Basis of Presentation and Summary of Significant Accounting Policies - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenues
Revenue	$ 399,643	$ 383,030	$ 410,382	$ 393,167	$ 386,289	$ 338,393	$ 209,382	$ 218,260	$ 1,586,222	$ 1,152,324	$ 789,926
United States
Disaggregation of Revenues
Revenue									1,347,516	1,000,827	654,565
Europe
Disaggregation of Revenues
Revenue									211,314	136,531	131,287
Other
Disaggregation of Revenues
Revenue									27,392	14,966	4,074
ITPS
Disaggregation of Revenues
Revenue									1,273,647	827,110	439,924
ITPS | United States
Disaggregation of Revenues
Revenue									1,034,941	675,613	304,563
ITPS | Europe
Disaggregation of Revenues
Revenue									211,314	136,531	131,287
ITPS | Other
Disaggregation of Revenues
Revenue									27,392	14,966	4,074
HS
Disaggregation of Revenues
Revenue									228,015	233,595	247,796
HS | United States
Disaggregation of Revenues
Revenue									228,015	233,595	247,796
LLPS
Disaggregation of Revenues
Revenue									84,560	91,619	102,206
LLPS | United States
Disaggregation of Revenues
Revenue									$ 84,560	$ 91,619	$ 102,206