Business Segment Information (Schedule Of Reconciliation Of Operating Profit (Loss) From Segments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Business Segment Information [Abstract]
Segment profits	$ 34,317	$ 129,835	$ 137,749	$ 351,136
General and administrative expenses	(35,984)	(41,516)	(110,861)	(124,028)
Depreciation and amortization	(60,328)	(54,485)	(181,488)	(157,975)
Loss on disposal of assets	(1,128)	(979)	(1,119)	(1,216)
Goodwill Impairment	(81,877)		(81,877)
Operating income (loss)	$ (145,000)	$ 32,855	$ (237,596)	$ 67,917