Derivative Financial Instruments - Summary of Derivative Activity and Related Impact on Consolidated Statements of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives					$ (14,566)		$ 4,296
Derivatives designated as hedging instruments | Interest rate risks | Interest rate swaps | Interest expense—borrowings
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	638		633		1,277		1,267
Derivatives designated as hedging instruments | Interest rate risks | Interest rate swaps | Gain (Loss) on Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	(13)		(33)		(25)		27
Derivatives designated as hedging instruments | Interest rate risks | Interest Rate Risk
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	625		600		1,252		1,294
Derivatives not designated as hedging instruments | Currency exchange risks
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	(147)		126		(198)		(738)
Derivatives not designated as hedging instruments | Currency exchange risks | Loans | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	(685)		(586)		293		(7,650)
Derivatives not designated as hedging instruments | Currency exchange risks | Foreign exchange forwards | Gain (Loss) on Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	538		712		(491)		6,912
Derivatives not designated as hedging instruments | Other derivative instruments | Foreign exchange forwards | Gain (Loss) on Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	170		124		472		173
Derivatives not designated as hedging instruments | Other derivative instruments | Equity warrant assets | Gain (Loss) on Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	12,329		7,190		37,702		10,695
Derivatives not designated as hedging instruments | Other derivative instruments | Other derivatives | Gain (Loss) on Derivative Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	$ (249)	[1]	$ 94	[1]	$ (716)	[1]	$ 572	[1]

[1] Primarily represents the change in fair value of loan conversion options.