Significant Accounting Policies (Details Textuals) (USD $) Share data in Millions, unless otherwise specified	1 Months Ended	12 Months Ended								12 Months Ended
	Jan. 31, 2012	Dec. 31, 2011 Year	Dec. 31, 2010	Dec. 31, 2009	Dec. 30, 2010 Encore Energy Partners LP ("ENP") [Member]	Dec. 30, 2010 Encore Energy Partners GP LLC ("GP LLC") [Member]	Dec. 31, 2009 Genesis Energy, L.P. ("Genesis") [Member]	Dec. 31, 2009 Genesis General Partner [Member]	Dec. 31, 2009 Genesis Common Units [Member]	Dec. 31, 2011 Co2 Property And Pipelines [Member] Year	Dec. 31, 2011 Vehicles and furniture and fixtures [Member] Year	Dec. 31, 2011 Computer equipment and software [Member] Year
Property, Plant and Equipment [Line Items]
Cumulative effect of change in accounting policy, before tax			$ 9,600,000
Cumulative effect of change in accounting policy, after tax			6,000,000
Reduction to CO2 properties			26,100,000
Adjustment to accumulated depletion, depreciation and amortization			35,700,000
Estimated useful lives, Minimum		15								15	5	3
Estimated useful lives, Maximum										50	10	5
Significant Accounting Policies [Line Items]
Ownership percentage					46.00%	100.00%	12.00%
Ownership percentage in equity method investments				12.00%				100.00%	10.00%
Net income attributable to noncontrolling interest		0	13,804,000	0
Cost basis of Vanguard investment			93,000,000
Interest and Other Income from Available-for-sale securities		7,200,000
Other than Temporary Impairment Loss on Investments		6,300,000
Proceeds from Sale of Available-for-sale Securities, Equity	83,500,000
Depletion, depreciation and amortization per BOE		16.42	15.82	13.39
Impairment of Goodwill		$ 0	$ 0	$ 0
Non-vested restricted stock excluded from basic weighted average common shares		3.4	3.2	2.5