Derivative Financial Instruments (Fair Value of Derivative Instruments) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Derivatives Fair Value [Line Items]
Liability Derivatives	$ 67,111	$ 72,126
Asset Derivatives	24,690	25,915
Interest Rate Contract [Member] | Other Assets [Member] | Designated As Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Asset Derivatives	934	878
Interest Rate Contract [Member] | Other Assets [Member] | Not Designated As Hedging Instruments [Member]
Derivatives Fair Value [Line Items]
Asset Derivatives	23,756	25,037
Interest Rate Contract [Member] | Other Liabilities [Member] | Designated As Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Liability Derivatives	46,894	51,172
Interest Rate Contract [Member] | Other Liabilities [Member] | Not Designated As Hedging Instruments [Member]
Derivatives Fair Value [Line Items]
Liability Derivatives	$ 20,217	$ 20,954