Income Taxes - Rate Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income (loss) before taxes - United States	$ 893	$ (197)	$ 2,799	$ (5,259)
Income Loss Before Income Taxes Foreign	2,013	850	4,502	1,319
Income (Loss) before income taxes	2,906	653	7,301	(3,940)
Federal Statutory Income Tax Rate, Amount	610	228	1,533	(1,379)
Non-U.S. effective tax rates	479	137	1,339	503
Canada disposition	0	(8)	0	(1,176)
Recovery of outside basis	(16)	(118)	(19)	(957)
Adjustment to tax reserves, amount	(3)	(17)	2	764
Adjustment to valuation allowances	(29)	0	13	24
APLNG impairment	0	0	0	834
State Income Taxes	38	14	83	(98)
Enhanded oil recovery credit	(36)	(5)	(73)	(49)
Other Reconciling Items	(10)	(14)	(4)	(15)
Income Tax Expense (Benefit)	$ 1,033	$ 217	$ 2,874	$ (1,549)
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation Abstract
Income (Loss) Before Income Taxes Domestic Percentage	30.70%	(30.20%)	38.30%	133.50%
Income (Loss) Before Income Taxes Foreign Percentage	69.30%	130.20%	61.70%	(33.50%)
Income (Loss) Before Income Taxes In Percent	100.00%	100.00%	100.00%	100.00%
Federal statutory rate percentage	21.00%	35.00%	21.00%	35.00%
Non US effective tax rates percentage	16.50%	21.00%	18.30%	(12.80%)
Canada disposition, percentage	0.00%	(1.20%)	0.00%	29.80%
Recovery of outside basis, percentage	(0.60%)	(18.10%)	(0.20%)	24.30%
Adjustment to tax reserves, percentage	(0.10%)	(2.60%)	0.00%	(19.40%)
Adjustment to Value Allowance, Percentage	(1.00%)	0.00%	0.20%	(0.60%)
APLNG Impairment, percentage	0.00%	0.00%	0.00%	(21.20%)
State income tax, percentage	1.30%	2.10%	1.10%	2.50%
Enhanced oil recovery, percentage	(1.30%)	(0.80%)	(1.00%)	1.20%
Other, percentage	(0.30%)	(2.20%)	0.00%	0.50%
Effective Income Tax Rate, Continuing Operations	35.50%	33.20%	39.40%	39.30%