Financial Derivatives and Hedging Activities - Fair Value Amounts Recorded as Component of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Balance at January 1,	$ (5,640)	$ 1,882
Deferred (losses) gains on cash flow hedges	(4,344)	(303)
Reclassified to earnings	1,959	(931)
Balance at March 31,	$ (8,025)	$ 648