Consolidated Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
OPERATING ACTIVITIES:
Net income (loss)	$ 198	$ 714	$ 193
Adjustments to reconcile to net cash provided (used) by operating activities:
Depreciation and amortization	1,721	1,714	1,725
Provision (benefit) for deferred income taxes	108	376	220
Equity (earnings) losses	(328)	(375)	(396)
Distributions from unconsolidated affiliates	653	657	693
Gain on disposition of equity-method investments (Note 7)	0	(122)	0
(Gain) on sale of certain assets and businesses (Note 3)	0	2	(692)
(Gain) loss on deconsolidation of businesses (Note 7)	0	29	(203)
Impairment of goodwill (Note 18)	187	0	0
Impairment of equity-method investments (Note 18)	1,046	186	32
Impairment of certain assets (Note 18)	182	464	1,915
Amortization of stock-based awards	52	57	55
Cash provided (used) by changes in current assets and liabilities:
Accounts receivable	(2)	34	(36)
Inventories	(11)	5	(16)
Other current assets and deferred charges	11	21	17
Accounts payable	(7)	(46)	(93)
Accrued liabilities	(309)	153	23
Other, including changes in noncurrent assets and liabilities	(5)	(176)	(144)
Net cash provided (used) by operating activities	3,496	3,693	3,293
FINANCING ACTIVITIES:
Proceeds from long-term debt	3,899	767	3,926
Payments of long-term debt	(3,841)	(909)	(3,204)
Proceeds from issuance of common stock	9	10	15
Common dividends paid	(1,941)	(1,842)	(1,386)
Dividends and distributions paid to noncontrolling interests	(185)	(124)	(591)
Proceeds from Noncontrolling Interests	7	36	15
Payments for debt issuance costs	(20)	0	(26)
Other – net	(13)	(17)	(48)
Net cash provided (used) by financing activities	(2,085)	(745)	(1,299)
INVESTING ACTIVITIES:
Capital expenditures (1)	(1,239)	(2,109)	(3,256)
Dispositions – net	(36)	(40)	(7)
Contributions in aid of construction	37	52	411
Proceeds from sale of businesses, net of cash divested (Note 3)	0	(2)	1,296
Purchases of businesses, net of cash acquired (Note 3)	0	(728)	0
Proceeds from dispositions of equity-method investments (Note 7)	0	485	0
Purchases of and contributions to equity-method investments (Note 7)	(325)	(453)	(1,132)
Other – net	5	(32)	(37)
Net cash provided (used) by investing activities	(1,558)	(2,827)	(2,725)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	(147)	121	(731)
Cash and cash equivalents at beginning of year	289	168	899
Cash and cash equivalents at end of year	142	289	168
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
(1) Increases to property, plant, and equipment	(1,160)	(2,023)	(3,021)
Changes in related accounts payable and accrued liabilities	(79)	(86)	(235)
Capital expenditures	(1,239)	(2,109)	(3,256)
Northeast JV [Member]
FINANCING ACTIVITIES:
Proceeds from Noncontrolling Interests	$ 0	$ 1,334	$ 0