Goodwill and Identifiable Intangible Assets - Schedule of Reportable Segments by Reporting Units (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Balance at beginning of period:	$ 928,993	$ 785,032
Goodwill acquired	0	79,372
Goodwill adjustment	(2,213)	0
Goodwill eliminated in connection with divestiture	(13,347)	0
Effect of foreign currency translation	(45,307)	64,589
Balance at end of period:	$ 868,126	$ 928,993