Segment and Geographic Information - Geographic Information Regarding Revenues (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenues:
Total revenues	$ 639,036	$ 547,567
United States [Member]
Revenues:
Total revenues	355,074	306,940
United Kingdom [Member]
Revenues:
Total revenues	163,827	141,704
Asia [Member]
Revenues:
Total revenues	56,751	48,618
France [Member]
Revenues:
Total revenues	25,567	20,827
Other Americas [Member]
Revenues:
Total revenues	14,607	12,434
Other Europe/MEA [Member]
Revenues:
Total revenues	$ 23,210	$ 17,044