Goodwill and Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Goodwill [Roll Forward]
Balance at December 31, 2017	$ 1,704,158
Foreign currency translation	17,493
Acquisition adjustments	1,117
Balance at March 31, 2018	1,722,768
FMT
Goodwill [Roll Forward]
Balance at December 31, 2017	586,064
Foreign currency translation	3,661
Acquisition adjustments	0
Balance at March 31, 2018	589,725
HST
Goodwill [Roll Forward]
Balance at December 31, 2017	740,032
Foreign currency translation	8,879
Acquisition adjustments	1,117
Balance at March 31, 2018	750,028
ESDP
Goodwill [Roll Forward]
Balance at December 31, 2017	378,062
Foreign currency translation	4,953
Acquisition adjustments	0
Balance at March 31, 2018	$ 383,015