Statement of Changes in Consolidated Equity (unaudited) - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Non-controlling Interest [Member]
Balance at Dec. 31, 2019	$ 5,886	$ 2	$ 9,639	$ (555)	$ (4,974)	$ 1,774
Net income (loss)	(11)			(117)		106
Other comprehensive (loss) income (G)	(476)				(306)	(170)
Stock-based compensation	17		17
Contributions	16					16
Distributions	(106)					(106)
Other	(2)		(1)			(1)
Balance at Jun. 30, 2020	5,324	2	9,655	(672)	(5,280)	1,619
Balance at Mar. 31, 2020	5,811	2	9,647	(476)	(4,898)	1,536
Net income (loss)	(150)			(197)		47
Other comprehensive (loss) income (G)	(287)				(382)	95
Stock-based compensation	9		9
Contributions	16					16
Distributions	(75)					(75)
Other			(1)	1
Balance at Jun. 30, 2020	5,324	2	9,655	(672)	(5,280)	1,619
Balance at Dec. 31, 2020	5,016	2	9,663	(725)	(5,629)	1,705
Net income (loss)	569			484		85
Other comprehensive (loss) income (G)	(61)				(58)	(3)
Stock-based compensation	18		18
Common stock issued: compensation plans	14		14
Distributions	(137)					(137)
Other	(1)					(1)
Balance at Jun. 30, 2021	5,418	2	9,695	(241)	(5,687)	1,649
Balance at Mar. 31, 2021	4,873	2	9,674	(550)	(5,878)	1,625
Net income (loss)	350			309		41
Other comprehensive (loss) income (G)	250				191	59
Stock-based compensation	10		10
Common stock issued: compensation plans	10		10
Distributions	(75)					(75)
Other			1			(1)
Balance at Jun. 30, 2021	$ 5,418	$ 2	$ 9,695	$ (241)	$ (5,687)	$ 1,649