Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Income from continuing operations	$ 691	$ 1,253	$ 2,602	$ 1,994
Income from discontinued operations, net of tax	0	0	0	320
Net income	$ 691	$ 1,253	$ 2,602	$ 2,314
Weighted average shares outstanding - basic (in shares)	1,248,189,719	1,238,450,665	1,246,441,464	1,111,511,964
Effect of dilutive securities:
Outstanding stock options and unvested stock awards (in shares)	5,471,526	11,348,075	7,950,323	10,528,564
Weighted average shares outstanding - diluted (in shares)	1,253,661,245	1,249,798,740	1,254,391,787	1,122,040,528
Basic earnings per share:
Continuing operations (in USD per share)	$ 0.55	$ 1.01	$ 2.09	$ 1.79
Discontinued operations (in USD per share)	0	0	0	0.29
Earnings per share - basic (in USD per share)	0.55	1.01	2.09	2.08
Diluted earnings per share:
Continuing operations (in USD per share)	0.55	1.00	2.07	1.78
Discontinued operations (in USD per share)	0	0	0	0.28
Earnings per share - diluted (in USD per share)	$ 0.55	$ 1.00	$ 2.07	$ 2.06
Outstanding stock options and unvested stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	127,732	54,485	87,968	30,469
SoftBank contingent consideration
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities (in shares)	48,751,557	48,751,557	48,751,557	32,738,272