Loans and Allowance for Loan Losses - Additional Information (Detail)	3 Months Ended				6 Months Ended				12 Months Ended
	Jun. 30, 2020 USD ($) TDR		Jun. 30, 2019 USD ($) TDR		Jun. 30, 2020 USD ($) TDR		Jun. 30, 2019 USD ($) TDR		Jun. 30, 2020 USD ($) TDR		Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Weighted average loan-to-value ratio	254.00%		210.00%		254.00%		210.00%		254.00%			190.00%
Allowance for loan loss	$ 66,977,000	[1],[2]	$ 40,670,000	[1],[2]	$ 66,977,000	[1],[2]	$ 40,670,000	[1],[2]	$ 66,977,000	[1],[2]	$ 54,057,000	$ 46,093,000	$ 36,862,000	$ 36,395,000
Medallion [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of loans modified as TDRs defaulted | TDR	17		3		30		10
Allowance for loan loss	$ 35,884,000				$ 35,884,000				35,884,000			25,410,000
Recreation [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of loans modified as TDRs defaulted | TDR	21				51
Allowance for loan loss	$ 27,021,000				$ 27,021,000				$ 27,021,000			$ 18,075,000
Troubled Debt Restructuring Defaulted [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of loans modified as TDRs defaulted | TDR							5
TDR investment value			$ 1,530,000				$ 1,530,000
Allowance for loan loss			$ 912,000				$ 912,000
Troubled Debt Restructuring Defaulted [Member] | Medallion [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of loans modified as TDRs defaulted | TDR									20
TDR investment value	11,419,000				11,419,000				$ 11,419,000
Allowance for loan loss	6,680,000				$ 6,680,000				6,680,000
Troubled Debt Restructuring Defaulted [Member] | Recreation [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Number of loans modified as TDRs defaulted | TDR					88
TDR investment value	802,000				$ 802,000				802,000
Allowance for loan loss	$ 37,000				$ 37,000				$ 37,000

[1] As of June 30, 2020, there was no allowance for loan loss and net charge-offs related to the strategic partnership loans.

[2] Includes $2,025 of a general reserve for the Company, for current and performing medallion loans under 90 days past due, as an additional buffer against future losses, representing 3% of the total allowance, and 1.94% of the medallion loans under 90 days past due as of June 30, 2020. This figure excludes $17,351 of a general reserve on loans at the Bank, which was netted against loan balances at consolidation on April 2, 2018. Subsequent to April 2, 2018, the Bank recorded a general reserve benefit of $11,555.