Financial Commitments (Summary Of Interest Expense As Reported In The Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest on debt	$ 3,623	$ 5,805	$ 7,910
Total cash interest expense	48,814	43,048	43,765
Total non-cash interest expense	10,968	2,095	2,270
Interest Expense, Total	59,782	45,143	46,035
2010 Notes [Member]
Interest on debt	22,875	22,875	22,875
Total non-cash interest expense	$ 1,002	979	951
Imputed interest rate (as a percent)	7.99%
Convertible Notes [Member]
Interest on debt	$ 3,115
Total non-cash interest expense	$ 4,519
Imputed interest rate (as a percent)	9.39%
2014 Credit Facility [Member]
Interest on debt	$ 19,201	14,368	12,980
Total non-cash interest expense	$ 5,447	$ 1,116	$ 1,319
Imputed interest rate (as a percent)	9.86%