Components of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at the beginning of the period	$ 1,551,113
Other comprehensive income (loss) before reclassifications	806	$ 65
Net (gains) losses reclassified from accumulated other comprehensive loss	(14)	(261)
Total other comprehensive income (loss)	792	(196)
Balance at the end of the period	1,456,117
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at the beginning of the period	(5,584)	(2,676)
Other comprehensive income (loss) before reclassifications	695	123
Net (gains) losses reclassified from accumulated other comprehensive loss	0	0
Total other comprehensive income (loss)	695	123
Balance at the end of the period	(4,889)	(2,553)
Derivatives Qualifying as Cash Flow Hedges [Member] | Foreign Exchange Contract [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at the beginning of the period	195	691
Other comprehensive income (loss) before reclassifications	111	(58)
Net (gains) losses reclassified from accumulated other comprehensive loss	(14)	(261)
Total other comprehensive income (loss)	97	(319)
Balance at the end of the period	292	372
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at the beginning of the period	(5,389)	(1,985)
Balance at the end of the period	$ (4,597)	$ (2,181)