Accrued Expenses and Other Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Payables and Accruals [Abstract]
Accrued compensation	$ 23,142	$ 13,659
Accrued expenses	12,818	6,220
Loan servicing liabilities at fair value	4,394	3,973
Deferred rent	4,150	1,377
Deferred tax liability	3,587	1,332
Deferred revenue	1,817	759
Loan funding payables	831	0
Contingent liabilities	810	1,995
Payable to issuing bank	703	267
Transaction fee refund reserve	672	828
Early stock option exercise and other equity-related liabilities	333	392
Other	880	818
Total accrued expenses and other liabilities	$ 54,137	$ 31,620