BancFirst (BANF) 10-K 26 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Jan. 31, 2021	Jun. 30, 2020
Document And Entity Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	BANCFIRST CORPORATION
Entity Central Index Key	0000760498
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity File Number	0-14384
Entity Incorporation, State or Country Code	OK
Entity Tax Identification Number	73-1221379
Entity Address, Address Line One	101 North Broadway
Entity Address, City or Town	Oklahoma City
Entity Address, State or Province	OK
Entity Address, Postal Zip Code	73102
City Area Code	405
Local Phone Number	270-1086
Document Annual Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		32,746,513
Entity Public Float			$ 767,536,284
Documents Incorporated by Reference	Portions of the Proxy Statement for the 2021 Annual Meeting of Stockholders of the registrant (the “2021 Proxy Statement”) to be filed pursuant to Regulation 14A are incorporated by reference into Part III of this report.
Common Stock [Member]
Document And Entity Information [Line Items]
Trading Symbol	BANF
Title of 12(b) Security	Common Stock, $1.00 Par Value Per Share
Security Exchange Name	NASDAQ
7.2% Cumulative Trust Preferred Securities [Member]
Document And Entity Information [Line Items]
Trading Symbol	BANFP
Security Exchange Name	NASDAQ
Title of 12(g) Security	7.2% Cumulative Trust Preferred Securities

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Cash and due from banks	$ 280,518	$ 222,043
Interest-bearing deposits with banks	1,336,394	1,646,238
Federal funds sold		1,000
Debt securities held for investment (fair value: $2,984 and $1,903, respectively)	2,964	1,903
Debt securities available for sale at fair value	552,232	489,723
Loans held for sale	53,719	11,001
Loans (net of unearned interest)	6,394,506	5,662,143
Allowance for credit losses	(91,366)	(54,238)
Loans, net of allowance for credit losses	6,303,140	5,607,905
Premises and equipment, net	261,677	206,275
Other real estate owned	32,179	5,607
Intangible assets, net	18,999	22,608
Goodwill	149,922	148,604
Accrued interest receivable and other assets	220,613	202,851
Total assets	9,212,357	8,565,758
Deposits:
Noninterest-bearing	3,790,900	2,956,370
Interest-bearing	4,273,804	4,527,265
Total deposits	8,064,704	7,483,635
Short-term borrowings	1,100	1,100
Accrued interest payable and other liabilities	51,864	49,230
Junior subordinated debentures	26,804	26,804
Total liabilities	8,144,472	7,560,769
Commitments and contingent liabilities (Note 19)
Stockholders' equity:
Common stock, $1.00 par, 40,000,000 shares authorized; shares issued and outstanding: 32,719,852 and 32,694,268, respectively	32,720	32,694
Capital surplus	156,574	153,353
Retained earnings	871,161	815,488
Accumulated other comprehensive income, net of income tax of $2,513 and $1,187, respectively	7,430	3,454
Total stockholders' equity	1,067,885	1,004,989
Total liabilities and stockholders' equity	9,212,357	8,565,758
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 ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Securities, fair value	$ 2,984	$ 1,903
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	32,719,852	32,694,268
Common stock, shares outstanding	32,719,852	32,694,268
Accumulated other comprehensive income, net of tax expense (benefit)	$ 2,513	$ 1,187
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 Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
INTEREST INCOME
Loans, including fees	$ 311,987	$ 291,519	$ 263,093
Debt securities:
Taxable	8,591	13,308	8,808
Tax-exempt	487	458	609
Federal funds sold		4	291
Interest-bearing deposits with banks	6,049	31,368	30,403
Total interest income	327,114	336,657	303,204
INTEREST EXPENSE
Deposits	18,472	52,738	40,462
Short-term borrowings	8	32	95
Junior subordinated debentures	1,966	1,966	2,171
Total interest expense	20,446	54,736	42,728
Net interest income	306,668	281,921	260,476
Provision for credit losses	62,648	8,287	3,802
Net interest income after provision for credit losses	244,020	273,634	256,674
NONINTEREST INCOME
Securities transactions (includes accumulated other comprehensive income reclassifications of $0, $0 and $9, respectively)	(389)	812	47
Income from sales of loans	6,067	3,619	2,902
Insurance commissions	20,996	20,296	18,926
Cash management	15,411	16,866	13,123
Gain/(loss) on sale of other assets	130	(39)	575
Other	7,439	5,495	5,950
Total noninterest income	137,222	137,229	125,199
NONINTEREST EXPENSE
Salaries and employee benefits	164,727	153,024	139,547
Occupancy, net	16,421	12,704	13,491
Depreciation	14,609	12,623	10,537
Amortization of intangible assets	3,815	3,366	3,009
Data processing services	6,753	5,843	4,956
Net (income)/expense from other real estate owned	(1,531)	(785)	239
Marketing and business promotion	6,996	8,554	8,028
Deposit insurance	2,081	1,143	2,427
Other	43,859	44,829	39,887
Total noninterest expense	257,730	241,301	222,121
Income before taxes	123,512	169,562	159,752
Income tax expense	23,926	34,683	33,938
Net income	$ 99,586	$ 134,879	$ 125,814
NET INCOME PER COMMON SHARE
Basic	$ 3.05	$ 4.13	$ 3.85
Diluted	$ 3	$ 4.05	$ 3.76
OTHER COMPREHENSIVE GAIN/(LOSS)
Unrealized gains/(losses) on securities, net of tax of $(1,326), $(1,918) and $139, respectively	$ 3,976	$ 5,593	$ (423)
Reclassification adjustment for gains included in net income, net of tax of $0, $0 and $2, respectively			(7)
Other comprehensive gain/(loss), net of tax of $(1,326), $(1,918) and $141, respectively	3,976	5,593	(430)
Comprehensive income	103,562	140,472	125,384
Trust Revenue [Member]
NONINTEREST INCOME
Revenue	13,130	13,599	12,829
Service Charges on Deposits [Member]
NONINTEREST INCOME
Revenue	$ 74,438	$ 76,581	$ 70,847

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Securities transactions accumulated other comprehensive income reclassifications	$ 0	$ 0	$ 9
Unrealized gains (losses) on securities, tax	(1,326)	(1,918)	139
Reclassification adjustment for gains included in net income, tax	0	0	2
Other comprehensive gain/(loss), tax	$ (1,326)	$ (1,918)	$ 141

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	CUMULATIVE EFFECT, PERIOD OF ADOPTION, ADJUSTMENT [Member]	Common Stock [Member]	CAPITAL SURPLUS [Member]	RETAINED EARNINGS [Member]	RETAINED EARNINGS [Member]CUMULATIVE EFFECT, PERIOD OF ADOPTION, ADJUSTMENT [Member]	ACCUMULATED OTHER COMPREHENSIVE INCOME [Member]	ACCUMULATED OTHER COMPREHENSIVE INCOME [Member]CUMULATIVE EFFECT, PERIOD OF ADOPTION, ADJUSTMENT [Member]
Balance at beginning of period, Shares at Dec. 31, 2017			31,894,563
Balance at beginning of period at Dec. 31, 2017			$ 31,895	$ 107,481	$ 638,580	$ (618)	$ (2,327)	$ 618
Accounting Standards Update Extensible List					us-gaap:AccountingStandardsUpdate201613Member		us-gaap:AccountingStandardsUpdate201613Member
Shares issued for stock options, Shares			127,816
Shares issued for stock options, Value			$ 127	2,111
Shares issued for acquisitions, Shares			732,811
Shares issued for acquisitions, Value			$ 733	38,765
Net income	$ 125,814				$ 125,814
Net change	$ (430)						$ (430)
Dividends on common stock					(33,398)
Stock-based compensation arrangements				1,352
Shares acquired and canceled, Shares			(151,264)
Shares acquired and canceled, Value			$ (151)		(7,763)
Balance at end of period, Shares at Dec. 31, 2018	32,603,926		32,603,926
Balance at end of period at Dec. 31, 2018	$ 902,789		$ 32,604	149,709	722,615		(2,139)
Shares issued for stock options, Shares			117,012
Shares issued for stock options, Value			$ 117	2,367
Net income	134,879				134,879
Net change	$ 5,593						5,593
Dividends on common stock					(40,432)
Stock-based compensation arrangements				1,277
Shares acquired and canceled, Shares			(26,670)
Shares acquired and canceled, Value			$ (27)		(1,574)
Balance at end of period, Shares at Dec. 31, 2019	32,694,268		32,694,268
Balance at end of period at Dec. 31, 2019	$ 1,004,989		$ 32,694	153,353	$ 815,488	$ 2,270	3,454
Accounting Standards Update Extensible List		us-gaap:AccountingStandardsUpdate201613Member			us-gaap:AccountingStandardsUpdate201613Member
Shares issued for stock options, Shares			84,868
Shares issued for stock options, Value			$ 85	1,705
Net income	99,586				$ 99,586
Net change	$ 3,976						3,976
Dividends on common stock					(43,144)
Stock-based compensation arrangements				1,516
Shares acquired and canceled, Shares			(59,284)
Shares acquired and canceled, Value			$ (59)		(3,039)
Balance at end of period, Shares at Dec. 31, 2020	32,719,852		32,719,852
Balance at end of period at Dec. 31, 2020	$ 1,067,885		$ 32,720	$ 156,574	$ 871,161		$ 7,430

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cumulative effect of change in accounting principle tax	$ 925
RETAINED EARNINGS [Member]
Dividend on common stock	$ 1.32	$ 1.24	$ 1.02

Consolidated Statements of Cash

Consolidated Statements of Cash Flow - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 99,586	$ 134,879	$ 125,814
Adjustments to reconcile to net cash provided by operating activities:
Provision for credit losses	62,648	8,287	3,802
Depreciation and amortization	18,424	15,989	13,546
Net amortization of securities premiums and discounts	(94)	(4,282)	(421)
Realized securities losses (gains)	389	(812)	(47)
Gain on sales of loans	(6,067)	(3,619)	(2,902)
Cash receipts from the sale of loans originated for sale	415,589	238,324	187,461
Cash disbursements for loans originated for sale	(430,653)	(237,543)	(186,632)
Deferred income tax (benefit) provision	(9,491)	1,148	3,155
Gain on other assets	(2,345)	(1,372)	(596)
(Increase)/decrease in interest receivable	(325)	887	(3,390)
(Decrease)/increase in interest payable	(1,641)	(17)	1,179
Amortization of stock-based compensation arrangements	1,516	1,277	1,352
Excess tax benefit from stock-based compensation arrangements	(500)	(928)	(1,112)
Other, net	7,305	6,740	(1,199)
Net cash provided by operating activities	154,341	158,958	140,010
INVESTING ACTIVITIES
Net cash received from acquisitions, net of cash paid	18,397	77,672	6,248
Net decrease/(increase) in federal funds sold	1,000	(1,000)	23,548
Purchases of held for investment debt securities	(1,395)	(1,010)	(225)
Purchases of available for sale debt securities	(605,069)	(174,090)	(465,684)
Proceeds from maturities, calls and paydowns of held for investment debt securities	561	535	1,089
Proceeds from maturities, calls and paydowns of available for sale debt securities	547,729	508,293	126,909
Proceeds from sales of available for sale debt securities			31,285
Purchase of equity securities	(811)	(3,966)	(3,190)
Proceeds from paydowns and sales of equity securities	445	2,178	1,484
Net change in loans	(798,024)	(310,053)	49,354
Purchases of premises, equipment and computer software	(66,446)	(27,054)	(51,863)
Purchase of tax credits	(2,200)	(29,025)	(8,864)
Other, net	7,820	7,867	(3,890)
Net cash (used in) provided by investing activities	(897,993)	50,347	(293,799)
FINANCING ACTIVITIES
Net change in deposits	536,063	274,218	(139,510)
Net change in short-term borrowings		(575)	775
Proceeds from long-term borrowings	3,000
Paydown of long-term borrowings	(3,000)
Issuance of common stock in connection with stock options, net	1,790	2,484	2,238
Common stock acquired	(3,098)	(1,601)	(7,914)
Redemption of Junior Subordinated debentures			(5,155)
Cash dividends paid	(42,472)	(39,805)	(30,265)
Net cash provided by (used in) financing activities	492,283	234,721	(179,831)
Net (decrease)/increase in cash, due from banks and interest-bearing deposits	(251,369)	444,026	(333,620)
Cash, due from banks and interest-bearing deposits at the beginning of the period	1,868,281	1,424,255	1,757,875
Cash, due from banks and interest-bearing deposits at the end of the period	1,616,912	1,868,281	1,424,255
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid during the period for interest	22,056	54,602	41,549
Cash paid during the period for income taxes	26,525	30,975	27,952
Noncash investing and financing activities:
Stock issued in acquisitions			39,498
Cash consideration for acquisitions	2,861	123,457	24,722
Fair value of assets acquired in acquisitions	47,838	729,378	377,320
Liabilities assumed in acquisitions	45,040	605,921	338,860
Unpaid common stock dividends declared	$ 11,125	$ 10,453	$ 9,826

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
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 (“BancFirst”), an Oklahoma state-chartered bank headquartered in Oklahoma City, Oklahoma. The Company also conducts operating activities through its wholly-owned subsidiary, Pegasus Bank (“Pegasus Bank”), a Texas state-chartered bank headquartered in Dallas, Texas. BancFirst and Pegasus Bank provide 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; and other services tailored for both individual and corporate customers. BancFirst also offers trust services and acts as executor, administrator, trustee, transfer agent and in various other fiduciary capacities. Through its Technology and Operations Center, BancFirst 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., BancFirst Risk & Insurance Company (consolidated financials include a full year of operations for BancFirst Risk & Insurance Company; however it was dissolved as of December 31, 2020), Pegasus Bank, and BancFirst and its subsidiaries. The principal operating subsidiaries of BancFirst are Council Oak Investment Corporation, Council Oak Real Estate Inc., BFTower, LLC, BFC-PNC LLC, and BancFirst Agency, Inc. 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 2019 and 2018 have been reclassified to conform to the 2020 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 U.S. GAAP 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 credit 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 invests in debt securities. Any sales of debt 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. Debt 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 debt securities available for sale are reported as a component of stockholders’ equity, net of income tax. Gains or losses from sales of debt securities are based upon the book values of the specific debt securities sold. Debt 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 debt securities in an unrealized loss position at least quarterly. The Company first assesses whether it intends to sell or it is more-likely-than-not that it will be required to sell the securities before recovery of the amortized cost basis. If either of these criteria is met, the securities amortized cost basis is written down to fair value as a current period expense. If either of the above criteria is not met, the Company evaluates whether the decline in fair value is the result of credit losses or other factors. In making this assessment, the Company considers, among other things, the period of time the security has been in an unrealized loss position, and performance of any underlying collateral and adverse conditions specifically related to the security. The Company does not consider the unrealized position of its debt securities to be the result of credit factors, because the decline in fair value is attributable to changes in interest rates and illiquidity, and not credit quality, and the Company does not have the intent to sell these securities and it is likely that it will not be required to sell the securities before their anticipated recovery. Therefore, the Company has not recorded an allowance for credit losses against its debt securities portfolio, as the credit risk is not material. The Company does not engage in securities trading activities. The Company invests in equity securities without readily determinable fair values and utilizes Level 3 inputs. These securities are reported at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. The realized and unrealized gains and losses are reported as securities transactions in the noninterest income section of the consolidated statements of comprehensive income. Equity securities are reported in other assets on the balance sheet. The Company reviews its portfolio of equity securities for impairment at least quarterly. Prior to the adoption of ASC 326, declines in the fair value of held-to-maturity and available-for-sale securities below their cost that were deemed to be other than temporary were reflected in earnings as realized losses. In estimating other-than-temporary impairment losses prior to January 1, 2020, management considered, among other things, (i) the length of time and the extent to which the fair value had been less than cost, (ii) the financial condition and near-term prospects of the issuer and (iii) the intent and our ability to retain our investment in the issuer 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 the use of prepayment penalties. 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 and residential and employment stability. 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 credit losses. Interest on all performing loans is recognized, on a simple interest basis, based upon the principal amount outstanding. See Note (5) for loan disclosures. 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. 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. Acquired Loans Loans acquired through business combinations are required to be carried at fair value as of the date of the combination. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction (that is, not a forced liquidation or distressed sale) between market participants at the measurement date. An allowance for credit loss is recorded for these acquired loans depending on whether the acquired loans are purchase credit deteriorated or non-purchase credit deteriorated. An allowance for credit loss for non-purchase credit deteriorated loans is determined and recorded in a manner consistent with originated loans. That is, the allowance for credit loss is calculated based on the loan’s amortized cost basis (i.e., the acquisition date fair value in a business combination) and is established through a charge to provision expense at the acquisition date. An allowance for credit loss for purchase credit deteriorated loans is recorded as an adjustment to the loans, in addition to the fair value amount recorded, as of the acquisition date, and not through provision expense. The acquisition date fair value plus the allowance for credit loss equals the loans new amortized cost basis as of the acquisition date. The difference between the new amortized cost basis and the unpaid principal balance of the loan represents the non-credit purchase discount/premium recorded. 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 credit 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 fair value. 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. At December 31, 2020, loans held for sale included loans at its Hugo, Oklahoma branch that it has entered into an agreement to sell to AmeriState Bank in Atoka, Oklahoma. Allowance for Credit Losses The allowance for credit losses is a valuation account that is deducted from the loans amortized cost basis to present the net amount expected to be collected on the loans. Loans are charged off against the allowance when management believes the uncollectibility of a loan balance is confirmed. Expected recoveries do not exceed the aggregate of amounts previously charged-off and expected to be charged-off. The allowance for credit losses is increased by provisions charged to operating expense and is reduced by net loan charge-offs. The allowance is estimated using relevant available information, from internal and external sources, relating to past events, current conditions, and reasonable and supportable forecasts. Historical credit loss experience provides the basis for the estimation of expected credit losses. Adjustments to historical loss information are made for differences in current loan-specific risk characteristics such as differences in underwriting standards, portfolio mix, delinquency level, or term as well as for changes in environmental conditions, such as the political, legal, and regulatory environment, technology and consumer preferences. Historical loss information is also adjusted for reasonable and supportable changes in national and local economic conditions. If a loan is individually evaluated a specific allowance is provided, if necessary, so that the loan is reported net, at the fair value of collateral. Interest payments on collateral dependent 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. Loans, or portions thereof, are charged off when deemed uncollectible. Prior to the adoption of ASC 326, the allowance for credit losses on loans was a contra-asset valuation account established through a provision for loan losses charged to expense, which represented management’s best estimate of inherent losses that had been incurred within the existing portfolio of loans. The allowance for credit losses on loans included allowance allocations calculated in accordance with ASC Topic 310, “Receivables” and allowance allocations calculated in accordance with ASC Topic 450, “Contingencies.” Loans were reported as impaired when, based on then current information and events, it was probable we would 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 was evaluated in total for smaller-balance loans of a similar nature and on an individual loan basis for other loans. If a loan was impaired, a specific valuation allowance was allocated, if necessary, so that the loan was 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 was expected solely from the collateral. Interest payments on impaired loans were typically applied to principal unless collectability of the principal amount was reasonably assured, in which case interest was recognized on a cash basis. Impaired loans, or portions thereof, were charged off when deemed uncollectible. Nonaccrual Policy A loan is placed on nonaccrual status when, in the opinion of management, the future collectability of both interest and 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. 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. 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. Construction in progress includes all the costs of construction associated with the building of fixed long-term assets and is included in premises and equipment, net as an asset. When construction is completed, the asset is reclassified as buildings or leasehold improvements and depreciated over its applicable useful life. Leases Certain operating leases are included as right of use lease assets in accrued interest receivable and other assets on the balance sheet and a related lease liability is included in accrued interest payable and other liabilities on the balance sheet. Right of use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The lease liability is measured as the present value of the unpaid lease payments, and the right of use assets value is derived from the calculation of the lease liability. To calculate the discount rate for each lease, the Company uses the rate implicit in the lease if available, otherwise an appropriate FHLB advance borrowing rate is used that correlates with the term of the lease. 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 credit 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. 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 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. Advertising Costs Advertising costs are expensed as incurred. Advertising costs for the year ended December 31, 2020 were $3.3 million. Advertising costs for the years ended December 31, 2019 and 2018 were $3.8 million and $3.5 million, respectively. 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 balance sheet 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. Revenue Recognition In addition to lending and related activities, the Company offers various services to customers that generate revenue. Contract performance typically occurs in one year or less. Incremental costs of obtaining a contract are expensed when incurred when the amortization period is one year or less. Sales of real estate The sale of real estate property is generally recognized, along with any associated gain or loss, when control of the property transfers to the buyer. Service and transaction fees on depository accounts Customers often pay certain fees to the bank to access the cash on deposit including certain non-transactional fees such as account maintenance or dormancy fees, and certain transaction based fees such as ATM, wire transfer, or foreign exchange fees. Revenue is recognized when the transactions occur or as services are performed over primarily monthly or quarterly periods. Payment is typically received in the period the transactions occur, or in some cases, within 90 days of the service period. Interchange Fees Interchange fees, or “swipe” fees, are charges that merchants pay to the processors who, in turn, share that revenue with us and other card-issuing banks for processing electronic payment transactions. Interchange fees represent the portion of the debit card transaction amount that the card issuer retains to compensate it for processing transactions and providing rewards. Interchange fees are settled and recognized on a daily or monthly basis. Insurance Commissions and Fees Insurance commissions are received on the sale of insurance products, and revenue is recognized upon the placement date of the insurance policies or when such commissions are received. Payment is normally received within the policy period. In addition to placement, the Company also provides insurance policy related risk management services. Revenue is recognized as these services are provided. Performance-based commissions are recognized when received or earlier when, upon consideration of past results and current condition, the revenue is deemed not probable of reversal. For accounts billed by BancFirst Insurance Services, Inc., commission revenue is recognized at the later of the billing date or the effective date of the related insurance policies. Commission revenue, for accounts that are directly billed by the insurance company to the insured, is recognized when determinable by BancFirst Insurance Services, Inc., which is generally when such commissions are received. BancFirst Insurance Services, Inc. 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 they place. Contingent commissions from insurance companies are recognized when determinable, which is generally when such commissions are received. Trust BancFirst offers trust services and acts as executor, administrator, trustee, transfer agent and in various other fiduciary capacities. There are four basic types of fees that are included in the trust department income. Administrative fees are assessed for managing trust accounts. Shareholder fees are received in connection with holding specific fund share classes. In return for these services, the mutual fund (or its distributor or investment advisor) pay a fee to BancFirst. Oil and gas fees are assessed for management of oil and gas related activities. There are also other types of fees charged on a one time basis such as those related to opening and closing trust accounts. BancFirst records trust fees on a monthly, quarterly or annual basis based on the size of the asset being managed. Fees may be fixed or, where applicable, based on a percentage of transaction size of managed assets. These fees are recorded as revenue at the time the fee is billed, according to the agreement with the customer. 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 debt 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 Standards Adopted During Current Period: In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2018-13, “Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement (Topic 820).” ASU 2018-13 modifies disclosure requirements on fair value measurements in Topic 820. ASU No. 2018-13 was adopted on January 1, 2020 and did not have a significant impact on the Company’s financial statements. On January 1, 2020, the Company adopted ASU No. 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” Accounting Standards Codification (“ASC”) 326 replaces the incurred loss methodology with an expected loss methodology that is referred to as the current expected credit loss (“CECL”) methodology. The measurement of expected credit losses under the CECL methodology is applicable to financial assets measured at amortized cost, including loan receivables and held-to-maturity debt securities. It also applies to off-balance sheet credit exposures not accounted for as insurance (loan commitments, standby letters of credit, financial guarantees, and other similar instruments) and net investments in leases recognized by a lessor in accordance with Topic 842 on leases. In addition, ASC 326 made changes to the accounting for purchased loans and securities with credit deterioration and available-for-sale debt securities. In connection with the adoption of ASC 326, the Company revised certain accounting policies and implemented accounting policy elections. The Company adopted ASC 326 using the modified retrospective method for all financial assets measured at amortized cost and off-balance sheet credit exposures. Operating results for periods from January 1, 2020 are presented in accordance with ASC 326 while prior period amounts continue to be reported in accordance with previously applicable standards and the accounting policies described in our 2019 Form 10-K. The Company recorded a net increase to retained earnings of $2.3 million, net of tax of $925,000, as of January 1, 2020 for the cumulative effect of adopting ASC 326. The Company’s results of operations were materially affected due to the increase in provisions related to the adoption of ASC 326 and the impact to the Company’s cash flows was not material. The Company adopted ASC 326 using the prospective transition approach for financial assets purchased with credit deterioration (PCD) that were previously classified as purchased credit impaired (PCI) and accounted for under ASC 310-30. In accordance with the standard, management did not reassess whether PCI assets met the criteria of PCD assets as of the date of adoption. On January 1, 2020, the amortized cost basis of the PCD assets was adjusted to reflect the addition of approximately $ 1.2 million to the allowance for credit losses. The Company has not recorded an allowance for credit losses against its available-for-sale securities, as the credit risk is not material. The following table illustrates the impact of ASC 326 on the allowance for credit losses on the Company’s loans as of January 1, 2020. January 1, 2020 As Reported Under ASC 326 Pre ASC 326 Adoption Impact of ASC 326 Adoption (Dollars in thousands) BancFirst Real estate: Commercial real estate owner occupied $ 2,819 $ 5,625 $ (2,806 ) Commercial real estate non-owner occupied 2,851 8,358 (5,507 ) Construction and development < 60 months 1,158 2,214 (1,056 ) Construction residential real estate < 60 months 1,155 1,933 (778 ) Residential real estate first lien 4,861 8,692 (3,831 ) Residential real estate all other 1,359 2,767 (1,408 ) Farmland 1,413 2,821 (1,408 ) Commercial and agricultural non-real estate 26,657 13,462 13,195 Consumer non-real estate 2,630 3,252 (622 ) Oil and gas 537 1,883 (1,346 ) Other loans 2,516 2,632 (116 ) Pegasus Bank 3,087 599 2,488 Allowance for credit losses on loans $ 51,043 $ 54,238 $ (3,195 ) The estimate of expected credit losses considers historical credit loss information that is adjusted for current conditions and reasonable and supportable forecasts. In order to estimate expected losses using historical loss information, the Company elected to utilize a methodology known as vintage loss analysis for

Recent Developments, Including

Recent Developments, Including Mergers and Acquisitions	12 Months Ended
	Dec. 31, 2020
Recent Developments Including Mergers And Acquisitions [Abstract]
Recent Developments, Including Mergers and Acquisitions	(2) RECENT DEVELOPMENTS, INCLUDING MERGERS AND ACQUISITIONS Section 4013 of the CARES Act and the Interagency Statement on Loan Modifications by Financial Institutions provides temporary relief from the accounting and reporting requirements for TDRs regarding certain loan modifications related to the Coronavirus Disease 2019 (“COVID-19”) that are offered by financial institutions. Specifically, the CARES Act provides that a financial institution may elect to suspend (1) the requirements under U.S. GAAP for certain loan modifications that would otherwise be categorized as a TDR and (2) any determination that such loan modifications would be considered a TDR, including the related impairment for accounting purposes. The modifications that would qualify for this exception include any modification involving a loan that was not more than 30 days past due as of December 31, 2019, that occurs during the “applicable period,” including any of the following: • A forbearance arrangement. • An interest rate modification. • A repayment plan. • Any other similar arrangement that defers or delays the payment of principal or interest. The exception does not apply to any adverse impact on the credit of a borrower that is not related to the COVID-19 pandemic. Furthermore, even when the exception is applied, an entity may determine that it is appropriate to place the loan on nonaccrual status. As of December 31, 2020, the Company has identified $81.7 million in loans that have been modified according to the CARES Act terms. As of December 31, 2020, these loans have not been deemed nonaccrual loans. On March 5, 2020 the Company purchased approximately $47.8 million in total assets, which included $22.9 million in loans, and assumed approximately $45.0 million in deposits and certain other obligations of The Citizens State Bank of Okemah, Oklahoma (“Citizens”) for a purchase price of $2.9 million. As a result of the purchase, the Company recorded a core deposit intangible of approximately $206,000 and goodwill of approximately $1.3 million. The effect of this purchase was included in the consolidated financial statements of the Company from the date of purchase forward. The purchase did not have a material effect on the Company’s consolidated financial statements. Citizens was an Oklahoma state-chartered bank with banking locations in Okemah and Paden, Oklahoma. These banking locations became branches of BancFirst. On August 15, 2019 BancFirst Corporation acquired Pegasus Bank, for an aggregate cash purchase price of $123.5 million. Pegasus Bank is a Texas state-charted bank with three banking locations in Dallas, Texas. At acquisition, Pegasus Bank had approximately $651.1 million in total assets, $389.9 million in loans and $603.9 million in deposits. Pegasus Bank will continue to operate as “Pegasus Bank” under a separate Texas state-charter and remain an independent subsidiary of BancFirst Corporation. BancFirst Corporation intends to provide an appropriate amount of capital or other support to increase Pegasus Bank’s ability to approve larger loans and allow Pegasus to continue to grow their assets. As a result of the acquisition, the Company recorded a core deposit intangible of approximately $9.9 million and goodwill of approximately $68.9 million. 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. The acquisition of Pegasus Bank complements the Company by expanding into the high-growth Dallas market. On August 31, 2018 BFTower, LLC, a wholly-owned subsidiary of BancFirst The BancFirst T ower will remain an income producing property as approximately 55 % is currently , and is intended to continue to be, leased to outside tenants. BancFirst Tower will allow the Company to consolidate operations from three locations to one and will improve operational efficiencies. Upon consolidation, the Company expects to occupy approximately 35 % of BancFirst Tower, resulting in approximately % total occupancy. Renovations on BancFirst Tower are expected to be completed by the fourth quarter of 2022 and are expected to cost approximately $ million. The renovation costs include substantial deferred maintenance including HVAC, plumbing, electrical, elevators, building skin and roof while also including much needed improvements to both the interior and exterior common areas including the lobby, underground and outdoor plaza. The Company start ed depreciating certain components of the renovation in December 2019 and ha s start ed depreciating other components of the renovation as they are put into service . The Company estimates spending approximately $ 10 million on tenant improvements for the approximate 165,000 square feet that the Company will occupy. The total purchase price , renovation costs , and Company tenant improvement costs were determined to be favorable to other alternatives, such as constructing a new corporate headquarter or leasing space . On December 14, 2018, BFTower LLC, purchased a 42.6 % ownership interest in SFPG, LLC, which is the owner of a parking gar age adjacent to BancFirst Tower. During 2020, BFTower LLC increased its ownership interest in SFPG, LLC to 49 %. The total amount paid for the interest in SFPG, LLC was $ 11.3 million. In addition, on December 31, 2019, BFTower LLC, purchased a 50 % ownership interest in ParcFirst Bricktown, LLC, which is the owner of an outdoor surface parking lot in close proximity to BancFirst Tower, for $ million. On January 11, 2018, the Company acquired First Wagoner Corp. and its subsidiary bank, First Bank & Trust Company, with locations in Carney, Grove, Ketchum, Luther, Tulsa and Wagoner. First Bank & Trust Company had approximately $290 million in total assets, $247 million in loans and $251 million in deposits. First Bank & Trust Company operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst on February 16, 2018. As a result of the acquisition, the Company recorded a core deposit intangible of approximately $6.3 million and goodwill of approximately $19.1 million. 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. The acquisition of First Wagoner Corp. and its subsidiary bank, First Bank & Trust Company complements the Company’s community banking strategy by adding an additional five communities to its banking network in Oklahoma. On January 11, 2018, the Company acquired First Chandler Corp. and its subsidiary bank, First Bank of Chandler, with two locations in Chandler. First Bank of Chandler had approximately $88 million in total assets, $66 million in loans and $79 million in deposits. First Bank of Chandler operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst on September 7, 2018. As a result of the acquisition, the Company recorded a core deposit intangible of approximately $2.2 million and goodwill of approximately $6.6 million. 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. The acquisition of First Chandler Corp. and its subsidiary bank, First Bank of Chandler complements the Company’s community banking strategy by increasing its banking network in Oklahoma.

Cash, Due from Banks, Interest-

Cash, Due from Banks, Interest-Bearing Deposits and Federal Funds Sold	12 Months Ended
	Dec. 31, 2020
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, 2020 and 2019, 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. On March 26, 2020, the Federal Reserve Board reduced reserve requirement ratios to zero percent, effectively eliminating reserve requirements for all depository institutions. Prior to this date, the Company was 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 December 31, 2019 is included in the following table: December 31, 2020 2019 (Dollars in thousands) Vault cash and funds on deposit with the Federal Reserve Bank $ 1,429,410 $ 1,738,523 Average required reserves — 63,842

Securities

Securities	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Securities	(4) SECURITIES The following table summarizes the amortized cost and estimated fair values of debt securities held for investment: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (Dollars in thousands) December 31, 2020 Mortgage backed securities (1) $ 59 $ 3 $ — $ 62 States and political subdivisions 2,405 18 (1 ) 2,422 Other securities 500 — — 500 Total $ 2,964 $ 21 $ (1 ) $ 2,984 December 31, 2019 Mortgage backed securities (1) $ 93 $ 4 $ — $ 97 States and political subdivisions 1,310 1 (5 ) 1,306 Other securities 500 — — 500 Total $ 1,903 $ 5 $ (5 ) $ 1,903 The following table summarizes the amortized cost and estimated fair values of debt securities available for sale: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (Dollars in thousands) December 31, 2020 U.S. treasuries $ 465,416 $ 9,820 $ — $ 475,236 U.S. federal agencies 19,697 1 (60 ) 19,638 Mortgage backed securities (1) 15,268 428 — 15,696 States and political subdivisions 28,571 377 — 28,948 Asset backed securities 13,337 — (623 ) 12,714 Total $ 542,289 $ 10,626 $ (683 ) $ 552,232 December 31, 2019 U.S. treasuries $ 409,488 $ 4,974 $ (13 ) $ 414,449 U.S. federal agencies 23,039 23 (38 ) 23,024 Mortgage backed securities (1) 16,941 128 (64 ) 17,005 States and political subdivisions 22,294 282 (45 ) 22,531 Asset backed securities 13,320 — (606 ) 12,714 Total $ 485,082 $ 5,407 $ (766 ) $ 489,723 (1) Primarily consists of FHLMC, FNMA, GNMA and mortgage backed securities through U.S. agencies. The maturities of debt 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, 2020 2019 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value (Dollars in thousands) Held for Investment Contractual maturity of debt securities: Within one year $ 807 $ 809 $ 300 $ 300 After one year but within five years 2,091 2,110 1,058 1,055 After five years but within ten years 65 64 543 546 After ten years 1 1 2 2 Total $ 2,964 $ 2,984 $ 1,903 $ 1,903 Available for Sale Contractual maturity of debt securities: Within one year $ 339,752 $ 341,102 $ 186,373 $ 186,539 After one year but within five years 162,401 171,135 252,519 257,430 After five years but within ten years 3,753 3,910 5,873 6,008 After ten years 36,383 36,085 40,317 39,746 Total debt securities $ 542,289 $ 552,232 $ 485,082 $ 489,723 The following is a detail of proceeds from sales and realized securities losses, on available for sale debt securities: Year Ended December 31, 2020 2019 2018 (Dollars Proceeds $ — $ — $ 31,285 Gross losses realized — — 109 Realized gains/losses on debt and equity securities are reported as securities transactions within the noninterest income section of the consolidated statement of comprehensive income. The following table is a summary of the Company’s book value of debt securities that were pledged as collateral for public funds on deposit, repurchase agreements and for other purposes as required or permitted by law: December 31, 2020 2019 (Dollars Book value of pledged securities $ 490,833 $ 445,702 The following table summarizes debt securities with unrealized losses, segregated by the duration of the unrealized loss, at December 31, 2020 and 2019 respectively: Less than 12 Months More than 12 Months Total Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses (Dollars in thousands) December 31, 2020 Held for Investment States and political subdivisions $ 119 $ 1 $ — $ — $ 119 $ 1 Total $ 119 $ 1 $ — $ — $ 119 $ 1 Available for Sale U.S. federal agencies $ 12,236 $ 41 $ 2,184 $ 19 $ 14,420 $ 60 Asset backed securities — — 12,714 623 12,714 623 Total $ 12,236 $ 41 $ 14,898 $ 642 $ 27,134 $ 683 December 31, 2019 Held for Investment Mortgage backed securities $ — $ — $ 3 $ — $ 3 $ — States and political subdivisions 1,016 5 — — 1,016 5 Total $ 1,016 $ 5 $ 3 $ — $ 1,019 $ 5 Available for Sale U.S. treasuries $ 8,999 $ 10 $ 19,988 $ 3 $ 28,987 $ 13 U.S. federal agencies 10,362 19 2,700 19 13,062 38 Mortgage backed securities 15,165 64 — — 15,165 64 States and political subdivisions 3,890 45 — — 3,890 45 Asset backed securities — — 12,714 606 12,714 606 Total $ 38,416 $ 138 $ 35,402 $ 628 $ 73,818 $ 766 Management has the ability and intent to hold the debt securities classified as held for investment until they mature, at which time the Company will receive full value for the debt securities. Furthermore, as of December 31, 2020 and 2019, the Company also had the ability and intent to hold the debt securities classified as available for sale for a period of time sufficient for a recovery of cost. The unrealized losses are due to increases in market interest rates over the yields available at the time the underlying debt securities were purchased. The fair value of those debt securities having unrealized losses is expected to recover as the securities approach their maturity date or repricing date, or if market yields for such investments decline. Management has no intent or requirement to sell before the recovery of the unrealized loss; therefore, no significant impairment loss was realized in the Company’s consolidated statement of comprehensive income.

Loans Held for Investment and A

Loans Held for Investment and Allowance for Credit Losses on Loans	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Loans Held for Investment and Allowance for Credit Losses on Loans	(5) LOANS HELD FOR INVESTMENT AND ALLOWANCE FOR CREDIT LOSSES ON LOANS In connection with our adoption of ASC 326 Loans held for investment are summarized by portfolio segment as follows: December 31, 2020 2019 Amount Amount (Dollars in thousands) BancFirst Real estate: Commercial real estate owner occupied $ 641,987 $ 621,188 Commercial real estate non-owner occupied 971,158 851,200 Construction and development < 60 months 229,615 287,138 Construction residential real estate < 60 months 206,195 189,480 Residential real estate first lien 853,316 834,849 Residential real estate all other 168,081 187,647 Farmland 252,958 246,988 Commercial and agricultural non-real estate 1,159,810 1,315,005 Consumer non-real estate 355,405 359,529 Oil and gas 179,355 184,399 Other loans (2) 822,078 154,015 Pegasus Bank 554,548 430,705 Total loans (1) $ 6,394,506 $ 5,662,143 (1) Excludes accrued interest receivable of $26.0 million at December 31, 2020 and $24.5 million at December 31, 2019, that is recorded in accrued interest receivable and other assets. (2) Includes PPP loans of $652.7 million, net of unamortized processing fees of $14.5 million at December 31, 2020. BancFirst’s loans are mostly to customers within Oklahoma and approximately 58% of the loans are secured by real estate. Credit risk on loans is managed through limits on amounts loaned to individual and related 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. BancFirst’s commercial and agricultural non-real estate and oil and gas loan categories include upstream and midstream energy loans and loans to companies that provide ancillary services to the energy industry, such as transportation, preparation contractors and equipment manufacturers. The balance of these upstream energy loans was approximately $191 million at December 31, 2020 and approximately $189 million at December 31, 2019. The balance of midstream energy loans was approximately $50 million at December 31, 2020 and approximately $41 million at December 31, 2019. The balance of the ancillary services energy loans was approximately $59 million at December 31, 2020 and approximately $90 million at December 31, 2019. Pegasus Bank’s loans are mostly to customers within Texas and approximately $272 million or 49% of the loans are secured by real estate at December 31, 2020. Pegasus Bank’s commercial and agricultural non-real estate loans were approximately $262 million at December 31, 2020, and approximately $172 million at December 31, 2019. Pegasus Bank’s commercial and agricultural non-real estate loan category includes upstream energy loans and loans to companies that provide ancillary services to the energy industry, such as transportation, preparation contractors and equipment manufacturers. The balance of upstream energy loans was approximately $107 million at December 31, 2020 and approximately $57 million at December 31, 2019. The balance of midstream energy loans was approximately $11 million at December 31, 2020 and zero at December 31, 2019. The balance of the ancillary services energy loans was approximately $13 million at December 31, 2020 and approximately $7 million at December 31, 2019. As of December 31, 2020, the Company had $ million in PPP loans held for investment, net of unamortized processing fees of $ million. Through December 31, 2020, $ million of processing fees were recognized as interest income. Troubled Debt Restructurings, Other Real Estate Owned and Repossessed Assets and Held for Sale Assets The following is a summary of troubled debt restructurings and other real estate owned and repossessed assets: December 31, 2020 2019 (Dollars in thousands) Troubled debt restructurings $ 7,784 $ 18,010 Other real estate owned and repossessed assets $ 32,480 $ 6,073 The Company charges interest on principal balances outstanding on troubled debt restructurings during deferral periods. The current and future financial effects of the recorded balance of loans considered to be troubled debt restructurings were not considered to be material. During 2020, the Company sold property held in other real estate owned for a total gain of $2.4 million compared to gains of $1.4 million in 2019 and $23,500 in 2018. At December 31, 2020, the Company’s principal subsidiary bank, BancFirst, had approximately $21.6 million in loans at its Hugo, Oklahoma branch that it has entered into an agreement to sell to AmeriState Bank in Atoka, Oklahoma. Accordingly, as of December 31, 2020, the Company has transferred $21.6 million from loans held for investment (net of unearned interest) to loans held for sale. Nonaccrual loans Had nonaccrual loans performed in accordance with their original contractual terms, the Company would have recognized additional interest income of approximately $2.8 million in 2020, $1.7 million in 2019 and $2.3 million in 2018. Approximately $7.8 million of nonaccrual loans are guaranteed by government agencies as of December 31, 2020. The following table is a summary of amounts included in nonaccrual loans, segregated by portfolio segment. December 31, 2020 (Dollars in thousands) BancFirst Real estate: Commercial real estate owner occupied $ 1,404 Commercial real estate non-owner occupied 4,719 Construction and development < 60 months 95 Construction residential real estate < 60 months — Residential real estate first lien 3,615 Residential real estate all other 1,362 Farmland 7,901 Commercial and agricultural non-real estate 12,782 Consumer non-real estate 268 Oil and gas — Other loans 5,399 Pegasus Bank — Total $ 37,545 December 31, 2019 (Dollars in thousands) BancFirst Real estate: Non-residential real estate owner occupied $ 2,275 Non-residential real estate other 1,815 Residential real estate permanent mortgage 1,206 Residential real estate other 3,060 Non-consumer non-real estate 2,915 Consumer other 264 Other loans 1,083 Acquired loans 4,496 Pegasus Bank 851 Total $ 17,965 Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due. The following table presents an age analysis of our loans held for investment: Age Analysis of Past Due Loans 30-59 Days Past Due 60-89 Days Past Due 90 Days and Greater Total Past Due Loans Current Loans Total Loans Accruing Loans 90 Days or More Past Due (Dollars in thousands) As of December 31, 2020 BancFirst Real estate: Commercial real estate owner occupied $ 1,096 $ 108 $ 1,164 $ 2,368 $ 639,619 $ 641,987 $ — Commercial real estate non-owner occupied 323 — 34 357 970,801 971,158 35 Construction and development < 60 months 511 86 — 597 229,018 229,615 — Construction residential real estate < 60 months 1,106 — 282 1,388 204,807 206,195 282 Residential real estate first lien 5,428 1,463 2,978 9,869 843,447 853,316 945 Residential real estate all other 520 55 1,606 2,181 165,900 168,081 384 Farmland 1,297 344 6,223 7,864 245,094 252,958 135 Commercial and agricultural non-real estate 2,788 1,794 4,345 8,927 1,150,883 1,159,810 465 Consumer non-real estate 2,154 501 534 3,189 352,216 355,405 386 Oil and gas — — — — 179,355 179,355 — Other loans 951 1,223 6,618 8,792 813,286 822,078 2,170 Pegasus Bank — — — — 554,548 554,548 — Total $ 16,174 $ 5,574 $ 23,784 $ 45,532 $ 6,348,974 $ 6,394,506 $ 4,802 As of December 31, 2019 BancFirst Real estate: Non-residential real estate owner occupied $ 1,600 $ 967 $ 5,159 $ 7,726 $ 699,690 $ 707,416 $ 3,799 Non-residential real estate other 971 — 1,228 2,199 1,134,976 1,137,175 — Residential real estate permanent mortgage 4,705 973 2,215 7,893 332,679 340,572 1,660 Residential real estate other 4,496 1,028 2,541 8,065 912,767 920,832 549 Non-consumer non-real estate 2,290 1,446 1,763 5,499 1,448,894 1,454,393 354 Consumer other 2,829 858 592 4,279 358,075 362,354 491 Other loans 1,670 8 4,613 6,291 147,724 154,015 4,426 Acquired loans 2,167 1,376 3,447 6,990 147,691 154,681 555 Pegasus Bank — — 851 851 429,854 430,705 — Total $ 20,728 $ 6,656 $ 22,409 $ 49,793 $ 5,612,350 $ 5,662,143 $ 11,834 Due to the impacts of the COVID-19 pandemic, the Company has approximately $81.7 million in modified loans, most of which are secured by commercial real estate, as of December 31, 2020. These modifications were undertaken in response to Section 4013 of the CARES Act and the regulatory intent outlined in the Interagency Statement on Loan Modifications by Financial Institutions Working with Customers Affected by the Coronavirus and to provide businesses financial flexibility until the economy has time to recover to a more normal level of activity. However, these modifications, which typically involve payment modifications and forbearance, also have the effect of delaying recognition of loans that may ultimately be permanently impaired. The timing and extent of such consequences are difficult to ascertain at this time and are dependent on the duration of the COVID-19 pandemic, the level and success of the government’s economic stimulus, and further regulatory guidance. These modified loans are included in current loans in the table above as of December 31, 2020. BancFirst Credit Quality Indicators The Company considers credit quality indicators to monitor the credit risk in the loan portfolio including volume and severity of loan delinquencies, nonaccrual loans, internal grading of loans, historical credit 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 complexities or potential weaknesses could result in deterioration of the repayment prospects for the loan or BancFirst’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 complexity or 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 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. Pegasus Bank Credit Quality Indicators Pegasus Bank categorizes loans into risk categories based on relevant information about the ability of borrowers to service their debt, including current financial information, historical payment experience, credit documentation, public information, and current economic trends, among other factors. Pegasus Bank analyzes loans individually by classifying the loans as to credit risk. Pegasus Bank uses the following definitions for risk ratings: Pass – Loans classified as a pass are loans with low to average risk. These loans are included in grade 1 and 2 for the purposes for the following table: Special Mention – Loans classified as special mention have a potential weakness that deserves management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the loan or of Pegasus Bank’s credit position at some future date. These loans are included in grade 3 for the purposes of the following table: Substandard – Loans classified as substandard are inadequately protected by the current net worth and paying capacity of the obligor or of the collateral pledged, if any. Loans so classified have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They are characterized by the distinct possibility that the Pegasus Bank will sustain some loss if the deficiencies are not corrected. These loans are included in grade 4 for the purposes of the following table: Doubtful – Loans classified as doubtful have all the weaknesses inherent in those classified as substandard, with the added characteristic that the weaknesses make collection or liquidation in full, on the basis of currently existing facts, conditions, and values, highly questionable and improbable. These loans, if any, would be included in grade 5 for the purposes of the following table: The Company’s revolving loans that are converted to term loans are not material and therefore have not been presented. The following table summarizes our gross loans held for investment by year of origination and internally assigned credit grades: Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Amortized Cost Basis Total (Dollars in thousands) As of December 31, 2020 BancFirst Commercial real estate owner occupied Grade 1 $ 142,574 $ 91,493 $ 73,845 $ 42,289 $ 37,097 $ 88,724 $ 17,153 $ 493,175 Grade 2 42,375 31,314 11,516 9,644 13,316 25,574 4,393 138,132 Grade 3 4,226 32 333 704 1,259 2,671 — 9,225 Grade 4 37 66 742 — 251 52 307 1,455 Total commercial real estate owner occupied loans 189,212 122,905 86,436 52,637 51,923 117,021 21,853 641,987 Commercial real estate non-owner occupied Grade 1 256,128 157,526 83,869 69,864 82,088 81,499 13,206 744,180 Grade 2 60,607 48,751 26,441 18,070 8,755 41,491 4,454 208,569 Grade 3 7,718 3,137 472 1,937 40 148 149 13,601 Grade 4 4,719 89 — — — — — 4,808 Total commercial real estate non-owner occupied loans 329,172 209,503 110,782 89,871 90,883 123,138 17,809 971,158 Construction and development < 60 months Grade 1 115,399 56,369 12,821 4,582 1,438 2,048 7,850 200,507 Grade 2 11,528 10,002 1,589 764 157 540 582 25,162 Grade 3 3,842 — 9 — — — — 3,851 Grade 4 — 64 9 22 — — — 95 Total construction and development < 60 months 130,769 66,435 14,428 5,368 1,595 2,588 8,432 229,615 Construction residential real estate < 60 months Grade 1 159,431 4,214 69 21 33 23 11,449 175,240 Grade 2 27,400 580 112 — — 468 390 28,950 Grade 3 1,885 120 — — — — — 2,005 Total construction residential real estate < 60 months 188,716 4,914 181 21 33 491 11,839 206,195 Residential real estate first lien Grade 1 241,771 134,184 80,793 64,392 48,686 136,059 — 705,885 Grade 2 28,305 19,425 21,742 11,666 12,365 34,312 — 127,815 Grade 3 2,754 2,029 1,375 2,073 1,213 5,194 — 14,638 Grade 4 730 733 478 210 1,186 1,590 — 4,927 Grade 5 — — — — 51 — — 51 Total residential real estate first lien 273,560 156,371 104,388 78,341 63,501 177,155 — 853,316 Residential real estate all other Grade 1 21,493 13,944 10,854 6,265 5,381 10,984 28,047 96,968 Grade 2 3,694 1,675 1,268 1,809 450 2,335 55,433 66,664 Grade 3 384 461 328 116 119 221 993 2,622 Grade 4 204 217 570 65 34 715 22 1,827 Total residential real estate all other 25,775 16,297 13,020 8,255 5,984 14,255 84,495 168,081 Farmland Grade 1 51,284 26,391 18,994 13,821 13,368 27,100 8,160 159,118 Grade 2 15,264 30,684 6,639 6,391 4,763 8,916 7,140 79,797 Grade 3 3,681 290 151 1,055 703 551 1,955 8,386 Grade 4 414 14 4,058 296 340 223 312 5,657 Total farmland 70,643 57,379 29,842 21,563 19,174 36,790 17,567 252,958 Commercial and agricultural non-real estate Grade 1 206,515 136,254 124,657 74,719 46,453 33,471 270,426 892,495 Grade 2 49,467 34,659 27,239 6,566 7,054 22,710 63,894 211,589 Grade 3 24,793 1,511 1,466 789 271 327 14,577 43,734 Grade 4 7,231 1,607 652 241 1,139 163 959 11,992 Total commercial and agricultural non-real estate 288,006 174,031 154,014 82,315 54,917 56,671 349,856 1,159,810 Consumer non-real estate Grade 1 166,934 93,232 41,449 13,157 4,471 1,768 7,673 328,684 Grade 2 12,773 5,902 3,399 796 499 266 328 23,963 Grade 3 445 840 450 175 75 63 2 2,050 Grade 4 89 287 144 94 47 40 7 708 Total consumer non-real estate 180,241 100,261 45,442 14,222 5,092 2,137 8,010 355,405 Oil and gas Grade 1 104,622 66 82 — — 4,679 16,529 125,978 Grade 2 42,713 745 — — — — 9,919 53,377 Total oil and gas 147,335 811 82 — — 4,679 26,448 179,355 Other loans Grade 1 685,426 32,392 25,707 20,638 16,378 10,341 22,976 813,858 Grade 2 — — 17 2,936 1,126 2,179 692 6,950 Grade 3 — — 78 — 53 67 36 234 Grade 4 — — — 124 208 33 671 1,036 Total other loans 685,426 32,392 25,802 23,698 17,765 12,620 24,375 822,078 Pegasus Bank Grade 1 100,631 66,875 27,235 19,025 12,414 44,237 113,824 384,241 Grade 2 28,187 26,733 6,774 23,367 3,822 5,300 74,671 168,854 Grade 3 123 — — — — 1,330 — 1,453 Total Pegasus Bank 128,941 93,608 34,009 42,392 16,236 50,867 188,495 554,548 Total loans held for investment $ 2,637,796 $ 1,034,907 $ 618,426 $ 418,683 $ 327,103 $ 598,412 $ 759,179 $ 6,394,506 The following table presents internal loan grading by class of loans as of December 31, 2019: Internal Loan Grading Grade 1 2 3 4 5 Total (Dollars in thousands) As of December 31, 2019 BancFirst Real estate: Non-residential real estate owner occupied $ 554,942 $ 130,783 $ 15,191 $ 6,500 $ — $ 707,416 Non-residential real estate other 861,108 252,134 23,048 868 17 1,137,175 Residential real estate permanent mortgage 289,350 41,754 6,975 2,442 51 340,572 Residential real estate other 722,983 179,951 14,382 3,446 70 920,832 Non-consumer non-real estate 1,166,155 261,003 25,276 1,959 — 1,454,393 Consumer other 335,916 23,407 2,327 704 — 362,354 Other loans 148,692 3,631 1,564 128 — 154,015 Acquired loans 88,205 55,087 6,800 4,446 143 154,681 Pegasus Bank 295,243 133,324 1,287 851 — 430,705 Total $ 4,462,594 $ 1,081,074 $ 96,850 $ 21,344 $ 281 $ 5,662,143 Allowance for Credit Losses Methodology On January 1, 2020, the Company adopted ASC 326, which replaces the incurred loss methodology for determining its provision for credit losses and allowance for credit losses with an expected loss methodology that is referred to as the CECL model. See Note (1) for additional information regarding the factors that influenced the Company’s current estimate of expected credit losses. Upon adoption, the allowance for credit losses was decreased by $3.2 million, with no impact to the consolidated statement of income. Subsequent to the adoption of ASC 326, the Company recorded a $62.6 million provision for credit losses for year ended December 31, 2020 utilizing the newly adopted CECL methodology, a significant increase from the year ended December 31, 2019. The increase resulted primarily from the anticipated impact on our loan portfolio resulting from the economic outlook related to the COVID-19 pandemic and the decline in energy prices and to a lesser degree, loan growth during 2020. Prolonged low energy prices will not only have a direct impact on the energy portfolio; it will have an indirect effect on the economies of Oklahoma and the Dallas, Texas market, including higher unemployment, with a residual effect on land values and real estate prices. The following table details activity in the allowance for credit losses on 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. Allowance for Credit Losses Balance at beginning of period Impact of CECL adoption Initial allowance on loans purchased with credit deterioration Charge- offs Recoveries Net charge-offs Provision for credit losses on loans Balance at end of period (Dollars in thousands) Year ended December 31, 2020 BancFirst Real estate: Commercial real estate owner occupied $ 5,625 $ (2,806 ) $ 432 $ (773 ) $ 10 $ (763 ) $ 4,547 $ 7,035 Commercial real estate non-owner occupied 8,358 (5,507 ) — (3,609 ) — (3,609 ) 12,600 11,842 Construction and development < 60 months 2,214 (1,056 ) — (59 ) 123 64 1,338 2,560 Construction residential real estate < 60 months 1,933 (778 ) — (29 ) — (29 ) (499 ) 627 Residential real estate first lien 8,692 (3,831 ) 7 (465 ) 44 (421 ) (1,877 ) 2,570 Residential real estate all other 2,767 (1,408 ) — (126 ) 54 (72 ) 943 2,230 Farmland 2,821 (1,408 ) 1 (2,055 ) — (2,055 ) 3,777 3,136 Commercial and agricultural non-real estate 13,462 13,195 62 (3,320 ) 116 (3,204 ) 8,885 32,400 Consumer non-real estate 3,252 (622 ) — (1,142 ) 224 (918 ) 1,665 3,377 Oil and gas 1,883 (1,346 ) — (11,245 ) — (11,245 ) 28,559 17,851 Other loans 2,632 (116 ) — (168 ) 10 (158 ) 824 3,182 Pegasus Bank 599 2,488 — (841 ) 424 (417 ) 1,886 4,556 Total $ 54,238 $ (3,195 ) $ 502 $ (23,832 ) $ 1,005 $ (22,827 ) $ 62,648 $ 91,366 Year ended December 31, 2019 BancFirst Real estate: Non-residential real estate owner occupied $ 6,328 $ — $ — $ (34 ) $ 25 $ (9 ) $ 721 $ 7,040 Non-residential real estate other 11,027 — — (67 ) 42 (25 ) 155 11,157 Residential real estate permanent mortgage 3,261 — — (146 ) 22 (124 ) 250 3,387 Residential real estate other 10,673 — — (2,697 ) 30 (2,667 ) 2,143 10,149 Non-consumer non-real estate 13,151 — — (514 ) 272 (242 ) 2,432 15,341 Consumer other 3,065 — — (868 ) 218 (650 ) 904 3,319 Other loans 2,423 — — — 90 90 119 2,632 Acquired loans 1,461 — — (2,060 ) 219 (1,841 ) 994 614 Pegasus Bank — — — — 30 30 569 599 Total $ 51,389 $ — $ — $ (6,386 ) $ 948 $ (5,438 ) $ 8,287 $ 54,238 The following table details the amount of allowance for credit losses by class of loans for the period presented, on the basis of impairment methodology used by the Company. Allowance for Credit Losses December 31, 2019 Individually evaluated for impairment Collectively evaluated for impairment (Dollars in thousands) BancFirst Real estate: Non-residential real estate owner occupied $ 900 $ 6,140 Non-residential real estate other 990 10,167 Residential real estate permanent mortgage 531 2,856 Residential real estate other 2,026 8,123 Non-consumer non-real estate 2,902 12,439 Consumer other 343 2,976 Other loans 13 2,619 Acquired loans — 614 Pegasus Bank — 599 Total $ 7,705 $ 46,533 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, 2019 Individually evaluated for impairment Collectively evaluated for impairment Loans acquired with deteriorated credit quality (Dollars in thousands) BancFirst Real estate: Non-residential real estate owner occupied $ 21,690 $ 685,726 $ — Non-residential real estate other 23,933 1,113,242 — Residential real estate permanent mortgage 9,468 331,104 — Residential real estate other 17,898 902,934 — Non-consumer non-real estate 27,016 1,427,377 — Consumer other 3,090 359,264 — Other loans 231 153,784 — Acquired loans 10,470 143,351 860 Pegasus Bank — 428,567 2,138 Total $ 113,796 $ 5,545,349 $ 2,998 Purchased Credit Deteriorated Loans The Company has purchased loans, for which there was, at acquisition, evidence of more than insignificant deterioration of credit quality since origination. The purchased credit deteriorated loans for the period are as follows: Loans acquired with deteriorated credit quality (Dollars in thousands) For the year ended December 31, 2020 Purchase price of loans at acquisition $ 1,761 Allowance for credit losses at acquisition 502 Par value of acquired loans at acquisition $ 2,263 Collateral Dependent Loans A loan is considered collateral-dependent when the borrower is experiencing financial difficulty and repayment is expected to be provided substantially through the operation or sale of the collateral. During the year ended December 31, 2020, no material amount of interest income was recognized on collateral-dependent loans subsequent to their classification as collateral-dependent. The following table summarizes collateral-dependent gross loans held for investment by collateral type and the related specific allocation as follows: Collateral Type Real Estate Business Assets Energy Reserves Other Assets Total Specific Allocation As of December 31, 2020 (Dollars in thousands) BancFirst Real estate: Commercial real estate owner occupied $ 848 $ — $ — $ — $ 848 $ 226 Commercial real estate non-owner occupied 4,719 — — — 4,719 1,000 Construction and development < 60 months — — — — — — Construction residential real estate < 60 months — — — — — — Residential real estate first lien 860 — — — 860 151 Residential real estate all other 866 — — — 866 616 Farmland 3,258 — — — 3,258 1,114 Commercial and agricultural non-real estate — 8,460 — 413 8,873 2,813 Consumer non-real estate — — — 109 109 58 Oil and gas — — — — — — Other loans — 13 — — 13 12 Pegasus Bank 1,257 — — — 1,257 222 Total collateral-dependent loans held for investment $ 11,808 $ 8,473 $ — $ 522 $ 20,803 $ 6,212 Impaired Loans Prior to the adoption of ASC 326, loans were considered impaired when, based on current information and events, it was probable the Company would 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 was impaired, a specific valuation allowance may be allocated, if necessary, so that the loan was reported, net of allowance for credit loss, at the present value of future cash flows using the loan’s existing rate, or the fair value of collateral if repayment was expected solely from the collateral. During the year ended December 31, 2019 no material amount of interest income was recognized on impaired loans subsequent to their classification as impaired. The following table presents impaired loans, segregated by class of loans. Impaired Loans Unpaid Principal Balance Recorded Investment with Allowance Related Allowance Average Recorded Investment (Dollars in thousands) As of December 31, 2019 BancFirst Real estate: Non-residential real estate owner occupied $ 13,253 $ 13,000 $ 514 $ 12,868 Non-residential real estate other 3,973 3,678 300 3,946 Residential real estate permanent mortgage 3,445 3,129 242 2,968 Residential real estate other 7,117 4,487 946 5,567 Non-consumer non-real estate 11,598 11,012 1,005 11,085 Consumer other 969 836 97 844 Other loans 5,711 5,510 105 1,130 Acquired loans 6,421 5,108 2 5,472 Pegasus Bank 2,960 2,138 — 2,161 Total $ 55,447 $ 48,898 $ 3,211 $ 46,041 Non-Cash Transfers from Loans and Premises and Equipment Transfers from loans and premises and equipment to other real estate owned, repossessed assets, and other assets are non-cash transactions, and are not included in the statements of cash flow. Transfers from loans and premises and equipment to other real estate owned, repossessed assets, and other assets during the periods presented are summarized as follows: Year ended December 31, 2020 2019 2018 (Dollars in thousands) Other real estate owned $ 32,093 $ 3,941 $ 5,437 Repossessed assets 1,418 1,473 1,122 Other assets 11,105 — — Total $ 44,616 $ 5,414 $ 6,559 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 Beginning of the Period Additions Collections/ Terminations Balance End of the Period (Dollars in thousands) 2020 $ 20,281 $ 19,682 $ (17,906 ) $ 22,057 2019 19,891 12,371 (11,981 ) 20,281 2018 24,001 7,986 (12,096 ) 19,891

Premises and Equipment, Net and

Premises and Equipment, Net and Other Assets	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Premises and Equipment, Net and Other Assets	(6) PREMISES AND EQUIPMENT, NET AND OTHER ASSETS The following is a summary of premises and equipment by classification: December 31, Estimated Useful Lives 2020 2019 (Dollars in thousands) Land $ 45,792 $ 45,561 Buildings 10 to 40 years 201,606 190,193 Furniture, fixtures and equipment 3 to 15 years 87,001 81,225 Construction in progress 61,300 12,760 Accumulated depreciation (134,022 ) (123,464 ) Premises and equipment, net $ 261,677 $ 206,275 Non-cash items in Premises and Equipment, Net As of December 31, 2020, the Company had approximately $2.4 million in construction in progress for retainage payable. Retainage payable is not remitted to the vendor until completion of the project and is therefore not included in the statement of cash flow. Construction in Progress Construction in progress included in the table above is primarily related to the construction of BancFirst Tower described in Note (2). When construction is completed, the asset will be reclassified as buildings and depreciated over its applicable useful life. Other Assets The Company recorded approximately $11.1 million in equity interest of a previous borrower in the oil and gas industry, which was received through bankruptcy proceedings in the fourth quarter of 2020. This asset is carried at cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. This equity interest is included in other assets on the balance sheet. Low Income Housing Tax Credit Investments The Company invests in affordable housing projects that qualify for the low income housing tax credit (LIHTC), which is designed to promote private development of low income housing. These investments generate a return primarily through realization of federal tax credits, and also through a tax deduction generated by operating losses of the investments. The investments are amortized through tax expense using the proportional amortization method as related tax credits are utilized. The Company is periodically required to provide additional contributions at the discretion of the project sponsors. Although in some cases the Company’s investment may exceed 50% of the equity interest in an entity, the Company does not consolidate these structures as variable interest entities due to the project sponsor’s ability to manage the projects, which is indicative of power in them. Total LIHTC investments were $18.1 million and $20.4 million at December 31, 2020 and 2019, respectively and are included in other assets on the balance sheet. The Company recognized tax credits and other tax benefits of $5.6 million, $5.4 million and $5.4 million in 2020, 2019 and 2018, respectively and amortization expense of $4.6 million, $4.5 million and $4.4 million in 2020, 2019 and 2018, respectively resulting from LIHTC investments. Additional contributions are committed during the investment periods through the year 2032. Unfunded commitments to these investments as of December 31, 2020 totaled $19.4 million. New Market Tax Credit Investments The Company also invests in active low income community businesses that qualify for New Market Tax Credits (NMTC). NMTC investments are made through Community Development Entities (CDE) and such entities are qualified through the US Department of the Treasury. NMTCs are earned for a qualified entity investment made by a taxpayer in CDEs if substantially all of the investment is used by the CDE to make qualified investments. It is through its equity contributions into the CDE entities that the Company is able to receive the benefits of the NMTCs. The amount of the NMTC is equal to 39% of the qualified investment taken over a seven year period. The investments are amortized through other noninterest expense using the effective yield method as related tax credits are utilized. The Company does not consolidate these CDEs as variable interest entities due to the control the allocatee of the tax credits has over the entity. Total NMTC investments were $18.5 million and $21.8 million at December 31, 2020 and 2019, respectively and are included in other assets on the balance sheet. The Company recognized tax credits of $4.0 million, $4.5 million and $1.8 million in 2020, 2019 and 2018, respectively and amortization expense of $3.3 million, $3.7 million, and $1.4 million in 2020, 2019 and 2018, respectively resulting from NMTC investments. NMTC investments are funded in full in the year they begin. There are no unfunded commitments.

Intangible Assets and Goodwill

Intangible Assets and Goodwill	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets and Goodwill	(7) INTANGIBLE ASSETS AND GOODWILL The following is a summary of intangible assets: Gross Carrying Amount Accumulated Amortization Net Carrying Amount (Dollars in thousands) As of December 31, 2020 Core deposit intangibles $ 33,411 $ (15,076 ) 18,335 Customer relationship intangibles 3,350 (2,686 ) 664 Total $ 36,761 $ (17,762 ) $ 18,999 As of December 31, 2019 Core deposit intangibles $ 35,856 $ (14,131 ) $ 21,725 Customer relationship intangibles 3,391 (2,508 ) 883 Total $ 39,247 $ (16,639 ) $ 22,608 The evaluation of intangible assets for the year ended December 31, 2019 resulted in an impairment of customer relationship intangibles of approximately $353,000 related to BancFirst Insurance Services, Inc. Estimated amortization of intangible assets for the next five years, as of December 31, 2020, is as follows (dollars in thousands): Estimated Amortization 2021 $ 2,977 2022 2,710 2023 2,693 2024 2,693 2025 2,476 At December 31, 2020, the weighted-average remaining life of all intangible assets was approximately 7.2 years which consisted of customer relationship intangibles with a weighted-average life of 4.0 years and core deposit intangibles with a weighted-average life of 7.3 years. The following is a summary of goodwill by business segment: Other Executive, Metropolitan Community Pegasus Financial Operations Banks Banks Bank Services & Support Consolidated (Dollars in thousands) Year Ended December 31, 2020 Balance at beginning of period $ 13,767 $ 59,894 $ 68,855 $ 5,464 $ 624 $ 148,604 Acquisitions — 1,318 — — — 1,318 Balance at end of period $ 13,767 $ 61,212 $ 68,855 $ 5,464 $ 624 $ 149,922 Year Ended December 31, 2019 Balance at beginning of period $ 13,767 $ 59,894 $ — $ 5,464 $ 624 $ 79,749 Acquisitions — — 68,855 — — 68,855 Balance at end of period $ 13,767 $ 59,894 $ 68,855 $ 5,464 $ 624 $ 148,604 The Company acquired Citizens on March 5, 2020, which added $1.3 million in goodwill. The Company acquired Pegasus Bank on August 15, 2019, which added $68.9 million in goodwill. The Company did not apply push down accounting and therefore the goodwill associated with this acquisition is included at the holding company level.

Time Deposits

Time Deposits	12 Months Ended
	Dec. 31, 2020
Deposits [Abstract]
Time Deposits	(8) TIME DEPOSITS Time deposits include certificates of deposit and individual retirement accounts. At December 31, 2020, the scheduled maturities of all time deposits are as follows (Dollars in thousands): 2021 $ 489,397 2022 100,196 2023 41,245 2024 23,696 2025 18,419 Thereafter 31 Total $ 672,984 The following table is a summary of time deposits that meet or exceed the current FDIC insurance limit for the periods presented: December 31, 2020 2019 (Dollars in thousands) Time deposits of $250,000 or more 154,646 153,987

Short-Term Borrowings

Short-Term Borrowings	12 Months Ended
	Dec. 31, 2020
Short Term Borrowings [Abstract]
Short-Term Borrowings	(9) SHORT-TERM BORROWINGS The following is a summary of short-term borrowings: December 31, 2020 2019 (Dollars in thousands) Federal funds purchased $ 1,100 $ 1,100 Weighted average interest rate 0.30 % 2.19 % End of period interest rate 0.05 % 1.45 % Federal funds purchased represent borrowings of overnight funds from other financial institutions.

Line of Credit

Line of Credit	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Line of Credit	(10) LINES OF CREDIT 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 $838.3 million, are pledged as collateral for the borrowings under the line of credit. As of December 31, 2020, the Company had the ability to draw up to $651.3 million on the FHLB line of credit based on FHLB stock holdings of $555,600 with no advances outstanding. In addition, the Company had a revolving line of credit with another financial institution with the ability to draw up to $10.0 million with no advances outstanding. This line of credit had a variable rate based on prime rate minus 25 basis points and matured in the third quarter of 2020.

Junior Subordinated Debentures

Junior Subordinated Debentures	12 Months Ended
	Dec. 31, 2020
Offsetting [Abstract]
Junior Subordinated Debentures	(11) JUNIOR SUBORDINATED DEBENTURES In January 2004, the Company established BFC Capital Trust II (“BFC II”), a trust formed under the Delaware Business Trust Act. The Company 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 the Company. 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 the Company. During any deferral period or during any event of default, the Company 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. On October 8, 2015, the Company acquired CSB Bancshares Statutory Trust I (CSB Trust I), a trust formed under the Delaware Business Trust Act, from the merger of CSB Bancshares Inc. CSB Trust I had issued $5.0 million aggregate liquidation amount of floating rate capital securities to other purchasers and $155,000 aggregate liquidation amount of common securities to CSB Bancshares Inc., which were assumed by the Company as a result of the merger. The proceeds from the sale of the securities of CSB Trust I were invested in $5.2 million of Floating Rate Junior Subordinated Deferrable Interest Debentures of CSB Bancshares Inc., which were assumed by the Company as a result of the merger. Interest payments on the $5.2 million of Floating Rate Junior Subordinated Deferrable Interest Debentures were payable March 15, June 15, September 15 and December 15 of each year. The interest rate on the $5.2 million of Floating Rate Junior Subordinated Deferrable Interest Debentures was set at three month LIBOR plus 182 basis points. The Floating Rate Junior Subordinated Deferrable Interest Debentures was due September 15, 2036. On December 17, 2018 the Company redeemed the Floating Rate Junior Subordinated Deferrable Interest Debentures and subsequently dissolved CSB Trust I.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 2018 (Dollars in thousands) Current taxes: Federal $ 25,974 $ 26,247 $ 23,700 State 7,443 7,288 7,083 Deferred taxes (9,491 ) 1,148 3,155 Total income taxes $ 23,926 $ 34,683 $ 33,938 Income tax (benefit) expense applicable to securities transactions approximated $(82,000), $171,000 and $10,000 for the years ended December 31, 2020, 2019 and 2018, respectively. A reconciliation of tax expense at the federal statutory tax rate applied to income before taxes is presented in the following table. The federal statutory tax rate was 21% in 2020, 2019 and 2018: Year Ended December 31, 2020 2019 2018 (Dollars in thousands) Tax expense at the federal statutory tax rate $ 25,937 $ 35,377 $ 33,546 Increase (decrease) in tax expense from: Tax-exempt income, net (507 ) (581 ) (510 ) Modified endowment life contracts (508 ) (519 ) (558 ) Share based compensation excess tax benefit (412 ) (765 ) (917 ) Tax deductible dividends paid on ESOP (453 ) — — State tax expense, net of federal tax benefit 5,606 5,757 5,595 Utilization of tax credits: New markets tax credits, net of tax expense (3,121 ) (3,547 ) (1,422 ) Low-income housing tax credits, net of amortization (1,273 ) (1,266 ) (1,273 ) Other tax credits (320 ) — — Other, net (1,023 ) 227 (523 ) Total tax expense $ 23,926 $ 34,683 $ 33,938 The net deferred tax asset consisted of the following and is reported in other assets: December 31, 2020 2019 (Dollars in thousands) Provision for credit losses $ 22,500 $ 13,763 Write-downs of other real estate owned 143 181 Deferred compensation 2,325 2,268 Stock-based compensation 1,672 1,514 Investments in partnership interests 4,695 3,677 Other 405 903 Gross deferred tax assets 31,740 22,306 Unrealized net gains on securities (2,513 ) (1,187 ) Premium on securities of banks acquired (144 ) (153 ) Intangibles (6,135 ) (6,757 ) Basis difference related to tax credits (2,127 ) (2,015 ) Depreciation (11,529 ) (10,349 ) Prepaid expense deducted (1,208 ) (1,000 ) Other (178 ) (180 ) Gross deferred tax liabilities (23,834 ) (21,641 ) Net deferred tax asset $ 7,906 $ 665 The Company recognizes accrued interest and penalties related to unrecognized tax benefits, if applicable, in income tax expense. During the years ended December 31, 2020, 2019 and 2018, 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 tax return years 2017 to 2019. In addition, the 2018 return will remain open through 2023 due to amending it in 2020. 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.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	(13) STOCK-BASED COMPENSATION The Company has had a nonqualified incentive stock option plan (the “BancFirst ISOP”) since May 1986. At December 31, 2020, there were 190,500 shares available for future grants. The BancFirst ISOP will terminate on December 31, 2024, if not extended. 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. 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 has had the BancFirst Corporation Non-Employee Directors’ Stock Option Plan (the “BancFirst Directors’ Stock Option Plan”) since June 1999. Each non-employee director is granted an option for 10,000 shares. At December 31, 2020, there were 30,000 shares available for future grants. The BancFirst Directors’ Stock Option Plan will terminate on December 31, 2024, if not extended. 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. 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: Wgtd. Avg. Wgtd. Avg. Remaining Aggregate Exercise Contractual Intrinsic Options Price Term Value (Dollars in thousands, except option data) Year Ended December 31, 2020 Outstanding at December 31, 2019 1,257,730 $ 32.70 Options granted 171,000 48.89 Options exercised (76,650 ) 20.53 Options canceled, forfeited, or expired (9,000 ) 58.26 Outstanding at December 31, 2020 1,343,080 35.28 8.61Yrs $ 31,453 Exercisable at December 31, 2020 710,330 25.06 6.94Yrs $ 23,894 Year Ended December 31, 2019 Outstanding at December 31, 2018 1,216,700 $ 28.48 Options granted 178,500 56.87 Options exercised (107,470 ) 21.23 Options canceled, forfeited, or expired (30,000 ) 46.42 Outstanding at December 31, 2019 1,257,730 32.70 9.28Yrs $ 37,408 Exercisable at December 31, 2019 644,730 23.09 7.10Yrs $ 25,370 The following table has additional information regarding options exercised under both the BancFirst ISOP and the BancFirst Directors’ Stock Option Plan: Year Ended December 31, 2020 2019 2018 (Dollars in thousands) Total intrinsic value of options exercised $ 2,315 $ 3,982 $ 4,810 Cash received from options exercised 1,574 2,282 2,159 Tax benefit realized from options exercised 590 1,014 1,225 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, 2020 2019 2018 (Dollars in thousands) Stock-based compensation expense $ 1,516 $ 1,277 $ 1,352 Tax benefit 386 325 345 Stock-based compensation expense, net of tax $ 1,130 $ 952 $ 1,007 The Company will continue to amortize the unearned stock-based compensation expense over the remaining vesting period of approximately seven years. The following table shows the unearned stock-based compensation expense: December 31, 2020 (Dollars in thousands) Unearned stock-based compensation expense $ 4,888 The following table shows the assumptions used for computing stock-based compensation expense under the fair value method on options granted during the periods presented: Year Ended December 31, 2020 2019 2018 Weighted average grant-date fair value per share of options granted $ 10.85 $ 13.34 $ 14.71 Risk-free interest rate 0.64 to 1.13% 1.55 to 2.76% 2.55 to 3.05% Dividend yield 2.00 % 2.00 % 2.00 % Stock price volatility 22.84 to 36.10% 22.93 to 23.63% 23.05 to 23.95% Expected term 10 Yrs 10 Yrs 10 Yrs 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. The Company accounts for forfeitures as they occur. The Company has had the BancFirst Corporation Directors’ Deferred Stock Compensation Plan (the “BancFirst Deferred Stock Compensation Plan”) since May 1999. As of December 31, 2020 there are 21,943 shares available for future issuance under the BancFirst Deferred Stock Compensation Plan. The BancFirst Deferred Stock Compensation Plan will terminate on December 31, 2024, if not extended. 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. There were 8,218 and 9,542 shares of common stock distributed from the BancFirst Deferred Stock Compensation Plan during the years ended December 31, 2020 and 2019, respectively. A summary of the accumulated stock units is as follows: December 31, 2020 2019 Accumulated stock units 148,278 143,362 Average price $ 28.57 $ 27.17

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2020
Compensation And Retirement Disclosure [Abstract]
Retirement Plans	(14) RETIREMENT PLANS Since January 1, 2009, the Company has had two individual retirement plans. The Thrift Plan (“401(k)”) and Employee Stock Ownership Plan (“ESOP”) cover all eligible employees, as defined in the plans, of the Company and its subsidiaries. The 401(k) 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, as determined by the Company’s Board of Directors. The ESOP sponsor purchases shares from the open market. These shares are included in the calculation of the basic earnings per share. Dividends issued on these shares are reinvested into the ESOP. The ESOP is not leveraged. The aggregate amounts of contributions by the Company to the 401(k) and ESOP are shown in the following table: December 31, 2020 2019 2018 (Dollars in thousands) 401(k) contributions $ 2,986 $ 2,526 $ 2,465 ESOP contributions 3,689 4,403 4,073 Total contributions $ 6,675 $ 6,929 $ 6,538

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Stockholders' Equity	(15) STOCKHOLDERS’ EQUITY As of December 31, 2020, 2019 and 2018 the Company’s authorized and outstanding preferred and common stock was as follows: No. of Shares Authorized at No. of Shares Outstanding at December 31, Class of Stock December 31, 2020 2020 2019 2018 Par Value Per Share Dividends Voting Rights Senior Preferred 10,000,000 — — — $ 1.00 As declared Voting 10% Cumulative Preferred 900,000 — — — 5.00 As declared Non-voting Common 40,000,000 32,719,852 32,694,268 32,603,926 1.00 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, 2020, 2019 and 2018 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, 2020 2019 2018 Number of shares repurchased 59,284 26,670 151,264 Average price of shares repurchased $ 52.26 $ 60.04 $ 52.32 Shares remaining to be repurchased 62,782 122,066 148,736 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, 2021, approximately $102.1 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, BancFirst and Pegasus Bank 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, BancFirst’s and Pegasus Bank’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, 2020, the Company, BancFirst and Pegasus Bank met all capital adequacy requirements to which they are subject. The actual and required capital amounts and ratios are shown in the following table: Required To Be Well For Capital With Capitalized Under Adequacy Capital Conservation Prompt Corrective Actual Purposes Buffer Action Provisions Amount Ratio Amount Ratio Amount Ratio Amount Ratio (Dollars in thousands) As of December 31, 2020: Total Capital (to Risk Weighted Assets)- BancFirst Corporation $ 997,383 15.64 % $ 510,110 8.00% $ 669,519 10.50 % N/A N/A BancFirst 898,714 15.59 % 461,142 8.00% 605,248 10.50 % $ 576,427 10.00 % Pegasus Bank 70,922 11.85 % 47,893 8.00% 62,860 10.50 % 59,866 10.00 % Common Equity Tier 1 Capital (to Risk Weighted Assets)- BancFirst Corporation $ 891,534 13.98 % $ 286,937 4.50% $ 446,346 7.00 % N/A N/A BancFirst 806,478 13.99 % 259,392 4.50% 403,499 7.00 % $ 374,678 6.50 % Pegasus Bank 66,150 11.05 % 26,940 4.50% 41,906 7.00 % 38,913 6.50 % Tier 1 Capital (to Risk Weighted Assets)- BancFirst Corporation $ 917,534 14.39 % $ 382,583 6.00% $ 541,992 8.50 % N/A N/A BancFirst 826,478 14.34 % 345,856 6.00% 489,963 8.50 % $ 461,142 8.00 % Pegasus Bank 66,150 11.05 % 35,920 6.00% 50,886 8.50 % 47,893 8.00 % Tier 1 Capital (to Total Assets)- BancFirst Corporation $ 917,534 9.63 % $ 380,952 4.00% N/A N/A N/A N/A BancFirst 826,478 9.48 % 348,666 4.00% N/A N/A $ 435,833 5.00 % Pegasus Bank 66,150 8.10 % 32,682 4.00% N/A N/A 40,852 5.00 % As of December 31, 2019: Total Capital (to Risk Weighted Assets)- BancFirst Corporation $ 910,561 14.42 % $ 505,050 8.00% $ 662,878 10.50 % N/A N/A BancFirst 827,928 14.14 % 468,107 8.00% 614,390 10.50 % $ 585,134 10.00 % Pegasus Bank 63,817 14.15 % 36,083 8.00% 47,359 10.50 % 45,104 10.00 % Common Equity Tier 1 Capital (to Risk Weighted Assets)- BancFirst Corporation $ 830,323 13.15 % $ 284,091 4.50% $ 441,919 7.00 % N/A N/A BancFirst 753,659 12.88 % 263,310 4.50% 409,594 7.00 % $ 380,337 6.50 % Pegasus Bank 60,214 13.35 % 20,297 4.50% 31,573 7.00 % 29,317 6.50 % Tier 1 Capital (to Risk Weighted Assets)- BancFirst Corporation $ 856,323 13.56 % $ 378,788 6.00% $ 536,616 8.50 % N/A N/A BancFirst 773,659 13.22 % 351,080 6.00% 497,364 8.50 % $ 468,107 8.00 % Pegasus Bank 60,214 13.35 % 27,062 6.00% 38,338 8.50 % 36,083 8.00 % Tier 1 Capital (to Total Assets)- BancFirst Corporation $ 856,323 10.28 % $ 333,171 4.00% N/A N/A N/A N/A BancFirst 773,659 10.22 % 302,845 4.00% N/A N/A $ 378,556 5.00 % Pegasus Bank 60,214 8.58 % 28,058 4.00% N/A N/A 35,072 5.00 % As of December 31, 2020, the most recent notification from the Federal Reserve Bank of Kansas City and the FDIC categorized BancFirst and Pegasus Bank as “well capitalized” under the prompt corrective action provisions. The Common Equity Tier 1 Capital of the Company, BancFirst and Pegasus Bank includes common stock and related paid-in capital and retained earnings. In connection with the adoption of the Basel III Capital Rules, the election was made to opt-out of the requirement to include most components of accumulated other comprehensive income in Common Equity Tier 1 Capital. Common Equity Tier 1 Capital for the Company, BancFirst and Pegasus Bank is reduced by goodwill and other intangible assets, net of associated deferred tax liabilities. The Company’s trust preferred securities have continued to be included in Tier 1 capital as the Company’s total assets do not exceed $ 15 billion. There are no conditions or events since the most recent notification of BancFirst and Pegasus Bank ’s capital category that management believes would materially change its category under capital requirements existing as of the report date. In April 2020, the Company began originating loans to qualified small businesses under the PPP administered by the SBA. Federal bank regulatory agencies have issued an interim final rule that permits banks to neutralize the regulatory capital effects of participating in the Paycheck Protection Program Lending Facility (the “PPP Facility”) and clarify that PPP loans have a zero percent risk weight under applicable risk-based capital rules. Specifically, a bank may exclude all PPP loans pledged as collateral to the PPP Facility from its average total consolidated assets for the purposes of calculating its leverage ratio, while PPP loans that are not pledged as collateral to the PPP Facility are included. The Company’s PPP loans are included in the calculation of the Company’s leverage ratio as of December 31, 2020 as the Company did not utilize the PPP Facility for funding purposes. As discussed in Note 1 – Description of Business and Summary of Significant Accounting Policies, in connection with the adoption of ASC 326, the Company recognized an after-tax cumulative effect reduction to retained earnings totaling $2.3 million. In February 2019, the federal bank regulatory agencies issued a final rule (the “2019 CECL Rule”) that revised certain capital regulations to account for changes to credit loss accounting under U.S. GAAP. The 2019 CECL Rule included a transition option that allows banking organizations to phase in, over a three-year period, the day-one adverse effects of CECL on their regulatory capital ratios (three-year transition option). In March 2020, the federal bank regulatory agencies issued an interim final rule that maintains the three-year transition option of the 2019 CECL Rule and also provides banking organizations that were required under U.S. GAAP (as of January 2020) to implement CECL before the end of 2020 the option to delay for two years an estimate of the effect of CECL on regulatory capital, relative to the incurred loss methodology’s effect on regulatory capital, followed by a three-year transition period (five-year transition option). The Company elected not to adopt the five-year transition option.

Net Income Per Common Share

Net Income Per Common Share	12 Months Ended
	Dec. 31, 2020
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 (Numerator) Shares (Denominator) Per Share Amount (Dollars in thousands, except per share data) Year Ended December 31, 2020 Basic Income available to common stockholders $ 99,586 32,672,522 $ 3.05 Dilutive effect of stock options — 538,430 Diluted Income available to common stockholders plus assumed exercises of stock options $ 99,586 33,210,952 $ 3.00 Year Ended December 31, 2019 Basic Income available to common stockholders $ 134,879 32,639,396 $ 4.13 Dilutive effect of stock options — 690,448 Diluted Income available to common stockholders plus assumed exercises of stock options $ 134,879 33,329,844 $ 4.05 Year Ended December 31, 2018 Basic Income available to common stockholders $ 125,814 32,689,228 $ 3.85 Dilutive effect of stock options — 741,486 Diluted Income available to common stockholders plus assumed exercises of stock options $ 125,814 33,430,714 $ 3.76 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 were anti-dilutive for the period. Shares Average Exercise December 31, 2020 402,575 $ 52.72 December 31, 2019 180,989 54.73 December 31, 2018 92,738 53.17

Condensed Parent Company Financ

Condensed Parent Company Financial Statements	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Condensed Parent Company Financial Statements	(17) CONDENSED PARENT COMPANY FINANCIAL STATEMENTS BALANCE SHEETS December 31, 2020 2019 (Dollars in thousands) ASSETS Cash $ 9,081 $ 5,761 Investments in subsidiaries 1,003,017 946,311 Goodwill 69,478 69,478 Core deposit premium 8,622 9,617 Dividends receivable 12,750 11,622 Other assets 5,331 2,313 Total assets $ 1,108,279 $ 1,045,102 LIABILITIES AND STOCKHOLDERS’ EQUITY Other liabilities $ 13,590 $ 13,309 Junior subordinated debentures 26,804 26,804 Stockholders’ equity 1,067,885 1,004,989 Total liabilities and stockholders’ equity $ 1,108,279 $ 1,045,102 STATEMENTS OF INCOME Year Ended December 31, 2020 2019 2018 (Dollars in thousands) OPERATING INCOME Dividends from subsidiaries $ 50,872 $ 77,559 $ 38,326 Interest on interest-bearing deposits 1 1,150 1,151 Other 886 451 16 Total operating income 51,759 79,160 39,493 OPERATING EXPENSE Interest 1,965 1,965 2,172 Other 3,317 5,017 698 Total operating expense 5,282 6,982 2,870 Income before taxes and equity in undistributed earnings of subsidiaries 46,477 72,178 36,623 Allocated income tax benefit 2,610 2,731 3,093 Income before equity in undistributed earnings of subsidiaries 49,087 74,909 39,716 Equity in undistributed earnings of subsidiaries 51,955 61,194 87,404 Amortization of stock-based compensation arrangements of subsidiaries (1,456 ) (1,224 ) (1,306 ) Net income $ 99,586 $ 134,879 $ 125,814 STATEMENTS OF CASH FLOW Year Ended December 31, 2020 2019 2018 (Dollars in thousands) CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 99,586 $ 134,879 $ 125,814 Adjustments to reconcile to net cash provided by operating activities: Equity in undistributed earnings of subsidiaries (51,955 ) (61,194 ) (87,404 ) Amortization of stock-based compensation arrangements of subsidiaries 1,456 1,224 1,306 Other, net 188 (440 ) (2,621 ) Net cash provided by operating activities 49,275 74,469 37,095 INVESTING ACTIVITIES Net cash provided by acquisitions — — 41,347 Payments for investments in subsidiaries (1,000 ) (134,457 ) — Other, net (1,175 ) (418 ) (174 ) Net cash (used in) provided by investing activities (2,175 ) (134,875 ) 41,173 FINANCING ACTIVITIES Issuance of common stock 1,790 2,484 2,238 Common stock acquired (3,098 ) (1,601 ) (7,914 ) Cash dividends paid (42,472 ) (39,805 ) (30,265 ) Redemption of Junior Subordinated debentures — — (5,155 ) Net cash used in financing activities (43,780 ) (38,922 ) (41,096 ) Net increase (decrease) in cash and due from banks 3,320 (99,328 ) 37,172 Cash and due from banks at the beginning of the period 5,761 105,089 67,917 Cash and due from banks at the end of the period $ 9,081 $ 5,761 $ 105,089 SUPPLEMENTAL DISCLOSURE Cash paid during the period for interest $ 1,966 $ 5,131 $ 2,171 Cash received during the period for income taxes, net $ 2,812 $ 4,518 $ 3,647

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
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 Liab

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 (Dollars in thousands) Loan commitments $ 1,779,857 $ 1,618,001 Stand-by letters of credit 96,311 64,702 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 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.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	(20) LEASES Lessee The Company has operating leases, which primarily consist of office space in buildings, ATM locations, storage facilities, parking lots, equipment and land on which it owns certain buildings. Rental expense on all operating leases, including those rented on a monthly or temporary basis were as follows (Dollars in thousands): Year Ending December 31: 2020 $ 1,894 2019 1,633 2018 1,857 As of December 31, 2020, a right of use lease asset included in accrued interest receivable and other assets on the balance sheet totaled $4.4 million, and a related lease liability included in accrued interest payable and other liabilities on the balance sheet totaled $4.3 million. As of December 31, 2020, our operating leases have a weighted-average remaining lease term of 3.3 years and a weighted-average discount rate of 3.1 percent. Maturity of Operating Lease Liabilities December 31, 2020 (Dollars in thousands) 2021 $ 1,413 2022 1,210 2023 706 2024 345 2025 277 Thereafter 887 Total lease payments 4,838 Less imputed interest (508 ) Operating lease liability $ 4,330 Lessor The Company is a lessor of operating leases, which primarily consist of office space in buildings and parking lots. These assets are classified on the balance sheet as premises and equipment. The Company had operating lease revenue of $5.3 million, $6.1 million and $2.5 million for the years ended December 31, 2020, 2019 and 2018, respectively. Lease revenue is included in occupancy, net on the consolidated statement of comprehensive income. Future Minimum Lease Payments to be received The Company does not have operating leases that extend beyond 2030. The following table presents the scheduled minimum future contractual rent to be received under the remaining non-cancelable term of the operating leases: December 31, 2020 (Dollars in thousands) 2021 $ 3,402 2022 2,707 2023 2,313 2024 2,229 2025 1,611 2026-2030 4,355 Total future minimum lease payments $ 16,617

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	(21) 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 (“ASC”) 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 collaterally dependent loans, impaired loans, repossessed 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. Debt Securities Available for Sale Debt securities classified as available for sale are reported at fair value. U.S. Treasuries are valued using Level 1 inputs. Other debt securities available for sale including U.S. federal agencies, registered 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 private label mortgage backed debt securities for which observable information is not readily available. These debt securities are reported at fair value utilizing Level 3 inputs. For these debt securities, management determines the fair value based on replacement cost, the income approach or information provided by outside consultants or lead investors. Discount rates are primarily based on reference to interest rate spreads on comparable securities of similar duration and credit rating as determined by the nationally recognized rating agencies adjusted for a lack of trading volume. Significant unobservable inputs are developed by investment securities professionals involved in the active trading of similar securities. 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 portfolio primarily 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 for pricing mentioned in the preceding paragraph adjusted for the specific issue. Periodically, the Company will validate prices supplied by the independent pricing service by comparison to prices obtained from third party sources. The following table summarizes financial assets and financial liabilities measured at fair value on a recurring basis as of the periods presented, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value: Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Fair Value (Dollars in thousands) December 31, 2020 Debt securities available for sale: U.S. Treasury $ 475,236 $ — $ — $ 475,236 U.S. federal agencies — 19,638 — 19,638 Mortgage-backed securities — 15,696 — 15,696 States and political subdivisions — 28,793 155 28,948 Asset backed securities — — 12,714 12,714 December 31, 2019 Debt securities available for sale: U.S. Treasury $ 414,449 $ — $ — $ 414,449 U.S. federal agencies — 23,024 — 23,024 Mortgage-backed securities — 17,005 — 17,005 States and political subdivisions — 22,531 — 22,531 Asset backed securities — — 12,714 12,714 The changes in Level 3 assets measured at estimated fair value on a recurring basis during the periods presented were as follows: Twelve Months Ended December 31, 2020 2019 (Dollars in thousands) Balance at the beginning of the year $ 12,714 $ 13,443 Transfers from level 2 $ 1,643 — Settlements (1,473 ) (695 ) Total unrealized losses (15 ) (34 ) Balance at the end of the period $ 12,869 $ 12,714 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 year ended December 31, 2020, the Company transferred securities from Level 2 to Level 3 due to a review of the pricing models that determined some state and political subdivisions bonds to be Level 3. During the year ended December 31, 2019, 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. The Company invests in equity securities without readily determinable fair values and utilizes Level 3 inputs. T hese securities are reported at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. The realized and unrealized gains and losses are reported as securities transactions in the noninterest income section of the consolidated statements of comprehensive income. Collateral dependent loans are reported at the fair value of the underlying collateral if repayment is dependent on liquidation of the collateral. When management determines that foreclosure is probable or when the borrower is experiencing financial difficulty at the reporting date and repayment is expected to be provided substantially through the operation or sale of the collateral, expected credit losses are based on the fair value of the collateral at the reporting date, adjusted for selling costs as appropriate. In no case does the fair value of a collateral dependent loan exceed the fair value of the underlying collateral. The collateral dependent loans are adjusted to fair value through a specific allocation of the allowance for credit losses or a direct charge-down of the loan. 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 credit losses or a direct charge-down of the loan. Repossessed assets, upon initial recognition, are measured and adjusted to fair value through a charge-off to the allowance for possible credit losses based upon the fair value of the repossessed 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. The fair value represents end of period values, which approximate fair value measurements that occurred on various measurement dates throughout the period: Total Fair Value Level 3 (Dollars in thousands) As of and for the Year-to-date Period Ended December 31, 2020 Equity securities $ 21,203 Collateral dependent loans 11,347 Repossessed assets 291 Other real estate owned 32,066 As of and for the Year-to-date Period Ended December 31, 2019 Equity securities $ 10,121 Impaired loans (less specific allowance) 45,687 Repossessed assets 465 Other real estate owned 3,024 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 with Banks The carrying amount of these short-term instruments is a reasonable estimate of fair value. Federal Funds Sold The carrying amount of these short-term instruments is a reasonable estimate of fair value. Debt S ecurities Held for Investment For debt 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 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. At December 31, 2020, the Company’s principal subsidiary bank, BancFirst, had approximately $21.6 million in loans at its Hugo, Oklahoma branch that it has entered into an agreement to sell to AmeriState Bank in Atoka, Oklahoma. Loans To determine the fair value of loans, the Company uses an exit price calculation, which takes into account factors such as liquidity, credit and the nonperformance risk of 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. 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, 2020 2019 Carrying Amount Fair Value Carrying Amount Fair Value (Dollars in thousands) FINANCIAL ASSETS Level 2 inputs: Cash and cash equivalents $ 1,616,912 $ 1,616,912 $ 1,868,281 $ 1,868,281 Federal funds sold — — 1,000 1,000 Debt securities held for investment 59 62 1,403 1,403 Loans held for sale 53,719 53,719 11,001 11,001 Level 3 inputs: Debt securities held for investment 2,905 2,922 500 500 Loans, net of allowance for credit losses 6,303,140 6,347,803 5,607,905 5,625,005 FINANCIAL LIABILITIES Level 2 inputs: Deposits 8,064,704 8,084,695 7,483,635 7,497,429 Short-term borrowings 1,100 1,100 1,100 1,100 Junior subordinated debentures 26,804 30,535 26,804 29,324 OFF-BALANCE SHEET FINANCIAL INSTRUMENTS Loan commitments 3,115 2,832 Letters of credit 722 485 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 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, 2020. The evaluation of intangible assets and goodwill for the year ended December 31, 2019 resulted in an impairment of customer relationship intangibles of approximately $353,000 related to BancFirst Insurance Services, Inc.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2020
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 five principal business units are metropolitan banks, community banks, Pegasus Bank, other financial services and executive, operations and support. Metropolitan banks, community banks and Pegasus Bank 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. Pegasus Bank consists of banking locations in the Dallas metropolitan area. 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 five business units are as follows: Metropolitan Banks Community Banks Pegasus Bank Other Financial Services Executive, Operations & Support Eliminations Consolidated (Dollars in thousands) December 31, 2020 Net interest income $ 85,464 $ 175,757 $ 21,360 $ 23,500 $ 79 $ 508 $ 306,668 Provision for credit losses 30,202 29,827 1,916 562 141 — 62,648 Noninterest income 18,664 60,386 1,071 41,549 118,491 (102,939 ) 137,222 Depreciation and amortization 2,639 10,603 760 500 3,922 — 18,424 Other expenses 36,746 111,341 13,831 44,918 33,588 (1,118 ) 239,306 Income before taxes $ 34,541 $ 84,372 $ 5,924 $ 19,069 $ 80,919 $ (101,313 ) $ 123,512 Total assets $ 2,729,886 $ 5,527,611 $ 919,572 $ 137,122 $ 1,073,507 $ (1,175,341 ) $ 9,212,357 Capital expenditures $ 1,087 $ 9,946 $ 1,775 $ 450 $ 53,188 $ — $ 66,446 December 31, 2019 Net interest income $ 86,511 $ 177,330 $ 8,657 $ 5,763 $ 3,660 $ — $ 281,921 Provision for credit losses 2,143 5,606 140 (69 ) 467 — 8,287 Noninterest income 18,608 64,485 483 40,270 152,320 (138,937 ) 137,229 Depreciation and amortization 2,463 10,218 274 603 2,431 — 15,989 Other expenses 37,549 109,044 4,939 25,408 50,941 (2,569 ) 225,312 Income before taxes $ 62,964 $ 116,947 $ 3,787 $ 20,091 $ 102,141 $ (136,368 ) $ 169,562 Total assets $ 2,806,021 $ 4,998,247 $ 738,351 $ 102,442 $ 950,920 $ (1,030,223 ) $ 8,565,758 Capital expenditures $ 4,349 $ 11,219 $ 83 $ 1,220 $ 10,183 $ — $ 27,054 December 31, 2018 Net interest income (expense) $ 84,043 $ 170,096 $ — $ 5,341 $ 996 $ — $ 260,476 Provision for credit losses 79 4,178 — (466 ) 11 — 3,802 Noninterest income 16,625 60,004 — 37,743 137,364 (126,537 ) 125,199 Depreciation and amortization 2,364 9,092 — 588 1,502 — 13,546 Other expenses 36,873 106,674 — 24,895 42,319 (2,186 ) 208,575 Income before taxes $ 61,352 $ 110,156 $ — $ 18,067 $ 94,528 $ (124,351 ) $ 159,752 Total assets $ 2,743,876 $ 4,892,946 $ — $ 84,706 $ 861,782 $ (1,009,052 ) $ 7,574,258 Capital expenditures $ 3,003 $ 21,393 $ — $ 1,035 $ 26,432 $ — $ 51,863 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.

Subsequent Event

Subsequent Event	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Event	(23) SUBSEQUENT EVENT On January 22, 2021, the Company sold approximately $21 million in loans and approximately $38 million in deposits from its Hugo, Oklahoma branch to AmeriState Bank in Atoka, Oklahoma. A gain on the transaction of $2.5 million will be reflected in the first quarter of 2021. On February 19, 2021, the Company entered into a purchase and assumption agreement with The First National Bank and Trust Company of Vinita, Oklahoma to purchase certain assets and assume the deposits and certain other obligations of The First National Bank and Trust Company of Vinita. The First National Bank and Trust Company of Vinita is a nationally chartered bank with banking locations in Vinita and Grove, Oklahoma. These banking locations would become branches of BancFirst. As of December 2020, The First National Bank and Trust Company of Vinita had approximately $285 million in total assets, $209 million in loans, and $258 million in deposits. The purchase and assumption is expected to be completed during the second quarter of 2021 and is subject to regulatory approval.

Description of Business and S_2

Description of Business and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
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 (“BancFirst”), an Oklahoma state-chartered bank headquartered in Oklahoma City, Oklahoma. The Company also conducts operating activities through its wholly-owned subsidiary, Pegasus Bank (“Pegasus Bank”), a Texas state-chartered bank headquartered in Dallas, Texas. BancFirst and Pegasus Bank provide 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; and other services tailored for both individual and corporate customers. BancFirst also offers trust services and acts as executor, administrator, trustee, transfer agent and in various other fiduciary capacities. Through its Technology and Operations Center, BancFirst 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., BancFirst Risk & Insurance Company (consolidated financials include a full year of operations for BancFirst Risk & Insurance Company; however it was dissolved as of December 31, 2020), Pegasus Bank, and BancFirst and its subsidiaries. The principal operating subsidiaries of BancFirst are Council Oak Investment Corporation, Council Oak Real Estate Inc., BFTower, LLC, BFC-PNC LLC, and BancFirst Agency, Inc. 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 2019 and 2018 have been reclassified to conform to the 2020 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 U.S. GAAP 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 credit 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 invests in debt securities. Any sales of debt 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. Debt 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 debt securities available for sale are reported as a component of stockholders’ equity, net of income tax. Gains or losses from sales of debt securities are based upon the book values of the specific debt securities sold. Debt 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 debt securities in an unrealized loss position at least quarterly. The Company first assesses whether it intends to sell or it is more-likely-than-not that it will be required to sell the securities before recovery of the amortized cost basis. If either of these criteria is met, the securities amortized cost basis is written down to fair value as a current period expense. If either of the above criteria is not met, the Company evaluates whether the decline in fair value is the result of credit losses or other factors. In making this assessment, the Company considers, among other things, the period of time the security has been in an unrealized loss position, and performance of any underlying collateral and adverse conditions specifically related to the security. The Company does not consider the unrealized position of its debt securities to be the result of credit factors, because the decline in fair value is attributable to changes in interest rates and illiquidity, and not credit quality, and the Company does not have the intent to sell these securities and it is likely that it will not be required to sell the securities before their anticipated recovery. Therefore, the Company has not recorded an allowance for credit losses against its debt securities portfolio, as the credit risk is not material. The Company does not engage in securities trading activities. The Company invests in equity securities without readily determinable fair values and utilizes Level 3 inputs. These securities are reported at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. The realized and unrealized gains and losses are reported as securities transactions in the noninterest income section of the consolidated statements of comprehensive income. Equity securities are reported in other assets on the balance sheet. The Company reviews its portfolio of equity securities for impairment at least quarterly. Prior to the adoption of ASC 326, declines in the fair value of held-to-maturity and available-for-sale securities below their cost that were deemed to be other than temporary were reflected in earnings as realized losses. In estimating other-than-temporary impairment losses prior to January 1, 2020, management considered, among other things, (i) the length of time and the extent to which the fair value had been less than cost, (ii) the financial condition and near-term prospects of the issuer and (iii) the intent and our ability to retain our investment in the issuer 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 the use of prepayment penalties. 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 and residential and employment stability. 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 credit losses. Interest on all performing loans is recognized, on a simple interest basis, based upon the principal amount outstanding. See Note (5) for loan disclosures. 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. 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.
Acquired Loans	Acquired Loans Loans acquired through business combinations are required to be carried at fair value as of the date of the combination. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction (that is, not a forced liquidation or distressed sale) between market participants at the measurement date. An allowance for credit loss is recorded for these acquired loans depending on whether the acquired loans are purchase credit deteriorated or non-purchase credit deteriorated. An allowance for credit loss for non-purchase credit deteriorated loans is determined and recorded in a manner consistent with originated loans. That is, the allowance for credit loss is calculated based on the loan’s amortized cost basis (i.e., the acquisition date fair value in a business combination) and is established through a charge to provision expense at the acquisition date. An allowance for credit loss for purchase credit deteriorated loans is recorded as an adjustment to the loans, in addition to the fair value amount recorded, as of the acquisition date, and not through provision expense. The acquisition date fair value plus the allowance for credit loss equals the loans new amortized cost basis as of the acquisition date. The difference between the new amortized cost basis and the unpaid principal balance of the loan represents the non-credit purchase discount/premium recorded. 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 credit 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 fair value. 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. At December 31, 2020, loans held for sale included loans at its Hugo, Oklahoma branch that it has entered into an agreement to sell to AmeriState Bank in Atoka, Oklahoma.
Allowance for Credit Losses	Allowance for Credit Losses The allowance for credit losses is a valuation account that is deducted from the loans amortized cost basis to present the net amount expected to be collected on the loans. Loans are charged off against the allowance when management believes the uncollectibility of a loan balance is confirmed. Expected recoveries do not exceed the aggregate of amounts previously charged-off and expected to be charged-off. The allowance for credit losses is increased by provisions charged to operating expense and is reduced by net loan charge-offs. The allowance is estimated using relevant available information, from internal and external sources, relating to past events, current conditions, and reasonable and supportable forecasts. Historical credit loss experience provides the basis for the estimation of expected credit losses. Adjustments to historical loss information are made for differences in current loan-specific risk characteristics such as differences in underwriting standards, portfolio mix, delinquency level, or term as well as for changes in environmental conditions, such as the political, legal, and regulatory environment, technology and consumer preferences. Historical loss information is also adjusted for reasonable and supportable changes in national and local economic conditions. If a loan is individually evaluated a specific allowance is provided, if necessary, so that the loan is reported net, at the fair value of collateral. Interest payments on collateral dependent 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. Loans, or portions thereof, are charged off when deemed uncollectible. Prior to the adoption of ASC 326, the allowance for credit losses on loans was a contra-asset valuation account established through a provision for loan losses charged to expense, which represented management’s best estimate of inherent losses that had been incurred within the existing portfolio of loans. The allowance for credit losses on loans included allowance allocations calculated in accordance with ASC Topic 310, “Receivables” and allowance allocations calculated in accordance with ASC Topic 450, “Contingencies.” Loans were reported as impaired when, based on then current information and events, it was probable we would 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 was evaluated in total for smaller-balance loans of a similar nature and on an individual loan basis for other loans. If a loan was impaired, a specific valuation allowance was allocated, if necessary, so that the loan was 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 was expected solely from the collateral. Interest payments on impaired loans were typically applied to principal unless collectability of the principal amount was reasonably assured, in which case interest was recognized on a cash basis. Impaired loans, or portions thereof, were charged off when deemed uncollectible.
Nonaccrual Policy	Nonaccrual Policy A loan is placed on nonaccrual status when, in the opinion of management, the future collectability of both interest and 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. 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.
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. Construction in progress includes all the costs of construction associated with the building of fixed long-term assets and is included in premises and equipment, net as an asset. When construction is completed, the asset is reclassified as buildings or leasehold improvements and depreciated over its applicable useful life.
Leases	Leases Certain operating leases are included as right of use lease assets in accrued interest receivable and other assets on the balance sheet and a related lease liability is included in accrued interest payable and other liabilities on the balance sheet. Right of use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The lease liability is measured as the present value of the unpaid lease payments, and the right of use assets value is derived from the calculation of the lease liability. To calculate the discount rate for each lease, the Company uses the rate implicit in the lease if available, otherwise an appropriate FHLB advance borrowing rate is used that correlates with the term of the lease.
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 credit 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. 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 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.
Advertising Costs	Advertising Costs Advertising costs are expensed as incurred. Advertising costs for the year ended December 31, 2020 were $3.3 million. Advertising costs for the years ended December 31, 2019 and 2018 were $3.8 million and $3.5 million, respectively.
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 balance sheet 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.
Revenue Recognition	Revenue Recognition In addition to lending and related activities, the Company offers various services to customers that generate revenue. Contract performance typically occurs in one year or less. Incremental costs of obtaining a contract are expensed when incurred when the amortization period is one year or less. Sales of real estate The sale of real estate property is generally recognized, along with any associated gain or loss, when control of the property transfers to the buyer. Service and transaction fees on depository accounts Customers often pay certain fees to the bank to access the cash on deposit including certain non-transactional fees such as account maintenance or dormancy fees, and certain transaction based fees such as ATM, wire transfer, or foreign exchange fees. Revenue is recognized when the transactions occur or as services are performed over primarily monthly or quarterly periods. Payment is typically received in the period the transactions occur, or in some cases, within 90 days of the service period. Interchange Fees Interchange fees, or “swipe” fees, are charges that merchants pay to the processors who, in turn, share that revenue with us and other card-issuing banks for processing electronic payment transactions. Interchange fees represent the portion of the debit card transaction amount that the card issuer retains to compensate it for processing transactions and providing rewards. Interchange fees are settled and recognized on a daily or monthly basis. Insurance Commissions and Fees Insurance commissions are received on the sale of insurance products, and revenue is recognized upon the placement date of the insurance policies or when such commissions are received. Payment is normally received within the policy period. In addition to placement, the Company also provides insurance policy related risk management services. Revenue is recognized as these services are provided. Performance-based commissions are recognized when received or earlier when, upon consideration of past results and current condition, the revenue is deemed not probable of reversal. For accounts billed by BancFirst Insurance Services, Inc., commission revenue is recognized at the later of the billing date or the effective date of the related insurance policies. Commission revenue, for accounts that are directly billed by the insurance company to the insured, is recognized when determinable by BancFirst Insurance Services, Inc., which is generally when such commissions are received. BancFirst Insurance Services, Inc. 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 they place. Contingent commissions from insurance companies are recognized when determinable, which is generally when such commissions are received. Trust BancFirst offers trust services and acts as executor, administrator, trustee, transfer agent and in various other fiduciary capacities. There are four basic types of fees that are included in the trust department income. Administrative fees are assessed for managing trust accounts. Shareholder fees are received in connection with holding specific fund share classes. In return for these services, the mutual fund (or its distributor or investment advisor) pay a fee to BancFirst. Oil and gas fees are assessed for management of oil and gas related activities. There are also other types of fees charged on a one time basis such as those related to opening and closing trust accounts. BancFirst records trust fees on a monthly, quarterly or annual basis based on the size of the asset being managed. Fees may be fixed or, where applicable, based on a percentage of transaction size of managed assets. These fees are recorded as revenue at the time the fee is billed, according to the agreement with the customer.
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 debt 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 Standards Adopted During Current Period: In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2018-13, “Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement (Topic 820).” ASU 2018-13 modifies disclosure requirements on fair value measurements in Topic 820. ASU No. 2018-13 was adopted on January 1, 2020 and did not have a significant impact on the Company’s financial statements. On January 1, 2020, the Company adopted ASU No. 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments.” Accounting Standards Codification (“ASC”) 326 replaces the incurred loss methodology with an expected loss methodology that is referred to as the current expected credit loss (“CECL”) methodology. The measurement of expected credit losses under the CECL methodology is applicable to financial assets measured at amortized cost, including loan receivables and held-to-maturity debt securities. It also applies to off-balance sheet credit exposures not accounted for as insurance (loan commitments, standby letters of credit, financial guarantees, and other similar instruments) and net investments in leases recognized by a lessor in accordance with Topic 842 on leases. In addition, ASC 326 made changes to the accounting for purchased loans and securities with credit deterioration and available-for-sale debt securities. In connection with the adoption of ASC 326, the Company revised certain accounting policies and implemented accounting policy elections. The Company adopted ASC 326 using the modified retrospective method for all financial assets measured at amortized cost and off-balance sheet credit exposures. Operating results for periods from January 1, 2020 are presented in accordance with ASC 326 while prior period amounts continue to be reported in accordance with previously applicable standards and the accounting policies described in our 2019 Form 10-K. The Company recorded a net increase to retained earnings of $2.3 million, net of tax of $925,000, as of January 1, 2020 for the cumulative effect of adopting ASC 326. The Company’s results of operations were materially affected due to the increase in provisions related to the adoption of ASC 326 and the impact to the Company’s cash flows was not material. The Company adopted ASC 326 using the prospective transition approach for financial assets purchased with credit deterioration (PCD) that were previously classified as purchased credit impaired (PCI) and accounted for under ASC 310-30. In accordance with the standard, management did not reassess whether PCI assets met the criteria of PCD assets as of the date of adoption. On January 1, 2020, the amortized cost basis of the PCD assets was adjusted to reflect the addition of approximately $ 1.2 million to the allowance for credit losses. The Company has not recorded an allowance for credit losses against its available-for-sale securities, as the credit risk is not material. The following table illustrates the impact of ASC 326 on the allowance for credit losses on the Company’s loans as of January 1, 2020. January 1, 2020 As Reported Under ASC 326 Pre ASC 326 Adoption Impact of ASC 326 Adoption (Dollars in thousands) BancFirst Real estate: Commercial real estate owner occupied $ 2,819 $ 5,625 $ (2,806 ) Commercial real estate non-owner occupied 2,851 8,358 (5,507 ) Construction and development < 60 months 1,158 2,214 (1,056 ) Construction residential real estate < 60 months 1,155 1,933 (778 ) Residential real estate first lien 4,861 8,692 (3,831 ) Residential real estate all other 1,359 2,767 (1,408 ) Farmland 1,413 2,821 (1,408 ) Commercial and agricultural non-real estate 26,657 13,462 13,195 Consumer non-real estate 2,630 3,252 (622 ) Oil and gas 537 1,883 (1,346 ) Other loans 2,516 2,632 (116 ) Pegasus Bank 3,087 599 2,488 Allowance for credit losses on loans $ 51,043 $ 54,238 $ (3,195 ) The estimate of expected credit losses considers historical credit loss information that is adjusted for current conditions and reasonable and supportable forecasts. In order to estimate expected losses using historical loss information, the Company elected to utilize a methodology known as vintage loss analysis for substantially all of our loan portfolio. Vintage loss analysis measures impairment based on the age of the accounts and the historical asset performance of assets with similar risk characteristics. Vintage loss analysis accounts for expected losses by allowing the Company to calculate the cumulative loss rates of a given loan pool and in so doing, determine the loan pool’s lifetime expected loss experience. This includes a reasonable approximation of probable and estimable future losses determined by applying historical net charge off information to forward looking qualitative and environmental factors. First, the Company determined the appropriate type of financial assets that share similar risk characteristics, and then the Company developed a cumulative loss curve for the applicable financial assets based on historical data using different “vintages” analyzed by year of origination. This is done by dividing each year’s net charge-offs by the original principal balance. The respective vintage’s original principal balance remains the denominator in each annual calculation, as it references the specific vintage’s original balance. The loss experience of this original balance is tracked annually and summed over the life of the loan for each separate loan pool leaving a cumulative, life of credit loss rate based on historic averages weighted towards more recent loss experience. In addition to life of credit loss data, primary drivers like macroeconomic indicators of qualitative factors are used as adjustments to the expected loss calculation to reach a forecast supported by both quantitative and qualitative data points. The intent is to express the impact of changes in external factors while incorporating analysis of where the loan pool is in its loss history. Loans that do not share risk characteristics are evaluated on an individual basis. Loans evaluated individually are not included in the collective evaluation. The Company has made the accounting policy election to use the fair value of the collateral to measure expected credit losses on collateral-dependent financial assets. When management determines that foreclosure is probable or when the borrower is experiencing financial difficulty at the reporting date and repayment is expected to be provided substantially through the operation or sale of the collateral, expected credit losses are based on the fair value of the collateral at the reporting date, adjusted for selling costs as appropriate. In connection with the adoption of ASC 326, the Company revised certain accounting policies and implemented accounting policy elections. The revised accounting policies are described below. Loans The Company has made the accounting policy election to exclude accrued interest receivable on loans from the estimate of credit losses. Interest income is accrued on the unpaid principal balance using the simple-interest method on the daily balances of the principal amounts outstanding. Interest income on consumer and commercial loans is discontinued and placed on nonaccrual status at the time the loan is 90 days delinquent unless the loan is well secured and in process of collection. Consumer loans are charged off at 180 days past due and commercial loans are charged off to the extent principal or interest is deemed uncollectible. Past-due status is based on the contractual terms of the loan. In all cases, loans are placed on nonaccrual or charged off at an earlier date if collection of principal or interest is considered doubtful. All interest accrued but not received for loans placed on nonaccrual is reversed against interest income. Interest received on such loans is accounted for on the cash-basis or cost-recovery method, until qualifying for return to accrual. Under the cost-recovery method, interest income is not recognized until the loan balance is reduced to zero. Under the cash-basis method, interest income is recorded when the payment is received in cash. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current and future payments are reasonably assured. Troubled debt restructurings are loans on which, due to the borrower’s financial difficulties, the Company has granted a concession that the Company would not otherwise consider for borrowers of similar credit quality. This may include a transfer of real estate or other assets from the borrower, a modification of loan terms, or a combination of the two. Modifications of terms that could potentially qualify as a restructuring include reduction of contractual interest rate, extension of the maturity date at a contractual interest rate lower than the current rate for new debt with similar risk, and a reduction of the face amount of debt or forgiveness of either principal or accrued interest. A loan continues to qualify as restructured until a consistent payment history or change in the borrower’s financial condition has been evidenced, generally for no less than twelve months. If the restructuring agreement specifies an interest rate at the time of the restructuring that is greater than or equal to the rate that the Company is willing to accept for a new extension of credit with comparable risk, then the loan is no longer considered a restructured loan if it is in compliance with the modified terms in calendar years after the year of restructure. Purchased Credit Deteriorated (PCD) Loans Allowance for Credit Losses - Loans The allowance for credit losses is measured on a collective (pool) basis when similar risk characteristics exist. In connection with our adoption of ASC 326, changes were made to our primary portfolio segments to align with the methodology applied in determining the allowance under CECL. The Company has identified the following portfolio segments, which includes the applicable weighted average remaining life, and measures the allowance for credit losses using the vintage loss analysis adjusted for qualitative factors: Loan Segment Life (in years) BancFirst Real estate: Commercial real estate owner occupied 9 Commercial real estate non-owner occupied 6 Construction and development < 60 months 3 Construction residential real estate < 60 months 1 Residential real estate first lien 13 Residential real estate all other 6 Farmland 12 Commercial and agricultural non-real estate 3 Consumer non-real estate 4 Oil and gas 1 Other loans 8 Pegasus Bank 4 These portfolio segments are separately identified because they exhibit distinctive risk characteristics, such as financial asset types, loan purpose, collateral, and industry of the borrower. A summary of our primary portfolio segments is as follows: Commercial real estate owner occupied. Commercial real estate owner occupied are nonresidential property loans for which the primary source of repayment is the cash flow from the ongoing operations and activities conducted by the entity, or an affiliate of the entity, who owns the property. This category includes, among other loans, loans secured by office buildings, garden office buildings, manufacturing facilities, warehouse and flex warehouse facilities, hospitals, and car washes unless the property is owned by an investor who leases the property to the operator who, in turn, is not related to or affiliated with the investor. Commercial real estate non-owner occupied. Commercial real estate non-owner occupied are nonresidential property loans where the primary source of repayment is derived from rental income associated with the property or the proceeds of the sale, refinancing, or permanent financing of the property. This category includes, among other loans, loans secured by shopping centers, office buildings, hotels/motels, nursing homes, assisted-living facilities, mini-storage warehouse facilities, and similar properties. Construction and development < 60 months . Residential development loans include loans to develop raw land into a residential development. Advances on the loans typically include land costs, hard costs (grading, utilities, roads, etc.), soft costs (engineering fees, development fees, entitlement fees, etc.) and carrying costs until the development is completed. Upon completion of the development, the loan is typically repaid through the sale of lots to homebuilders. Construction residential real estate < 60 months. Residential construction includes loans to builders for speculative or custom homes, as well as direct loans to individuals for construction of their personal residence. Custom construction and self-construction loans typically will have commitments in place for long-term financing at the completion of construction. Speculative construction loans generally will have periodic curtailment plans beginning after completion of construction and a reasonable time for sales to have occurred. Residential real estate first lien. Residential real estate first lien loans includes all closed-end loans secured by first liens on 1-to-4 family residential properties. This category includes property containing 1-to-4 dwelling units (including vacation homes) or more than four dwelling units if each is separated from other units by dividing walls that extend from ground to roof. This category also includes individual condominium dwelling units and loans secured by an interest in individual cooperative housing units, even if in a building with five or more dwelling units. Residential real estate all other. Residential real estate all other loans includes loans secured by junior (i.e., other than first) liens on 1-to-4 family residential properties. This category includes loans secured by junior liens even if the Company also holds a loan secured by a first lien on the same 1-to-4 family residential property. Farmland. This category includes loans secured by all land known to be used or usable for agricultural purposes, such as crop and livestock production. Farmland includes grazing or pasture land, whether tillable or not and whether wooded or not. Commercial and agricultural non-real estate. Commercial and agricultural non-real estate represent loans for working capital, facilities acquisition or expansion, purchase of equipment and other needs of commercial customers primarily located within Oklahoma. Loans in this category include commercial and industrial, agriculture and state and political subdivisions. Consumer non-real estate. Consumer loans are loans to individuals for household, family and other personal expenditures. Commonly, such loans are made to finance purchases of consumer goods, such as automobiles, boats, household goods, vacations and education. Oil and gas. Oil and gas loans represent loans for producing oil and gas properties and any other mineral interests that may be pumped, mined, quarried or otherwise extracted from the earth primarily located within Oklahoma. Other loans. Other loans consist of loans approved by the Small Business Administration (“SBA”), which include loans funded through the Paycheck Protection Program (“PPP”). Since PPP loans are fully guaranteed by the SBA, there is no expected credit loss related to these loans. Pegasus Bank. Pegasus Bank’s loans are commercial and consumer loans mostly to customers within Texas secured by real estate. Pegasus Bank also includes commercial and industrial loans, which includes loans to companies in the oil and gas industry. 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. Management estimates the allowance balance using relevant available information, from internal and external sources, relating to past events, current conditions, and reasonable and supportable forecasts. Historical credit loss experience provides the basis for the estimation of expected credit losses. Adjustments to historical loss information are made for differences in current loan-specific risk characteristics such as differences in underwriting standards, portfolio mix, delinquency level, or term as well as for changes in environmental conditions, such as the political, legal, and regulatory environment, technology and consumer preferences. Historical loss information is also adjusted for reasonable and supportable changes in national and local economic conditions, such as oil and gas prices, national and local unemployment, real gross domestic product (“GDP”), house price index (“HPI”), consumer price index (“CPI”), rental vacancies, and retail sales. Economic conditions are forecast as "current conditions" over the forecast period. Forecast models were used to validate credit performance during the forecast period. Beyond the reasonable and supportable forecast, the economic expectation reverts to the historical average, which is determined by the weighted average life of each loan pool. Determining the Contractual Term: Troubled Debt Restructurings (TDRs Allowance for Credit Losses on Off-Balance Sheet Credit Exposures Allowance for Credit Losses - Available-for-Sale Debt Securities Therefore, the Company has not recorded an allowance for credit losses against its debt securities portfolio, as the credit risk is not material. PPP Fee Income Policy:

Description of Business and S_3

Description of Business and Summary of Significant Accounting Policies (Tables) - ASC 326 [Member]	12 Months Ended
	Dec. 31, 2020
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Schedule of Impact of ASC 326 Adoption on Allowance for Credit losses on Loans	The Company has not recorded an allowance for credit losses against its available-for-sale securities, as the credit risk is not material. The following table illustrates the impact of ASC 326 on the allowance for credit losses on the Company’s loans as of January 1, 2020. January 1, 2020 As Reported Under ASC 326 Pre ASC 326 Adoption Impact of ASC 326 Adoption (Dollars in thousands) BancFirst Real estate: Commercial real estate owner occupied $ 2,819 $ 5,625 $ (2,806 ) Commercial real estate non-owner occupied 2,851 8,358 (5,507 ) Construction and development < 60 months 1,158 2,214 (1,056 ) Construction residential real estate < 60 months 1,155 1,933 (778 ) Residential real estate first lien 4,861 8,692 (3,831 ) Residential real estate all other 1,359 2,767 (1,408 ) Farmland 1,413 2,821 (1,408 ) Commercial and agricultural non-real estate 26,657 13,462 13,195 Consumer non-real estate 2,630 3,252 (622 ) Oil and gas 537 1,883 (1,346 ) Other loans 2,516 2,632 (116 ) Pegasus Bank 3,087 599 2,488 Allowance for credit losses on loans $ 51,043 $ 54,238 $ (3,195 )
Schedule of Portfolio Segments Weighted Average Life, and Measures the Allowance for Credit Losses	The allowance for credit losses is measured on a collective (pool) basis when similar risk characteristics exist. In connection with our adoption of ASC 326, changes were made to our primary portfolio segments to align with the methodology applied in determining the allowance under CECL. The Company has identified the following portfolio segments, which includes the applicable weighted average remaining life, and measures the allowance for credit losses using the vintage loss analysis adjusted for qualitative factors: Loan Segment Life (in years) BancFirst Real estate: Commercial real estate owner occupied 9 Commercial real estate non-owner occupied 6 Construction and development < 60 months 3 Construction residential real estate < 60 months 1 Residential real estate first lien 13 Residential real estate all other 6 Farmland 12 Commercial and agricultural non-real estate 3 Consumer non-real estate 4 Oil and gas 1 Other loans 8 Pegasus Bank 4

Cash, Due from Banks, Interes_2

Cash, Due from Banks, Interest-Bearing Deposits and Federal Funds Sold (Tables)	12 Months Ended
	Dec. 31, 2020
Cash And Cash Equivalents [Abstract]
Summary of Average Amount of Required Reserves	The average amount of required reserves for December 31, 2019 is included in the following table: December 31, 2020 2019 (Dollars in thousands) Vault cash and funds on deposit with the Federal Reserve Bank $ 1,429,410 $ 1,738,523 Average required reserves — 63,842

Securities (Tables)

Securities (Tables)	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Summary of Amortized Cost and Estimated Fair Values of Debt Securities Held for Investment	The following table summarizes the amortized cost and estimated fair values of debt securities held for investment: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (Dollars in thousands) December 31, 2020 Mortgage backed securities (1) $ 59 $ 3 $ — $ 62 States and political subdivisions 2,405 18 (1 ) 2,422 Other securities 500 — — 500 Total $ 2,964 $ 21 $ (1 ) $ 2,984 December 31, 2019 Mortgage backed securities (1) $ 93 $ 4 $ — $ 97 States and political subdivisions 1,310 1 (5 ) 1,306 Other securities 500 — — 500 Total $ 1,903 $ 5 $ (5 ) $ 1,903
Summary of Amortized Cost and Estimated Fair Values of Debt Securities Available for Sale	The following table summarizes the amortized cost and estimated fair values of debt securities available for sale: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (Dollars in thousands) December 31, 2020 U.S. treasuries $ 465,416 $ 9,820 $ — $ 475,236 U.S. federal agencies 19,697 1 (60 ) 19,638 Mortgage backed securities (1) 15,268 428 — 15,696 States and political subdivisions 28,571 377 — 28,948 Asset backed securities 13,337 — (623 ) 12,714 Total $ 542,289 $ 10,626 $ (683 ) $ 552,232 December 31, 2019 U.S. treasuries $ 409,488 $ 4,974 $ (13 ) $ 414,449 U.S. federal agencies 23,039 23 (38 ) 23,024 Mortgage backed securities (1) 16,941 128 (64 ) 17,005 States and political subdivisions 22,294 282 (45 ) 22,531 Asset backed securities 13,320 — (606 ) 12,714 Total $ 485,082 $ 5,407 $ (766 ) $ 489,723 (1) Primarily consists of FHLMC, FNMA, GNMA and mortgage backed securities through U.S. agencies.
Maturity of Debt Securities	The maturities of debt 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, 2020 2019 Amortized Cost Estimated Fair Value Amortized Cost Estimated Fair Value (Dollars in thousands) Held for Investment Contractual maturity of debt securities: Within one year $ 807 $ 809 $ 300 $ 300 After one year but within five years 2,091 2,110 1,058 1,055 After five years but within ten years 65 64 543 546 After ten years 1 1 2 2 Total $ 2,964 $ 2,984 $ 1,903 $ 1,903 Available for Sale Contractual maturity of debt securities: Within one year $ 339,752 $ 341,102 $ 186,373 $ 186,539 After one year but within five years 162,401 171,135 252,519 257,430 After five years but within ten years 3,753 3,910 5,873 6,008 After ten years 36,383 36,085 40,317 39,746 Total debt securities $ 542,289 $ 552,232 $ 485,082 $ 489,723
Proceeds from Sales and Realized Securities Losses, on Available for Sale Debt Securities	The following is a detail of proceeds from sales and realized securities losses, on available for sale debt securities: Year Ended December 31, 2020 2019 2018 (Dollars Proceeds $ — $ — $ 31,285 Gross losses realized — — 109
Company's Book Value of Pledged Debt Securities	The following table is a summary of the Company’s book value of debt securities that were pledged as collateral for public funds on deposit, repurchase agreements and for other purposes as required or permitted by law: December 31, 2020 2019 (Dollars Book value of pledged securities $ 490,833 $ 445,702
Summary of Debt Securities with Unrealized Losses, Segregated by Duration of Unrealized Loss	The following table summarizes debt securities with unrealized losses, segregated by the duration of the unrealized loss, at December 31, 2020 and 2019 respectively: Less than 12 Months More than 12 Months Total Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses (Dollars in thousands) December 31, 2020 Held for Investment States and political subdivisions $ 119 $ 1 $ — $ — $ 119 $ 1 Total $ 119 $ 1 $ — $ — $ 119 $ 1 Available for Sale U.S. federal agencies $ 12,236 $ 41 $ 2,184 $ 19 $ 14,420 $ 60 Asset backed securities — — 12,714 623 12,714 623 Total $ 12,236 $ 41 $ 14,898 $ 642 $ 27,134 $ 683 December 31, 2019 Held for Investment Mortgage backed securities $ — $ — $ 3 $ — $ 3 $ — States and political subdivisions 1,016 5 — — 1,016 5 Total $ 1,016 $ 5 $ 3 $ — $ 1,019 $ 5 Available for Sale U.S. treasuries $ 8,999 $ 10 $ 19,988 $ 3 $ 28,987 $ 13 U.S. federal agencies 10,362 19 2,700 19 13,062 38 Mortgage backed securities 15,165 64 — — 15,165 64 States and political subdivisions 3,890 45 — — 3,890 45 Asset backed securities — — 12,714 606 12,714 606 Total $ 38,416 $ 138 $ 35,402 $ 628 $ 73,818 $ 766

Loans Held for Investment and_2

Loans Held for Investment and Allowance for Credit Losses on Loans (Tables)	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Summary of Loans Held for Investment by Portfolio Segment	Loans held for investment are summarized by portfolio segment as follows: December 31, 2020 2019 Amount Amount (Dollars in thousands) BancFirst Real estate: Commercial real estate owner occupied $ 641,987 $ 621,188 Commercial real estate non-owner occupied 971,158 851,200 Construction and development < 60 months 229,615 287,138 Construction residential real estate < 60 months 206,195 189,480 Residential real estate first lien 853,316 834,849 Residential real estate all other 168,081 187,647 Farmland 252,958 246,988 Commercial and agricultural non-real estate 1,159,810 1,315,005 Consumer non-real estate 355,405 359,529 Oil and gas 179,355 184,399 Other loans (2) 822,078 154,015 Pegasus Bank 554,548 430,705 Total loans (1) $ 6,394,506 $ 5,662,143 (1) Excludes accrued interest receivable of $26.0 million at December 31, 2020 and $24.5 million at December 31, 2019, that is recorded in accrued interest receivable and other assets. (2) Includes PPP loans of $652.7 million, net of unamortized processing fees of $14.5 million at December 31, 2020.
Summary of Troubled Debt Restructurings and Other Real Estate Owned and Repossessed Assets	The following is a summary of troubled debt restructurings and other real estate owned and repossessed assets: December 31, 2020 2019 (Dollars in thousands) Troubled debt restructurings $ 7,784 $ 18,010 Other real estate owned and repossessed assets $ 32,480 $ 6,073
Summary of Amounts Included in Nonaccrual Loans Segregated by Portfolio Segment	The following table is a summary of amounts included in nonaccrual loans, segregated by portfolio segment. December 31, 2020 (Dollars in thousands) BancFirst Real estate: Commercial real estate owner occupied $ 1,404 Commercial real estate non-owner occupied 4,719 Construction and development < 60 months 95 Construction residential real estate < 60 months — Residential real estate first lien 3,615 Residential real estate all other 1,362 Farmland 7,901 Commercial and agricultural non-real estate 12,782 Consumer non-real estate 268 Oil and gas — Other loans 5,399 Pegasus Bank — Total $ 37,545 December 31, 2019 (Dollars in thousands) BancFirst Real estate: Non-residential real estate owner occupied $ 2,275 Non-residential real estate other 1,815 Residential real estate permanent mortgage 1,206 Residential real estate other 3,060 Non-consumer non-real estate 2,915 Consumer other 264 Other loans 1,083 Acquired loans 4,496 Pegasus Bank 851 Total $ 17,965
Age Analysis of Loans Held for Investments	Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due. The following table presents an age analysis of our loans held for investment: Age Analysis of Past Due Loans 30-59 Days Past Due 60-89 Days Past Due 90 Days and Greater Total Past Due Loans Current Loans Total Loans Accruing Loans 90 Days or More Past Due (Dollars in thousands) As of December 31, 2020 BancFirst Real estate: Commercial real estate owner occupied $ 1,096 $ 108 $ 1,164 $ 2,368 $ 639,619 $ 641,987 $ — Commercial real estate non-owner occupied 323 — 34 357 970,801 971,158 35 Construction and development < 60 months 511 86 — 597 229,018 229,615 — Construction residential real estate < 60 months 1,106 — 282 1,388 204,807 206,195 282 Residential real estate first lien 5,428 1,463 2,978 9,869 843,447 853,316 945 Residential real estate all other 520 55 1,606 2,181 165,900 168,081 384 Farmland 1,297 344 6,223 7,864 245,094 252,958 135 Commercial and agricultural non-real estate 2,788 1,794 4,345 8,927 1,150,883 1,159,810 465 Consumer non-real estate 2,154 501 534 3,189 352,216 355,405 386 Oil and gas — — — — 179,355 179,355 — Other loans 951 1,223 6,618 8,792 813,286 822,078 2,170 Pegasus Bank — — — — 554,548 554,548 — Total $ 16,174 $ 5,574 $ 23,784 $ 45,532 $ 6,348,974 $ 6,394,506 $ 4,802 As of December 31, 2019 BancFirst Real estate: Non-residential real estate owner occupied $ 1,600 $ 967 $ 5,159 $ 7,726 $ 699,690 $ 707,416 $ 3,799 Non-residential real estate other 971 — 1,228 2,199 1,134,976 1,137,175 — Residential real estate permanent mortgage 4,705 973 2,215 7,893 332,679 340,572 1,660 Residential real estate other 4,496 1,028 2,541 8,065 912,767 920,832 549 Non-consumer non-real estate 2,290 1,446 1,763 5,499 1,448,894 1,454,393 354 Consumer other 2,829 858 592 4,279 358,075 362,354 491 Other loans 1,670 8 4,613 6,291 147,724 154,015 4,426 Acquired loans 2,167 1,376 3,447 6,990 147,691 154,681 555 Pegasus Bank — — 851 851 429,854 430,705 — Total $ 20,728 $ 6,656 $ 22,409 $ 49,793 $ 5,612,350 $ 5,662,143 $ 11,834
Gross Loans Held for Investment by Year of Origination and Internally Assigned Credit Grades	The following table summarizes our gross loans held for investment by year of origination and internally assigned credit grades: Term Loans Amortized Cost Basis by Origination Year 2020 2019 2018 2017 2016 Prior Revolving Loans Amortized Cost Basis Total (Dollars in thousands) As of December 31, 2020 BancFirst Commercial real estate owner occupied Grade 1 $ 142,574 $ 91,493 $ 73,845 $ 42,289 $ 37,097 $ 88,724 $ 17,153 $ 493,175 Grade 2 42,375 31,314 11,516 9,644 13,316 25,574 4,393 138,132 Grade 3 4,226 32 333 704 1,259 2,671 — 9,225 Grade 4 37 66 742 — 251 52 307 1,455 Total commercial real estate owner occupied loans 189,212 122,905 86,436 52,637 51,923 117,021 21,853 641,987 Commercial real estate non-owner occupied Grade 1 256,128 157,526 83,869 69,864 82,088 81,499 13,206 744,180 Grade 2 60,607 48,751 26,441 18,070 8,755 41,491 4,454 208,569 Grade 3 7,718 3,137 472 1,937 40 148 149 13,601 Grade 4 4,719 89 — — — — — 4,808 Total commercial real estate non-owner occupied loans 329,172 209,503 110,782 89,871 90,883 123,138 17,809 971,158 Construction and development < 60 months Grade 1 115,399 56,369 12,821 4,582 1,438 2,048 7,850 200,507 Grade 2 11,528 10,002 1,589 764 157 540 582 25,162 Grade 3 3,842 — 9 — — — — 3,851 Grade 4 — 64 9 22 — — — 95 Total construction and development < 60 months 130,769 66,435 14,428 5,368 1,595 2,588 8,432 229,615 Construction residential real estate < 60 months Grade 1 159,431 4,214 69 21 33 23 11,449 175,240 Grade 2 27,400 580 112 — — 468 390 28,950 Grade 3 1,885 120 — — — — — 2,005 Total construction residential real estate < 60 months 188,716 4,914 181 21 33 491 11,839 206,195 Residential real estate first lien Grade 1 241,771 134,184 80,793 64,392 48,686 136,059 — 705,885 Grade 2 28,305 19,425 21,742 11,666 12,365 34,312 — 127,815 Grade 3 2,754 2,029 1,375 2,073 1,213 5,194 — 14,638 Grade 4 730 733 478 210 1,186 1,590 — 4,927 Grade 5 — — — — 51 — — 51 Total residential real estate first lien 273,560 156,371 104,388 78,341 63,501 177,155 — 853,316 Residential real estate all other Grade 1 21,493 13,944 10,854 6,265 5,381 10,984 28,047 96,968 Grade 2 3,694 1,675 1,268 1,809 450 2,335 55,433 66,664 Grade 3 384 461 328 116 119 221 993 2,622 Grade 4 204 217 570 65 34 715 22 1,827 Total residential real estate all other 25,775 16,297 13,020 8,255 5,984 14,255 84,495 168,081 Farmland Grade 1 51,284 26,391 18,994 13,821 13,368 27,100 8,160 159,118 Grade 2 15,264 30,684 6,639 6,391 4,763 8,916 7,140 79,797 Grade 3 3,681 290 151 1,055 703 551 1,955 8,386 Grade 4 414 14 4,058 296 340 223 312 5,657 Total farmland 70,643 57,379 29,842 21,563 19,174 36,790 17,567 252,958 Commercial and agricultural non-real estate Grade 1 206,515 136,254 124,657 74,719 46,453 33,471 270,426 892,495 Grade 2 49,467 34,659 27,239 6,566 7,054 22,710 63,894 211,589 Grade 3 24,793 1,511 1,466 789 271 327 14,577 43,734 Grade 4 7,231 1,607 652 241 1,139 163 959 11,992 Total commercial and agricultural non-real estate 288,006 174,031 154,014 82,315 54,917 56,671 349,856 1,159,810 Consumer non-real estate Grade 1 166,934 93,232 41,449 13,157 4,471 1,768 7,673 328,684 Grade 2 12,773 5,902 3,399 796 499 266 328 23,963 Grade 3 445 840 450 175 75 63 2 2,050 Grade 4 89 287 144 94 47 40 7 708 Total consumer non-real estate 180,241 100,261 45,442 14,222 5,092 2,137 8,010 355,405 Oil and gas Grade 1 104,622 66 82 — — 4,679 16,529 125,978 Grade 2 42,713 745 — — — — 9,919 53,377 Total oil and gas 147,335 811 82 — — 4,679 26,448 179,355 Other loans Grade 1 685,426 32,392 25,707 20,638 16,378 10,341 22,976 813,858 Grade 2 — — 17 2,936 1,126 2,179 692 6,950 Grade 3 — — 78 — 53 67 36 234 Grade 4 — — — 124 208 33 671 1,036 Total other loans 685,426 32,392 25,802 23,698 17,765 12,620 24,375 822,078 Pegasus Bank Grade 1 100,631 66,875 27,235 19,025 12,414 44,237 113,824 384,241 Grade 2 28,187 26,733 6,774 23,367 3,822 5,300 74,671 168,854 Grade 3 123 — — — — 1,330 — 1,453 Total Pegasus Bank 128,941 93,608 34,009 42,392 16,236 50,867 188,495 554,548 Total loans held for investment $ 2,637,796 $ 1,034,907 $ 618,426 $ 418,683 $ 327,103 $ 598,412 $ 759,179 $ 6,394,506 The following table presents internal loan grading by class of loans as of December 31, 2019: Internal Loan Grading Grade 1 2 3 4 5 Total (Dollars in thousands) As of December 31, 2019 BancFirst Real estate: Non-residential real estate owner occupied $ 554,942 $ 130,783 $ 15,191 $ 6,500 $ — $ 707,416 Non-residential real estate other 861,108 252,134 23,048 868 17 1,137,175 Residential real estate permanent mortgage 289,350 41,754 6,975 2,442 51 340,572 Residential real estate other 722,983 179,951 14,382 3,446 70 920,832 Non-consumer non-real estate 1,166,155 261,003 25,276 1,959 — 1,454,393 Consumer other 335,916 23,407 2,327 704 — 362,354 Other loans 148,692 3,631 1,564 128 — 154,015 Acquired loans 88,205 55,087 6,800 4,446 143 154,681 Pegasus Bank 295,243 133,324 1,287 851 — 430,705 Total $ 4,462,594 $ 1,081,074 $ 96,850 $ 21,344 $ 281 $ 5,662,143
Activity in Allowance for Credit Losses on Loans	The following table details activity in the allowance for credit losses on 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. Allowance for Credit Losses Balance at beginning of period Impact of CECL adoption Initial allowance on loans purchased with credit deterioration Charge- offs Recoveries Net charge-offs Provision for credit losses on loans Balance at end of period (Dollars in thousands) Year ended December 31, 2020 BancFirst Real estate: Commercial real estate owner occupied $ 5,625 $ (2,806 ) $ 432 $ (773 ) $ 10 $ (763 ) $ 4,547 $ 7,035 Commercial real estate non-owner occupied 8,358 (5,507 ) — (3,609 ) — (3,609 ) 12,600 11,842 Construction and development < 60 months 2,214 (1,056 ) — (59 ) 123 64 1,338 2,560 Construction residential real estate < 60 months 1,933 (778 ) — (29 ) — (29 ) (499 ) 627 Residential real estate first lien 8,692 (3,831 ) 7 (465 ) 44 (421 ) (1,877 ) 2,570 Residential real estate all other 2,767 (1,408 ) — (126 ) 54 (72 ) 943 2,230 Farmland 2,821 (1,408 ) 1 (2,055 ) — (2,055 ) 3,777 3,136 Commercial and agricultural non-real estate 13,462 13,195 62 (3,320 ) 116 (3,204 ) 8,885 32,400 Consumer non-real estate 3,252 (622 ) — (1,142 ) 224 (918 ) 1,665 3,377 Oil and gas 1,883 (1,346 ) — (11,245 ) — (11,245 ) 28,559 17,851 Other loans 2,632 (116 ) — (168 ) 10 (158 ) 824 3,182 Pegasus Bank 599 2,488 — (841 ) 424 (417 ) 1,886 4,556 Total $ 54,238 $ (3,195 ) $ 502 $ (23,832 ) $ 1,005 $ (22,827 ) $ 62,648 $ 91,366 Year ended December 31, 2019 BancFirst Real estate: Non-residential real estate owner occupied $ 6,328 $ — $ — $ (34 ) $ 25 $ (9 ) $ 721 $ 7,040 Non-residential real estate other 11,027 — — (67 ) 42 (25 ) 155 11,157 Residential real estate permanent mortgage 3,261 — — (146 ) 22 (124 ) 250 3,387 Residential real estate other 10,673 — — (2,697 ) 30 (2,667 ) 2,143 10,149 Non-consumer non-real estate 13,151 — — (514 ) 272 (242 ) 2,432 15,341 Consumer other 3,065 — — (868 ) 218 (650 ) 904 3,319 Other loans 2,423 — — — 90 90 119 2,632 Acquired loans 1,461 — — (2,060 ) 219 (1,841 ) 994 614 Pegasus Bank — — — — 30 30 569 599 Total $ 51,389 $ — $ — $ (6,386 ) $ 948 $ (5,438 ) $ 8,287 $ 54,238
Allowance for Credit Losses Outstanding by Impairment Methodology	The following table details the amount of allowance for credit losses by class of loans for the period presented, on the basis of impairment methodology used by the Company. Allowance for Credit Losses December 31, 2019 Individually evaluated for impairment Collectively evaluated for impairment (Dollars in thousands) BancFirst Real estate: Non-residential real estate owner occupied $ 900 $ 6,140 Non-residential real estate other 990 10,167 Residential real estate permanent mortgage 531 2,856 Residential real estate other 2,026 8,123 Non-consumer non-real estate 2,902 12,439 Consumer other 343 2,976 Other loans 13 2,619 Acquired loans — 614 Pegasus Bank — 599 Total $ 7,705 $ 46,533
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, 2019 Individually evaluated for impairment Collectively evaluated for impairment Loans acquired with deteriorated credit quality (Dollars in thousands) BancFirst Real estate: Non-residential real estate owner occupied $ 21,690 $ 685,726 $ — Non-residential real estate other 23,933 1,113,242 — Residential real estate permanent mortgage 9,468 331,104 — Residential real estate other 17,898 902,934 — Non-consumer non-real estate 27,016 1,427,377 — Consumer other 3,090 359,264 — Other loans 231 153,784 — Acquired loans 10,470 143,351 860 Pegasus Bank — 428,567 2,138 Total $ 113,796 $ 5,545,349 $ 2,998
Purchased Credit Deteriorated Loans	The Company has purchased loans, for which there was, at acquisition, evidence of more than insignificant deterioration of credit quality since origination. The purchased credit deteriorated loans for the period are as follows: Loans acquired with deteriorated credit quality (Dollars in thousands) For the year ended December 31, 2020 Purchase price of loans at acquisition $ 1,761 Allowance for credit losses at acquisition 502 Par value of acquired loans at acquisition $ 2,263
Collateral-Dependent Gross Loans Held for Investment by Collateral Type and Related Specific Allocation	The following table summarizes collateral-dependent gross loans held for investment by collateral type and the related specific allocation as follows: Collateral Type Real Estate Business Assets Energy Reserves Other Assets Total Specific Allocation As of December 31, 2020 (Dollars in thousands) BancFirst Real estate: Commercial real estate owner occupied $ 848 $ — $ — $ — $ 848 $ 226 Commercial real estate non-owner occupied 4,719 — — — 4,719 1,000 Construction and development < 60 months — — — — — — Construction residential real estate < 60 months — — — — — — Residential real estate first lien 860 — — — 860 151 Residential real estate all other 866 — — — 866 616 Farmland 3,258 — — — 3,258 1,114 Commercial and agricultural non-real estate — 8,460 — 413 8,873 2,813 Consumer non-real estate — — — 109 109 58 Oil and gas — — — — — — Other loans — 13 — — 13 12 Pegasus Bank 1,257 — — — 1,257 222 Total collateral-dependent loans held for investment $ 11,808 $ 8,473 $ — $ 522 $ 20,803 $ 6,212
Impaired Loans Segregated by Class of Loans	The following table presents impaired loans, segregated by class of loans. Impaired Loans Unpaid Principal Balance Recorded Investment with Allowance Related Allowance Average Recorded Investment (Dollars in thousands) As of December 31, 2019 BancFirst Real estate: Non-residential real estate owner occupied $ 13,253 $ 13,000 $ 514 $ 12,868 Non-residential real estate other 3,973 3,678 300 3,946 Residential real estate permanent mortgage 3,445 3,129 242 2,968 Residential real estate other 7,117 4,487 946 5,567 Non-consumer non-real estate 11,598 11,012 1,005 11,085 Consumer other 969 836 97 844 Other loans 5,711 5,510 105 1,130 Acquired loans 6,421 5,108 2 5,472 Pegasus Bank 2,960 2,138 — 2,161 Total $ 55,447 $ 48,898 $ 3,211 $ 46,041
Transfers from Loans and Premises and Equipment to Other Real Estate Owned, Repossessed Assets and Other Assets	Transfers from loans and premises and equipment to other real estate owned, repossessed assets, and other assets during the periods presented are summarized as follows: Year ended December 31, 2020 2019 2018 (Dollars in thousands) Other real estate owned $ 32,093 $ 3,941 $ 5,437 Repossessed assets 1,418 1,473 1,122 Other assets 11,105 — — Total $ 44,616 $ 5,414 $ 6,559
Related Party Loans	A summary of these loans is as follows: Year Ended December 31, Balance Beginning of the Period Additions Collections/ Terminations Balance End of the Period (Dollars in thousands) 2020 $ 20,281 $ 19,682 $ (17,906 ) $ 22,057 2019 19,891 12,371 (11,981 ) 20,281 2018 24,001 7,986 (12,096 ) 19,891

Premises and Equipment, Net a_2

Premises and Equipment, Net and Other Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Summary of Premises and Equipment by Classification	The following is a summary of premises and equipment by classification: December 31, Estimated Useful Lives 2020 2019 (Dollars in thousands) Land $ 45,792 $ 45,561 Buildings 10 to 40 years 201,606 190,193 Furniture, fixtures and equipment 3 to 15 years 87,001 81,225 Construction in progress 61,300 12,760 Accumulated depreciation (134,022 ) (123,464 ) Premises and equipment, net $ 261,677 $ 206,275

Intangible Assets and Goodwill

Intangible Assets and Goodwill (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets	The following is a summary of intangible assets: Gross Carrying Amount Accumulated Amortization Net Carrying Amount (Dollars in thousands) As of December 31, 2020 Core deposit intangibles $ 33,411 $ (15,076 ) 18,335 Customer relationship intangibles 3,350 (2,686 ) 664 Total $ 36,761 $ (17,762 ) $ 18,999 As of December 31, 2019 Core deposit intangibles $ 35,856 $ (14,131 ) $ 21,725 Customer relationship intangibles 3,391 (2,508 ) 883 Total $ 39,247 $ (16,639 ) $ 22,608
Estimated Amortization of Intangible Assets	Estimated amortization of intangible assets for the next five years, as of December 31, 2020, is as follows (dollars in thousands): Estimated Amortization 2021 $ 2,977 2022 2,710 2023 2,693 2024 2,693 2025 2,476
Summary of Goodwill by Business Segment	The following is a summary of goodwill by business segment: Other Executive, Metropolitan Community Pegasus Financial Operations Banks Banks Bank Services & Support Consolidated (Dollars in thousands) Year Ended December 31, 2020 Balance at beginning of period $ 13,767 $ 59,894 $ 68,855 $ 5,464 $ 624 $ 148,604 Acquisitions — 1,318 — — — 1,318 Balance at end of period $ 13,767 $ 61,212 $ 68,855 $ 5,464 $ 624 $ 149,922 Year Ended December 31, 2019 Balance at beginning of period $ 13,767 $ 59,894 $ — $ 5,464 $ 624 $ 79,749 Acquisitions — — 68,855 — — 68,855 Balance at end of period $ 13,767 $ 59,894 $ 68,855 $ 5,464 $ 624 $ 148,604

Time Deposits (Tables)

Time Deposits (Tables)	12 Months Ended
	Dec. 31, 2020
Deposits [Abstract]
Schedule of Maturities of Time Deposits	At December 31, 2020, the scheduled maturities of all time deposits are as follows (Dollars in thousands): 2021 $ 489,397 2022 100,196 2023 41,245 2024 23,696 2025 18,419 Thereafter 31 Total $ 672,984
Summary of time Deposits Meet or Exceed Current FDIC Insurance Limit for Periods Presented	The following table is a summary of time deposits that meet or exceed the current FDIC insurance limit for the periods presented: December 31, 2020 2019 (Dollars in thousands) Time deposits of $250,000 or more 154,646 153,987

Short-Term Borrowings (Tables)

Short-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2020
Short Term Borrowings [Abstract]
Summary of Short-Term Borrowings	The following is a summary of short-term borrowings: December 31, 2020 2019 (Dollars in thousands) Federal funds purchased $ 1,100 $ 1,100 Weighted average interest rate 0.30 % 2.19 % End of period interest rate 0.05 % 1.45 %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 2018 (Dollars in thousands) Current taxes: Federal $ 25,974 $ 26,247 $ 23,700 State 7,443 7,288 7,083 Deferred taxes (9,491 ) 1,148 3,155 Total income taxes $ 23,926 $ 34,683 $ 33,938
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. The federal statutory tax rate was 21% in 2020, 2019 and 2018: Year Ended December 31, 2020 2019 2018 (Dollars in thousands) Tax expense at the federal statutory tax rate $ 25,937 $ 35,377 $ 33,546 Increase (decrease) in tax expense from: Tax-exempt income, net (507 ) (581 ) (510 ) Modified endowment life contracts (508 ) (519 ) (558 ) Share based compensation excess tax benefit (412 ) (765 ) (917 ) Tax deductible dividends paid on ESOP (453 ) — — State tax expense, net of federal tax benefit 5,606 5,757 5,595 Utilization of tax credits: New markets tax credits, net of tax expense (3,121 ) (3,547 ) (1,422 ) Low-income housing tax credits, net of amortization (1,273 ) (1,266 ) (1,273 ) Other tax credits (320 ) — — Other, net (1,023 ) 227 (523 ) Total tax expense $ 23,926 $ 34,683 $ 33,938
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, 2020 2019 (Dollars in thousands) Provision for credit losses $ 22,500 $ 13,763 Write-downs of other real estate owned 143 181 Deferred compensation 2,325 2,268 Stock-based compensation 1,672 1,514 Investments in partnership interests 4,695 3,677 Other 405 903 Gross deferred tax assets 31,740 22,306 Unrealized net gains on securities (2,513 ) (1,187 ) Premium on securities of banks acquired (144 ) (153 ) Intangibles (6,135 ) (6,757 ) Basis difference related to tax credits (2,127 ) (2,015 ) Depreciation (11,529 ) (10,349 ) Prepaid expense deducted (1,208 ) (1,000 ) Other (178 ) (180 ) Gross deferred tax liabilities (23,834 ) (21,641 ) Net deferred tax asset $ 7,906 $ 665

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
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: Wgtd. Avg. Wgtd. Avg. Remaining Aggregate Exercise Contractual Intrinsic Options Price Term Value (Dollars in thousands, except option data) Year Ended December 31, 2020 Outstanding at December 31, 2019 1,257,730 $ 32.70 Options granted 171,000 48.89 Options exercised (76,650 ) 20.53 Options canceled, forfeited, or expired (9,000 ) 58.26 Outstanding at December 31, 2020 1,343,080 35.28 8.61Yrs $ 31,453 Exercisable at December 31, 2020 710,330 25.06 6.94Yrs $ 23,894 Year Ended December 31, 2019 Outstanding at December 31, 2018 1,216,700 $ 28.48 Options granted 178,500 56.87 Options exercised (107,470 ) 21.23 Options canceled, forfeited, or expired (30,000 ) 46.42 Outstanding at December 31, 2019 1,257,730 32.70 9.28Yrs $ 37,408 Exercisable at December 31, 2019 644,730 23.09 7.10Yrs $ 25,370
Options Exercised Under Stock Option Plan	The following table has additional information regarding options exercised under both the BancFirst ISOP and the BancFirst Directors’ Stock Option Plan: Year Ended December 31, 2020 2019 2018 (Dollars in thousands) Total intrinsic value of options exercised $ 2,315 $ 3,982 $ 4,810 Cash received from options exercised 1,574 2,282 2,159 Tax benefit realized from options exercised 590 1,014 1,225
Stock-based Employee Compensation Expense	The following table is a summary of the Company’s recorded stock-based compensation expense: Year Ended December 31, 2020 2019 2018 (Dollars in thousands) Stock-based compensation expense $ 1,516 $ 1,277 $ 1,352 Tax benefit 386 325 345 Stock-based compensation expense, net of tax $ 1,130 $ 952 $ 1,007
Unearned Stock-based Compensation Expense	The Company will continue to amortize the unearned stock-based compensation expense over the remaining vesting period of approximately seven years. The following table shows the unearned stock-based compensation expense: December 31, 2020 (Dollars in thousands) Unearned stock-based compensation expense $ 4,888
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 on options granted during the periods presented: Year Ended December 31, 2020 2019 2018 Weighted average grant-date fair value per share of options granted $ 10.85 $ 13.34 $ 14.71 Risk-free interest rate 0.64 to 1.13% 1.55 to 2.76% 2.55 to 3.05% Dividend yield 2.00 % 2.00 % 2.00 % Stock price volatility 22.84 to 36.10% 22.93 to 23.63% 23.05 to 23.95% Expected term 10 Yrs 10 Yrs 10 Yrs
Summary of Accumulated Stock Units	A summary of the accumulated stock units is as follows: December 31, 2020 2019 Accumulated stock units 148,278 143,362 Average price $ 28.57 $ 27.17

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2020
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 are shown in the following table: December 31, 2020 2019 2018 (Dollars in thousands) 401(k) contributions $ 2,986 $ 2,526 $ 2,465 ESOP contributions 3,689 4,403 4,073 Total contributions $ 6,675 $ 6,929 $ 6,538

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Summary of Authorized Outstanding Preferred and Common Stock	As of December 31, 2020, 2019 and 2018 the Company’s authorized and outstanding preferred and common stock was as follows: No. of Shares Authorized at No. of Shares Outstanding at December 31, Class of Stock December 31, 2020 2020 2019 2018 Par Value Per Share Dividends Voting Rights Senior Preferred 10,000,000 — — — $ 1.00 As declared Voting 10% Cumulative Preferred 900,000 — — — 5.00 As declared Non-voting Common 40,000,000 32,719,852 32,694,268 32,603,926 1.00 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, 2020 2019 2018 Number of shares repurchased 59,284 26,670 151,264 Average price of shares repurchased $ 52.26 $ 60.04 $ 52.32 Shares remaining to be repurchased 62,782 122,066 148,736
Required Capital Amounts and Company's Respective Ratios	The actual and required capital amounts and ratios are shown in the following table: Required To Be Well For Capital With Capitalized Under Adequacy Capital Conservation Prompt Corrective Actual Purposes Buffer Action Provisions Amount Ratio Amount Ratio Amount Ratio Amount Ratio (Dollars in thousands) As of December 31, 2020: Total Capital (to Risk Weighted Assets)- BancFirst Corporation $ 997,383 15.64 % $ 510,110 8.00% $ 669,519 10.50 % N/A N/A BancFirst 898,714 15.59 % 461,142 8.00% 605,248 10.50 % $ 576,427 10.00 % Pegasus Bank 70,922 11.85 % 47,893 8.00% 62,860 10.50 % 59,866 10.00 % Common Equity Tier 1 Capital (to Risk Weighted Assets)- BancFirst Corporation $ 891,534 13.98 % $ 286,937 4.50% $ 446,346 7.00 % N/A N/A BancFirst 806,478 13.99 % 259,392 4.50% 403,499 7.00 % $ 374,678 6.50 % Pegasus Bank 66,150 11.05 % 26,940 4.50% 41,906 7.00 % 38,913 6.50 % Tier 1 Capital (to Risk Weighted Assets)- BancFirst Corporation $ 917,534 14.39 % $ 382,583 6.00% $ 541,992 8.50 % N/A N/A BancFirst 826,478 14.34 % 345,856 6.00% 489,963 8.50 % $ 461,142 8.00 % Pegasus Bank 66,150 11.05 % 35,920 6.00% 50,886 8.50 % 47,893 8.00 % Tier 1 Capital (to Total Assets)- BancFirst Corporation $ 917,534 9.63 % $ 380,952 4.00% N/A N/A N/A N/A BancFirst 826,478 9.48 % 348,666 4.00% N/A N/A $ 435,833 5.00 % Pegasus Bank 66,150 8.10 % 32,682 4.00% N/A N/A 40,852 5.00 % As of December 31, 2019: Total Capital (to Risk Weighted Assets)- BancFirst Corporation $ 910,561 14.42 % $ 505,050 8.00% $ 662,878 10.50 % N/A N/A BancFirst 827,928 14.14 % 468,107 8.00% 614,390 10.50 % $ 585,134 10.00 % Pegasus Bank 63,817 14.15 % 36,083 8.00% 47,359 10.50 % 45,104 10.00 % Common Equity Tier 1 Capital (to Risk Weighted Assets)- BancFirst Corporation $ 830,323 13.15 % $ 284,091 4.50% $ 441,919 7.00 % N/A N/A BancFirst 753,659 12.88 % 263,310 4.50% 409,594 7.00 % $ 380,337 6.50 % Pegasus Bank 60,214 13.35 % 20,297 4.50% 31,573 7.00 % 29,317 6.50 % Tier 1 Capital (to Risk Weighted Assets)- BancFirst Corporation $ 856,323 13.56 % $ 378,788 6.00% $ 536,616 8.50 % N/A N/A BancFirst 773,659 13.22 % 351,080 6.00% 497,364 8.50 % $ 468,107 8.00 % Pegasus Bank 60,214 13.35 % 27,062 6.00% 38,338 8.50 % 36,083 8.00 % Tier 1 Capital (to Total Assets)- BancFirst Corporation $ 856,323 10.28 % $ 333,171 4.00% N/A N/A N/A N/A BancFirst 773,659 10.22 % 302,845 4.00% N/A N/A $ 378,556 5.00 % Pegasus Bank 60,214 8.58 % 28,058 4.00% N/A N/A 35,072 5.00 %

Net Income Per Common Share (Ta

Net Income Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2020
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 (Numerator) Shares (Denominator) Per Share Amount (Dollars in thousands, except per share data) Year Ended December 31, 2020 Basic Income available to common stockholders $ 99,586 32,672,522 $ 3.05 Dilutive effect of stock options — 538,430 Diluted Income available to common stockholders plus assumed exercises of stock options $ 99,586 33,210,952 $ 3.00 Year Ended December 31, 2019 Basic Income available to common stockholders $ 134,879 32,639,396 $ 4.13 Dilutive effect of stock options — 690,448 Diluted Income available to common stockholders plus assumed exercises of stock options $ 134,879 33,329,844 $ 4.05 Year Ended December 31, 2018 Basic Income available to common stockholders $ 125,814 32,689,228 $ 3.85 Dilutive effect of stock options — 741,486 Diluted Income available to common stockholders plus assumed exercises of stock options $ 125,814 33,430,714 $ 3.76
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 were anti-dilutive for the period. Shares Average Exercise December 31, 2020 402,575 $ 52.72 December 31, 2019 180,989 54.73 December 31, 2018 92,738 53.17

Condensed Parent Company Fina_2

Condensed Parent Company Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Summary of Balance Sheet of Parent Company	BALANCE SHEETS December 31, 2020 2019 (Dollars in thousands) ASSETS Cash $ 9,081 $ 5,761 Investments in subsidiaries 1,003,017 946,311 Goodwill 69,478 69,478 Core deposit premium 8,622 9,617 Dividends receivable 12,750 11,622 Other assets 5,331 2,313 Total assets $ 1,108,279 $ 1,045,102 LIABILITIES AND STOCKHOLDERS’ EQUITY Other liabilities $ 13,590 $ 13,309 Junior subordinated debentures 26,804 26,804 Stockholders’ equity 1,067,885 1,004,989 Total liabilities and stockholders’ equity $ 1,108,279 $ 1,045,102
Summary of Income Statement of Parent Company	STATEMENTS OF INCOME Year Ended December 31, 2020 2019 2018 (Dollars in thousands) OPERATING INCOME Dividends from subsidiaries $ 50,872 $ 77,559 $ 38,326 Interest on interest-bearing deposits 1 1,150 1,151 Other 886 451 16 Total operating income 51,759 79,160 39,493 OPERATING EXPENSE Interest 1,965 1,965 2,172 Other 3,317 5,017 698 Total operating expense 5,282 6,982 2,870 Income before taxes and equity in undistributed earnings of subsidiaries 46,477 72,178 36,623 Allocated income tax benefit 2,610 2,731 3,093 Income before equity in undistributed earnings of subsidiaries 49,087 74,909 39,716 Equity in undistributed earnings of subsidiaries 51,955 61,194 87,404 Amortization of stock-based compensation arrangements of subsidiaries (1,456 ) (1,224 ) (1,306 ) Net income $ 99,586 $ 134,879 $ 125,814
Summary of Cash Flow of Parent Company	STATEMENTS OF CASH FLOW Year Ended December 31, 2020 2019 2018 (Dollars in thousands) CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 99,586 $ 134,879 $ 125,814 Adjustments to reconcile to net cash provided by operating activities: Equity in undistributed earnings of subsidiaries (51,955 ) (61,194 ) (87,404 ) Amortization of stock-based compensation arrangements of subsidiaries 1,456 1,224 1,306 Other, net 188 (440 ) (2,621 ) Net cash provided by operating activities 49,275 74,469 37,095 INVESTING ACTIVITIES Net cash provided by acquisitions — — 41,347 Payments for investments in subsidiaries (1,000 ) (134,457 ) — Other, net (1,175 ) (418 ) (174 ) Net cash (used in) provided by investing activities (2,175 ) (134,875 ) 41,173 FINANCING ACTIVITIES Issuance of common stock 1,790 2,484 2,238 Common stock acquired (3,098 ) (1,601 ) (7,914 ) Cash dividends paid (42,472 ) (39,805 ) (30,265 ) Redemption of Junior Subordinated debentures — — (5,155 ) Net cash used in financing activities (43,780 ) (38,922 ) (41,096 ) Net increase (decrease) in cash and due from banks 3,320 (99,328 ) 37,172 Cash and due from banks at the beginning of the period 5,761 105,089 67,917 Cash and due from banks at the end of the period $ 9,081 $ 5,761 $ 105,089 SUPPLEMENTAL DISCLOSURE Cash paid during the period for interest $ 1,966 $ 5,131 $ 2,171 Cash received during the period for income taxes, net $ 2,812 $ 4,518 $ 3,647

Commitments and Contingent Li_2

Commitments and Contingent Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 (Dollars in thousands) Loan commitments $ 1,779,857 $ 1,618,001 Stand-by letters of credit 96,311 64,702

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Summary of Rental Expense	Rental expense on all operating leases, including those rented on a monthly or temporary basis were as follows (Dollars in thousands): Year Ending December 31: 2020 $ 1,894 2019 1,633 2018 1,857
Schedule of Maturity of Operating Lease Liabilities	Maturity of Operating Lease Liabilities December 31, 2020 (Dollars in thousands) 2021 $ 1,413 2022 1,210 2023 706 2024 345 2025 277 Thereafter 887 Total lease payments 4,838 Less imputed interest (508 ) Operating lease liability $ 4,330
Scheduled of Minimum Future Contractual Rent To be Received Under The Remaining Non-Cancelable Term of Operating Leases	The following table presents the scheduled minimum future contractual rent to be received under the remaining non-cancelable term of the operating leases: December 31, 2020 (Dollars in thousands) 2021 $ 3,402 2022 2,707 2023 2,313 2024 2,229 2025 1,611 2026-2030 4,355 Total future minimum lease payments $ 16,617

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
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 the periods presented, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value: Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Fair Value (Dollars in thousands) December 31, 2020 Debt securities available for sale: U.S. Treasury $ 475,236 $ — $ — $ 475,236 U.S. federal agencies — 19,638 — 19,638 Mortgage-backed securities — 15,696 — 15,696 States and political subdivisions — 28,793 155 28,948 Asset backed securities — — 12,714 12,714 December 31, 2019 Debt securities available for sale: U.S. Treasury $ 414,449 $ — $ — $ 414,449 U.S. federal agencies — 23,024 — 23,024 Mortgage-backed securities — 17,005 — 17,005 States and political subdivisions — 22,531 — 22,531 Asset backed securities — — 12,714 12,714
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 periods presented were as follows: Twelve Months Ended December 31, 2020 2019 (Dollars in thousands) Balance at the beginning of the year $ 12,714 $ 13,443 Transfers from level 2 $ 1,643 — Settlements (1,473 ) (695 ) Total unrealized losses (15 ) (34 ) Balance at the end of the period $ 12,869 $ 12,714
Assets Measured at Fair Value on Nonrecurring Basis	The following table summarizes assets measured at fair value on a nonrecurring basis. The fair value represents end of period values, which approximate fair value measurements that occurred on various measurement dates throughout the period: Total Fair Value Level 3 (Dollars in thousands) As of and for the Year-to-date Period Ended December 31, 2020 Equity securities $ 21,203 Collateral dependent loans 11,347 Repossessed assets 291 Other real estate owned 32,066 As of and for the Year-to-date Period Ended December 31, 2019 Equity securities $ 10,121 Impaired loans (less specific allowance) 45,687 Repossessed assets 465 Other real estate owned 3,024
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, 2020 2019 Carrying Amount Fair Value Carrying Amount Fair Value (Dollars in thousands) FINANCIAL ASSETS Level 2 inputs: Cash and cash equivalents $ 1,616,912 $ 1,616,912 $ 1,868,281 $ 1,868,281 Federal funds sold — — 1,000 1,000 Debt securities held for investment 59 62 1,403 1,403 Loans held for sale 53,719 53,719 11,001 11,001 Level 3 inputs: Debt securities held for investment 2,905 2,922 500 500 Loans, net of allowance for credit losses 6,303,140 6,347,803 5,607,905 5,625,005 FINANCIAL LIABILITIES Level 2 inputs: Deposits 8,064,704 8,084,695 7,483,635 7,497,429 Short-term borrowings 1,100 1,100 1,100 1,100 Junior subordinated debentures 26,804 30,535 26,804 29,324 OFF-BALANCE SHEET FINANCIAL INSTRUMENTS Loan commitments 3,115 2,832 Letters of credit 722 485

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Results of Operations and Selected Financial Information	The results of operations and selected financial information for the five business units are as follows: Metropolitan Banks Community Banks Pegasus Bank Other Financial Services Executive, Operations & Support Eliminations Consolidated (Dollars in thousands) December 31, 2020 Net interest income $ 85,464 $ 175,757 $ 21,360 $ 23,500 $ 79 $ 508 $ 306,668 Provision for credit losses 30,202 29,827 1,916 562 141 — 62,648 Noninterest income 18,664 60,386 1,071 41,549 118,491 (102,939 ) 137,222 Depreciation and amortization 2,639 10,603 760 500 3,922 — 18,424 Other expenses 36,746 111,341 13,831 44,918 33,588 (1,118 ) 239,306 Income before taxes $ 34,541 $ 84,372 $ 5,924 $ 19,069 $ 80,919 $ (101,313 ) $ 123,512 Total assets $ 2,729,886 $ 5,527,611 $ 919,572 $ 137,122 $ 1,073,507 $ (1,175,341 ) $ 9,212,357 Capital expenditures $ 1,087 $ 9,946 $ 1,775 $ 450 $ 53,188 $ — $ 66,446 December 31, 2019 Net interest income $ 86,511 $ 177,330 $ 8,657 $ 5,763 $ 3,660 $ — $ 281,921 Provision for credit losses 2,143 5,606 140 (69 ) 467 — 8,287 Noninterest income 18,608 64,485 483 40,270 152,320 (138,937 ) 137,229 Depreciation and amortization 2,463 10,218 274 603 2,431 — 15,989 Other expenses 37,549 109,044 4,939 25,408 50,941 (2,569 ) 225,312 Income before taxes $ 62,964 $ 116,947 $ 3,787 $ 20,091 $ 102,141 $ (136,368 ) $ 169,562 Total assets $ 2,806,021 $ 4,998,247 $ 738,351 $ 102,442 $ 950,920 $ (1,030,223 ) $ 8,565,758 Capital expenditures $ 4,349 $ 11,219 $ 83 $ 1,220 $ 10,183 $ — $ 27,054 December 31, 2018 Net interest income (expense) $ 84,043 $ 170,096 $ — $ 5,341 $ 996 $ — $ 260,476 Provision for credit losses 79 4,178 — (466 ) 11 — 3,802 Noninterest income 16,625 60,004 — 37,743 137,364 (126,537 ) 125,199 Depreciation and amortization 2,364 9,092 — 588 1,502 — 13,546 Other expenses 36,873 106,674 — 24,895 42,319 (2,186 ) 208,575 Income before taxes $ 61,352 $ 110,156 $ — $ 18,067 $ 94,528 $ (124,351 ) $ 159,752 Total assets $ 2,743,876 $ 4,892,946 $ — $ 84,706 $ 861,782 $ (1,009,052 ) $ 7,574,258 Capital expenditures $ 3,003 $ 21,393 $ — $ 1,035 $ 26,432 $ — $ 51,863

Description of Business and S_4

Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	Jan. 01, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
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		7 years 2 months 12 days
Advertising costs		$ 3,300,000	$ 3,800,000	$ 3,500,000
Revenue recognition, description of performance obligation		the Company offers various services to customers that generate revenue. Contract performance typically occurs in one year or less.
Incremental cost of obtaining contract		true
Revenue recognition, description of payment terms		Revenue is recognized when the transactions occur or as services are performed over primarily monthly or quarterly periods. Payment is typically received in the period the transactions occur, or in some cases, within 90 days of the service period.
Increase to retained earnings for cumulative effect of adopting ASU		$ 871,161,000	815,488,000
Increase to retained earnings for cumulative effect of adopting ASU tax		925,000
Addition to allowance for credit losses for financial assets purchased with credit deterioration		502,000
Accrued interest receivable		$ 26,000,000	$ 24,500,000
Paycheck Protection Program, CARES Act [Member] | Small Business Administration (SBA) [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of processing fees		5.00%
Processing fees received from the SBA		$ 30,200,000
CUMULATIVE EFFECT, PERIOD OF ADOPTION, ADJUSTMENT [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Increase to retained earnings for cumulative effect of adopting ASU		2,300,000
ASU No. 2018-13 [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 1, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true
ASC 326 [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 1, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true
Addition to allowance for credit losses for financial assets purchased with credit deterioration	$ 1,200,000
Accrued interest receivable		$ 26,000,000
Delinquency period placed on nonaccrual status loan		90 days
Commercial loans are charged off deemed uncollectible period		180 days
ASC 326 [Member] | U.S. Treasury or U.S. Government-sponsored Entities and Agencies [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of available for sale securities held		95.00%	95.00%
ASC 326 [Member] | CUMULATIVE EFFECT, PERIOD OF ADOPTION, ADJUSTMENT [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Increase to retained earnings for cumulative effect of adopting ASU	2,300,000
Increase to retained earnings for cumulative effect of adopting ASU tax	$ 925,000
Core Deposit Intangibles [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, Estimated useful lives		7 years 3 months 18 days
Core Deposit Intangibles [Member] | Minimum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, Estimated useful lives		7 years
Core Deposit Intangibles [Member] | Maximum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, Estimated useful lives		10 years
Customer Relationship Intangibles [Member] | Minimum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, Estimated useful lives		3 years
Customer Relationship Intangibles [Member] | Maximum [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, Estimated useful lives		18 years

Description of Business and S_5

Description of Business and Summary of Significant Accounting Policies - Schedule of Impact of ASC 326 Adoption on Allowance for Credit losses on Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans	$ 91,366		$ 54,238	$ 51,389
Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		$ 54,238
ASC 326 [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		51,043
ASC 326 [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		(3,195)
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans	7,035		5,625
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		5,625
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans	11,842		8,358
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		8,358
Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans	2,560		2,214
Real Estate [Member] | Construction and Development Less than 60 Months [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		2,214
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans	627		1,933
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		1,933
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans	2,570		8,692
Real Estate [Member] | Residential Real Estate First Lien [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		8,692
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans	2,230		2,767
Real Estate [Member] | Residential Real Estate All Other [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		2,767
Real Estate [Member] | Farmland [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		2,821
Real Estate [Member] | ASC 326 [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		2,819
Real Estate [Member] | ASC 326 [Member] | Commercial Real Estate Owner Occupied [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		(2,806)
Real Estate [Member] | ASC 326 [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		2,851
Real Estate [Member] | ASC 326 [Member] | Commercial Real Estate Non-Owner Occupied [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		(5,507)
Real Estate [Member] | ASC 326 [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		1,158
Real Estate [Member] | ASC 326 [Member] | Construction and Development Less than 60 Months [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		(1,056)
Real Estate [Member] | ASC 326 [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		1,155
Real Estate [Member] | ASC 326 [Member] | Construction Residential Real Estate Less than 60 Months [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		(778)
Real Estate [Member] | ASC 326 [Member] | Residential Real Estate First Lien [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		4,861
Real Estate [Member] | ASC 326 [Member] | Residential Real Estate First Lien [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		(3,831)
Real Estate [Member] | ASC 326 [Member] | Residential Real Estate All Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		1,359
Real Estate [Member] | ASC 326 [Member] | Residential Real Estate All Other [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		(1,408)
Real Estate [Member] | ASC 326 [Member] | Farmland [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		1,413
Real Estate [Member] | ASC 326 [Member] | Farmland [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		(1,408)
Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans	32,400		13,462
Commercial and Agricultural Non-Real Estate [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		13,462
Commercial and Agricultural Non-Real Estate [Member] | ASC 326 [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		26,657
Commercial and Agricultural Non-Real Estate [Member] | ASC 326 [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		13,195
Consumer Non-real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans	3,377		3,252
Consumer Non-real Estate [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		3,252
Consumer Non-real Estate [Member] | ASC 326 [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		2,630
Consumer Non-real Estate [Member] | ASC 326 [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		(622)
Oil and Gas [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		1,883
Oil and Gas [Member] | ASC 326 [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		537
Oil and Gas [Member] | ASC 326 [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		(1,346)
Other Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans	3,182		2,632	$ 2,423
Other Loans [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		2,632
Other Loans [Member] | ASC 326 [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		2,516
Other Loans [Member] | ASC 326 [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		(116)
Pegasus Bank [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans	$ 4,556		$ 599
Pegasus Bank [Member] | Pre ASC 326 Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		599
Pegasus Bank [Member] | ASC 326 [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		3,087
Pegasus Bank [Member] | ASC 326 [Member] | Impact of ASC Adoption [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans		$ 2,488

Description of Business and S_6

Description of Business and Summary of Significant Accounting Policies - Schedule of Portfolio Segments Weighted Average Life, and Measures the Allowance for Credit Losses (Detail) - ASC 326 [Member]	12 Months Ended
	Dec. 31, 2020
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	9 years
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	6 years
Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	3 years
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	1 year
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	13 years
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	6 years
Real Estate [Member] | Farmland [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	12 years
Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	3 years
Consumer Non-real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	4 years
Oil and Gas [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	1 year
Other Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	8 years
Pegasus Bank [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loan Segment, Life (in years)	4 years

Recent Developments Including M

Recent Developments Including Mergers and Acquisitions - Additional Information (Detail)	Mar. 05, 2020USD ($)	Dec. 31, 2019USD ($)	Aug. 15, 2019USD ($)	Aug. 31, 2018USD ($)ft²Floor	Jan. 11, 2018USD ($)CommunityLocation	Dec. 31, 2020USD ($)	Dec. 31, 2018USD ($)	Dec. 14, 2018
Business Combination Separately Recognized Transactions [Line Items]
Goodwill		$ 148,604,000				$ 149,922,000	$ 79,749,000
Number of additional banking communities | Community					5
BFTower LLC [Member] | ParcFirst LLC [Member]
Business Combination Separately Recognized Transactions [Line Items]
Ownership interest acquired		50.00%
Payment to acquire ownership interest		$ 1,500,000
COVID 19 [Member]
Business Combination Separately Recognized Transactions [Line Items]
Loans modification						$ 81,700,000
Citizens Bankshares, Inc [Member]
Business Combination Separately Recognized Transactions [Line Items]
Date of acquisition	Mar. 5, 2020
Total assets acquired	$ 47,800,000
Loans	22,900,000
Deposits	45,000,000
Purchase price	2,900,000
Intangibles assets, net	206,000
Goodwill	$ 1,300,000
Pegasus Bank [Member]
Business Combination Separately Recognized Transactions [Line Items]
Date of acquisition			Aug. 15, 2019
Total assets acquired			$ 651,100,000
Loans			389,900,000
Deposits			603,900,000
Purchase price			123,500,000
Intangibles assets, net			9,900,000
Goodwill			$ 68,900,000
Cotter Ranch Tower [Member] | BFTower LLC [Member]
Business Combination Separately Recognized Transactions [Line Items]
Date of acquisition				Aug. 31, 2018
Purchase price				$ 21,000,000
Number of square feet | ft²				507,000
Number of floors | Floor				36
Percentage of property leased				55.00%
Percentage of occupancy				35.00%
Percentage of occupancy including leased space				90.00%
Renovations completion year				2022
Renovations cost				$ 70,000,000
Tenant improvements				$ 10,000,000
Number of square feet to be occupied | ft²				165,000
Cotter Ranch Tower [Member] | BFTower LLC [Member] | SFPG, LLC [Member]
Business Combination Separately Recognized Transactions [Line Items]
Ownership interest acquired						49.00%		42.60%
Payment to acquire ownership interest						$ 11,300,000
First Bank & Trust Company [Member]
Business Combination Separately Recognized Transactions [Line Items]
Date of acquisition					Jan. 11, 2018
Total assets acquired					$ 290,000,000
Loans					247,000,000
Deposits					251,000,000
Intangibles assets, net					6,300,000
Goodwill					$ 19,100,000
First Bank of Chandler [Member]
Business Combination Separately Recognized Transactions [Line Items]
Date of acquisition					Jan. 11, 2018
Total assets acquired					$ 88,000,000
Loans					66,000,000
Deposits					79,000,000
Intangibles assets, net					2,200,000
Goodwill					$ 6,600,000
Number of locations acquired | Location					2

Cash Due from Banks, Interest-B

Cash Due from Banks, Interest-Bearing Deposits and Federal Funds Sold - Additional Information (Detail)	Mar. 26, 2020
Cash And Cash Equivalents [Abstract]
Reserve requirement ratio	0.00%

Cash Due from Banks, Interest_2

Cash Due from Banks, Interest-Bearing Deposits and Federal Funds Sold - Summary of Average Amount of Required Reserves (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Average Amount Of Required Reserves [Abstract]
Vault cash and funds on deposit with the Federal Reserve Bank	$ 1,429,410	$ 1,738,523
Average required reserves		$ 63,842

Securities - Summary of Amortiz

Securities - Summary of Amortized Cost and Estimated Fair Values of Debt Securities Held for Investment (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 2,964	$ 1,903
Gross Unrealized Gains	21	5
Gross Unrealized Losses	(1)	(5)
Estimated Fair Value	2,984	1,903
Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	59	93
Gross Unrealized Gains	3	4
Estimated Fair Value	62	97
States and Political Subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	2,405	1,310
Gross Unrealized Gains	18	1
Gross Unrealized Losses	(1)	(5)
Estimated Fair Value	2,422	1,306
Other Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	500	500
Estimated Fair Value	$ 500	$ 500

Securities - Summary of Amort_2

Securities - Summary of Amortized Cost and Estimated Fair Values of Debt Securities Available for Sale (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 542,289	$ 485,082
Gross Unrealized Gains	10,626	5,407
Gross Unrealized Losses	(683)	(766)
Estimated Fair Value	552,232	489,723
U.S. Treasuries [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	465,416	409,488
Gross Unrealized Gains	9,820	4,974
Gross Unrealized Losses		(13)
Estimated Fair Value	475,236	414,449
U.S. Federal Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	19,697	23,039
Gross Unrealized Gains	1	23
Gross Unrealized Losses	(60)	(38)
Estimated Fair Value	19,638	23,024
Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15,268	16,941
Gross Unrealized Gains	428	128
Gross Unrealized Losses		(64)
Estimated Fair Value	15,696	17,005
States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	28,571	22,294
Gross Unrealized Gains	377	282
Gross Unrealized Losses		(45)
Estimated Fair Value	28,948	22,531
Asset backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,337	13,320
Gross Unrealized Losses	(623)	(606)
Estimated Fair Value	$ 12,714	$ 12,714

Securities - Maturity of Debt S

Securities - Maturity of Debt Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Held for Investment, Contractual maturity of debt securities, Amortized Cost
Amortized cost, Within one year	$ 807	$ 300
Amortized cost, After one year but within five years	2,091	1,058
Amortized cost, After five years but within ten years	65	543
Amortized cost, After ten years	1	2
Amortized Cost	2,964	1,903
Available for sale, Contractual maturity of debt securities, Amortized Cost
Amortized Cost, Within one year	339,752	186,373
Amortized Cost, After one year but within five years	162,401	252,519
Amortized Cost, After five years but within ten years	3,753	5,873
Amortized Cost, After ten years	36,383	40,317
Amortized Cost	542,289	485,082
Held for Investment, Contractual maturity of debt securities, Estimated Fair Value
Estimated Fair Value, Within one year	809	300
Estimated Fair Value, After one year but within five years	2,110	1,055
Estimated Fair Value, After five years but within ten years	64	546
Estimated Fair Value, After ten years	1	2
Estimated Fair Value	2,984	1,903
Available for sale, Contractual maturity of debt securities, Estimated Fair Value
Estimated Fair Value, Within one year	341,102	186,539
Estimated Fair Value, After one year but within five years	171,135	257,430
Estimated Fair Value, After five years but within ten years	3,910	6,008
Estimated Fair Value, After ten years	36,085	39,746
Total debt securities	$ 552,232	$ 489,723

Securities - Proceeds from Sale

Securities - Proceeds from Sales and Realized Securities Losses, on Available for Sale Debt Securities (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Available For Sale Securities Gross Realized Gain Loss [Abstract]
Proceeds	$ 31,285
Gross losses realized	$ 109

Securities - Company's Book Val

Securities - Company's Book Value of Pledged Debt Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Pledged Financial Instruments Not Separately Reported Securities Pledged By Type Of Security [Abstract]
Book value of pledged securities	$ 490,833	$ 445,702

Securities - Summary of Debt Se

Securities - Summary of Debt Securities with Unrealized Losses, Segregated by Duration of Unrealized Loss (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 12,236	$ 38,416
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	41	138
Available-for-sale Securities, 12 Months or Longer, Fair Value	14,898	35,402
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	642	628
Available-for-sale Securities, Fair Value, Total	27,134	73,818
Available-for-sale Securities, Unrealized Losses, Total	683	766
Held for Investment
Held-to-maturity Securities, Less than 12 Months, Fair Value	119	1,016
Held-to-maturity Securities, Less than 12 Months, Unrealized Losses	1	5
Held-to-maturity Securities, 12 Months or Longer, Fair Value		3
Held-to-maturity Securities, Fair Value, Total	119	1,019
Held-to-maturity Securities, Unrealized Losses, Total	1	5
U.S. Federal Agencies [Member]
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value	12,236	10,362
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	41	19
Available-for-sale Securities, 12 Months or Longer, Fair Value	2,184	2,700
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	19	19
Available-for-sale Securities, Fair Value, Total	14,420	13,062
Available-for-sale Securities, Unrealized Losses, Total	60	38
Asset backed Securities [Member]
Available for Sale
Available-for-sale Securities, 12 Months or Longer, Fair Value	12,714	12,714
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	623	606
Available-for-sale Securities, Fair Value, Total	12,714	12,714
Available-for-sale Securities, Unrealized Losses, Total	623	606
U.S. Treasuries [Member]
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value		8,999
Available-for-sale Securities, Less than 12 Months, Unrealized Losses		10
Available-for-sale Securities, 12 Months or Longer, Fair Value		19,988
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses		3
Available-for-sale Securities, Fair Value, Total		28,987
Available-for-sale Securities, Unrealized Losses, Total		13
Mortgage Backed Securities [Member]
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value		15,165
Available-for-sale Securities, Less than 12 Months, Unrealized Losses		64
Available-for-sale Securities, Fair Value, Total		15,165
Available-for-sale Securities, Unrealized Losses, Total		64
Held for Investment
Held-to-maturity Securities, 12 Months or Longer, Fair Value		3
Held-to-maturity Securities, Fair Value, Total		3
States and Political Subdivisions [Member]
Available for Sale
Available-for-sale Securities, Less than 12 Months, Fair Value		3,890
Available-for-sale Securities, Less than 12 Months, Unrealized Losses		45
Available-for-sale Securities, Fair Value, Total		3,890
Available-for-sale Securities, Unrealized Losses, Total		45
Held for Investment
Held-to-maturity Securities, Less than 12 Months, Fair Value	119	1,016
Held-to-maturity Securities, Less than 12 Months, Unrealized Losses	1	5
Held-to-maturity Securities, Fair Value, Total	119	1,016
Held-to-maturity Securities, Unrealized Losses, Total	$ 1	$ 5

Loans Held for Investment and_3

Loans Held for Investment and Allowance for Credit Losses on Loans - Summary of Loans Held for Investment by Portfolio Segment (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	$ 6,394,506	$ 5,662,143
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	641,987	621,188
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	971,158	851,200
Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	229,615	287,138
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	206,195	189,480
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	853,316	834,849
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	168,081	187,647
Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	252,958	246,988
Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	1,159,810	1,315,005
Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	355,405	359,529
Oil and Gas [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	179,355	184,399
Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	822,078	154,015
Pegasus Bank [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	554,548	$ 430,705
Pegasus Bank [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans (net of unearned interest)	$ 272,000

Loans Held for Investment and_4

Loans Held for Investment and Allowance for Credit Losses on Loans - Summary of Loans Held for Investment by Portfolio Segment (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Receivables [Abstract]
Accrued interest receivable	$ 26	$ 24.5
Pay check protection program loans	652.7
Paycheck protection program unamortized processing fees	$ 14.5

Loans Held for Investment and_5

Loans Held for Investment and Allowance for Credit Losses on Loans - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 6,394,506,000	$ 5,662,143,000
Pay check protection program loan held for investment	652,700,000
Paycheck protection program unamortized processing fees	14,500,000
Paycheck protection program unamortized processing fees recognized as interest income	15,600,000
Gains on sale of property held in other real estate owned	2,400,000	1,400,000	$ 23,500
Interest income that would have been recognized	2,800,000	1,700,000	$ 2,300,000
Decrease in allowance for credit losses upon adoption of ASC 326	3,195,000
Provision for credit losses on loans	62,648,000	8,287,000
Interest income recognized on collateral-dependent loans	0
Interest income recognized on impaired loans		0
Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Loans modification	81,700,000
U.S. Federal Agencies [Member]
Financing Receivable Recorded Investment [Line Items]
Nonaccrual loans guaranteed by government agencies	7,800,000
BancFirst [Member]
Financing Receivable Recorded Investment [Line Items]
Sale of Loans	21,600,000
Amount transferred from loans held for investment (net of unearned interest) to loans held for sale	$ 21,600,000
BancFirst’s [Member]
Financing Receivable Recorded Investment [Line Items]
Percentage of loans secured by real estate	58.00%
BancFirst’s [Member] | Energy [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 191,000,000	189,000,000
BancFirst’s [Member] | Energy [Member] | Midstream Energy Loans
Financing Receivable Recorded Investment [Line Items]
Total loans	50,000,000	41,000,000
BancFirst’s [Member] | Commercial and Agricultural Non-Real Estate [Member] | Ancillary Services [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	59,000,000	90,000,000
Pegasus Bank [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	554,548,000	430,705,000
Decrease in allowance for credit losses upon adoption of ASC 326	(2,488,000)
Provision for credit losses on loans	1,886,000	569,000
Pegasus Bank [Member] | Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 272,000,000
Percentage of loans secured by real estate	49.00%
Pegasus Bank [Member] | Energy [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 107,000,000	57,000,000
Pegasus Bank [Member] | Energy [Member] | Midstream Energy Loans
Financing Receivable Recorded Investment [Line Items]
Total loans	11,000,000	0
Pegasus Bank [Member] | Energy [Member] | Ancillary Services [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	13,000,000	7,000,000
Pegasus Bank [Member] | Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 262,000,000	$ 172,000,000

Loans Held for Investment and_6

Loans Held for Investment and Allowance for Credit Losses on Loans - Summary of Troubled Debt Restructurings and Other Real Estate Owned and Repossessed Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Summary Of Nonperforming And Restructured Assets [Abstract]
Troubled debt restructurings	$ 7,784	$ 18,010
Other real estate owned and repossessed assets	$ 32,480	$ 6,073

Loans Held for Investment and_7

Loans Held for Investment and Allowance for Credit Losses on Loans - Summary of Amounts Included in Nonaccrual Loans Segregated by Portfolio Segment (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total	$ 37,545	$ 17,965
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total	1,404
Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total		2,275
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total	4,719
Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total		1,815
Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total	95
Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total		1,206
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total	3,615
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total	1,362
Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total		3,060
Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total	7,901
Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total		2,915
Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total	12,782
Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total	5,399	1,083
Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total	$ 268
Acquired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total		4,496
Consumer Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total		264
Pegasus Bank [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual Loans, Total		$ 851

Loans Held for Investment and_8

Loans Held for Investment and Allowance for Credit Losses on Loans - Age Analysis of Loans Held for Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	$ 45,532	$ 49,793
Current Loans	6,348,974	5,612,350
Total Loans	6,394,506	5,662,143
Accruing Loans 90 Days or More Past Due	4,802	11,834
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	2,368
Current Loans	639,619
Total Loans	641,987	621,188
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	357
Current Loans	970,801
Total Loans	971,158	851,200
Accruing Loans 90 Days or More Past Due	35
Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	597
Current Loans	229,018
Total Loans	229,615	287,138
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	2,181
Current Loans	165,900
Total Loans	168,081	187,647
Accruing Loans 90 Days or More Past Due	384
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,388
Current Loans	204,807
Total Loans	206,195	189,480
Accruing Loans 90 Days or More Past Due	282
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	9,869
Current Loans	843,447
Total Loans	853,316	834,849
Accruing Loans 90 Days or More Past Due	945
Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		7,726
Current Loans		699,690
Total Loans		707,416
Accruing Loans 90 Days or More Past Due		3,799
Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		2,199
Current Loans		1,134,976
Total Loans		1,137,175
Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		7,893
Current Loans		332,679
Total Loans		340,572
Accruing Loans 90 Days or More Past Due		1,660
Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		8,065
Current Loans		912,767
Total Loans		920,832
Accruing Loans 90 Days or More Past Due		549
Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	7,864
Current Loans	245,094
Total Loans	252,958	246,988
Accruing Loans 90 Days or More Past Due	135
Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	3,189
Current Loans	352,216
Total Loans	355,405	359,529
Accruing Loans 90 Days or More Past Due	386
Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	8,792	6,291
Current Loans	813,286	147,724
Total Loans	822,078	154,015
Accruing Loans 90 Days or More Past Due	2,170	4,426
Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	8,927
Current Loans	1,150,883
Total Loans	1,159,810	1,315,005
Accruing Loans 90 Days or More Past Due	465
Oil and Gas [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	179,355
Total Loans	179,355	184,399
Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		5,499
Current Loans		1,448,894
Total Loans		1,454,393
Accruing Loans 90 Days or More Past Due		354
Acquired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		6,990
Current Loans		147,691
Total Loans		154,681
Accruing Loans 90 Days or More Past Due		555
Consumer Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		4,279
Current Loans		358,075
Total Loans		362,354
Accruing Loans 90 Days or More Past Due		491
Pegasus Bank [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		851
Current Loans	554,548	429,854
Total Loans	554,548	430,705
Pegasus Bank [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	272,000
30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	16,174	20,728
30 to 59 Days Past Due [Member] | Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,096
30 to 59 Days Past Due [Member] | Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	323
30 to 59 Days Past Due [Member] | Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	511
30 to 59 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	520
30 to 59 Days Past Due [Member] | Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,106
30 to 59 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	5,428
30 to 59 Days Past Due [Member] | Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		1,600
30 to 59 Days Past Due [Member] | Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		971
30 to 59 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		4,705
30 to 59 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		4,496
30 to 59 Days Past Due [Member] | Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,297
30 to 59 Days Past Due [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	2,154
30 to 59 Days Past Due [Member] | Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	951	1,670
30 to 59 Days Past Due [Member] | Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	2,788
30 to 59 Days Past Due [Member] | Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		2,290
30 to 59 Days Past Due [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		2,167
30 to 59 Days Past Due [Member] | Consumer Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		2,829
60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	5,574	6,656
60 to 89 Days Past Due [Member] | Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	108
60 to 89 Days Past Due [Member] | Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	86
60 to 89 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	55
60 to 89 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,463
60 to 89 Days Past Due [Member] | Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		967
60 to 89 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		973
60 to 89 Days Past Due [Member] | Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		1,028
60 to 89 Days Past Due [Member] | Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	344
60 to 89 Days Past Due [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	501
60 to 89 Days Past Due [Member] | Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,223	8
60 to 89 Days Past Due [Member] | Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,794
60 to 89 Days Past Due [Member] | Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		1,446
60 to 89 Days Past Due [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		1,376
60 to 89 Days Past Due [Member] | Consumer Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		858
90 Days and Greater [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	23,784	22,409
90 Days and Greater [Member] | Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,164
90 Days and Greater [Member] | Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	34
90 Days and Greater [Member] | Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	1,606
90 Days and Greater [Member] | Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	282
90 Days and Greater [Member] | Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	2,978
90 Days and Greater [Member] | Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		5,159
90 Days and Greater [Member] | Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		1,228
90 Days and Greater [Member] | Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		2,215
90 Days and Greater [Member] | Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		2,541
90 Days and Greater [Member] | Real Estate [Member] | Farmland [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	6,223
90 Days and Greater [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	534
90 Days and Greater [Member] | Other Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	6,618	4,613
90 Days and Greater [Member] | Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans	$ 4,345
90 Days and Greater [Member] | Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		1,763
90 Days and Greater [Member] | Acquired Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		3,447
90 Days and Greater [Member] | Consumer Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		592
90 Days and Greater [Member] | Pegasus Bank [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due Loans		$ 851

Loans Held for Investment and_9

Loans Held for Investment and Allowance for Credit Losses on Loans - Gross Loans Held for Investment by Year of Origination and Internally Assigned Credit Grades (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable Recorded Investment [Line Items]
2020	$ 2,637,796
2019	1,034,907
2018	618,426
2017	418,683
2016	327,103
Prior	598,412
Revolving Loans Amortized Cost Basis	759,179
Total Loans	6,394,506	$ 5,662,143
Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
Total Loans		4,462,594
Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
Total Loans		1,081,074
Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
Total Loans		96,850
Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
Total Loans		21,344
Grade 5 [Member]
Financing Receivable Recorded Investment [Line Items]
Total Loans		281
Pegasus Bank [Member]
Financing Receivable Recorded Investment [Line Items]
2020	128,941
2019	93,608
2018	34,009
2017	42,392
2016	16,236
Prior	50,867
Revolving Loans Amortized Cost Basis	188,495
Total Loans	554,548	430,705
Pegasus Bank [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	100,631
2019	66,875
2018	27,235
2017	19,025
2016	12,414
Prior	44,237
Revolving Loans Amortized Cost Basis	113,824
Total Loans	384,241	295,243
Pegasus Bank [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	28,187
2019	26,733
2018	6,774
2017	23,367
2016	3,822
Prior	5,300
Revolving Loans Amortized Cost Basis	74,671
Total Loans	168,854	133,324
Pegasus Bank [Member] | Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	123
Prior	1,330
Total Loans	1,453	1,287
Pegasus Bank [Member] | Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
Total Loans		851
Real Estate [Member] | Pegasus Bank [Member]
Financing Receivable Recorded Investment [Line Items]
Total Loans	272,000
Real Estate [Member] | Farmland [Member]
Financing Receivable Recorded Investment [Line Items]
2020	70,643
2019	57,379
2018	29,842
2017	21,563
2016	19,174
Prior	36,790
Revolving Loans Amortized Cost Basis	17,567
Total Loans	252,958	246,988
Real Estate [Member] | Farmland [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	51,284
2019	26,391
2018	18,994
2017	13,821
2016	13,368
Prior	27,100
Revolving Loans Amortized Cost Basis	8,160
Total Loans	159,118
Real Estate [Member] | Farmland [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	15,264
2019	30,684
2018	6,639
2017	6,391
2016	4,763
Prior	8,916
Revolving Loans Amortized Cost Basis	7,140
Total Loans	79,797
Real Estate [Member] | Farmland [Member] | Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	3,681
2019	290
2018	151
2017	1,055
2016	703
Prior	551
Revolving Loans Amortized Cost Basis	1,955
Total Loans	8,386
Real Estate [Member] | Farmland [Member] | Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	414
2019	14
2018	4,058
2017	296
2016	340
Prior	223
Revolving Loans Amortized Cost Basis	312
Total Loans	5,657
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
2020	189,212
2019	122,905
2018	86,436
2017	52,637
2016	51,923
Prior	117,021
Revolving Loans Amortized Cost Basis	21,853
Total Loans	641,987	621,188
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	142,574
2019	91,493
2018	73,845
2017	42,289
2016	37,097
Prior	88,724
Revolving Loans Amortized Cost Basis	17,153
Total Loans	493,175
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	42,375
2019	31,314
2018	11,516
2017	9,644
2016	13,316
Prior	25,574
Revolving Loans Amortized Cost Basis	4,393
Total Loans	138,132
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member] | Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	4,226
2019	32
2018	333
2017	704
2016	1,259
Prior	2,671
Total Loans	9,225
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member] | Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	37
2019	66
2018	742
2016	251
Prior	52
Revolving Loans Amortized Cost Basis	307
Total Loans	1,455
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
2020	329,172
2019	209,503
2018	110,782
2017	89,871
2016	90,883
Prior	123,138
Revolving Loans Amortized Cost Basis	17,809
Total Loans	971,158	851,200
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	256,128
2019	157,526
2018	83,869
2017	69,864
2016	82,088
Prior	81,499
Revolving Loans Amortized Cost Basis	13,206
Total Loans	744,180
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	60,607
2019	48,751
2018	26,441
2017	18,070
2016	8,755
Prior	41,491
Revolving Loans Amortized Cost Basis	4,454
Total Loans	208,569
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member] | Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	7,718
2019	3,137
2018	472
2017	1,937
2016	40
Prior	148
Revolving Loans Amortized Cost Basis	149
Total Loans	13,601
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member] | Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	4,719
2019	89
Total Loans	4,808
Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable Recorded Investment [Line Items]
2020	130,769
2019	66,435
2018	14,428
2017	5,368
2016	1,595
Prior	2,588
Revolving Loans Amortized Cost Basis	8,432
Total Loans	229,615	287,138
Real Estate [Member] | Construction and Development Less than 60 Months [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	115,399
2019	56,369
2018	12,821
2017	4,582
2016	1,438
Prior	2,048
Revolving Loans Amortized Cost Basis	7,850
Total Loans	200,507
Real Estate [Member] | Construction and Development Less than 60 Months [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	11,528
2019	10,002
2018	1,589
2017	764
2016	157
Prior	540
Revolving Loans Amortized Cost Basis	582
Total Loans	25,162
Real Estate [Member] | Construction and Development Less than 60 Months [Member] | Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	3,842
2018	9
Total Loans	3,851
Real Estate [Member] | Construction and Development Less than 60 Months [Member] | Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
2019	64
2018	9
2017	22
Total Loans	95
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable Recorded Investment [Line Items]
2020	188,716
2019	4,914
2018	181
2017	21
2016	33
Prior	491
Revolving Loans Amortized Cost Basis	11,839
Total Loans	206,195	189,480
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	159,431
2019	4,214
2018	69
2017	21
2016	33
Prior	23
Revolving Loans Amortized Cost Basis	11,449
Total Loans	175,240
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	27,400
2019	580
2018	112
Prior	468
Revolving Loans Amortized Cost Basis	390
Total Loans	28,950
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member] | Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	1,885
2019	120
Total Loans	2,005
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable Recorded Investment [Line Items]
2020	273,560
2019	156,371
2018	104,388
2017	78,341
2016	63,501
Prior	177,155
Total Loans	853,316	834,849
Real Estate [Member] | Residential Real Estate First Lien [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	241,771
2019	134,184
2018	80,793
2017	64,392
2016	48,686
Prior	136,059
Total Loans	705,885
Real Estate [Member] | Residential Real Estate First Lien [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	28,305
2019	19,425
2018	21,742
2017	11,666
2016	12,365
Prior	34,312
Total Loans	127,815
Real Estate [Member] | Residential Real Estate First Lien [Member] | Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	2,754
2019	2,029
2018	1,375
2017	2,073
2016	1,213
Prior	5,194
Total Loans	14,638
Real Estate [Member] | Residential Real Estate First Lien [Member] | Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	730
2019	733
2018	478
2017	210
2016	1,186
Prior	1,590
Total Loans	4,927
Real Estate [Member] | Residential Real Estate First Lien [Member] | Grade 5 [Member]
Financing Receivable Recorded Investment [Line Items]
2016	51
Total Loans	51
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable Recorded Investment [Line Items]
2020	25,775
2019	16,297
2018	13,020
2017	8,255
2016	5,984
Prior	14,255
Revolving Loans Amortized Cost Basis	84,495
Total Loans	168,081	187,647
Real Estate [Member] | Residential Real Estate All Other [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	21,493
2019	13,944
2018	10,854
2017	6,265
2016	5,381
Prior	10,984
Revolving Loans Amortized Cost Basis	28,047
Total Loans	96,968
Real Estate [Member] | Residential Real Estate All Other [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	3,694
2019	1,675
2018	1,268
2017	1,809
2016	450
Prior	2,335
Revolving Loans Amortized Cost Basis	55,433
Total Loans	66,664
Real Estate [Member] | Residential Real Estate All Other [Member] | Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	384
2019	461
2018	328
2017	116
2016	119
Prior	221
Revolving Loans Amortized Cost Basis	993
Total Loans	2,622
Real Estate [Member] | Residential Real Estate All Other [Member] | Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	204
2019	217
2018	570
2017	65
2016	34
Prior	715
Revolving Loans Amortized Cost Basis	22
Total Loans	1,827
Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
2020	288,006
2019	174,031
2018	154,014
2017	82,315
2016	54,917
Prior	56,671
Revolving Loans Amortized Cost Basis	349,856
Total Loans	1,159,810	1,315,005
Commercial and Agricultural Non-Real Estate [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	206,515
2019	136,254
2018	124,657
2017	74,719
2016	46,453
Prior	33,471
Revolving Loans Amortized Cost Basis	270,426
Total Loans	892,495
Commercial and Agricultural Non-Real Estate [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	49,467
2019	34,659
2018	27,239
2017	6,566
2016	7,054
Prior	22,710
Revolving Loans Amortized Cost Basis	63,894
Total Loans	211,589
Commercial and Agricultural Non-Real Estate [Member] | Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	24,793
2019	1,511
2018	1,466
2017	789
2016	271
Prior	327
Revolving Loans Amortized Cost Basis	14,577
Total Loans	43,734
Commercial and Agricultural Non-Real Estate [Member] | Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	7,231
2019	1,607
2018	652
2017	241
2016	1,139
Prior	163
Revolving Loans Amortized Cost Basis	959
Total Loans	11,992
Consumer Non-real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
2020	180,241
2019	100,261
2018	45,442
2017	14,222
2016	5,092
Prior	2,137
Revolving Loans Amortized Cost Basis	8,010
Total Loans	355,405	359,529
Consumer Non-real Estate [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	166,934
2019	93,232
2018	41,449
2017	13,157
2016	4,471
Prior	1,768
Revolving Loans Amortized Cost Basis	7,673
Total Loans	328,684
Consumer Non-real Estate [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	12,773
2019	5,902
2018	3,399
2017	796
2016	499
Prior	266
Revolving Loans Amortized Cost Basis	328
Total Loans	23,963
Consumer Non-real Estate [Member] | Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	445
2019	840
2018	450
2017	175
2016	75
Prior	63
Revolving Loans Amortized Cost Basis	2
Total Loans	2,050
Consumer Non-real Estate [Member] | Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	89
2019	287
2018	144
2017	94
2016	47
Prior	40
Revolving Loans Amortized Cost Basis	7
Total Loans	708
Oil and Gas [Member]
Financing Receivable Recorded Investment [Line Items]
2020	147,335
2019	811
2018	82
Prior	4,679
Revolving Loans Amortized Cost Basis	26,448
Total Loans	179,355	184,399
Oil and Gas [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	104,622
2019	66
2018	82
Prior	4,679
Revolving Loans Amortized Cost Basis	16,529
Total Loans	125,978
Oil and Gas [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	42,713
2019	745
Revolving Loans Amortized Cost Basis	9,919
Total Loans	53,377
Other Loans [Member]
Financing Receivable Recorded Investment [Line Items]
2020	685,426
2019	32,392
2018	25,802
2017	23,698
2016	17,765
Prior	12,620
Revolving Loans Amortized Cost Basis	24,375
Total Loans	822,078	154,015
Other Loans [Member] | Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
2020	685,426
2019	32,392
2018	25,707
2017	20,638
2016	16,378
Prior	10,341
Revolving Loans Amortized Cost Basis	22,976
Total Loans	813,858	148,692
Other Loans [Member] | Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
2018	17
2017	2,936
2016	1,126
Prior	2,179
Revolving Loans Amortized Cost Basis	692
Total Loans	6,950	3,631
Other Loans [Member] | Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
2018	78
2016	53
Prior	67
Revolving Loans Amortized Cost Basis	36
Total Loans	234	1,564
Other Loans [Member] | Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
2017	124
2016	208
Prior	33
Revolving Loans Amortized Cost Basis	671
Total Loans	$ 1,036	$ 128

Loans Held for Investment an_10

Loans Held for Investment and Allowance for Credit Losses on Loans - Internal Loan Grading by Class of Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 6,394,506	$ 5,662,143
Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		707,416
Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		1,137,175
Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		340,572
Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		920,832
Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		1,454,393
Consumer Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		362,354
Other Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	822,078	154,015
Acquired Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		154,681
Pegasus Bank [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	554,548	430,705
Pegasus Bank [Member] | Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	272,000
Grade 1 [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		4,462,594
Grade 1 [Member] | Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		554,942
Grade 1 [Member] | Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		861,108
Grade 1 [Member] | Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		289,350
Grade 1 [Member] | Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		722,983
Grade 1 [Member] | Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		1,166,155
Grade 1 [Member] | Consumer Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		335,916
Grade 1 [Member] | Other Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	813,858	148,692
Grade 1 [Member] | Acquired Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		88,205
Grade 1 [Member] | Pegasus Bank [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	384,241	295,243
Grade 2 [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		1,081,074
Grade 2 [Member] | Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		130,783
Grade 2 [Member] | Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		252,134
Grade 2 [Member] | Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		41,754
Grade 2 [Member] | Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		179,951
Grade 2 [Member] | Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		261,003
Grade 2 [Member] | Consumer Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		23,407
Grade 2 [Member] | Other Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	6,950	3,631
Grade 2 [Member] | Acquired Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		55,087
Grade 2 [Member] | Pegasus Bank [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	168,854	133,324
Grade 3 [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		96,850
Grade 3 [Member] | Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		15,191
Grade 3 [Member] | Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		23,048
Grade 3 [Member] | Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		6,975
Grade 3 [Member] | Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		14,382
Grade 3 [Member] | Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		25,276
Grade 3 [Member] | Consumer Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		2,327
Grade 3 [Member] | Other Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	234	1,564
Grade 3 [Member] | Acquired Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		6,800
Grade 3 [Member] | Pegasus Bank [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,453	1,287
Grade 4 [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		21,344
Grade 4 [Member] | Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		6,500
Grade 4 [Member] | Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		868
Grade 4 [Member] | Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		2,442
Grade 4 [Member] | Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		3,446
Grade 4 [Member] | Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		1,959
Grade 4 [Member] | Consumer Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		704
Grade 4 [Member] | Other Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 1,036	128
Grade 4 [Member] | Acquired Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		4,446
Grade 4 [Member] | Pegasus Bank [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		851
Grade 5 [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		281
Grade 5 [Member] | Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		17
Grade 5 [Member] | Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		51
Grade 5 [Member] | Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		70
Grade 5 [Member] | Acquired Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		$ 143

Loans Held for Investment an_11

Loans Held for Investment and Allowance for Credit Losses on Loans - Activity in Allowance for Credit Losses on Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	$ 54,238	$ 51,389
Impact of CECL adoption	(3,195)
Initial allowance on loans purchased with credit deterioration	502
Charge- offs	(23,832)	(6,386)
Recoveries	1,005	948
Net charge-offs	(22,827)	(5,438)
Provision for credit losses on loans	62,648	8,287
Balance at end of period	91,366	54,238
Non-consumer Non-real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	15,341	13,151
Charge- offs		(514)
Recoveries		272
Net charge-offs		(242)
Provision for credit losses on loans		2,432
Balance at end of period		15,341
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	5,625
Impact of CECL adoption	(2,806)
Initial allowance on loans purchased with credit deterioration	432
Charge- offs	(773)
Recoveries	10
Net charge-offs	(763)
Provision for credit losses on loans	4,547
Balance at end of period	7,035	5,625
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	8,358
Impact of CECL adoption	(5,507)
Charge- offs	(3,609)
Net charge-offs	(3,609)
Provision for credit losses on loans	12,600
Balance at end of period	11,842	8,358
Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	2,214
Impact of CECL adoption	(1,056)
Charge- offs	(59)
Recoveries	123
Net charge-offs	64
Provision for credit losses on loans	1,338
Balance at end of period	2,560	2,214
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	1,933
Impact of CECL adoption	(778)
Charge- offs	(29)
Net charge-offs	(29)
Provision for credit losses on loans	(499)
Balance at end of period	627	1,933
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	8,692
Impact of CECL adoption	(3,831)
Initial allowance on loans purchased with credit deterioration	7
Charge- offs	(465)
Recoveries	44
Net charge-offs	(421)
Provision for credit losses on loans	(1,877)
Balance at end of period	2,570	8,692
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	2,767
Impact of CECL adoption	(1,408)
Charge- offs	(126)
Recoveries	54
Net charge-offs	(72)
Provision for credit losses on loans	943
Balance at end of period	2,230	2,767
Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	7,040	6,328
Charge- offs		(34)
Recoveries		25
Net charge-offs		(9)
Provision for credit losses on loans		721
Balance at end of period		7,040
Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	11,157	11,027
Charge- offs		(67)
Recoveries		42
Net charge-offs		(25)
Provision for credit losses on loans		155
Balance at end of period		11,157
Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	3,387	3,261
Charge- offs		(146)
Recoveries		22
Net charge-offs		(124)
Provision for credit losses on loans		250
Balance at end of period		3,387
Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	10,149	10,673
Charge- offs		(2,697)
Recoveries		30
Net charge-offs		(2,667)
Provision for credit losses on loans		2,143
Balance at end of period		10,149
Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	13,462
Impact of CECL adoption	13,195
Initial allowance on loans purchased with credit deterioration	62
Charge- offs	(3,320)
Recoveries	116
Net charge-offs	(3,204)
Provision for credit losses on loans	8,885
Balance at end of period	32,400	13,462
Consumer Non-real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	3,252
Impact of CECL adoption	(622)
Charge- offs	(1,142)
Recoveries	224
Net charge-offs	(918)
Provision for credit losses on loans	1,665
Balance at end of period	3,377	3,252
Oil and Gas [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	1,883
Impact of CECL adoption	(1,346)
Charge- offs	(11,245)
Net charge-offs	(11,245)
Provision for credit losses on loans	28,559
Balance at end of period	17,851	1,883
Other Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	2,632	2,423
Impact of CECL adoption	(116)
Charge- offs	(168)
Recoveries	10	90
Net charge-offs	(158)	90
Provision for credit losses on loans	824	119
Balance at end of period	3,182	2,632
Consumer Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	3,319	3,065
Charge- offs		(868)
Recoveries		218
Net charge-offs		(650)
Provision for credit losses on loans		904
Balance at end of period		3,319
Acquired Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	614	1,461
Charge- offs		(2,060)
Recoveries		219
Net charge-offs		(1,841)
Provision for credit losses on loans		994
Balance at end of period		614
Farmland [Member] | Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	2,821
Impact of CECL adoption	(1,408)
Initial allowance on loans purchased with credit deterioration	1
Charge- offs	(2,055)
Net charge-offs	(2,055)
Provision for credit losses on loans	3,777
Balance at end of period	3,136	2,821
Pegasus Bank [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Balance at beginning of period	599
Impact of CECL adoption	2,488
Charge- offs	(841)
Recoveries	424	30
Net charge-offs	(417)	30
Provision for credit losses on loans	1,886	569
Balance at end of period	$ 4,556	$ 599

Loans Held for Investment an_12

Loans Held for Investment and Allowance for Credit Losses on Loans - Allowance for Credit Losses Outstanding by Impairment Methodology (Detail) $ in Thousands	Dec. 31, 2019USD ($)
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	$ 7,705
Collectively evaluated for impairment	46,533
Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	900
Collectively evaluated for impairment	6,140
Real Estate [Member] | Non-residential Real Estate Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	990
Collectively evaluated for impairment	10,167
Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	531
Collectively evaluated for impairment	2,856
Real Estate [Member] | Residential Real Estate Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	2,026
Collectively evaluated for impairment	8,123
Consumer Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	343
Collectively evaluated for impairment	2,976
Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	2,902
Collectively evaluated for impairment	12,439
Other Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Individually evaluated for impairment	13
Collectively evaluated for impairment	2,619
Acquired Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collectively evaluated for impairment	614
Pegasus Bank [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collectively evaluated for impairment	$ 599

Loans Held for Investment an_13

Loans Held for Investment and Allowance for Credit Losses on Loans - Loans Outstanding by Impairment Methodology (Detail) $ in Thousands	Dec. 31, 2019USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	$ 113,796
Collectively evaluated for impairment	5,545,349
Loans Acquired with Deteriorated Credit Quality [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans acquired with deteriorated credit quality	2,998
Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	21,690
Collectively evaluated for impairment	685,726
Real Estate [Member] | Non-residential Real Estate Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	23,933
Collectively evaluated for impairment	1,113,242
Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	9,468
Collectively evaluated for impairment	331,104
Real Estate [Member] | Residential Real Estate Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	17,898
Collectively evaluated for impairment	902,934
Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	27,016
Collectively evaluated for impairment	1,427,377
Consumer Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	3,090
Collectively evaluated for impairment	359,264
Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	231
Collectively evaluated for impairment	153,784
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	10,470
Collectively evaluated for impairment	143,351
Acquired Loans [Member] | Loans Acquired with Deteriorated Credit Quality [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans acquired with deteriorated credit quality	860
Pegasus Bank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment	428,567
Pegasus Bank [Member] | Loans Acquired with Deteriorated Credit Quality [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans acquired with deteriorated credit quality	$ 2,138

Loans Held for Investment an_14

Loans Held for Investment and Allowance for Credit Losses on Loans - Purchased Credit Deteriorated Loans (Detail) - Loans Acquired with Deteriorated Credit Quality [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Financing Receivable Allowance For Credit Losses [Line Items]
Purchase price of loans at acquisition	$ 1,761
Allowance for credit losses at acquisition	502
Par value of acquired loans at acquisition	$ 2,263

Loans Held for Investment an_15

Loans Held for Investment and Allowance for Credit Losses on Loans - Collateral-dependent Gross Loans Held for Investment by Collateral Type and Related Specific Allocation (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	$ 20,803
Real Estate Asset [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	11,808
Business Assets [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	8,473
Other Assets [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	522
Specific Allocation [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	6,212
Pegasus Bank [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	1,257
Pegasus Bank [Member] | Real Estate Asset [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	1,257
Pegasus Bank [Member] | Specific Allocation [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	222
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	848
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	4,719
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	860
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	866
Real Estate [Member] | Farmland [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	3,258
Real Estate [Member] | Real Estate Asset [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	848
Real Estate [Member] | Real Estate Asset [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	4,719
Real Estate [Member] | Real Estate Asset [Member] | Residential Real Estate First Lien [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	860
Real Estate [Member] | Real Estate Asset [Member] | Residential Real Estate All Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	866
Real Estate [Member] | Real Estate Asset [Member] | Farmland [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	3,258
Real Estate [Member] | Specific Allocation [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	226
Real Estate [Member] | Specific Allocation [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	1,000
Real Estate [Member] | Specific Allocation [Member] | Residential Real Estate First Lien [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	151
Real Estate [Member] | Specific Allocation [Member] | Residential Real Estate All Other [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	616
Real Estate [Member] | Specific Allocation [Member] | Farmland [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	1,114
Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	8,873
Commercial and Agricultural Non-Real Estate [Member] | Business Assets [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	8,460
Commercial and Agricultural Non-Real Estate [Member] | Other Assets [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	413
Commercial and Agricultural Non-Real Estate [Member] | Specific Allocation [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	2,813
Consumer Non-real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	109
Consumer Non-real Estate [Member] | Other Assets [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	109
Consumer Non-real Estate [Member] | Specific Allocation [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	58
Other Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	13
Other Loans [Member] | Business Assets [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	13
Other Loans [Member] | Specific Allocation [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Collateral Dependent Loans	$ 12

Loans Held for Investment an_16

Loans Held for Investment and Allowance for Credit Losses on Loans - Impaired Loans Segregated by Class of Loans (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	$ 55,447
Recorded Investment with Allowance	48,898
Related Allowance	3,211
Average Recorded Investment	46,041
Real Estate [Member] | Non-residential Real Estate Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	13,253
Recorded Investment with Allowance	13,000
Related Allowance	514
Average Recorded Investment	12,868
Real Estate [Member] | Non-residential Real Estate Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	3,973
Recorded Investment with Allowance	3,678
Related Allowance	300
Average Recorded Investment	3,946
Real Estate [Member] | Residential Real Estate Permanent Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	3,445
Recorded Investment with Allowance	3,129
Related Allowance	242
Average Recorded Investment	2,968
Real Estate [Member] | Residential Real Estate Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	7,117
Recorded Investment with Allowance	4,487
Related Allowance	946
Average Recorded Investment	5,567
Commercial and Financial [Member] | Non-consumer Non-real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	11,598
Recorded Investment with Allowance	11,012
Related Allowance	1,005
Average Recorded Investment	11,085
Consumer Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	969
Recorded Investment with Allowance	836
Related Allowance	97
Average Recorded Investment	844
Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	5,711
Recorded Investment with Allowance	5,510
Related Allowance	105
Average Recorded Investment	1,130
Acquired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	6,421
Recorded Investment with Allowance	5,108
Related Allowance	2
Average Recorded Investment	5,472
Pegasus Bank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	2,960
Recorded Investment with Allowance	2,138
Average Recorded Investment	$ 2,161

Loans Held for Investment an_17

Loans Held for Investment and Allowance for Credit Losses on Loans - Transfers from Loans and Premises and Equipment to Other Real Estate Owned, Repossessed Assets and Other Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Noncash Investing And Financing Items [Abstract]
Other real estate owned	$ 32,093	$ 3,941	$ 5,437
Repossessed assets	1,418	1,473	1,122
Other assets	11,105
Total	$ 44,616	$ 5,414	$ 6,559

Loans Held for Investment an_18

Loans Held for Investment and Allowance for Credit Losses on Loans - Related Party Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Balance Beginning of the Period	$ 20,281	$ 19,891	$ 24,001
Additions	19,682	12,371	7,986
Collections/ Terminations	(17,906)	(11,981)	(12,096)
Balance End of the Period	$ 22,057	$ 20,281	$ 19,891

Premises and Equipment, Net a_3

Premises and Equipment, Net and Other Assets - Summary of Premises and Equipment by Classification (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Accumulated depreciation	$ (134,022)	$ (123,464)
Premises and equipment, net	261,677	206,275
Buildings [Member]
Property Plant And Equipment [Line Items]
Premises and Equipment, gross	$ 201,606	190,193
Buildings [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Lives	10 years
Buildings [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Lives	40 years
Furniture Fixtures and Equipment [Member]
Property Plant And Equipment [Line Items]
Premises and Equipment, gross	$ 87,001	81,225
Furniture Fixtures and Equipment [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Lives	3 years
Furniture Fixtures and Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Estimated Useful Lives	15 years
Land [Member]
Property Plant And Equipment [Line Items]
Premises and Equipment, gross	$ 45,792	45,561
Construction in Progress [Member]
Property Plant And Equipment [Line Items]
Premises and Equipment, gross	$ 61,300	$ 12,760

Premises and Equipment, Net a_4

Premises and Equipment, Net and Other Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Noncash construction in progress for retainage payable	$ 2,400,000
Other assets in equity interest	$ 11,100,000
Percentage of equity investment	50.00%
Low income housing tax credit investments	$ 18,100,000	$ 20,400,000
Tax credits and other tax benefits recognized from LIHTC investments	5,600,000	5,400,000	$ 5,400,000
Amortization expense resulting from LIHTC investments	4,600,000	4,500,000	4,400,000
Unfunded commitment on investments	$ 19,400,000
Percentage of qualified investment	39.00%
Period of qualified investments taken	7 years
New market tax credit investments	$ 18,500,000	21,800,000
Tax credits and other tax benefits recognized from NMTC investments	4,000,000	4,500,000	1,800,000
Amortization expense resulting from NMTC investments	3,300,000	$ 3,700,000	$ 1,400,000
Unfunded commitment on NMTC investments	$ 0

Intangible Assets and Goodwil_2

Intangible Assets and Goodwill - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 36,761	$ 39,247
Accumulated Amortization	(17,762)	(16,639)
Net Carrying Amount	18,999	22,608
Core Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	33,411	35,856
Accumulated Amortization	(15,076)	(14,131)
Net Carrying Amount	18,335	21,725
Customer Relationship Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	3,350	3,391
Accumulated Amortization	(2,686)	(2,508)
Net Carrying Amount	$ 664	$ 883

Intangible Assets and Goodwil_3

Intangible Assets and Goodwill - Additional Information (Detail) - USD ($)	Mar. 05, 2020	Aug. 15, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Weighted-average life			7 years 2 months 12 days
Goodwill			$ 149,922,000	$ 148,604,000	$ 79,749,000
Pegasus Bank [Member]
Finite-Lived Intangible Assets [Line Items]
Date of acquisition		Aug. 15, 2019
Goodwill		$ 68,900,000	$ 68,855,000	68,855,000
Citizens Bankshares, Inc [Member]
Finite-Lived Intangible Assets [Line Items]
Date of acquisition	Mar. 5, 2020
Goodwill	$ 1,300,000
Customer Related Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-average life			4 years
Customer Related Intangibles [Member] | BancFirst Insurance Services, Inc. [Member]
Finite-Lived Intangible Assets [Line Items]
Impairment of intangible assets				$ 353,000
Core Deposit Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted-average life			7 years 3 months 18 days

Intangible Assets and Goodwil_4

Intangible Assets and Goodwill - Estimated Amortization of Intangible Assets (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
2021	$ 2,977
2022	2,710
2023	2,693
2024	2,693
2025	$ 2,476

Intangible Assets and Goodwil_5

Intangible Assets and Goodwill - Summary of Goodwill by Business Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Balance at beginning of period	$ 148,604	$ 79,749
Acquisitions	1,318	68,855
Balance at end of period	149,922	148,604
Metropolitan Banks [Member]
Goodwill [Line Items]
Balance at beginning of period	13,767	13,767
Balance at end of period	13,767	13,767
Community Banks [Member]
Goodwill [Line Items]
Balance at beginning of period	59,894	59,894
Acquisitions	1,318
Balance at end of period	61,212	59,894
Pegasus Bank [Member]
Goodwill [Line Items]
Balance at beginning of period	68,855
Acquisitions		68,855
Balance at end of period	68,855	68,855
Other Financial Services [Member]
Goodwill [Line Items]
Balance at beginning of period	5,464	5,464
Balance at end of period	5,464	5,464
Executive, Operations & Support [Member]
Goodwill [Line Items]
Balance at beginning of period	624	624
Balance at end of period	$ 624	$ 624

Time Deposits - Summary of Sche

Time Deposits - Summary of Scheduled Maturities of all Time Deposits (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Deposits [Abstract]
2021	$ 489,397
2022	100,196
2023	41,245
2024	23,696
2025	18,419
Thereafter	31
Total	$ 672,984

Time Deposits - Summary of time

Time Deposits - Summary of time Deposits Meet or Exceed Current FDIC Insurance Limit for Periods Presented (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deposits [Abstract]
Time deposits of $250,000 or more	$ 154,646	$ 153,987

Short-Term Borrowings - Summary

Short-Term Borrowings - Summary of Short-Term Borrowings (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Short-term Debt [Line Items]
Short-term borrowings	$ 1,100	$ 1,100
Weighted average interest rate	0.30%	2.19%
Federal Funds Purchased [Member]
Short-term Debt [Line Items]
Short-term borrowings	$ 1,100	$ 1,100
Short-term Debt [Member]
Short-term Debt [Line Items]
End of period interest rate	0.05%	1.45%

Line of Credit - Additional Inf

Line of Credit - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Maximum drawing capacity	$ 651,300,000
FHLB stock holdings	555,600
Advances outstanding	0
Residential Mortgage [Member]
Debt Instrument [Line Items]
Line of credit assets pledged as collateral	838,300,000
Revolving Line of Credit Member]
Debt Instrument [Line Items]
Maximum drawing capacity	10,000,000
Advances outstanding	$ 0
Description of variable interest rate	prime rate minus 25 basis points
Line of credit maturity date description	third quarter of 2020

Junior Subordinated Debentures

Junior Subordinated Debentures - Additional Information (Detail) - USD ($)	Oct. 08, 2015	Mar. 31, 2004	Feb. 29, 2004	Dec. 31, 2020	Dec. 31, 2019
Junior Subordinated Debentures [Line Items]
Junior subordinated notes assumed				$ 26,804,000	$ 26,804,000
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
Debt instrument maturity date				Mar. 31, 2034
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%
CSB Bancshares Statutory Trust I [Member]
Junior Subordinated Debentures [Line Items]
Business combination, acquisition of capital securities	$ 5,000,000
Business combination, acquisition of common securities	155,000
CSB Bancshares Statutory Trust I [Member] | Subordinated Deferrable Interest Debentures [Member]
Junior Subordinated Debentures [Line Items]
Frequency of payment				payable March 15, June 15, September 15 and December 15 of each year
Junior subordinated notes assumed	$ 5,200,000
Debt instrument maturity date	Sep. 15, 2036
CSB Bancshares Statutory Trust I [Member] | Subordinated Deferrable Interest Debentures [Member] | LIBOR [Member]
Junior Subordinated Debentures [Line Items]
Debt instrument, Basis point rate	1.82%

Income Taxes - Components of th

Income Taxes - Components of the Company's Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current taxes:
Federal	$ 25,974	$ 26,247	$ 23,700
State	7,443	7,288	7,083
Deferred taxes	(9,491)	1,148	3,155
Total income taxes	$ 23,926	$ 34,683	$ 33,938

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Securities transactions income tax (benefit) expense	$ (82,000)	$ 171,000	$ 10,000
Federal tax rate, percentage	21.00%	21.00%	21.00%
Recognition of interest and penalties related to unrecognized tax benefits	$ 0	$ 0	$ 0
Earliest Tax Year [Member]
Income Taxes [Line Items]
Year under examination	2017		2018
Latest Tax Year [Member]
Income Taxes [Line Items]
Year under examination	2019		2023

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Tax Expense at the Federal Statutory Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Tax expense at the federal statutory tax rate	$ 25,937	$ 35,377	$ 33,546
Increase (decrease) in tax expense from:
Tax-exempt income, net	(507)	(581)	(510)
Modified endowment life contracts	(508)	(519)	(558)
Share based compensation excess tax benefit	(412)	(765)	(917)
Tax deductible dividends paid on ESOP	(453)
State tax expense, net of federal tax benefit	5,606	5,757	5,595
Utilization of tax credits:
New markets tax credits, net of tax expense	(3,121)	(3,547)	(1,422)
Low-income housing tax credits, net of amortization	(1,273)	(1,266)	(1,273)
Other tax credits	(320)
Other, net	(1,023)	227	(523)
Total income taxes	$ 23,926	$ 34,683	$ 33,938

Income Taxes - Summary of Net D

Income Taxes - Summary of Net Deferred Tax Asset Reported in Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Provision for credit losses	$ 22,500	$ 13,763
Write-downs of other real estate owned	143	181
Deferred compensation	2,325	2,268
Stock-based compensation	1,672	1,514
Investments in partnership interests	4,695	3,677
Other	405	903
Gross deferred tax assets	31,740	22,306
Unrealized net gains on securities	(2,513)	(1,187)
Premium on securities of banks acquired	(144)	(153)
Intangibles	(6,135)	(6,757)
Basis difference related to tax credits	(2,127)	(2,015)
Depreciation	(11,529)	(10,349)
Prepaid expense deducted	(1,208)	(1,000)
Other	(178)	(180)
Gross deferred tax liabilities	(23,834)	(21,641)
Net deferred tax asset	$ 7,906	$ 665

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options expire period	15 years
Deferred board fees percentage for stock units accumulation	100.00%
Nonqualified Incentive Stock Option Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period in years	7 years
Nonqualified Incentive Stock Option Plan [Member] | Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares for future grants	190,500
Stock option plan termination date	Dec. 31, 2024
Option exercisable rate	25.00%
Option exercisable period	4 years
Options expire period	15 years
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
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]
Shares for future grants	30,000
Stock option plan termination date	Dec. 31, 2024
Option exercisable rate	25.00%
Option exercisable period	1 year
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
Number of options granted for non-employee director	10,000
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]
Stock option plan termination date	Dec. 31, 2024
Number of shares available for future issuance under deferred compensation plan	21,943
Number of shares of common stock distributed	8,218	9,542

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Activity Under Stock Option Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding at beginning period - Options	1,257,730	1,216,700
Options granted	171,000	178,500
Options exercised	(76,650)	(107,470)
Options canceled, forfeited, or expired	(9,000)	(30,000)
Outstanding at ending period - Options	1,343,080	1,257,730
Exercisable at ending period - Options	710,330	644,730
Outstanding at beginning period - Wgtd. Avg. Exercise Price	$ 32.70	$ 28.48
Options granted - Wgtd. Avg. Exercise Price	48.89	56.87
Options exercised - Wgtd. Avg. Exercise Price	20.53	21.23
Options cancelled, forfeited, or expired - Wgtd. Avg. Exercise Price	58.26	46.42
Outstanding at ending period - Wgtd. Avg. Exercise Price	35.28	32.70
Exercisable at ending period - Wgtd. Avg. Exercise Price	$ 25.06	$ 23.09
Outstanding at ending period - Wgtd. Avg. Remaining Contractual Term, years	8 years 7 months 9 days	9 years 3 months 10 days
Exercisable at ending period - Wgtd. Avg. Remaining Contractual Term, years	6 years 11 months 8 days	7 years 1 month 6 days
Outstanding at ending period - Aggregate Intrinsic Value	$ 31,453	$ 37,408
Exercisable at ending period - Aggregate Intrinsic Value	$ 23,894	$ 25,370

Stock-Based Compensation - Opti

Stock-Based Compensation - Options Exercised Under Stock Option Plan (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award Options Additional Disclosures [Abstract]
Total intrinsic value of options exercised	$ 2,315	$ 3,982	$ 4,810
Cash received from options exercised	1,574	2,282	2,159
Tax benefit realized from options exercised	$ 590	$ 1,014	$ 1,225

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Employee Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Labor And Related Expense [Abstract]
Stock-based compensation expense	$ 1,516	$ 1,277	$ 1,352
Tax benefit	386	325	345
Stock-based compensation expense, net of tax	$ 1,130	$ 952	$ 1,007

Stock-Based Compensation - Unea

Stock-Based Compensation - Unearned Stock-based Compensation Expense (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Share Based Compensation [Abstract]
Unearned stock-based compensation expense	$ 4,888

Stock-Based Compensation - Assu

Stock-Based Compensation - Assumptions Used for Computing Stock-Based Compensation Expense (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract]
Weighted average grant-date fair value per share of options granted	$ 10.85	$ 13.34	$ 14.71
Risk-free interest rate, minimum	0.64%	1.55%	2.55%
Risk-free interest rate, maximum	1.13%	2.76%	3.05%
Dividend yield	2.00%	2.00%	2.00%
Stock price volatility, minimum	22.84%	22.93%	23.05%
Stock price volatility, maximum	36.10%	23.63%	23.95%
Expected term	10 years	10 years	10 years

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Accumulated Stock Units (Detail) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Accumulated stock units	148,278	143,362
Average price	$ 28.57	$ 27.17

Retirement Plans - Additional I

Retirement Plans - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020Plans
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 Am

Retirement Plans - Aggregate Amounts of Contributions to the 401(k) and ESOP Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Contribution Plan Disclosure [Line Items]
Total contributions	$ 6,675	$ 6,929	$ 6,538
401(k) contributions [Member]
Defined Contribution Plan Disclosure [Line Items]
Aggregate amounts of contributions	2,986	2,526	2,465
ESOP contributions [Member]
Defined Contribution Plan Disclosure [Line Items]
Aggregate amounts of contributions	$ 3,689	$ 4,403	$ 4,073

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Authorized Outstanding Preferred and Common Stock (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares outstanding	32,719,852	32,694,268	32,603,926
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 - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Jan. 01, 2021	Dec. 31, 2019
Stockholders Equity [Line Items]
Increase to retained earnings for cumulative effect of adopting ASU	$ 871,161,000		$ 815,488,000
Small Business Administration (SBA), CARES Act, Paycheck Protection Program Lending Facility [Member]
Stockholders Equity [Line Items]
Percentage of risk weight under risk based capital rules	0.00%
Cumulative Effect Period of Adoption Adjustment [Member]
Stockholders Equity [Line Items]
Increase to retained earnings for cumulative effect of adopting ASU	$ 2,300,000
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Maximum [Member]
Stockholders Equity [Line Items]
Quantitative limit for trust preferred securities to be included in tier 1 capital	$ 15,000,000,000
Subsequent Event [Member]
Stockholders Equity [Line Items]
Available equity of BancFirst for dividend payments to the company		$ 102,100,000
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 - Summar_2

Stockholders' Equity - Summary of Shares Repurchased Under Stock Purchase Program (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Summary Of Shares Repurchased Under Stock Purchase Program [Abstract]
Number of shares repurchased	59,284	26,670	151,264
Average price of shares repurchased	$ 52.26	$ 60.04	$ 52.32
Shares remaining to be repurchased	62,782	122,066	148,736

Stockholders' Equity - Required

Stockholders' Equity - Required Capital Amounts and Company's Respective Ratios (Detail) $ in Thousands	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Parent Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital Amount	$ 997,383	$ 910,561
Total Capital To Risk Weighted Assets Actual Ratio	15.64	14.42
Capital Required For Capital Adequacy Amount	$ 510,110	$ 505,050
Capital Required For Capital Adequacy to Risk Weighted Assets Ratio	8	8
Capital With Capital Conservation Buffer Amount	$ 669,519	$ 662,878
Capital With Capital Conservation To Risk Based Weighted Assets Buffer Ratio	10.50	10.50
Common Equity Tier 1 Risk Based Capital Amount	$ 891,534	$ 830,323
Common Equity Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	13.98	13.15
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy Amount	$ 286,937	$ 284,091
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	4.50	4.50
Common Equity Tier 1 Risk Based Capital With Capital Conservation Buffer Amount	$ 446,346	$ 441,919
Common Equity Tier 1 Risk Based Capital With Capital Conservation Buffer To Risk Weighted Assets Ratio	7	7
Tier 1 Risk Based Capital Amount	$ 917,534	$ 856,323
Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	14.39	13.56
Tier 1 Risk Based Capital Required For Capital Adequacy Amount	$ 382,583	$ 378,788
Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	6	6
Tier 1 Risk Based Capital With Capital Conservation Buffer Amount	$ 541,992	$ 536,616
Tier 1 Risk Based Capital With Capital Conservation Buffer To Risk Weighted Assets Ratio	8.50	8.50
Tier 1 Capital Amount	$ 917,534	$ 856,323
Tier 1 Capital To Average Assets Ratio	9.63	10.28
Tier 1 Capital Required For Capital Adequacy Amount	$ 380,952	$ 333,171
Tier 1 Capital Required For Capital Adequacy To Average Assets Ratio	4	4
BancFirst [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital Amount	$ 898,714	$ 827,928
Total Capital To Risk Weighted Assets Actual Ratio	15.59	14.14
Capital Required For Capital Adequacy Amount	$ 461,142	$ 468,107
Capital Required For Capital Adequacy to Risk Weighted Assets Ratio	8	8
Capital With Capital Conservation Buffer Amount	$ 605,248	$ 614,390
Capital With Capital Conservation To Risk Based Weighted Assets Buffer Ratio	10.50	10.50
Capital Required To Be Well Capitalized Amount	$ 576,427	$ 585,134
Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	10	10
Common Equity Tier 1 Risk Based Capital Amount	$ 806,478	$ 753,659
Common Equity Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	13.99	12.88
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy Amount	$ 259,392	$ 263,310
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	4.50	4.50
Common Equity Tier 1 Risk Based Capital With Capital Conservation Buffer Amount	$ 403,499	$ 409,594
Common Equity Tier 1 Risk Based Capital With Capital Conservation Buffer To Risk Weighted Assets Ratio	7	7
Common Equity Tier 1 Risk Based Capital Required To Be Well Capitalized Amount	$ 374,678	$ 380,337
Common Equity Tier 1 Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	6.50	6.50
Tier 1 Risk Based Capital Amount	$ 826,478	$ 773,659
Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	14.34	13.22
Tier 1 Risk Based Capital Required For Capital Adequacy Amount	$ 345,856	$ 351,080
Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	6	6
Tier 1 Risk Based Capital With Capital Conservation Buffer Amount	$ 489,963	$ 497,364
Tier 1 Risk Based Capital With Capital Conservation Buffer To Risk Weighted Assets Ratio	8.50	8.50
Tier 1 Risk Based Capital Required To Be Well Capitalized Amount	$ 461,142	$ 468,107
Tier 1 Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	8	8
Tier 1 Capital Amount	$ 826,478	$ 773,659
Tier 1 Capital To Average Assets Ratio	9.48	10.22
Tier 1 Capital Required For Capital Adequacy Amount	$ 348,666	$ 302,845
Tier 1 Capital Required For Capital Adequacy To Average Assets Ratio	4	4
Tier 1 Capital Required To Be Well Capitalized Amount	$ 435,833	$ 378,556
Tier 1 Capital Required To Be Well Capitalized To Average Assets Ratio	5	5
Pegasus Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital Amount	$ 70,922	$ 63,817
Total Capital To Risk Weighted Assets Actual Ratio	11.85	14.15
Capital Required For Capital Adequacy Amount	$ 47,893	$ 36,083
Capital Required For Capital Adequacy to Risk Weighted Assets Ratio	8	8
Capital With Capital Conservation Buffer Amount	$ 62,860	$ 47,359
Capital With Capital Conservation To Risk Based Weighted Assets Buffer Ratio	10.50	10.50
Capital Required To Be Well Capitalized Amount	$ 59,866	$ 45,104
Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	10	10
Common Equity Tier 1 Risk Based Capital Amount	$ 66,150	$ 60,214
Common Equity Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	11.05	13.35
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy Amount	$ 26,940	$ 20,297
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	4.50	4.50
Common Equity Tier 1 Risk Based Capital With Capital Conservation Buffer Amount	$ 41,906	$ 31,573
Common Equity Tier 1 Risk Based Capital With Capital Conservation Buffer To Risk Weighted Assets Ratio	7	7
Common Equity Tier 1 Risk Based Capital Required To Be Well Capitalized Amount	$ 38,913	$ 29,317
Common Equity Tier 1 Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	6.50	6.50
Tier 1 Risk Based Capital Amount	$ 66,150	$ 60,214
Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	11.05	13.35
Tier 1 Risk Based Capital Required For Capital Adequacy Amount	$ 35,920	$ 27,062
Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	6	6
Tier 1 Risk Based Capital With Capital Conservation Buffer Amount	$ 50,886	$ 38,338
Tier 1 Risk Based Capital With Capital Conservation Buffer To Risk Weighted Assets Ratio	8.50	8.50
Tier 1 Risk Based Capital Required To Be Well Capitalized Amount	$ 47,893	$ 36,083
Tier 1 Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	8	8
Tier 1 Capital Amount	$ 66,150	$ 60,214
Tier 1 Capital To Average Assets Ratio	8.10	8.58
Tier 1 Capital Required For Capital Adequacy Amount	$ 32,682	$ 28,058
Tier 1 Capital Required For Capital Adequacy To Average Assets Ratio	4	4
Tier 1 Capital Required To Be Well Capitalized Amount	$ 40,852	$ 35,072
Tier 1 Capital Required To Be Well Capitalized To Average Assets Ratio	5	5

Net Income Per Common Share - B

Net Income Per Common Share - Basic and Diluted Net Income Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share Reconciliation [Abstract]
Income available to common stockholders	$ 99,586	$ 134,879	$ 125,814
Income available to common stockholders plus assumed exercises of stock options	$ 99,586	$ 134,879	$ 125,814
Income available to common stockholders - Shares	32,672,522	32,639,396	32,689,228
Dilutive effect of stock options - Shares	538,430	690,448	741,486
Income available to common stockholders plus assumed exercises of stock options - Shares	33,210,952	33,329,844	33,430,714
Income available to common stockholders - Per Share Amount	$ 3.05	$ 4.13	$ 3.85
Income available to common stockholders plus assumed exercises of stock options - Per Share Amount	$ 3	$ 4.05	$ 3.76

Net Income Per Common Share - A

Net Income Per Common Share - Average Exercise Prices of Options Excluded from Computation of Diluted Net Income Per Common Share (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Antidilutive Securities Excluded From Computation Of Earnings Per Share [Abstract]
Shares	402,575	180,989	92,738
Average Exercise Price	$ 52.72	$ 54.73	$ 53.17

Condensed Parent Company Fina_3

Condensed Parent Company Financial Statements - Summary of Balance Sheet of Parent Company (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
ASSETS
Cash	$ 280,518	$ 222,043
Goodwill	149,922	148,604	$ 79,749
Total assets	9,212,357	8,565,758	7,574,258
LIABILITIES AND STOCKHOLDERS' EQUITY
Other liabilities	51,864	49,230
Junior subordinated debentures	26,804	26,804
Stockholders’ equity	1,067,885	1,004,989	$ 902,789
Total liabilities and stockholders' equity	9,212,357	8,565,758
Parent Company [Member]
ASSETS
Cash	9,081	5,761
Investments in subsidiaries	1,003,017	946,311
Goodwill	69,478	69,478
Core deposit premium	8,622	9,617
Dividends receivable	12,750	11,622
Other assets	5,331	2,313
Total assets	1,108,279	1,045,102
LIABILITIES AND STOCKHOLDERS' EQUITY
Other liabilities	13,590	13,309
Junior subordinated debentures	26,804	26,804
Stockholders’ equity	1,067,885	1,004,989
Total liabilities and stockholders' equity	$ 1,108,279	$ 1,045,102

Condensed Parent Company Fina_4

Condensed Parent Company Financial Statements- Summary of Income Statement of Parent Company (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
OPERATING INCOME
Interest on interest-bearing deposits	$ 6,049	$ 31,368	$ 30,403
OPERATING EXPENSE
Other	43,859	44,829	39,887
Allocated income tax benefit	(23,926)	(34,683)	(33,938)
Amortization of stock-based compensation arrangements of subsidiaries	(1,516)	(1,277)	(1,352)
Net income	99,586	134,879	125,814
Parent Company [Member]
OPERATING INCOME
Dividends from subsidiaries	50,872	77,559	38,326
Interest on interest-bearing deposits	1	1,150	1,151
Other	886	451	16
Total operating income	51,759	79,160	39,493
OPERATING EXPENSE
Interest	1,965	1,965	2,172
Other	3,317	5,017	698
Total operating expense	5,282	6,982	2,870
Income before taxes	46,477	72,178	36,623
Allocated income tax benefit	2,610	2,731	3,093
Income before equity in undistributed earnings of subsidiaries	49,087	74,909	39,716
Equity in undistributed earnings of subsidiaries	51,955	61,194	87,404
Amortization of stock-based compensation arrangements of subsidiaries	(1,456)	(1,224)	(1,306)
Net income	$ 99,586	$ 134,879	$ 125,814

Condensed Parent Company Fina_5

Condensed Parent Company Financial Statements - Summary of Cash Flow of Parent Company (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 99,586	$ 134,879	$ 125,814
Adjustments to reconcile to net cash provided by operating activities:
Amortization of stock-based compensation arrangements of subsidiaries	1,516	1,277	1,352
Other, net	7,305	6,740	(1,199)
Net cash provided by operating activities	154,341	158,958	140,010
INVESTING ACTIVITIES
Other, net	7,820	7,867	(3,890)
Net cash (used in) provided by investing activities	(897,993)	50,347	(293,799)
FINANCING ACTIVITIES
Common stock acquired	(3,098)	(1,601)	(7,914)
Cash dividends paid	(42,472)	(39,805)	(30,265)
Redemption of Junior Subordinated debentures			(5,155)
Net cash provided by (used in) financing activities	492,283	234,721	(179,831)
Net (decrease)/increase in cash, due from banks and interest-bearing deposits	(251,369)	444,026	(333,620)
Cash, due from banks and interest-bearing deposits at the beginning of the period	1,868,281	1,424,255	1,757,875
Cash, due from banks and interest-bearing deposits at the end of the period	1,616,912	1,868,281	1,424,255
SUPPLEMENTAL DISCLOSURE
Cash paid during the period for interest	22,056	54,602	41,549
Cash received during the period for income taxes, net	26,525	30,975	27,952
Parent Company [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	99,586	134,879	125,814
Adjustments to reconcile to net cash provided by operating activities:
Equity in undistributed earnings of subsidiaries	(51,955)	(61,194)	(87,404)
Amortization of stock-based compensation arrangements of subsidiaries	1,456	1,224	1,306
Other, net	188	(440)	(2,621)
Net cash provided by operating activities	49,275	74,469	37,095
INVESTING ACTIVITIES
Net cash provided by acquisitions			41,347
Payments for investments in subsidiaries	(1,000)	(134,457)
Other, net	(1,175)	(418)	(174)
Net cash (used in) provided by investing activities	(2,175)	(134,875)	41,173
FINANCING ACTIVITIES
Issuance of common stock	1,790	2,484	2,238
Common stock acquired	(3,098)	(1,601)	(7,914)
Cash dividends paid	(42,472)	(39,805)	(30,265)
Redemption of Junior Subordinated debentures			(5,155)
Net cash provided by (used in) financing activities	(43,780)	(38,922)	(41,096)
Net (decrease)/increase in cash, due from banks and interest-bearing deposits	3,320	(99,328)	37,172
Cash, due from banks and interest-bearing deposits at the beginning of the period	5,761	105,089	67,917
Cash, due from banks and interest-bearing deposits at the end of the period	9,081	5,761	105,089
SUPPLEMENTAL DISCLOSURE
Cash paid during the period for interest	1,966	5,131	2,171
Cash received during the period for income taxes, net	$ 2,812	$ 4,518	$ 3,647

Commitments and Contingent Li_3

Commitments and Contingent Liabilities - Summary of Financial Instruments with Off-Balance-Sheet Risks (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Loan commitments	$ 1,779,857	$ 1,618,001
Stand-by letters of credit	$ 96,311	$ 64,702

Leases - Summary of Rental Expe

Leases - Summary of Rental Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Rent expense on all property and equipment rented	$ 1,894	$ 1,633	$ 1,857

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Right of use lease asset	$ 4,400
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	banf:AccruedInterestReceivableAndOtherAssetsMember
Operating lease liability	$ 4,330
Operating Lease, Liability, Statement of Financial Position [Extensible List]	banf:AccruedInterestPayableAndOtherLiabilitiesMember
Operating lease weighted-average remaining lease term	3 years 3 months 18 days
Operating lease weighted-average discount rate	3.10%
Operating lease revenue	$ 5,300	$ 6,100	$ 2,500

Leases - Schedule of Maturity o

Leases - Schedule of Maturity of Operating Lease Liabilities (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 1,413
2022	1,210
2023	706
2024	345
2025	277
Thereafter	887
Total lease payments	4,838
Less imputed interest	(508)
Operating lease liability	$ 4,330

Leases - Scheduled of Minimum F

Leases - Scheduled of Minimum Future Contractual Rent To be Received Under The Remaining Non-Cancelable Term of Operating Leases (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 3,402
2022	2,707
2023	2,313
2024	2,229
2025	1,611
2026-2030	4,355
Total future minimum lease payments	$ 16,617

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Financial Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	$ 552,232	$ 489,723
U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	475,236	414,449
U.S. Federal Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	19,638	23,024
Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	15,696	17,005
States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	28,948	22,531
Asset backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	12,714	12,714
Level 1 Inputs [Member] | U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	475,236	414,449
Level 2 Inputs [Member] | U.S. Federal Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	19,638	23,024
Level 2 Inputs [Member] | Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	15,696	17,005
Level 2 Inputs [Member] | States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	28,793	22,531
Level 3 Inputs [Member] | States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	155
Level 3 Inputs [Member] | Asset backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	$ 12,714	$ 12,714

Fair Value Measurements - Chang

Fair Value Measurements - Changes in Level 3 Assets Measured at Estimated Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation Calculation Roll Forward
Balance at the beginning of the year	$ 12,714	$ 13,443
Transfers from level 2	1,643
Settlements	(1,473)	(695)
Total unrealized losses	(15)	(34)
Balance at the end of the period	$ 12,869	$ 12,714

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Transfer of securities between levels of fair value hierarchy		$ 0
Days from origination after which mortgage loans are sold	30 days
Amount of non-financial assets (liabilities) measured at fair value on a recurring basis	$ 0	0
Non-financial assets or liabilities for which no impairment was provided	0
BancFirst [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans held for sale	$ 21,600,000
BancFirst Insurance Services, Inc. [Member] | Customer Related Intangibles [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Impairment of intangible assets		$ 353,000

Fair Value Measurements - Asset

Fair Value Measurements - Assets Measured at Fair Value on Nonrecurring Basis (Detail) - Level 3 [Member] - Nonrecurring [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Equity Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	$ 21,203	$ 10,121
Collateral Dependent Loans [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	11,347
Repossessed Assets [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	291	465
Impaired Loans (Less Specific Allowance) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value		45,687
Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total Fair Value	$ 32,066	$ 3,024

Fair Value Measurements - Estim

Fair Value Measurements - Estimated Fair Values of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
FINANCIAL ASSETS
Federal funds sold, Carrying Amount		$ 1,000
Debt securities held for investment, Carrying Amount	$ 2,964	1,903
Loans, net of allowance for credit losses, Carrying Amount	6,303,140	5,607,905
Debt securities held for investment, Fair Value	2,984	1,903
Loans held for sale, Fair Value	53,719	11,001
FINANCIAL LIABILITIES
Deposits, Carrying Amount	8,064,704	7,483,635
Short-term borrowings, Carrying Amount	1,100	1,100
Junior subordinated debentures, Carrying Amount	26,804	26,804
OFF-BALANCE SHEET FINANCIAL INSTRUMENTS
Loan commitments, Fair Value	3,115	2,832
Letters of credit, Fair Value	722	485
Level 2 Inputs [Member]
FINANCIAL ASSETS
Cash and cash equivalents, Carrying Amount	1,616,912	1,868,281
Federal funds sold, Carrying Amount		1,000
Debt securities held for investment, Carrying Amount	59	1,403
Loans held for sale, Carrying Amount	53,719	11,001
Cash and cash equivalents, Fair Value	1,616,912	1,868,281
Federal funds sold, Fair Value		1,000
Debt securities held for investment, Fair Value	62	1,403
Loans held for sale, Fair Value	53,719	11,001
FINANCIAL LIABILITIES
Deposits, Carrying Amount	8,064,704	7,483,635
Short-term borrowings, Carrying Amount	1,100	1,100
Junior subordinated debentures, Carrying Amount	26,804	26,804
Deposits, Fair Value	8,084,695	7,497,429
Short-term borrowings, Fair Value	1,100	1,100
Junior subordinated debentures, Fair Value	30,535	29,324
Level 3 Inputs [Member]
FINANCIAL ASSETS
Debt securities held for investment, Carrying Amount	2,905	500
Loans, net of allowance for credit losses, Carrying Amount	6,303,140	5,607,905
Debt securities held for investment, Fair Value	2,922	500
Loans, net of allowance for credit losses, Fair Value	$ 6,347,803	$ 5,625,005

Segment Information - Additiona

Segment Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020Business_Unit
Segment Reporting [Abstract]
Number of principal business units	5

Segment Information - Results o

Segment Information - Results of Operations and Selected Financial Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net interest income (expense)	$ 306,668	$ 281,921	$ 260,476
Provision for credit losses	62,648	8,287	3,802
Noninterest income	137,222	137,229	125,199
Depreciation and amortization	18,424	15,989	13,546
Other expenses	239,306	225,312	208,575
Income before taxes	123,512	169,562	159,752
Total assets	9,212,357	8,565,758	7,574,258
Capital expenditures	66,446	27,054	51,863
Operating Segments [Member] | Metropolitan Banks [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	85,464	86,511	84,043
Provision for credit losses	30,202	2,143	79
Noninterest income	18,664	18,608	16,625
Depreciation and amortization	2,639	2,463	2,364
Other expenses	36,746	37,549	36,873
Income before taxes	34,541	62,964	61,352
Total assets	2,729,886	2,806,021	2,743,876
Capital expenditures	1,087	4,349	3,003
Operating Segments [Member] | Community Banks [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	175,757	177,330	170,096
Provision for credit losses	29,827	5,606	4,178
Noninterest income	60,386	64,485	60,004
Depreciation and amortization	10,603	10,218	9,092
Other expenses	111,341	109,044	106,674
Income before taxes	84,372	116,947	110,156
Total assets	5,527,611	4,998,247	4,892,946
Capital expenditures	9,946	11,219	21,393
Operating Segments [Member] | Pegasus Bank [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	21,360	8,657
Provision for credit losses	1,916	140
Noninterest income	1,071	483
Depreciation and amortization	760	274
Other expenses	13,831	4,939
Income before taxes	5,924	3,787
Total assets	919,572	738,351
Capital expenditures	1,775	83
Operating Segments [Member] | Other Financial Services [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	23,500	5,763	5,341
Provision for credit losses	562	(69)	(466)
Noninterest income	41,549	40,270	37,743
Depreciation and amortization	500	603	588
Other expenses	44,918	25,408	24,895
Income before taxes	19,069	20,091	18,067
Total assets	137,122	102,442	84,706
Capital expenditures	450	1,220	1,035
Operating Segments [Member] | Executive, Operations & Support [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	79	3,660	996
Provision for credit losses	141	467	11
Noninterest income	118,491	152,320	137,364
Depreciation and amortization	3,922	2,431	1,502
Other expenses	33,588	50,941	42,319
Income before taxes	80,919	102,141	94,528
Total assets	1,073,507	950,920	861,782
Capital expenditures	53,188	10,183	26,432
Eliminations [Member]
Segment Reporting Information [Line Items]
Net interest income (expense)	508
Noninterest income	(102,939)	(138,937)	(126,537)
Other expenses	(1,118)	(2,569)	(2,186)
Income before taxes	(101,313)	(136,368)	(124,351)
Total assets	$ (1,175,341)	$ (1,030,223)	$ (1,009,052)

Subsequent Event - Additional I

Subsequent Event - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 22, 2021
Subsequent Event [Line Items]
Gain on transaction		$ 6,067	$ 3,619	$ 2,902
Total assets		9,212,357	8,565,758	$ 7,574,258
Total loans		6,394,506	5,662,143
Deposits		8,064,704	$ 7,483,635
First Bank & Trust Company [Member]
Subsequent Event [Line Items]
Total assets		285,000
Total loans		209,000
Deposits		$ 258,000
Scenario Forecast [Member]
Subsequent Event [Line Items]
Gain on transaction	$ 2,500
Subsequent Event [Member]
Subsequent Event [Line Items]
Sale of Loans					$ 21,000
Deposits sold					$ 38,000