Derivative Financial Instruments (Narrative) (Detail) (USD $)	6 Months Ended		3 Months Ended		6 Months Ended					6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 Not Designated As Hedging Instruments [Member] DerivativeInstruments	Jun. 30, 2013 Not Designated As Hedging Instruments [Member] DerivativeInstruments	Jun. 30, 2014 Not Designated As Hedging Instruments [Member] DerivativeInstruments	Jun. 30, 2013 Not Designated As Hedging Instruments [Member] DerivativeInstruments	Jun. 30, 2014 Cash Flow Hedges [Member]	Dec. 31, 2013 Cash Flow Hedges [Member]	Jun. 30, 2013 Cash Flow Hedges [Member]	Jun. 30, 2014 Cash Flow Hedges [Member] Interest Expense [Member]	Jun. 30, 2014 Cash Flow Hedges [Member] Interest Rate Swaps [Member] DerivativeInstruments	Dec. 31, 2013 Cash Flow Hedges [Member] Interest Rate Swaps [Member] DerivativeInstruments	Jun. 30, 2013 Cash Flow Hedges [Member] Interest Rate Swaps [Member] DerivativeInstruments
Derivative [Line Items]
Number of derivative instruments held			285	263	285	263					13	14	14
Future annual time period	12 months
Aggregate notional amount			$ 1,806,139,000	$ 1,605,531,000	$ 1,806,139,000	$ 1,605,531,000	$ 1,117,859,000	$ 1,146,437,000	$ 1,150,284,000
Estimated amount to be reclassified										20,243,000
Net (loss) gain related to changes in fair value of derivatives			(902,000)	1,848,000	(1,612,000)	1,615,000
Fair value of derivatives in net liability position with credit-risk-related Contingent Features	43,164,000	50,247,000
Cash collateral posted with derivative counterparties	$ 43,826,000	$ 42,813,000