Fixed Assets and Asset Retirement Obligations - (Schedule Of Reconciliation Of Liability For Asset Retirement Obligations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations, beginning balance	$ 188,662	$ 14,790
AROs arising from acquisitions and consolidations	20,940	158,230
AROs from the consolidation of historical interests in CHOPS and SEKCO		1,988
Accretion expense	10,800	4,941
Revisions in timing, expected settlement and estimated costs of AROs	(2,254)	9,986
Settlements	(4,422)	(1,273)
Asset retirement obligations, ending balance	$ 213,726	$ 188,662