Segment Information - Revenue Classified by Major Geographic Areas (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 218,945	$ 211,804	$ 212,074	$ 214,956	$ 225,189	$ 207,478	$ 227,959	$ 237,175	$ 857,779	$ 897,801	$ 981,135
Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									815,231	853,221	932,032
Europe/Middle East
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									39,048	40,603	43,087
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									$ 3,500	$ 3,977	$ 6,016