Loans and Allowance for Loan Losses - Summary of Activity in Allowance for Loan Losses (Parenthetical) (Detail) - USD ($)		3 Months Ended			6 Months Ended
		Jun. 30, 2022		Jun. 30, 2021	Jun. 30, 2022		Jun. 30, 2021	Mar. 31, 2022	Dec. 31, 2021	[1]	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Losses [Line Items]
Cumulative charges of loans and loan collateral process of foreclosure		$ 26,974,000	[1]	$ 49,039,000	$ 26,974,000	[1]	$ 49,039,000	$ 33,834,000	$ 37,430,000		$ 50,733,000	$ 54,560,000
Net charge-offs	[2]	(707,000)		$ 10,181,000	2,013,000		12,938,000
Strategic Partnership [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs					0		$ 0
Medallion Bank [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Cumulative charges of loans and loan collateral process of foreclosure		$ 252,100,000			$ 252,100,000

[1] Includes financed sales of this collateral to third parties that are reported separately from the loan portfolio, of $7.7 million as of June 30, 2022 and $7.4 million as of December 31, 2021

[2] As of June 30, 2022, cumulative net charge-offs of loans and loan collateral in process of foreclosure in the medallion loan portfolio were $252.1 million, some of which may represent collection opportunities for the Company.