Organization and Basis of Presentation (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) item	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) segment item	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Number of reportable operating segments | segment			4
Income tax benefit	$ (45,012)	$ 3,887	$ (43,965)	$ 9,460
Retained earnings	491,683		491,683		$ 536,350
Increase in deferred tax assets	4,663		4,663		38,688
Additional paid-in capital	245,669		245,669		$ 248,748
ASU 2016-09
Income tax benefit	100		1,200
Retained earnings	(600)		(600)
Increase in deferred tax assets	300		300
Additional paid-in capital	$ 900		$ 900
Minimum
Number of countries in which execution services are offered | item	50		50