Debt And Interest Expense (Carrying Amounts Of Liability And Equity Components) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Mar. 27, 2015	Apr. 16, 2013	Aug. 15, 2007
Debt Disclosure [Abstract]
Carrying amount of equity component (net of issuance costs of $14,449)	$ 418,996	$ 418,996
Principal amount of debt	1,250,000	1,250,000	$ 500,000	$ 750,000	$ 1,250,000
Unamortized discount of liability component	(624,315)	(635,378)
Unamortized Debt Issuance Expense	(10,260)	(10,422)
Carrying amount of liability component	615,425	604,200
Contingent interest derivative	14,339	30,126
Convertible Debt	$ 629,764	$ 634,326