Commitments and Contingencies - Gains (Losses) Related to Interest Rate Derivatives Designated as Hedges of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 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	$ (37,548)	$ (40,730)	$ (39,577)	$ (38,899)	$ (42,296)	$ (40,791)	$ (39,745)	$ (39,014)	$ (156,754)	$ (161,846)	$ (168,377)
Amount of gain (loss) recognized in other comprehensive income (loss)									(12,360)	(20,910)	4,255
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									$ (7,075)	$ (6,663)	$ (6,898)