Loans and Allowance for Loan Losses - Summary of Performance Status of Loan (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 1,160,855	$ 1,017,882
Percentage of Nonperforming to Total		5.38%	4.71%
Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 1,098,362	$ 969,908
Non - Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans	[1]	62,493	47,974
Recreation [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 713,332	$ 587,038
Percentage of Nonperforming to Total		1.16%	0.99%
Recreation [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 705,070	$ 581,250
Recreation [Member] | Non - Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		8,262	5,788
Home Improvement [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 247,324	$ 183,155
Percentage of Nonperforming to Total		0.07%	0.07%
Home Improvement [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 247,139	$ 183,018
Home Improvement [Member] | Non - Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		185	137
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 69,767	$ 64,083
Percentage of Nonperforming to Total		17.00%	5.98%
Commercial [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 57,905	$ 60,249
Commercial [Member] | Non - Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		11,862	3,834
Medallion [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 130,432	$ 183,606
Percentage of Nonperforming to Total		32.34%	20.81%
Medallion [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 88,248	$ 145,391
Medallion [Member] | Non - Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 42,184	$ 38,215

[1] Includes $36,009 and $13,097 of TDRs as of December 31, 2019 and 2018, which are accruing and paying currently, but which are considered nonperforming loans under GAAP.