Loans and Allowance for Loan Losses - Summary of Performance Status of Loan (Detail) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended
		Sep. 30, 2020		Dec. 31, 2019
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 1,281,054		$ 1,160,855
Percentage of Nonperforming to Total		8.96%		5.38%
Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 1,166,313		$ 1,098,362
Non - Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans	[1]	114,741		62,493
Recreation [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 802,938		$ 713,332
Percentage of Nonperforming to Total		0.82%		1.16%
Recreation [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 796,369		$ 705,070
Recreation [Member] | Non - Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		6,569		8,262
Home Improvement [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 315,442		$ 247,324
Percentage of Nonperforming to Total		0.03%		0.07%
Home Improvement [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 315,339		$ 247,139
Home Improvement [Member] | Non - Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		103		185
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 71,369		$ 69,767
Percentage of Nonperforming to Total		23.50%		17.00%
Commercial [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 54,598		$ 57,905
Commercial [Member] | Non - Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		16,771		11,862
Medallion [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 91,298		$ 130,432
Percentage of Nonperforming to Total		100.00%		32.34%
Medallion [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans				$ 88,248
Medallion [Member] | Non - Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 91,298	[2]	$ 42,184
Strategic Partnership [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		7
Strategic Partnership [Member] | Performing [Member]
Financing Receivable, Recorded Investment [Line Items]
Status of loans		$ 7

[1] Includes $429 and $36,009 of TDRs as of September 30, 2020 and December 31, 2019, which are accruing and paying currently, but which are considered nonperforming loans under GAAP.

[2] Includes medallion loan premiums of $3,145 as of September 30, 2020.