857,535	1,945,148	1,707,733
Cash, due from banks and interest-bearing deposits at the end of the period	1,913,895	1,857,535	1,945,148
SUPPLEMENTAL DISCLOSURE
Cash paid during the year for interest	13,135	14,142	18,312
Cash received during the period for income taxes, net	26,178	20,946	25,975
Parent Company [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	63,887	54,317	51,900
Adjustments to reconcile to net cash provided by operating activities:
Equity in undistributed earnings of subsidiaries	-42,196	-34,351	-34,281
Amortization of stock-based compensation arrangements	1,076	1,137	1,517
Other, net	-656	-2,116	2,944
Net cash provided by operating activities	22,111	18,987	22,080
INVESTING ACTIVITIES
Net cash and due from banks provided by acquisitions			19,866
Sales and maturities of held for investment and available for sale securities	8	63
Net cash used in investing activities	8	63	19,866
FINANCING ACTIVITIES
Issuance of common stock	6,532	5,200	3,540
Common stock acquired		-2,710	-256
Cash dividends paid	-19,543	-13,583	-21,090
Redemption of junior subordinated debentures			-9,279
Net cash provided by (used in) financing activities	-13,011	-11,093	-27,085
Net increase /(decrease) in cash, due from banks and interest-bearing deposits	9,108	7,957	14,861
Cash, due from banks and interest-bearing deposits at the beginning of the period	27,592	19,635	4,774
Cash, due from banks and interest-bearing deposits at the end of the period	36,700	27,592	19,635
SUPPLEMENTAL DISCLOSURE
Cash paid during the year for interest	1,965	1,965	2,128
Cash received during the period for income taxes, net	$1,822	$4,449	$1,884

Commitments_and_Contingent_Lia2

Commitments and Contingent Liabilities - Summary of Financial Instruments with Off-Balance-Sheet Risks (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Commitments And Contingencies Disclosure [Abstract]
Loan commitments	$937,221	$945,270
Stand-by letters of credit	$63,734	$61,262

Commitments_and_Contingent_Lia3

Commitments and Contingent Liabilities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014
	Buildings
	ParkingSpaces
	ATM
	Land_Parcel
	StorageSpaces
Commitments And Contingencies Disclosure [Abstract]
Number of buildings	13
Parcels of land	2
Number of ATM locations	19
Number of storage facilities	2
Number of parking lots	3
Lease expiry period maximum	2064

Commitments_and_Contingent_Lia4

Commitments and Contingent Liabilities - Summary of Future Minimum Rental Payments Under Lease (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Operating Leases Future Minimum Payments Due [Abstract]
2015	$1,060
2016	981
2017	699
2018	186
2019	128
Later years	624
Total	$3,678

Commitments_and_Contingent_Lia5

Commitments and Contingent Liabilities - Summary of Rental Expense (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leases Rent Expense [Abstract]
Rent expense on all property and equipment rented	$1,255	$1,175	$1,159

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument Fair Value Disclosure [Abstract]
Days from origination after which mortgage loan are sold	30 days
Transfer of securities between levels of fair value hierarchy	$0	$0
Amount of non-financial assets (liabilities)	0	0
Non-financial assets or liabilities for which no impairment was provided	$0	$0

Fair_Value_Measurements_Fair_V

Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	$516,190	$515,641
Derivative assets	6,124	2,211
Derivative liabilities	4,756	1,029
Loans held for sale	9,433	6,469
Mortgage servicing intangibles	450	568
U.S. Treasuries [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	248,993	29,861
U.S. Federal Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	172,449	387,285
Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	26,457	32,678
States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	53,373	50,334
Other Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	14,918	15,483
Level 1 Inputs [Member] | U.S. Treasuries [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	248,993	29,861
Level 2 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	6,124	2,211
Derivative liabilities	4,756	1,029
Loans held for sale	9,433	6,469
Level 2 Inputs [Member] | U.S. Federal Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	172,449	387,285
Level 2 Inputs [Member] | Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	9,425	13,262
Level 2 Inputs [Member] | States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	53,373	50,334
Level 2 Inputs [Member] | Other Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	3,491	3,465
Level 3 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing intangibles	450	568
Level 3 Inputs [Member] | Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	17,032	19,416
Level 3 Inputs [Member] | Other Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	$11,427	$12,018

Fair_Value_Measurements_Change

Fair Value Measurements - Changes in Level 3 Assets Measured at Estimated Fair Value on Recurring Basis (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation Calculation Roll Forward
Balance at the beginning of the year	$32,002	$10,779
Purchases, issuances and settlements	-1,314	20,499
Sales	-3,433	-251
Gains included in earnings	1,469	234
Total unrealized gains/(losses)	185	741
Balance at the end of the year	$28,909	$32,002

Fair_Value_Measurements_Assets

Fair Value Measurements - Assets Measured at Fair Value on Nonrecurring Basis (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Impaired Loans (Less Specific Allowance) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	$33,797	$34,848
Foreclosed Assets [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	220	237
Gains (Losses)	-18	-35
Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	7,859	8,149
Gains (Losses)	-304	-170
Level 3 Inputs [Member] | Impaired Loans (Less Specific Allowance) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	33,797	34,848
Level 3 Inputs [Member] | Foreclosed Assets [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	220	237
Level 3 Inputs [Member] | Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	$7,859	$8,149

Fair_Value_Measurements_Estima

Fair Value Measurements - Estimated Fair Values of Company's Financial Instruments (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
FINANCIAL ASSETS
Securities held for investment	$8,593	$11,986
Loans, net	3,819,942	3,348,112
FINANCIAL LIABILITIES
Deposits	5,904,704	5,419,519
Short-term borrowings	3,982	4,590
Long-term borrowings		6,938
Junior subordinated debentures	26,804	26,804
Carrying Amount [Member] | Level 2 Inputs [Member]
FINANCIAL ASSETS
Cash and cash equivalents	1,913,895	1,857,535
Securities held for investment	8,593	11,986
FINANCIAL LIABILITIES
Deposits	5,904,704	5,419,519
Short-term borrowings	3,982	4,590
Long-term borrowings		6,938
Junior subordinated debentures	26,804	26,804
Carrying Amount [Member] | Level 3 Inputs [Member]
FINANCIAL ASSETS
Loans, net	3,819,942	3,348,112
Fair Value [Member]
OFF-BALANCE SHEET FINANCIAL INSTRUMENTS
Loan commitments	1,640	1,654
Letters of credit	478	459
Fair Value [Member] | Level 2 Inputs [Member]
FINANCIAL ASSETS
Cash and cash equivalents	1,913,895	1,857,535
Securities held for investment	8,671	12,094
FINANCIAL LIABILITIES
Deposits	5,945,502	5,451,114
Short-term borrowings	3,982	4,590
Long-term borrowings		6,908
Junior subordinated debentures	31,200	29,259
Fair Value [Member] | Level 3 Inputs [Member]
FINANCIAL ASSETS
Loans, net	$3,857,224	$3,364,940

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Notional Amounts and Estimated Fair Values of Outstanding Derivative Positions (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Derivative assets, Estimated Fair Value	$6,124	$2,211
Derivative liabilities, Estimated Fair Value	-4,756	-1,029
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative assets, Estimated Fair Value	6,124	2,211
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities, Estimated Fair Value	-4,756	-1,029
Oil [Member]
Derivatives, Fair Value [Line Items]
Notional Units	Barrels
Derivative assets, Notional Amount	312	335
Derivative assets, Estimated Fair Value	4,629	827
Derivative liabilities, Notional Amount	-312	-335
Derivative liabilities, Estimated Fair Value	-4,271	-378
Natural Gas [Member]
Derivatives, Fair Value [Line Items]
Notional Units	MMBTUs
Derivative assets, Notional Amount	2,010	5,128
Derivative assets, Estimated Fair Value	1,495	1,384
Derivative liabilities, Notional Amount	-2,010	-5,128
Derivative liabilities, Estimated Fair Value	($485)	($651)

Derivative_Financial_Instrumen3

Derivative Financial Instruments - Recognized Derivative Income Included in Other Noninterest Income (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative Gain Loss On Derivative Net [Abstract]
Derivative income	$500	$521	$599

Derivative_Financial_Instrumen4

Derivative Financial Instruments - Summary of Company's Net Credit Exposure Relating to Oil and Gas Swaps and Options with Bank Counterparties (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Credit Risk Derivatives At Fair Value Net [Abstract]
Credit exposure	$4,028	$9

Segment_Information_Additional

Segment Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014
	Business_Unit
Segment Reporting [Abstract]
Number of principal business units	4

Segment_Information_Results_of

Segment Information - Results of Operations and Selected Financial Information (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Net interest income (expense)	$47,319	$46,514	$45,489	$42,029	$41,921	$40,712	$40,630	$40,256	$181,351	$163,519	$164,815
Provision for loan losses	1,840	-3,115	3,129	1,218	454	-12	516	300	3,072	1,258	3,100
Noninterest income	24,302	24,938	23,611	23,562	22,235	23,652	21,733	22,535	96,413	90,155	87,717
Depreciation and amortization									11,349	11,077	10,840
Other expenses									172,172	160,497	159,588
Income before taxes									91,171	80,842	79,004
Total assets	6,574,972				6,038,974				6,574,972	6,038,974	6,022,250
Capital expenditures									11,490	13,896	13,438
Operating Segments [Member] | Metropolitan Banks [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)									59,923	56,346	54,062
Provision for loan losses									3,077	-154	1,202
Noninterest income									13,752	12,881	11,222
Depreciation and amortization									2,216	2,178	1,956
Other expenses									32,300	31,396	29,511
Income before taxes									36,082	35,807	32,615
Total assets	2,298,828				2,079,444				2,298,828	2,079,444	1,996,539
Capital expenditures									1,948	5,534	4,099
Operating Segments [Member] | Community Banks [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)									116,935	102,705	105,966
Provision for loan losses									-488	1,205	1,607
Noninterest income									51,415	48,418	43,809
Depreciation and amortization									7,277	7,011	6,898
Other expenses									89,888	84,011	80,535
Income before taxes									71,673	58,896	60,735
Total assets	4,113,783				3,764,429				4,113,783	3,764,429	3,801,653
Capital expenditures									7,972	6,445	8,045
Operating Segments [Member] | Other Financial Services [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)									6,155	6,239	7,055
Provision for loan losses									481	121	182
Noninterest income									28,079	25,659	29,624
Depreciation and amortization									522	521	485
Other expenses									22,304	21,604	22,056
Income before taxes									10,927	9,652	13,956
Total assets	145,814				103,656				145,814	103,656	186,473
Capital expenditures									121	219	398
Operating Segments [Member] | Executive, Operations & Support [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)									-1,662	-1,771	-2,268
Provision for loan losses									2	86	109
Noninterest income									69,442	59,298	56,848
Depreciation and amortization									1,334	1,367	1,501
Other expenses									27,998	23,818	27,783
Income before taxes									38,446	32,256	25,187
Total assets	679,194				703,294				679,194	703,294	602,342
Capital expenditures									1,449	1,698	896
Eliminations [Member]
Segment Reporting Information [Line Items]
Noninterest income									-66,275	-56,101	-53,786
Other expenses									-318	-332	-297
Income before taxes									-65,957	-55,769	-53,489
Total assets	($662,647)				($611,849)				($662,647)	($611,849)	($564,757)

Selected_Quarterly_Financial_D2

Selected Quarterly Financial Data (Unaudited) - Summary of the Unaudited Quarterly Results of Operations (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Net interest income	$47,319	$46,514	$45,489	$42,029	$41,921	$40,712	$40,630	$40,256	$181,351	$163,519	$164,815
Provision for loan losses	1,840	-3,115	3,129	1,218	454	-12	516	300	3,072	1,258	3,100
Securities transactions	822	284	85	450	79	90	129	122	1,641	420	4,915
Noninterest income	24,302	24,938	23,611	23,562	22,235	23,652	21,733	22,535	96,413	90,155	87,717
Noninterest expense	46,886	46,942	45,857	43,836	43,854	43,321	42,455	41,944	183,521	171,574	170,428
Net income	$15,749	$18,793	$14,688	$14,657	$13,861	$14,491	$12,593	$13,372	$63,887	$54,317	$51,900
Net income per common share:
Basic	$1.02	$1.22	$0.94	$0.96	$0.91	$0.94	$0.83	$0.88	$4.14	$3.56	$3.42
Diluted	$0.99	$1.19	$0.92	$0.94	$0.88	$0.93	$0.82	$0.86	$4.04	$3.49	$3.36