Debt And Interest Expense (Components Of Interest Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Short-term Debt [Line Items]
Contractual interest on Convertible Debentures	$ 87,063	$ 87,063	$ 73,638
Interest Expense, Debt	0	20,015	47,432
Amortization of debt discount on the Convertible Debentures	0	4,236	12,012
Other interest expense	3,548	3,531	3,254
Total interest expense	$ 90,611	$ 114,845	$ 136,336