Supplemental Cash Flow Information (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Cash Flow Information [Abstract]
Income Taxes Paid Net, Discontinued Operations			$ 1,312	$ 2,270
Operating activities:
Interest paid (net of amounts capitalized)		$ (325)	(279)	(289)
Income taxes paid to taxing authorities	[1]	(171)	(1,679)	(3,904)
Commercial paper:
Issuances		0	2,345	10,870
Repayments		0	(2,480)	(10,935)
Net commercial paper		0	(135)	(65)
Noncash investing and financing activities:
Asset retirement costs capitalized, excluding acquisitions		(85)	151	290
Increase in capital expenditure accrual		0	335	6
Asset Retirement Obligation, Liabilities Transferred		$ 251	$ 359	$ 92

[1] Income taxes paid to taxing authorities includes $1,312 million and $2,270 million in 2014, and 2013