Organization and Basis of Presentation (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) segment item	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
Number of reportable operating segments | segment	4
Income tax benefit	$ (1,491)	$ (1,132)
Retained earnings	538,678		$ 536,350
Increase in deferred tax assets	43,169		38,688
Additional paid-in capital	236,995		$ 248,748
ASU 2016-09
Income tax benefit	1,100
Retained earnings	600
Increase in deferred tax assets	300
Additional paid-in capital	$ 900
Minimum
Number of countries in which execution services are offered | item	50