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				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives					$ 16,594	$ 4,411
Derivatives designated as hedging instruments | Interest rate risks | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	(7)		74		20	571
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	634		612		1,901	4,537
Derivatives designated as hedging instruments | Interest rate risks | Interest Rate Risk
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	627		686		1,921	5,108
Derivatives not designated as hedging instruments | Currency exchange risks
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	(322)		1,798		(1,060)	1,258
Derivatives not designated as hedging instruments | Currency exchange risks | Loans
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives					451	96
Derivatives not designated as hedging instruments | Currency exchange risks | Loans | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	8,101		1,578
Derivatives not designated as hedging instruments | Currency exchange risks | Foreign exchange forwards
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	(8,423)		220		(1,511)	1,162
Derivatives not designated as hedging instruments | Other derivative instruments | Foreign exchange forwards
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	369		607		2,179	3,002
Derivatives not designated as hedging instruments | Other derivative instruments | Equity warrant assets
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	18,780		547		29,475	12,358
Derivatives not designated as hedging instruments | Other derivative instruments | Other derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives	$ (517)	[1]	$ (337)	[1]	$ 55	$ (1,293)

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