Derivative Instruments and Hedging Activities - Schedule of Pre-tax Effect of Derivative Financial Instruments on Unaudited Condensed Consolidated Statements of Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivatives in Cash Flow Hedging Relationships:
Gain related to effective portion of derivatives recognized in accumulated other comprehensive income (loss)	$ 3,777	$ 2,130	$ 15,893	$ 9,768
(Loss) related to effective portion of derivatives reclassified from accumulated other comprehensive income (loss) to interest expense	$ (383)	$ (3,305)	$ (2,234)	$ (6,941)