Other Noninterest Income and Other Noninterest Expense - Summary of Other Noninterest Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Other Noninterest Income [Line Items]
Fund management fees	$ 5,231	$ 4,074	$ 14,149	$ 11,657
Service-based fee income	2,029	1,931	6,270	6,450
Other (3)	11,350	4,884	19,711	16,052
Total other noninterest income	20,692	11,077	42,917	22,315
Client Instruments
Other Noninterest Income [Line Items]
(Losses) gains on revaluation of internal foreign currency instruments, net (2)	3,488	2	7,009	(177)
Internal Instruments
Other Noninterest Income [Line Items]
(Losses) gains on revaluation of internal foreign currency instruments, net (2)	$ (1,406)	$ 186	$ (4,222)	$ (11,667)