Finance Receivables and Allowance for Credit Losses - Schedule of Accretable Yield of Noncovered Purchased Credit Impaired Loans, or Income Expected to be Collected (Detail) - Purchased Credit Impaired Loans [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at January 1	$ 45,310	$ 62,533	$ 101,502
New loans purchased	3,217	1,812	8,274
Accretion of income	(23,447)	(35,526)	(77,929)
Reclassifications from (to) nonaccretable difference	10,589	14,189	27,536
Disposals/other adjustments	(2,066)	2,302	3,150
Balance at December 31	$ 33,603	$ 45,310	$ 62,533