Derivative Financial Instruments (Fair Value of Derivative Instruments) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 28,739	$ 26,463
Liability Derivatives	79,276	73,161
Interest Rate Contract [Member] | Other Liabilities [Member] | Designated As Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	55,789	52,028
Interest Rate Contract [Member] | Other Liabilities [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	23,487	21,133
Interest Rate Contract [Member] | Other Assets [Member] | Designated As Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	964	3,693
Interest Rate Contract [Member] | Other Assets [Member] | Derivatives Not Designated As Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 27,775	$ 22,770