Loans and Allowance for Loan Losses - Summary of Activities of the Loans Collateral in Process of Foreclosure Related to Recreation and Medallion Loans (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019
Loans and Leases Receivable Disclosure [Line Items]
Loans collateral in process of foreclosure - beginning balance		$ 52,711	[1]	$ 49,495
Transfer from loans, net		47,274		31,348
Sales		(7,812)		(9,106)
Cash payments received		(5,687)		(7,697)
Collateral valuation adjustments		(31,926)		(11,329)
Loans collateral in process of foreclosure - ending balance	[1]	54,560		52,711
Recreation [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans collateral in process of foreclosure - beginning balance		1,476		1,503
Transfer from loans, net		14,871		14,512
Sales		(7,512)		(7,591)
Collateral valuation adjustments		(7,403)		(6,948)
Loans collateral in process of foreclosure - ending balance		1,432		1,476
Medallion [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans collateral in process of foreclosure - beginning balance		51,235		47,992
Transfer from loans, net		32,403		16,836
Sales		(300)		(1,515)
Cash payments received		(5,687)		(7,697)
Collateral valuation adjustments		(24,523)		(4,381)
Loans collateral in process of foreclosure - ending balance		$ 53,128		$ 51,235

[1] Includes financed sales of this collateral to third parties that are reported separately from the loan portfolio, and that are conducted by Medallion Bank of $3,535 and $8,163 as of December 31, 2020 and 2019.