Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flows From Operating Activities [Abstract]
Net Income (Loss)	$ (2,441)	$ 1,214	$ 978
Adjustments to Reconcile Net Income (Loss) to Net Cash Provided by Operating Activities
Depreciation, Depletion and Amortization	2,131	1,759	1,570
Asset Impairments	533	500	86
Goodwill Impairment	779	0	0
Dry Hole Cost	266	226	149
Deferred Income Taxes	117	268	269
(Income) Loss from Equity Method Investees, Net of Dividends	(14)	33	(17)
(Gain) Loss on Commodity Derivative Instruments	(501)	(976)	133
Net Cash Received (Paid) in Settlement of Commodity Derivative Instruments	1,009	29	(2)
(Gain) Loss on Divestitures	0	(73)	(93)
Loss on Fair Value Adjustment to Inventory	20	0	0
Stock Based Compensation	86	87	80
Non-cash Pension Termination Expense	82	0	0
Expiration and Amortization of Unproved Leaseholds	113	43	30
Other Adjustments for Noncash Items Included in Income	11	(16)	45
Changes in Operating Assets and Liabilities, Net of Assets Acquired and Liabilities Assumed
(Increase) Decrease in Accounts Receivable	453	29	(239)
Increase (Decrease) in Accounts Payable	(364)	318	(87)
Increase (Decrease) in Current Income Taxes Payable	(94)	18	(47)
Increase (Decrease) in Other Current Liabilities	(70)	45	20
Other Operating Assets and Liabilities, Net	(54)	2	62
Net Cash Provided by Operating Activities	2,062	3,506	2,937
Cash Flows From Investing Activities
Additions to Property, Plant and Equipment	(2,979)	(4,871)	(3,947)
Proceeds from Divestitures	151	321	327
Rosetta Merger	61	0	0
Additions to Equity Method Investments	(104)	(71)	(48)
Distributions from Equity Method Investments	0	156	0
Other	0	0	(7)
Net Cash Used in Investing Activities	(2,871)	(4,465)	(3,675)
Cash Flows From Financing Activities
Exercise of Stock Options	8	48	51
Excess Tax Benefits from Stock-Based Awards	(1)	19	20
Dividends Paid, Common Stock	(291)	(249)	(198)
Purchase of Treasury Stock	(21)	(16)	(14)
Proceeds from Issuance of Shares of Common Stock to Public, Net of Offering Costs	1,112	0	0
Proceeds from Credit Facilities	0	1,050	900
Repayment of Credit Facilities	(70)	(1,050)	(900)
Proceeds from Issuance of Senior Long-Term Debt, Net	0	1,478	985
Repayment of Senior Notes	(12)	(200)	0
Repayment of Capital Lease Obligation	(67)	(55)	(48)
Repayment of Installment Loan and Other	(4)	0	(328)
Net Cash Provided By Financing Activities	654	1,025	468
Increase (Decrease) in Cash and Cash Equivalents	(155)	66	(270)
Cash and Cash Equivalents at Beginning of Period	1,183	1,117	1,387
Cash and Cash Equivalents at End of Period	$ 1,028	$ 1,183	$ 1,117