Basis of Presentation (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	3 Months Ended				12 Months Ended
	Mar. 03, 2015	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014		Mar. 03, 2015
Underwritten public offering (in shares)	21,000,000
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01				$ 0.01		$ 0.01
Sale of stock (in dollars per share)	$ 47.5							$ 47.5
Proceeds from Issuance of Shares of Common Stock to Public, Net of Offering Costs		$ 1,112		$ 0
Repayment of outstanding indebtedness		150
Common stock, shares authorized (in shares)		500,000,000				500,000,000
Debt Issuance Cost		48				50
Production Expense
Lease Operating Expense		157		142
Production and Ad Valorem Taxes		32		49
Transportation and Gathering Expense		56		38
Total		245		229
Other Operating Expense Net [Abstract]
Midstream Gathering and Processing Expense		4		3
Other, Net		(4)		(7)
Total		8		10
Other Non-Operating (Income) Expense, Net
Deferred Compensation Expense		2	[1]	4	[1]
Other (Income) Expense, Net		(1)		1
Total		1		5
Accounts Receivable, Net
Commodity Sales		303				405
Joint Interest Billings		343				297
Other		140				171
Allowance for Doubtful Accounts		(17)				(16)
Total		769				857
Other Current Assets
Inventories, Materials and Supplies		89				81
Inventories, Crude Oil		28				24
Assets Held-for-Sale		106	[2]			180	[2]
Prepaid Expenses and Other Current Assets		36				40
Total		259				325
Other Noncurrent Assets
Equity Method Investments		384				325
Mutual Fund Investments		112				111
Commodity Derivative Assets		169				180
Other Assets		119				99
Total		784				715
Other Current Liabilities
Production and Ad Valorem Taxes		119				110
Income Taxes Payable		182				180
Deferred Income Taxes, Current		151				158
Accrued Benefit Costs, Current		109				125
Asset Retirement Obligations		81				81
Interest Payable		83				70
Current Portion of Capital Lease Obligations		65				68
Other		84				152
Total		874				944
Other Noncurrent Liabilities
Deferred Compensation Liabilities		224				218
Asset Retirement Obligations		706				670
Accrued Benefit Costs		23				24
Other		204				175
Total		1,157				1,087
Offshore Israel
Other Current Assets
Assets Held-for-Sale		$ 76	[2]
Additional Shares Issued - shoe [Member]
Underwritten public offering (in shares)	3,150,000
Common Stock Authorized after Stock Issuance [Member]
Common stock, shares authorized (in shares)		1,000,000,000

[1] Amounts represent increases in the fair value of shares of our common stock held in a rabbi trust.

[2] (1) Assets held for sale includes $76 million related to our Tanin and Karish natural gas discoveries, offshore Israel. See Update on Core Area – Israel, above.