CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 1,883	$ 4,553
Accounts receivable
Allowance for uncollectible accounts	11	14
Customers	1,644	1,222
Others	547	607
Property, Plant and Equipment, Net [Abstract]
Net properties and equipment related to VIEs	28,744	27,451
Accumulated depreciation, depletion and amortization	36,375	34,107
Other Assets	2,292	2,211
Goodwill and Other Intangible Assets	5,638	5,662
Accounts payable
Trade	2,144	1,894
Other	201	266
Other Long-term Liabilities
Asset retirement obligations	$ 2,538	$ 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	576,200,000	574,200,000
Treasury stock, shares	82,300,000	43,400,000
Variable Interest Entity, Primary Beneficiary [Member]
Current Assets
Cash and cash equivalents	$ 133	$ 80
Accounts receivable
Customers	159	106
Others	15	19
Property, Plant and Equipment, Net [Abstract]
Net properties and equipment related to VIEs	6,419	5,731
Other Assets	801	579
Goodwill and Other Intangible Assets	1,170	1,191
Accounts payable
Trade	337	305
Other	16	1
Other Long-term Liabilities
Asset retirement obligations	$ 158	$ 143