Variable Interest Entities - Schedule of Fair Value and Carrying Value of Assets and Liabilities of the CUSO (Parenthetical) (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
CUSO [Member]
Variable Interest Entity [Line Items]
Allowance for loan losses	$ 2,412	$ 1,796	$ 2,480