Additional Financial Statement Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Production Expense
Lease Operating Expense	$ 604		$ 530		$ 431
Production and Ad Valorem Taxes	184		188		151
Transportation Expense	170		132		91
Total	958		850		673
Other Operating Expense, Net
Gas Gathering, Transportation, Marketing and Processing Costs	16		36		23
Other, Net	22		7		2
Total	38		43		25
Other Non-Operating (Income) Expense, Net
Deferred Compensation Expense	(25)	[1]	26	[1]	6	[1]
Other (Income) Expense, Net	(1)		(5)		0
Total	(26)		21		6
Accounts Receivable, Net
Commodity Sales	405		495
Joint Interest Billings	297		382
Other	171		81
Allowance for Doubtful Accounts	(16)		(11)
Total	857		947
Other Current Assets
Inventories, Materials and Supplies	81		96
Inventories, Crude Oil	24		25
Deferred Income Taxes, Net, Current	0		62
Assets Held for Sale	180		292
Prepaid Expenses and Other Assets, Current	40		71
Total	325		546
Other Noncurrent Assets
Equity Method Investments	325		437		367
Mutual Fund Investments	111		114
Commodity Derivative Assets, Noncurrent	180		16
Other Assets, Noncurrent	99		112
Total	715		679
Other Current Liabilities
Production and Ad Valorem Taxes	110		103
Commodity Derivative Liabilities, Current	0		65
Income Taxes Payable - Current	180		156
Deferred Tax Liabilities, Gross, Current	158		0
Asset Retirement Obligations, Current	81		39
Accrued Employee Benefits, Current	125		10
Interest Payable	70		63
Current Portion of Long Term Debt	0		200
Current Portion of Capital Lease and Other Obligations	68		58
Liabilities Associated with Assets Held for Sale	9		111
Other Liabilities, Current	143		183
Total	944		988
Other Noncurrent Liabilities
Deferred Compensation Liabilities, Noncurrent	218		253
Asset Retirement Obligations, Noncurrent	670		547
Noncurrent Liabilities	24		155
Other Liabilities, Noncurrent	175		154
Total	$ 1,087		$ 1,109

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