DEBT (Bank Credit Facility) (Details) (USD $)	3 Months Ended	9 Months Ended	1 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Oct. 29, 2012 Subsequent Event Divestiture Louisiana	Sep. 30, 2012 Credit Facility	Sep. 17, 2012 Credit Facility	Sep. 15, 2012 Credit Facility	Oct. 29, 2012 Credit Facility Subsequent Event	Oct. 05, 2012 Credit Facility Subsequent Event
Bank Credit Facility
Maximum borrowing capacity				$ 1,500,000,000
Increase in the credit agreement's borrowing capacity available subject to the agreement				300,000,000
Maximum borrowing capacity optional expansion				1,800,000,000
Borrowing base under the Credit Facility				1,200,000,000		1,250,000,000		1,150,000,000
Credit Facility borrowing capacity reduction as percentage of the stated principal amount of issued senior notes (as a percent)				25.00%
Credit Facility borrowing base reduction due to issuance of Senior Notes					50,000,000
Credit Facility borrowing capacity reduction due to sale of properties with value in excess of this percentage of the borrowing base then in effect (as a percent)				10.00%
Proceeds from sale of oil and natural gas assets and properties	7,800,000	8,800,000	220,000,000
Credit Facility borrowing base reduction due to sale of properties							$ 80,000,000
Credit Facility collateral as percentage of present value of oil and gas properties (as a percent)				75.00%
Credit Facility covenant based on ratio of total debt outstanding to EBITDA, Numerator				4.5
Credit Facility covenant based on ratio of total debt outstanding to EBITDA, Denominator				1.0