Derivative Financial Instruments (Effect of Derivative Instruments on Earnings) (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Not Designated As Hedging Instruments [Member]
Derivative Instruments Gain Loss [Line Items]
Amount Of Gain (Loss) Recognized In Income On Derivatives	$ 1,545,000	$ (4,064,000)	$ 3,159,000	$ (4,870,000)
Cash Flow Hedges [Member] | Interest Rate Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Amount Of Gain (Loss) Recognized In OCI	831,000	(1,659,000)	10,030,000	(4,139,000)
Interest Expense [Member] | Cash Flow Hedges [Member] | Interest Rate Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Amount Of Loss Reclassified From Accumulated OCI Into Income	(5,023,000)	(4,434,000)	(14,225,000)	(13,083,000)
Other Expense [Member] | Interest Rate Contract [Member] | Not Designated As Hedging Instruments [Member]
Derivative Instruments Gain Loss [Line Items]
Amount Of Gain (Loss) Recognized In Income On Derivatives	0	(10,000)	(1,000)	(47,000)
Other Expense [Member] | Cash Flow Hedges [Member] | Interest Rate Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Amount Of Loss Recognized In Income (Ineffective Portion)	0	0	0	0
Other Income [Member] | Interest Rate Contract [Member] | Not Designated As Hedging Instruments [Member]
Derivative Instruments Gain Loss [Line Items]
Amount Of Gain (Loss) Recognized In Income On Derivatives	$ 1,545,000	$ (4,054,000)	$ 3,160,000	$ (4,823,000)