Derivative Instruments and Hedging Activities - Schedule of Pre-tax Effect of Derivative Financial Instruments on Unaudited Condensed Consolidated Statements of Comprehensive Income (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivatives in Cash Flow Hedging Relationships:
(Loss) gain related to effective portion of derivatives recognized in accumulated other comprehensive loss	$ (17,490,000)	$ 1,005,000	$ (26,471,000)	$ (1,868,000)
Gain related to effective portion of derivatives reclassified from accumulated other comprehensive loss to interest expense	843,000	746,000	2,312,000	1,879,000
Loss related to ineffective portion of derivatives recognized in other expense (income), net	$ (1,000)	$ 0	$ (288,000)	$ 0