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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 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	$ (39,745)	$ (42,483)	$ (78,759)	$ (85,480)
Amount of loss recognized in other comprehensive income	(8,368)	3,508	(14,666)	3,375
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	$ (1,664)	$ (1,714)	$ (3,312)	$ (3,594)