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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivatives in Cash Flow Hedging Relationships:
Gain related to effective portion of derivatives recognized in accumulated other comprehensive income (loss)	$ 1,875	$ 6,298	$ 17,768	$ 16,066
(Loss) related to effective portion of derivatives reclassified from accumulated other comprehensive income (loss) to interest expense	$ (301)	$ (2,957)	$ (2,535)	$ (9,897)