Finance Receivables and Allowance for Credit Losses - Schedule of Activity in Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				$ 52,233				$ 47,849	$ 52,233	$ 47,849	$ 47,145
Charge-offs									(14,610)	(12,877)	(12,650)
Recoveries									11,225	14,338	10,257
Provision	$ (1,756)	$ 1,306	$ 1,319	91	$ 484	$ 167	$ 2,271	1	960	2,923	3,097
Ending balance	49,808				52,233				49,808	52,233	47,849
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				26,347				20,670	26,347	20,670	16,565
Charge-offs									(5,047)	(3,513)	(3,535)
Recoveries									3,102	5,218	3,125
Provision									(2,921)	3,972	4,515
Ending balance	21,481				26,347				21,481	26,347	20,670
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				15,993				17,348	15,993	17,348	22,401
Charge-offs									(2,632)	(1,921)	(3,647)
Recoveries									4,763	4,685	3,871
Provision									49	(4,119)	(5,277)
Ending balance	18,173				15,993				18,173	15,993	17,348
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				2,051				2,962	2,051	2,962	3,239
Charge-offs									(800)	(1,039)	(793)
Recoveries									174	354	205
Provision									218	(226)	311
Ending balance	1,643				2,051				1,643	2,051	2,962
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance				$ 7,842				$ 6,869	7,842	6,869	4,940
Charge-offs									(6,131)	(6,404)	(4,675)
Recoveries									3,186	4,081	3,056
Provision									3,614	3,296	3,548
Ending balance	$ 8,511				$ 7,842				$ 8,511	$ 7,842	$ 6,869