Earnings Per Share of Common Stock - Computation (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
Weighted-average number of shares on which earnings per share calculations are based
Weighted-average shares outstanding during period (in shares)	897,097,073	891,381,032	895,257,004	889,595,181
Add - Incremental shares under stock-based compensation plans (in shares)	6,946,467	4,595,327	7,000,190	4,875,369
Add - Incremental shares associated with contingently issuable shares (in shares)	1,909,573	1,315,874	1,720,345	1,286,300
Assuming dilution (in shares)	905,953,114	897,292,233	903,977,539	895,756,850
Net income on which basic earnings per share is calculated
Income from continuing operations	$ 1,130	$ 1,698	$ 3,411	$ 4,237
Income/(loss) from discontinued operations, net of tax		(1)	(1)	(2)
Net income on which basic earnings per share is calculated	1,130	1,698	3,410	4,234
Net income on which diluted earnings per share is calculated
Income from continuing operations	1,130	1,698	3,411	4,237
Net income applicable to contingently issuable shares				(2)
Income from continuing operations on which diluted earnings per share is calculated	1,130	1,698	3,411	4,234
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	$ 1,130	$ 1,698	$ 3,410	$ 4,232
Assuming dilution
Continuing operations (in dollars per share)	$ 1.25	$ 1.89	$ 3.77	$ 4.72
Discontinued operations (in dollars per share)		0.00	0.00	0.00
Total (in dollars per share)	1.25	1.89	3.77	4.72
Basic
Continuing operations (in dollars per share)	1.26	1.90	3.81	4.76
Discontinued operations (in dollars per share)		0.00	0.00	0.00
Total (in dollars per share)	$ 1.26	$ 1.90	$ 3.81	$ 4.76