Loans and Allowance for Loan Losses - Summary of Allowance for Loan Losses by Type (Detail) - USD ($) $ in Thousands	Jun. 30, 2020		Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	[1],[2]	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amount	$ 66,977	[1],[2]	$ 54,057	$ 46,093	$ 40,670		$ 36,862	$ 36,395
Percentage of Allowance	100.00%			100.00%
Allowance as a Percent of Loan Category	5.31%			3.97%
Recreation [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amount	$ 27,021			$ 18,075
Percentage of Allowance	40.00%			39.00%
Allowance as a Percent of Loan Category	3.43%			2.53%
Home Improvement [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amount	$ 4,072			$ 2,608
Percentage of Allowance	6.00%			6.00%
Allowance as a Percent of Loan Category	1.44%			1.05%
Medallion [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Amount	$ 35,884			$ 25,410
Percentage of Allowance	54.00%			55.00%
Allowance as a Percent of Loan Category	29.84%			19.48%

[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.