Derivative Instruments and Hedging Activities - Schedule of Changes in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Accumulated other comprehensive loss:
Beginning Balance	$ 461,215	$ 504,120
Ending Balance	287,466	461,215
Gains (Losses) on Cash Flow Hedges [Member]
Accumulated other comprehensive loss:
Beginning Balance	(13,694)	(13,137)
Other comprehensive income (loss) before reclassifications	972	(1,690)
Amounts reclassified from accumulated other comprehensive loss to interest expense	7,646	1,133
Unrealized (loss) gain on derivatives, net of tax	8,618	(557)
Ending Balance	$ (5,076)	$ (13,694)