Condensed Consolidated Statements of Changes in Equity (unaudited) - USD ($) $ in Millions		Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock		Additional paid-in capital	Treasury Stock	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Cumulative Effect, Period of Adoption, Adjustment	Total Stockholders’ Equity	Total Stockholders’ Equity Cumulative Effect, Period of Adoption, Adjustment	Noncontrolling Interests	Noncontrolling Interests Cumulative Effect, Period of Adoption, Adjustment
Balance, beginning of period (in shares) at Dec. 31, 2018	[1]			309,005,272
Balance, beginning of period at Dec. 31, 2018		$ 15,403	$ (1)	$ 3		$ 13,657	$ (12)	$ 1,528	$ 11	$ (72)	$ (12)	$ 15,104	$ (1)	$ 299	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		460						477				477		(17)
Other Comprehensive Income (Loss)		(15)								(15)		(15)
Comprehensive Income		445
Dividends declared		(408)						(408)				(408)
Stock-based compensation		2				2						2
Distributions to noncontrolling interests		(47)												(47)
Contributions from noncontrolling interests		124						(9)				(9)		133
Balance, end of period (in shares) at Sep. 30, 2019	[1]			309,005,272
Balance, end of period at Sep. 30, 2019		15,518		$ 3		13,659	(12)	1,599		(99)		15,150		368
Balance, beginning of period (in shares) at Jun. 30, 2019	[1]			309,005,272
Balance, beginning of period at Jun. 30, 2019		15,549		$ 3		13,659	(12)	1,594		(109)		15,135		414
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		139						150				150		(11)
Other Comprehensive Income (Loss)		10								10		10
Comprehensive Income		149
Dividends declared		(136)						(136)				(136)
Distributions to noncontrolling interests		(37)												(37)
Contributions from noncontrolling interests		(7)						(9)				(9)		2
Balance, end of period (in shares) at Sep. 30, 2019	[1]			309,005,272
Balance, end of period at Sep. 30, 2019		$ 15,518		$ 3		13,659	(12)	1,599		(99)		15,150		368
Balance, beginning of period (in shares) at Dec. 31, 2019		309,005,272		309,005,272	[1]
Balance, beginning of period at Dec. 31, 2019		$ 15,586	$ (1)	$ 3		13,660	(12)	1,681	$ (1)	(95)		15,237	$ (1)	349
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		387						415				415		(28)
Other Comprehensive Income (Loss)		(19)								(19)		(19)
Comprehensive Income		368
Dividends declared		(408)						(408)				(408)
Release of common stock held in trust (in shares)	[1]			213
Issuances of common stock (in shares)	[1]			42,777
Issuance of common stock		(1)				(1)						(1)
Repurchase of common stock (in shares)	[1]			(42,777)
Repurchase of common stock		(2)					(2)					(2)
Stock-based compensation		5				5						5
Distributions to noncontrolling interests		(5)												(5)
Contributions from noncontrolling interests		$ 312						(3)				(3)		315
Balance, end of period (in shares) at Sep. 30, 2020		309,005,485		309,005,485	[1]
Balance, end of period at Sep. 30, 2020		$ 15,854		$ 3		13,664	(14)	1,684		(114)		15,223		631
Balance, beginning of period (in shares) at Jun. 30, 2020	[1]			309,005,485
Balance, beginning of period at Jun. 30, 2020		15,916		$ 3		13,664	(14)	1,733		(108)		15,278		638
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		81						87				87		(6)
Other Comprehensive Income (Loss)		(6)								(6)		(6)
Comprehensive Income		75
Dividends declared		(136)						(136)				(136)
Distributions to noncontrolling interests		$ (1)												(1)
Balance, end of period (in shares) at Sep. 30, 2020		309,005,485		309,005,485	[1]
Balance, end of period at Sep. 30, 2020		$ 15,854		$ 3		$ 13,664	$ (14)	$ 1,684		$ (114)		$ 15,223		$ 631

[1] (*) Par value of share amounts is $0.01