Financial Commitments (Summary Of Interest Expense As Reported In The Condensed Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Other interest	$ 757	$ 862
Total cash interest expense	12,138	11,728
Total non-cash interest expense	2,927	3,836
Total interest expense	15,065	15,564
Convertible Notes [Member]
Interest on debt	1,438	1,438
Total non-cash interest expense	$ 2,376	2,164
Effective interest rates	9.39%
2017 Senior Notes [Member] | Senior Notes [Member]
Interest on debt	$ 8,594
Total non-cash interest expense	$ 191
Effective interest rates	7.13%
2017 Credit Facility [Member] | Credit Facility [Member]
Interest on debt	$ 1,349
Total non-cash interest expense	$ 360
2010 Senior Notes [Member] | Senior Notes [Member]
Interest on debt		5,719
Total non-cash interest expense		254
2014 Credit Facility [Member] | Credit Facility [Member]
Interest on debt		3,709
Total non-cash interest expense		$ 1,418