Financial Commitments (Summary Of Interest Expense As Reported In The Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other interest		$ 2,172	$ 2,747	$ 3,261
Cash portion of loss on extinguishment				1,913
Non-cash portion of loss on extinguishment	[1]			5,139
Total cash interest expense		54,287	51,447	51,789
Total non-cash interest expense		13,207	12,072	17,595
Total interest expense		67,494	63,519	69,384
Convertible Notes [Member]
Interest on debt		5,750	5,750	5,750
Total non-cash interest expense	[1]	$ 10,811	9,846	8,967
Effective interest rates		9.39%
2017 Senior Notes [Member] | Senior Notes [Member]
Interest on debt		$ 34,375	34,375	23,967
Total non-cash interest expense	[1]	$ 844	787	516
Effective interest rates		7.13%
2017 Credit Facility [Member] | Credit Facility [Member]
Interest on debt		$ 11,990	8,575	5,517
Total non-cash interest expense	[1]	$ 1,552	$ 1,439	962
2010 Senior Notes [Member] | Senior Notes [Member]
Interest on debt				6,926
Total non-cash interest expense	[1]			308
2014 Credit Facility [Member] | Credit Facility [Member]
Interest on debt				4,455
Total non-cash interest expense	[1]			$ 1,703

[1] The combination of cash and non-cash interest expense produces effective interest rates that are higher than contractual rates. Accordingly, the effective interest rates for the 2017 Senior Notes and the Convertible Notes were 7.13% and 9.39%, respectively, for the year ended December 31, 2019.