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		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Servicing Assets, Changes in fair value due to:
Fair value at beginning of period			$ 2,181
Fair value at end of period	$ 7,249		7,249		$ 2,181
Servicing Liabilities, Changes in fair value due to:
Fair value at beginning of period			3,973
Fair value at end of period	4,394		4,394		3,973
Fair Value, Measurements, Recurring
Servicing Assets, Changes in fair value due to:
Fair value at beginning of period	5,225	$ 1,034	2,181	$ 534	534
Additions, included in other/deferred revenue	3,092	481	6,476	1,355
Changes in fair value, included in servicing fees	(1,436)	(182)	(2,467)	(841)
Fair value at end of period	7,249	1,520	7,249	1,520	2,181
Servicing Liabilities, Changes in fair value due to:
Fair value at beginning of period	4,831	2,736	3,973	936	936
Additions, included in other/deferred revenue	1,402	1,809	4,340	3,464
Changes in fair value, included in servicing fees	(1,839)	(833)	(3,919)	(688)
Fair value at end of period	4,394	3,712	4,394	3,712	$ 3,973
Deferred Revenue | Fair Value, Measurements, Recurring
Servicing Assets, Changes in fair value due to:
Additions, included in other/deferred revenue	368	187	1,059	472
Servicing Liabilities, Changes in fair value due to:
Additions, included in other/deferred revenue	$ 0	$ 0	$ 0	$ 0