Loans and Allowance for Loan Losses - Summary of Activity in Allowance for Loan Losses (Parenthetical) (Detail) - USD ($)		3 Months Ended			9 Months Ended
		Sep. 30, 2022		Sep. 30, 2021	Sep. 30, 2022		Sep. 30, 2021	Jun. 30, 2022	Dec. 31, 2021	[1]	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Losses [Line Items]
Cumulative charges of loans and loan collateral process of foreclosure		$ 24,331,000	[1]	$ 42,544,000	$ 24,331,000	[1]	$ 42,544,000	$ 26,974,000	$ 37,430,000		$ 49,039,000	$ 54,560,000
Net charge-offs	[2]	7,664,000		$ (839,000)	9,677,000		12,100,000
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		$ 252,500,000			$ 252,500,000

[1] Includes financed sales of this collateral to third parties that are reported separately from the loan portfolio, of $7.8 million as of September 30, 2022 and $7.4 million as of December 31, 2021

[2] As of September 30, 2022, cumulative net charge-offs of loans and loan collateral in process of foreclosure in the medallion loan portfolio were $252.5 million, some of which may represent collection opportunities for the Company.