Fair Value of Assets and Liabilities - Additional Information about Servicing Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Servicing Assets, Changes in fair value due to:
Fair value at beginning of period	$ 10,250
Fair value at end of period	16,964		$ 10,250
Servicing Liabilities, Changes in fair value due to:
Fair value at beginning of period	(3,973)
Fair value at end of period	(2,827)		(3,973)
Fair Value, Measurements, Recurring
Servicing Assets, Changes in fair value due to:
Fair value at beginning of period	10,250	$ 2,181	2,181
Additions, included in other/deferred revenue	5,631	1,508
Changes in fair value, included in servicing fees	232	(491)
Fair value at end of period	16,964	3,496	10,250
Servicing Liabilities, Changes in fair value due to:
Fair value at beginning of period	(3,973)	(3,973)	(3,973)
Additions, included in other/deferred revenue	(932)	(1,412)
Changes in fair value, included in servicing fees	2,078	988
Fair value at end of period	(2,827)	(4,397)	$ (3,973)
Deferred Revenue | Fair Value, Measurements, Recurring
Servicing Assets, Changes in fair value due to:
Additions, included in other/deferred revenue	851	298
Servicing Liabilities, Changes in fair value due to:
Additions, included in other/deferred revenue	$ 0	$ 0