Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Income from continuing operations	$ (893)	$ 283	$ 294	$ 568	$ 772	$ 605	$ 689	$ 421	$ 252	$ 2,487	$ 1,433
Income from discontinued operations, net of income taxes	2,862	(19)	10,440	73	73	59	57	2,991	13,356	3,180	353
Net income	$ 1,969	$ 264	$ 10,734	$ 641	$ 845	$ 664	$ 746	$ 3,412	$ 13,608	$ 5,667	$ 1,786
Denominator:
Weighted average shares of common stock - basic (in shares)	606	647	674	681	688	696	703	753	652	710	849
Dilutive effect of equity incentive awards (in shares)									11	8	7
Weighted average shares of common stock - diluted (in shares)	606	658	685	693	697	708	711	757	663	718	856
Income per share - basic:
Continuing operations (in usd per share)	$ (1.47)	$ 0.44	$ 0.44	$ 0.83	$ 1.12	$ 0.87	$ 0.98	$ 0.56	$ 0.39	$ 3.50	$ 1.69
Discontinued operations (in usd per share)	4.72	(0.03)	15.48	0.11	0.11	0.08	0.08	3.97	20.48	4.48	0.41
Net income per share - basic (in usd per share)	3.25	0.41	15.92	0.94	1.23	0.95	1.06	4.53	20.87	7.98	2.10
Income per share - diluted:
Continuing operations (in usd per share)	(1.47)	0.43	0.43	0.82	1.11	0.86	0.97	0.56	0.38	3.46	1.68
Discontinued operations (in usd per share)	4.72	(0.03)	15.25	0.10	0.10	0.08	0.08	3.95	20.16	4.43	0.41
Net income per share - diluted (in usd per share)	$ 3.25	$ 0.40	$ 15.68	$ 0.92	$ 1.21	$ 0.94	$ 1.05	$ 4.51	$ 20.54	$ 7.89	$ 2.09
Common stock equivalents excluded from income per diluted share because their effect would have been anti-dilutive (in shares)									1	5	18