Segment, Geographic and Product Information - Geographic Information Regarding Revenues (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Total revenues	$ 2,104,231	$ 1,937,810	$ 1,750,951
U.K. [Member]
Revenues:
Total revenues	864,955	811,542	716,167
U.S. [Member]
Revenues:
Total revenues	564,037	544,887	514,704
Asia [Member]
Revenues:
Total revenues	331,328	278,141	244,855
France [Member]
Revenues:
Total revenues	83,664	77,992	85,729
Other Americas [Member]
Revenues:
Total revenues	58,103	54,687	53,942
Other Europe/MEA [Member]
Revenues:
Total revenues	$ 202,144	$ 170,561	$ 135,554