Income Taxes (Schedule Of Total Provision For Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Current taxes, Federal	$ 0	$ (20,612)	$ 8,594
Current taxes, State	15	(4)	784
Current taxes	15	(20,616)	9,378
Deferred taxes, Federal	(62,923)	(535,691)	68,360
Deferred taxes, State	(8,286)	(70,641)	8,925
Deferred taxes	(71,209)	(606,332)	77,285
Total provision	$ (71,194)	$ (626,948)	$ 86,663