Consolidated Statements of Changes in Equity - USD ($) shares in Millions, $ in Millions	Total	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]
Balance (shares) at Dec. 31, 2018		77
Balance at Dec. 31, 2018	$ 29,723	$ 0	$ 6,371	$ (457)	$ 25,624	$ (1,945)	$ 130
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	625	0	0		622	0	3
Other comprehensive income (loss)	115	0	0		0	115	0
Common stock purchases	(293)	0	(16)		(277)	0	0
Distributions	(7)	0	0		0	0	(7)
Other equity transactions	(1)	$ 0	0		(1)	0	0
Balance (shares) at Mar. 31, 2019		77
Balance at Mar. 31, 2019	$ 30,162	$ 0	6,355	(457)	25,968	(1,830)	126
Balance (shares) at Dec. 31, 2019	77	77
Balance at Dec. 31, 2019	$ 32,578	$ 0	6,389	(530)	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, shares		(1)
Common stock purchases	(126)	$ 0	(6)		(120)	0	0
Distributions	(5)	0	0		0	0	(5)
Other equity transactions	$ (1)	$ 0	(1)		0	0	0
Balance (shares) at Mar. 31, 2020	76	76
Balance at Mar. 31, 2020	$ 32,572	$ 0	$ 6,382	$ (530)	$ 28,846	$ (2,253)	$ 127