Income Taxes (Provision For Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal, Current	$ (71,878)	$ 480,446	$ 294,509
State, Current	(7,304)	71,750	40,325
Federal, Deferred	100,208	(127,714)	(168,756)
State, Deferred	(1,615)	(18,422)	(24,906)
Income tax provision total	$ 19,411	$ 406,060	$ 141,172