Segment Information - Revenues By Region (Details) - USD ($)	3 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	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers [Line Items]
Total revenues	$ 628,383,000	$ 624,474,000	$ 635,037,000	$ 614,576,000	$ 587,044,000	$ 595,962,000	$ 585,890,000	$ 607,221,000	$ 2,502,470,000	$ 2,376,117,000	$ 2,018,197,000
United States and Canada [Member]
Revenues from External Customers [Line Items]
Total revenues									1,629,742,000	1,442,792,000	1,137,508,000
EMEA [Member]
Revenues from External Customers [Line Items]
Total revenues									663,851,000	733,732,000	672,942,000
Other Countries [Member]
Revenues from External Customers [Line Items]
Total revenues									$ 208,877,000	$ 199,593,000	$ 207,747,000