Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Long-term income tax receivable [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income, Net [Member]	Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Value, Outstanding		$ 0
Common Stock, Value, Outstanding			$ 0
Long-term income tax receivable					$ (530)
Balance at Dec. 31, 2019	$ 32,578			$ 6,389		$ 28,296	$ (1,706)	$ 129
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	673		0	0		670	0	3
Other comprehensive income (loss)	(547)		0	0		0	(547)	0
Common stock purchases	(126)		0	(6)		(120)	0	0
Dividends, Preferred Stock	0
Distributions to noncontrolling interests	(5)		0	0		0	0	(5)
Other equity transactions	(1)		0	(1)		0	0	0
Balance at Mar. 31, 2020	32,572			6,382		28,846	(2,253)	127
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Value, Outstanding		0
Common Stock, Value, Outstanding			0
Long-term income tax receivable					(530)
Preferred Stock, Value, Outstanding		3,750
Common Stock, Value, Outstanding			0
Long-term income tax receivable	(658)				(658)
Balance at Dec. 31, 2020	46,977			6,377		35,093	(1,552)	3,967
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	110		0	0		4	0	106
Other comprehensive income (loss)	112		0	0		0	112	0
Dividends, Preferred Stock	(38)					(38)
Distributions to noncontrolling interests	(113)		0	0	0	0	0	(113)
Other equity transactions	3		0	0	0	1	0	2
Balance at Mar. 31, 2021	47,051			$ 6,377		$ 35,060	$ (1,440)	$ 3,962
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Value, Outstanding		$ 3,750
Common Stock, Value, Outstanding			$ 0
Long-term income tax receivable	$ (658)				$ (658)