Financial Commitments (Summary Of Interest Expense As Reported In The Condensed Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other interest	$ 626	$ 831	$ 1,383	$ 1,693
Cash portion of loss on extinguishment		1,913		1,913
Non-cash portion of loss on extinguishment		5,139		5,139
Total cash interest expense	13,011	14,405	25,149	26,133
Total non-cash interest expense	2,987	8,114	5,914	11,950
Total interest expense	15,998	22,519	31,063	38,083
Convertible Notes [Member]
Interest on debt	1,437	1,437	2,875	2,875
Total non-cash interest expense	$ 2,432	2,214	$ 4,808	4,378
Effective interest rates	9.39%		9.39%
2017 Senior Notes [Member] | Senior Notes [Member]
Interest on debt	$ 8,594	6,780	$ 17,187	6,780
Total non-cash interest expense	$ 195	141	$ 386	141
Effective interest rates	7.13%		7.13%
2017 Credit Facility [Member] | Credit Facility [Member]
Interest on debt	$ 2,354	1,491	$ 3,704	1,491
Total non-cash interest expense	$ 360	281	$ 720	281
2010 Senior Notes [Member] | Senior Notes [Member]
Interest on debt		1,207		6,926
Total non-cash interest expense		54		308
2014 Credit Facility [Member] | Credit Facility [Member]
Interest on debt		746		4,455
Total non-cash interest expense		$ 285		$ 1,703