Commitments and Contingencies (Details) (USD $)	6 Months Ended
	Jun. 30, 2011
Long-term Purchase Commitment [Line Items]
Expected amount of CO2 to be delivered by third parties in future years	365 MMcf/d
Commitments and Contingencies (Textuals) [Abstract]
Assessment from Mississippi taxing authority for use tax, penalties and interest	$ 15,000,000
Tax refund due to change in tax accounting method	10,600,000
Air Products Llc Anthropogenic Contract [Member]
Long-term Purchase Commitment [Line Items]
Percentage of third party's CO2 which we are obligated to purchase	100.00%
Expected amount of CO2 to be delivered by third parties in future years	50 MMcf/d of CO2 from Air Products in late 2012
Medicine Bow Fuel and Power Anthropogenic Contract [Member]
Long-term Purchase Commitment [Line Items]
Percentage of third party's CO2 which we are obligated to purchase	100.00%
Expected amount of CO2 to be delivered by third parties in future years	200 MMCF/d of CO2 from the MBFP project in 2015
Mississippi Power Company Anthropogenic Contract [Member]
Long-term Purchase Commitment [Line Items]
Percentage of third party's CO2 which we are obligated to purchase	70.00%
Expected amount of CO2 to be delivered by third parties in future years	115 MMcf/d of CO2 from the IGCC project by 2014
Anthropogenic Co2 Contracts [Member]
Long-term Purchase Commitment [Line Items]
Purchase obligation term	15 to 16 years
Aggregate purchase obligation of CO2	110,000,000
Oil price assumption for obligation estimate	$ 100
Amount which we may be contractually obligated to purchase	460