Stock-Based Compensation (Schedule Of Non-Cash Compensation Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
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	$ 32,915	$ 28,747	$ 22,671
Amount charged against loss	32,915	28,747	22,671
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	418	405	386
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	$ 32,497	$ 28,342	$ 22,285