Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Days from origination after which mortgage loans are sold	30 days
Loan upon which a default of principal or interest has existed for a period	90 days
Intangible assets, Estimated useful lives	6 years 7 months 6 days
Advertising costs	$ 3.0	$ 3.3	$ 3.8
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.
Delinquency period placed on nonaccrual status loan	90 days
Commercial loans are charged off deemed uncollectible period	180 days
Oklahoma [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Commercial loans past due period	90 days
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%
Unamortized balances of fees	$ 2.0	14.5
Processing fees received from the SBA	$ 23.8	$ 30.2
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%
Core Deposit Intangibles [Member]
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, Estimated useful lives	6 years 8 months 12 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