Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Cash Flows [Abstract]
Net income (loss)	$ (5,723)	$ (2,140)	$ (2,204)
Adjustments to reconcile net income to net cash provided by operating activities:
Discontinued operations	4,893	53	503
Depreciation, depletion and amortization	2,372	2,156	2,721
Impairments	229	67	721
Exploratory dry well costs and unproved property impairments	323	220	867
Net (gain) loss on disposal of assets	(58)	(389)	(120)
Deferred income taxes	(61)	828	(804)
Gain (Loss) on Sale of Derivatives	(11)	63	(126)
Net cash received (paid) in settlement of derivative instruments	98	61	55
Share-based Compensation	50	48	45
Equity method investments, net	20	17	33
Changes in:
Current receivables	(334)	67	790
Inventories	10	64	25
Current accounts payable and accrued liabilities	297	(137)	(906)
All other operating, net	(117)	(77)	(63)
Net cash provided by continuing operations	1,988	901	1,537
Investing activities:
Additions to property, plant and equipment	(1,974)	(1,204)	(3,485)
Acquisitions, net of cash acquired	(1,891)	(902)	0
Disposal of assets	1,787	1,219	225
Investments - return of capital	64	55	77
Payments to Acquire Investments	0	0	(925)
Proceeds from Sale, Maturity and Collection of Investments	0	0	925
All other investing, net	(30)	(1)	24
Net cash used in investing activities	(2,044)	(833)	(3,159)
Financing activities:
Borrowings	988	0	1,996
Debt repayments	(2,764)	(1)	(1,069)
Payment for Debt Extinguishment or Debt Prepayment Cost	(46)	0	0
Proceeds from Issuance of Common Stock	0	1,236	0
Purchases of common stock	(11)	(6)	(11)
Dividends paid	(170)	(162)	(460)
All other financing, net	0	1	(5)
Net cash provided by (used in) financing activities	(2,003)	1,068	451
Cash Provided by (Used in) Operating Activities, Discontinued Operations	141	177	39
Investing activities of discontinued operations	(13)	(41)	(43)
Change in cash included in current assets held for sale	2	100	90
Net cash provided by discontinued operations	130	236	86
Effect of Exchange Rate on Cash and Cash Equivalents, Continuing Operations	4	(3)	(3)
Net increase (decrease) in cash and cash equivalents	(1,925)	1,369	(1,088)
Cash and cash equivalents at beginning of period	2,488	1,119	2,207
Cash and cash equivalents at end of period	$ 563	$ 2,488	$ 1,119