CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 4,553	$ 3,184
Accounts Receivable
Accounts receivable (net of allowance of $14 and $14)	14	14
Customers	1,222	1,007
Others	607	721
Properties and Equipment
Net properties and equipment	27,451	32,168
Other assets	2,211	2,226
Goodwill and Other Intangible Assets	5,662	5,904
Accounts Payable [Abstract]
Accounts payable	1,894	1,617
Other Long-term Liabilities
Asset retirement obligations ($143 and $140 related to VIEs)	$ 2,500	$ 2,802
Common stock, par value (in usd per share)	$ 0.1	$ 0.1
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	574,200,000	572,000,000
Treasury stock, shares	43,400,000	20,800,000
Variable Interest Entity, Primary Beneficiary [Member]
Current Assets
Cash and cash equivalents	$ 80	$ 359
Accounts Receivable
Customers	106	70
Others	19	80
Properties and Equipment
Net properties and equipment	5,731	5,050
Other assets	579	609
Goodwill and Other Intangible Assets	1,191	1,221
Accounts Payable [Abstract]
Accounts payable	305	234
Other Long-term Liabilities
Asset retirement obligations ($143 and $140 related to VIEs)	$ 143	$ 140