Basis of Presentation (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Feb. 01, 2016
Share Price					$ 31.65
Production Expense
Lease Operating Expense		$ 161		$ 157
Production and Ad Valorem Taxes (1)	[1]	4		32
Transportation and Gathering Expense (2)	[2]	107		65
Total		272		254
Other Operating (Income) Expense, Net
Loss on Asset Due to Terminated Contract	[3]	42		0
Midstream Gathering and Processing (Income) Expense, Net	[4]	22		6
Asset Impairments	[5]	0		27
Gain on Extinguishment of Debt	[6]	(80)		0
Other, Net		19		1
Total		3		34
Other Non-Operating (Income) Expense, Net
Deferred Compensation Expense	[7]	0		2
Other (Income) Expense, Net		(4)		(1)
Total		(4)		$ 1
Additional expense due to unutilized firm transportation and shortfalls in delivering or transporting minimum volumes under certain commitments		16
Accounts Receivable, Net
Commodity Sales		308	$ 298
Joint Interest Billings		51	20
Proceeds Receivable	[8]	40	0
Severance Tax Refund	[9]	28	0
Other		128	151
Allowance for Doubtful Accounts		(24)	(19)
Total		531	450
Other Current Assets
Inventories, Materials and Supplies		90	92
Inventories, Crude Oil		27	23
Assets Held-for-Sale	[10]	0	67
Prepaid Expenses and Other Current Assets		37	34
Total		154	216
Other Noncurrent Assets
Investments in Unconsolidated Subsidiaries		461	453
Mutual Fund Investments		77	90
Commodity Derivative Assets		6	10
Other Assets		70	67
Total		614	620
Other Current Liabilities
Production and Ad Valorem Taxes		162	166
Income Taxes Payable		71	86
Asset Retirement Obligations		128	128
Interest Payable		94	83
Current Portion of Capital Lease Obligations		54	53
Other		92	161
Total		601	677
Other Noncurrent Liabilities
Deferred Compensation Liabilities		214	217
Asset Retirement Obligations		872	861
Accrual for Taxes Other than Income Taxes		76	68
Other		71	73
Total		$ 1,233	$ 1,219
Percentage of divestiture farmed out		35.00%	35.00%
Phantom Units [Member]
Shares issued					1
State and Local Jurisdiction [Member]
Other Non-Operating (Income) Expense, Net
Accrual of severance tax refund		$ 28

[1] The reduction in production and ad valorem taxes is primarily due to the accrual of a $28 million onshore US severance tax receivable during first quarter 2016.

[2] Certain of our revenue received from purchasers was historically presented with deductions for transportation, gathering, fractionation or processing costs. Beginning in 2016, we have changed our presentation of revenue to no longer include these expenses as deductions from revenue. These costs are now included within production expense and prior year amounts have been reclassified to conform to the current presentation.

[3] Amount relates to the termination of a rig contract offshore Falkland Islands as a result of a supplier's non-performance. See Note 8. Capitalized Exploratory Well Costs and Undeveloped Leasehold

[4] In 2016, amount includes $16 million of expense due to unutilized firm transportation and shortfalls in delivering or transporting minimum volumes under certain commitments.

[5] Impairments during 2015 were related to facility costs at South Raton (Deepwater Gulf of Mexico) and increases in expected field abandonment cost for the Noa and Pinnacles fields (Eastern Mediterranean).

[6] Amount relates to the tendering of senior notes assumed in the Rosetta Merger. See Note 6. Debt.

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

[8] Amount relates to proceeds to be received from our farm-out of 35% interest in Block 12 offshore Cyprus. See Note 4. Divestitures.

[9] Amount relates to the accrual of a $28 million onshore US severance tax receivable.

[10] Assets held for sale at December 31, 2015 included our Karish and Tanin natural gas discoveries, offshore Israel. The sale closed first quarter 2016. See Note 4. Divestitures