Basis of Presentation (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012		Dec. 31, 2012
Production Expense
Lease Operating Expense	$ 140		$ 100		$ 257		$ 205
Production and Ad Valorem Taxes	43		44		86		81
Transportation and Gathering Expense	27		24		55		45
Total	210		168		398		331
Other Operating (Income) Expense, Net
Gain on Divestitures	0		(9)	[1]	(12)	[1]	(9)	[1]
Asset Impairments	0		73	[2]	0		73	[2]
Other, Net	16		7		20		19
Total	16		71		8		83
Other Non-Operating (Income) Expense, Net
Deferred Compensation (Income) Expense	3	[3]	(11)	[3]	14	[3]	(8)	[3]
Other (Income) Expense, Net	0		8		(2)		5
Total	3		(3)		12		(3)
Accounts Receivable, Net
Commodity Sales	383				383				349
Joint Interest Billings	406				406				486
Other	68				68				139
Allowance for Doubtful Accounts	(10)				(10)				(10)
Total	847				847				964
Other Current Assets
Inventories, Current	109				109				90
Commodity Derivative Assets	72				72				63
Deferred Income Taxes, Net	45				45				106
Probable Insurance Claims	0	[4]			0	[4]			45	[4]
Assets Held-for-Sale	37	[5]			37	[5]			45	[5]
Prepaid Expenses and Other Current Assets	95				95				71
Total	358				358				420
Other Noncurrent Assets
Equity Method Investments	410				410				367
Mutual Fund Investments	110				110				103
Commodity Derivative Assets	95				95				21
Other Assets	88				88				106
Total	703				703				597
Other Current Liabilities
Production and Ad Valorem Taxes	100				100				113
Commodity Derivative Liabilities	13				13				7
Income Taxes Payable	123				123				203
Asset Retirement Obligations	69				69				69
Interest Payable	57				57				55
Current Portion of Long Term Debt	527	[6]			527	[6]			324	[6]
Current Portion of FPSO and Other Capital Lease Obligations	50				50				48
Liabilities Associated with Assets Held for Sale	42	[5]			42	[5]			12	[5]
Other	142				142				193
Total	1,123				1,123				1,024
Other Noncurrent Liabilities
Deferred Compensation Liabilities	252				252				229
Asset Retirement Obligations	346				346				333
Accrued Benefit Costs	119				119				116
Other	97				97				132
Total	$ 814				$ 814				$ 810

[1] See Note 3. Divestitures

[2] Amounts for 2012 related primarily to our South Raton development in the deepwater Gulf of Mexico and our Piceance development, onshore US. The assets were written down to their estimated fair values, which were determined using discounted cash flow models.

[3] Amounts represent increases (decreases) in the fair value of shares of our common stock held in a rabbi trust.

[4] Amounts represent the costs incurred to date of the Leviathan-2 appraisal well and expected well abandonment costs in excess of the insurance deductible less insurance proceeds received to date.

[5] Assets held for sale consist primarily of North Sea oil and gas properties. Liabilities associated with assets held for sale consist primarily of asset retirement obligations related to these assets. See Note 3. Divestitures.

[6] See Note 5. Debt.