Other Noninterest Income and Other Noninterest Expense - Summary of Other Noninterest Income (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other Noninterest Income [Line Items]
Fund management fees		$ 5,198	$ 5,231	$ 15,903	$ 14,149
Service-based fee income		469	2,029	3,860	6,270
Unrealized Gain (Loss) on Derivatives				(8,214)	4,370
Other (3)		10,329	11,378	19,910	19,018
Total other noninterest income	[1]	15,896	18,878	41,128	36,511
Client Instruments
Other Noninterest Income [Line Items]
Gains (losses) on revaluation of internal foreign currency instruments, net (2)		3,760	3,488	8,889	7,009
Internal Instruments
Other Noninterest Income [Line Items]
Gains (losses) on revaluation of internal foreign currency instruments, net (2)		10,561	(1,406)	29,265	(4,222)
Derivatives not designated as hedging instruments | Foreign Exchange Contract
Other Noninterest Income [Line Items]
Unrealized Gain (Loss) on Derivatives		11	(54)	916	(1,155)
Derivatives not designated as hedging instruments | Other derivative instruments
Other Noninterest Income [Line Items]
Unrealized Gain (Loss) on Derivatives		(111)	294	539	(1,771)
Other noninterest income | Derivatives not designated as hedging instruments | Foreign Exchange Contract
Other Noninterest Income [Line Items]
Unrealized Gain (Loss) on Derivatives		(10,550)	1,352	(28,349)	3,067
Other noninterest income | Derivatives not designated as hedging instruments | Other derivative instruments
Other Noninterest Income [Line Items]
Unrealized Gain (Loss) on Derivatives		$ (3,871)	$ (3,194)	$ (8,350)	$ (8,780)

[1] Our consolidated statements of income for the three and nine months ended September 30, 2016 were modified from prior period's presentation to conform to the current period's presentation, which reflects a new line item to separately disclose net gains on equity warrant assets. In prior periods, net gains on equity warrant assets were reported as a component of gains on derivative instruments, net. We removed the line item gains on derivative instruments, net and reclassified all other gains on derivative instruments, net to other noninterest income.