Earnings Per Share of Common Stock - Computation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Weighted-average number of shares on which earnings per share calculations are based
Weighted-average shares outstanding during period (in shares)	895,043,024	889,435,166	894,336,970	888,702,256
Add - Incremental shares under stock-based compensation plans (in shares)	7,431,661	4,290,365	7,027,051	5,015,390
Add - Incremental shares associated with contingently issuable shares (in shares)	1,758,754	1,213,549	1,625,732	1,271,513
Assuming dilution (in shares)	904,233,439	894,939,080	902,989,752	894,989,159
Net income on which basic earnings per share is calculated
Income from continuing operations	$ 1,325	$ 1,362	$ 2,281	$ 2,538
Income/(loss) from discontinued operations, net of tax		(1)	(1)	(2)
Net income on which basic earnings per share is calculated	1,325	1,361	2,280	2,536
Net income on which diluted earnings per share is calculated
Income from continuing operations	1,325	1,362	2,281	2,538
Net income applicable to contingently issuable shares				(2)
Income from continuing operations on which diluted earnings per share is calculated	1,325	1,362	2,281	2,536
Income/(loss) from discontinued operations, net of tax, on which basic and diluted earnings per share is calculated		(1)	(1)	(2)
Net income on which diluted earnings per share is calculated	$ 1,325	$ 1,361	$ 2,280	$ 2,534
Assuming dilution
Continuing operations (in dollars per share)	$ 1.47	$ 1.52	$ 2.52	$ 2.83
Discontinued operations (in dollars per share)		0.00	0.00	0.00
Total (in dollars per share)	1.47	1.52	2.52	2.83
Basic
Continuing operations (in dollars per share)	1.48	1.53	2.55	2.85
Discontinued operations (in dollars per share)		0.00	0.00	0.00
Total (in dollars per share)	$ 1.48	$ 1.53	$ 2.55	$ 2.85