Derivative Instruments and Hedging Activities - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)
Accumulated other comprehensive income (loss):
Beginning Balance	$ 287,466
Ending Balance	373,336
Accumulated Other Comprehensive (Loss) Income [Member]
Accumulated other comprehensive income (loss):
Beginning Balance	(5,076)
Impact of adoption of ASU 2018-02	(1,094)
Ending Balance	4,946
Gains (Losses) on Cash Flow Hedges [Member]
Accumulated other comprehensive income (loss):
Other comprehensive income before reclassifications	12,966
Amounts reclassified from accumulated other comprehensive income to interest expense	(1,850)
Unrealized gain on derivatives, net of tax	11,116
Gains (Losses) on Cash Flow Hedges [Member] | ASU 2018-02 [Member]
Accumulated other comprehensive income (loss):
Impact of adoption of ASU 2018-02	$ (1,094)