Stock-based Compensation Employee Service Share-based Compensation, Allocation of Costs (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 9,900	$ 34,194	$ 22,942	$ 22,079
Cost of services and sales, exclusive of depreciation [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation		8,648	8,879	10,073
General and Adminstrative Expense, exclusive of depreciation [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation		$ 25,546	$ 14,063	$ 12,006