Financial Commitments (Summary Of Interest Expense As Reported In The Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other interest		$ 2,747	$ 3,261	$ 3,623
Cash portion of loss on extinguishment			1,913
Non-cash portion of loss on extinguishment	[1]		5,139
Total cash interest expense		51,447	51,789	48,814
Total non-cash interest expense		12,072	17,595	10,968
Total interest expense		63,519	69,384	59,782
Convertible Notes [Member]
Interest on debt		5,750	5,750	3,115
Total non-cash interest expense	[1]	$ 9,846	8,967	4,519
Effective interest rates		9.39%
2017 Senior Notes [Member] | Senior Notes [Member]
Interest on debt		$ 34,375	23,967
Total non-cash interest expense	[1]	$ 787	516
Effective interest rates		7.13%
2017 Credit Facility [Member] | Credit Facility [Member]
Interest on debt		$ 8,575	5,517
Total non-cash interest expense	[1]	$ 1,439	962
2010 Senior Notes [Member] | Senior Notes [Member]
Interest on debt			6,926	22,875
Total non-cash interest expense	[1]		308	1,002
2014 Credit Facility [Member] | Credit Facility [Member]
Interest on debt			4,455	19,201
Total non-cash interest expense	[1]		$ 1,703	$ 5,447

[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, 2018.