Stock-Based Compensation (Schedule of Non-Cash Compensation Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total cost of non-cash compensation included in loss before provision for income taxes	$ 42,327	$ 38,249	$ 32,915
Amount charged against loss	42,327	38,249	32,915
Cost of Revenues [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total cost of non-cash compensation included in loss before provision for income taxes	1,182	1,013	418
Selling, General And Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total cost of non-cash compensation included in loss before provision for income taxes	$ 41,145	$ 37,236	$ 32,497