Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	$ 367,951	$ 414,263
Liability derivatives, Fair value	220,710	254,189
Derivatives designated and qualifying as hedging instruments [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	96,019	109,832
Liability derivatives, Fair value	1,160	487
Derivatives not designated and qualifying as hedging instruments [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	271,932	304,431
Liability derivatives, Fair value	219,550	253,702
Interest rate swap agreements [Member] | Derivatives designated and qualifying as hedging instruments [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	94,716	102,875
Commitments to sell real estate loans [Member] | Derivatives designated and qualifying as hedging instruments [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	1,303	6,957
Liability derivatives, Fair value	1,160	487
Commitments to sell real estate loans [Member] | Derivatives not designated and qualifying as hedging instruments [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	2,807	6,120
Liability derivatives, Fair value	1,895	230
Mortgage-related commitments to originate real estate loans for sale [Member] | Derivatives not designated and qualifying as hedging instruments [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	13,878	7,616
Liability derivatives, Fair value	1,289	3,675
Interest rate contracts [Member] | Derivatives not designated and qualifying as hedging instruments [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	246,284	274,864
Liability derivatives, Fair value	207,179	234,455
Foreign exchange and other option and futures contracts [Member] | Derivatives not designated and qualifying as hedging instruments [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	8,963	15,831
Liability derivatives, Fair value	$ 9,187	$ 15,342