Loans and Allowance for Loan Losses - Summary of Aging of Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2019		Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	$ 60,413		$ 59,894
Current	1,076,281		933,894
Total	1,136,694	[1]	993,788	[2]
Accruing	0		0
31-60 [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	40,779		29,027
61-90 [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	10,971		9,642
91+ [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	8,663		21,225
Recreation [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	41,583		29,915
Current	648,227		537,294
Total	689,810	[1]	567,209	[2]
Accruing	0		0
Recreation [Member] | 31-60 [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	27,357		19,584
Recreation [Member] | 61-90 [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	8,426		6,198
Recreation [Member] | 91+ [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	5,800		4,133
Home Improvement [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	1,542		1,154
Current	249,288		184,507
Total	250,830	[1]	185,661	[2]
Accruing	0		0
Home Improvement [Member] | 31-60 [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	931		723
Home Improvement [Member] | 61-90 [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	427		296
Home Improvement [Member] | 91+ [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	184		135
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	107		733
Current	69,660		63,350
Total	69,767	[1]	64,083	[2]
Accruing	0		0
Commercial Loans [Member] | 61-90 [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59			454
Commercial Loans [Member] | 91+ [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	107		279
Medallion [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	17,181		28,092
Current	109,106		148,743
Total	126,287	[1]	176,835	[2]
Accruing	0		0
Medallion [Member] | 31-60 [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	12,491		8,720
Medallion [Member] | 61-90 [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	2,118		2,694
Medallion [Member] | 91+ [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-59	$ 2,572		$ 16,678

[1] Excludes loan premiums of $5,758 resulting from purchase price accounting and $18,403 of capitalized loan origination costs.

[2] Excludes loan premiums of $9,047 resulting from purchase price accounting and $15,047 of capitalized loan origination costs.