CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 3,361	$ 4,553
Accounts receivable
Allowance for uncollectible accounts	14	14
Customers	1,156	1,222
Others	639	607
Property, Plant and Equipment, Net [Abstract]
Net properties and equipment related to VIEs	27,758	27,451
Accumulated depreciation, depletion and amortization	34,220	34,146
Other Assets	2,134	2,211
Goodwill and Other Intangible Assets	5,654	5,662
Accounts payable
Trade	2,059	1,894
Other Long-term Liabilities
Asset retirement obligations	$ 2,510	$ 2,500
Stockholders’ equity
Common stock, par value per share (in usd per share)	$ 0.1	$ 0.10
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	575,200,000	574,200,000
Treasury stock, shares	71,300,000	43,400,000
Variable Interest Entity, Primary Beneficiary [Member]
Current Assets
Cash and cash equivalents	$ 524	$ 80
Accounts receivable
Customers	125	106
Others	13	19
Property, Plant and Equipment, Net [Abstract]
Net properties and equipment related to VIEs	6,064	5,731
Other Assets	572	579
Goodwill and Other Intangible Assets	1,184	1,191
Accounts payable
Trade	331	305
Other Long-term Liabilities
Asset retirement obligations	$ 147	$ 143