Segment, Geographic and Product Information - Geographic Information Regarding Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues:
Total revenues	$ 544,751	$ 524,774
United States [Member]
Revenues:
Total revenues	146,420	147,660
United Kingdom [Member]
Revenues:
Total revenues	231,780	223,114
Asia [Member]
Revenues:
Total revenues	81,567	68,611
Other Europe/MEA [Member]
Revenues:
Total revenues	49,843	50,020
France [Member]
Revenues:
Total revenues	21,489	21,430
Other Americas [Member]
Revenues:
Total revenues	$ 13,652	$ 13,939