Basis of Presentation (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016		Dec. 31, 2016
Oil, NGL and Gas Sales		$ 994	$ 705
Production Expense
Lease Operating Expense		139	161
Production and Ad Valorem Taxes (1)		45	4
Gathering, Transportation and Processing Expense (2)	[1]	119	111
Total		303	276
Other Operating (Income) Expense, Net
Loss on Asset Due to Terminated Contract	[2]	4
Midstream Gathering and Processing (Income) Expense, Net	[3]	19	18
Business combination costs			42
Gain on Extinguishment of Debt		0	(80)	[4]
Other, Net		6	19
Total		29	(1)
Other Non-Operating Expense (Income), Net
Other Income, Net		(1)	(4)
Total		(1)	(4)
Severance tax refunds		7	28
Accounts Receivable, Net
Commodity Sales		362			$ 403
Joint Interest Billings		119			106
Proceeds Receivable	[5]	0			40
Other		63			86
Allowance for Doubtful Accounts		(21)			(20)
Total		523			615
Other Current Assets
Inventories, Materials and Supplies		71			71
Inventories, Crude Oil		21			18
Restricted Cash and Cash Equivalents, Current		0			30
Prepaid Expenses and Other Current Assets		43			41
Total		135			160
Other Noncurrent Assets
Investments in Unconsolidated Subsidiaries		407			400
Mutual Fund Investments		74			71
Other Assets		54			37
Total		535			508
Other Current Liabilities
Production and Ad Valorem Taxes		116			115
Derivative Liability, Current		23			102
Income Taxes Payable		30			53
Asset Retirement Obligations		160			160
Interest Payable		93			76
Current Portion of Capital Lease Obligations		66			63
Other		110			173
Total		598			742
Other Noncurrent Liabilities
Deferred Compensation Liabilities		215			218
Asset Retirement Obligations		772			775
Accrual for Taxes Other than Income Taxes		61			47
Other		44			63
Total		$ 1,092			$ 1,103
Percentage of divestiture farmed out		35.00%			35.00%
Scenario, Previously Reported [Member]
Other Operating (Income) Expense, Net
Midstream Gathering and Processing (Income) Expense, Net		$ 3	$ 4

[1] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjk1YmYwYzc1YTZjMzRiODlhMjM5ZGQxOWU2MGYxYWI5fFRleHRTZWxlY3Rpb246RUYyRjFEQzc0QTk1NTdGOUEwRDQ1RjlDRTMzNUM1NjAM}

[2] Amounts relate to the termination and final settlement of a rig contract for offshore Falkland Islands as a result of a supplier's non-performance.

[3] .

[4] .

[5] 35%