Segment Information - Revenue Classified by Major Geographic Areas (Details) - USD ($) $ in Thousands	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 and Long-Lived Assets [Line Items]
Total revenue	$ 295,881	$ 234,793	$ 250,935	$ 251,770	$ 243,254	$ 237,814	$ 242,556	$ 234,530	$ 1,033,379	$ 958,154	$ 920,338
Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									998,344	925,127	880,602
Europe/Middle East
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									31,599	29,292	36,364
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									$ 3,436	$ 3,735	$ 3,372