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	1,313	0	0		1,306	0	7
Other comprehensive income (loss)	57	0	0		0	57	0
Common stock purchases	(293)	0	(16)		(277)	0	0
Distributions	(10)	0	0		0	0	(10)
Other equity transactions	(3)	$ 0	0		(2)	0	(1)
Balance (shares) at Jun. 30, 2019		77
Balance at Jun. 30, 2019	30,787	$ 0	6,355	(457)	26,651	(1,888)	126
Balance (shares) at Mar. 31, 2019		77
Balance at Mar. 31, 2019	30,162	$ 0	6,355	(457)	25,968	(1,830)	126
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	688	0	0		684	0	4
Other comprehensive income (loss)	(58)	0	0		0	(58)	0
Distributions	(3)	0	0		0	0	(3)
Other equity transactions	(2)	$ 0	0		(1)	0	(1)
Balance (shares) at Jun. 30, 2019		77
Balance at Jun. 30, 2019	$ 30,787	$ 0	6,355	(457)	26,651	(1,888)	126
Balance (shares) at Dec. 31, 2019	0	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	1,793	0	0		1,786	0	7
Other comprehensive income (loss)	(419)	$ 0	0		0	(419)	0
Common stock purchases, shares		(1)
Common stock purchases	(126)	$ 0	(6)		(120)	0	0
Distributions	(7)	0	0		0	0	(7)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	(33)	0	(5)	0	0	0	(28)
Other equity transactions	$ (1)	$ 0	(1)		0	0	0
Balance (shares) at Jun. 30, 2020	0	76
Balance at Jun. 30, 2020	$ 33,785	$ 0	6,377	(530)	29,962	(2,125)	101
Balance (shares) at Mar. 31, 2020		76
Balance at Mar. 31, 2020	32,572	$ 0	6,382	(530)	28,846	(2,253)	127
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,120	0	0		1,116	0	4
Other comprehensive income (loss)	128	0	0		0	128	0
Distributions	(2)	0	0		0	0	(2)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	$ (33)	$ 0	(5)	0	0	0	(28)
Balance (shares) at Jun. 30, 2020	0	76
Balance at Jun. 30, 2020	$ 33,785	$ 0	$ 6,377	$ (530)	$ 29,962	$ (2,125)	$ 101