CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
OPERATING ACTIVITIES
Net loss	$ (1,232)	$ (5,269)	$ (1,733)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	4,710	4,829	5,120
Goodwill impairment	2,642	6,506	2,746
Deferred income taxes	366	440	522
Provision for uncollectible accounts	189	145	153
Net loss (gain) on early retirement and modification of debt	105	(72)	7
Share-based compensation	175	162	186
Changes in current assets and liabilities:
Accounts receivable	115	(5)	25
Accounts payable	(543)	(261)	124
Accrued income and other taxes	27	20	75
Other current assets and liabilities, net	(262)	(32)	127
Retirement benefits	(111)	(12)	(667)
Changes in other noncurrent assets and liabilities, net	246	245	329
Other, net	97	(16)	18
Net cash provided by operating activities	6,524	6,680	7,032
INVESTING ACTIVITIES
Capitalized expenditures	(3,729)	(3,628)	(3,175)
Proceeds from sale of property, plant and equipment and other assets	153	93	158
Other, net	12	(35)	(61)
Net cash used in investing activities	(3,564)	(3,570)	(3,078)
FINANCING ACTIVITIES
Net proceeds from issuance of long-term debt	4,361	3,707	130
Payments of long-term debt	(7,315)	(4,157)	(1,936)
Payments on credit facility and revolving line of credit	(100)	(300)
Proceeds on credit facility and revolving line of credit			145
Dividends paid	(1,109)	(1,100)	(2,312)
Other, net	(87)	(61)	(50)
Net cash used in financing activities	(4,250)	(1,911)	(4,023)
Net (decrease) increase in cash, cash equivalents and restricted cash	(1,290)	1,199	(69)
Cash, cash equivalents and restricted cash at beginning of period	1,717	518	587
Cash, cash equivalents and restricted cash at end of period	427	1,717	518
Supplemental cash flow information:
Income taxes received, net	28	34	674
Interest paid (net of capitalized interest of $75, $72 and $53)	(1,627)	(2,028)	(2,138)
Cash, cash equivalents and restricted cash:
Total	$ 427	$ 518	$ 587