Loans and Allowance for Loan Losses - Summary of Aging of Loans (Detail) - USD ($) $ in Thousands		Jun. 30, 2018		Apr. 02, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		$ 51,386			$ 88,886
Current		1,072,083			230,341
Total	[1]	1,123,469			319,227
Accruing		506			265
Recreation [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		18,625
Current		554,995
Total	[1]	573,620
Home Improvement [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		679
Current		200,882
Total	[1]	201,561
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		707			749
Current		79,398			90,062
Total	[1]	80,105			90,811
Medallion [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		31,375			88,137
Current		236,808			140,279
Total		268,183	[1]		228,416
Accruing		506			265
Secured Mezzanine Term Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current					88,334
Total					88,334
Other Secured Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60					749
Current					1,728
Total	[1]				2,477
31-60 [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		22,381			16,049
31-60 [Member] | Recreation [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		12,981
31-60 [Member] | Home Improvement [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		391
31-60 [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		492
31-60 [Member] | Medallion [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		8,517			16,049
61-90 [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		13,844		$ 12,387	12,387
61-90 [Member] | Recreation [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		3,242
61-90 [Member] | Home Improvement [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		173
61-90 [Member] | Medallion [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		10,429			12,387
91+ [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		15,161			60,450
91+ [Member] | Recreation [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		2,402
91+ [Member] | Home Improvement [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		115
91+ [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		215			749
91+ [Member] | Medallion [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60		$ 12,429			59,701
91+ [Member] | Other Secured Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
31-60					$ 749

[1] Excludes loan premiums of $12,378 resulting from purchase price accounting and $14,267 of capitalized loan origination costs.