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	2,457	0	0		2,443	0	14
Other comprehensive income (loss)	(134)	0	0		0	(134)	0
Common stock purchases	(293)	0	(16)		(277)	0	0
Distributions	(16)	0	0		0	0	(16)
Other equity transactions	3	$ 0	0		(1)	0	4
Balance (shares) at Sep. 30, 2019		77
Balance at Sep. 30, 2019	31,740	$ 0	6,355	(457)	27,789	(2,079)	132
Balance (shares) at Jun. 30, 2019		77
Balance at Jun. 30, 2019	30,787	$ 0	6,355	(457)	26,651	(1,888)	126
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,144	0	0		1,137	0	7
Other comprehensive income (loss)	(191)	0	0		0	(191)	0
Distributions	(6)	0	0		0	0	(6)
Other equity transactions	6	$ 0	0		1	0	5
Balance (shares) at Sep. 30, 2019		77
Balance at Sep. 30, 2019	$ 31,740	$ 0	6,355	(457)	27,789	(2,079)	132
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	4,638	0	0		4,628	0	10
Other comprehensive income (loss)	(177)	$ 0	0		0	(177)	0
Common stock purchases, shares		(1)
Common stock purchases	(126)	$ 0	(6)		(120)	0	0
Distributions	(11)	0	0		0	0	(11)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	(33)	0	(5)	0	0	0	(28)
Other equity transactions	$ 0	$ 0	(1)		0	0	1
Balance (shares) at Sep. 30, 2020	0	76
Balance at Sep. 30, 2020	$ 36,869	$ 0	6,377	(530)	32,804	(1,883)	101
Balance (shares) at Jun. 30, 2020		76
Balance at Jun. 30, 2020	33,785	$ 0	6,377	(530)	29,962	(2,125)	101
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	2,845	0	0		2,842	0	3
Other comprehensive income (loss)	242	0	0		0	242	0
Distributions	(4)	0	0		0	0	(4)
Other equity transactions	$ 1	$ 0	0		0	0	1
Balance (shares) at Sep. 30, 2020	0	76
Balance at Sep. 30, 2020	$ 36,869	$ 0	$ 6,377	$ (530)	$ 32,804	$ (1,883)	$ 101