Derivative Instruments and Hedging Activities - Losses Related to Interest Rate Derivatives Designated as Hedges of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Amounts Related To Interest Rate Derivatives Included In Income Designated As Hedges Of Cash Flows [Line Items]
Amount of loss reclassified from accumulated other comprehensive loss to interest expense	$ (40,791)	$ (42,110)	$ (119,550)	$ (127,590)
Amount of loss recognized in other comprehensive income	2,155	(4,818)	(12,511)	(1,443)
Reclassification Out of Accumulated Other Comprehensive Income (Loss) [Member]
Amounts Related To Interest Rate Derivatives Included In Income Designated As Hedges Of Cash Flows [Line Items]
Amount of loss reclassified from accumulated other comprehensive loss to interest expense	$ (1,674)	$ (1,637)	$ (4,986)	$ (5,231)