Financial Commitments (Summary Of Interest Expense As Reported In The Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other interest	$ 3,261	$ 3,623	$ 5,805
Cash portion of loss on extinguishment	1,913
Non-cash portion of loss on extinguishment	5,139
Total cash interest expense	51,789	48,814	43,048
Total non-cash interest expense	17,595	10,968	2,095
Total interest expense	69,384	59,782	45,143
Convertible Notes [Member]
Interest on debt	5,750	3,115
Total non-cash interest expense	$ 8,967	4,519
Effective interest rates	9.39%
2017 Senior Notes [Member] | Senior Notes [Member]
Interest on debt	$ 23,967
Total non-cash interest expense	$ 516
Effective interest rates	7.13%
2017 Credit Facility [Member] | Credit Facility [Member]
Interest on debt	$ 5,517
Total non-cash interest expense	962
2010 Senior Notes [Member] | Senior Notes [Member]
Interest on debt	6,926	22,875	22,875
Total non-cash interest expense	308	1,002	979
2014 Credit Facility [Member] | Credit Facility [Member]
Interest on debt	4,455	19,201	14,368
Total non-cash interest expense	$ 1,703	$ 5,447	$ 1,116