Income Taxes (Reconciliation Of Effective Tax Rate) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Tax computed at statutory rate	$ 304,102	$ (60,037)	$ 422,999
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	(307,101)
State income taxes, net of federal tax benefit	21,343	(14,056)	40,385
Domestic production activities deduction	(9,937)	4,170	(35,200)
Noncontrolling interest in net income	(29,357)	(26,903)	(24,155)
Goodwill	0	119,722
Other	8,571	(3,485)	2,031
Income tax provision total	$ (12,379)	$ 19,411	$ 406,060