Basis of Presentation and Summary of Significant Accounting Policies - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenues
Revenue	$ 393,586	$ 373,545	$ 390,849	$ 404,357	$ 399,643	$ 383,030	$ 410,382	$ 393,167	$ 795,206	$ 803,549	$ 1,168,751	$ 1,186,579	$ 1,562,337	$ 1,586,222	$ 1,145,891
United States
Disaggregation of Revenues
Revenue													1,286,678	1,347,516	1,000,827
EMEA
Disaggregation of Revenues
Revenue													248,466	211,314	130,098
Other
Disaggregation of Revenues
Revenue													27,193	27,392	14,966
ITPS
Disaggregation of Revenues
Revenue	306,665	292,607	309,840	325,172	324,267	307,313	330,131	311,936					1,234,284	1,273,647	820,677
ITPS | United States
Disaggregation of Revenues
Revenue													958,625	1,034,941	675,613
ITPS | EMEA
Disaggregation of Revenues
Revenue													248,466	211,314	130,098
ITPS | Other
Disaggregation of Revenues
Revenue													27,193	27,392	14,966
HS
Disaggregation of Revenues
Revenue	69,806	62,132	63,440	61,343	56,293	56,776	56,314	58,632					256,721	228,015	233,595
HS | United States
Disaggregation of Revenues
Revenue													256,721	228,015	233,595
LLPS
Disaggregation of Revenues
Revenue	$ 17,115	$ 18,806	$ 17,569	$ 17,842	$ 19,083	$ 18,941	$ 23,937	$ 22,599					71,332	84,560	91,619
LLPS | United States
Disaggregation of Revenues
Revenue													$ 71,332	$ 84,560	$ 91,619