Stock-based Compensation Employee Service Share-based Compensation, Allocation of Costs (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	$ 7,200	$ 7,394	$ 20,879	$ 34,194
Cost of services and sales, exclusive of depreciation [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation		5,170	7,288	8,648
General and Adminstrative Expense, exclusive of depreciation [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation		$ 2,224	$ 13,591	$ 25,546