Financial Commitments (Summary Of Interest Expense As Reported In The Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Interest on debt		$ 12,950	$ 13,251
Other interest		504	574
Total non-cash interest expense	[1]	3,486	3,174
Total interest expense		16,436	16,425
Convertible Notes [Member]
Interest on debt		1,437	1,438
Total non-cash interest expense	[1]	$ 2,864	2,608
Effective interest rates		9.39%
2017 Senior Notes [Member] | Senior Notes [Member]
Interest on debt		$ 8,594	8,594
Total non-cash interest expense	[1]	$ 220	205
Effective interest rates		7.13%
2017 Credit Facility [Member] | Revolving Credit Facility [Member]
Interest on debt		$ 2,415	2,645
Total non-cash interest expense	[1]	$ 402	$ 361

[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 three months ended March 31, 2020.