Earnings Per Share of Common Stock - Computation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Weighted-average number of shares on which earnings per share calculations are based
Weighted-average shares outstanding during period (in shares)	891,381,032	886,018,372	889,595,181	887,291,199
Add - Incremental shares under stock-based compensation plans (in shares)	4,595,327	5,368,268	4,875,369	4,007,433
Add - Incremental shares associated with contingently issuable shares (in shares)	1,315,874	1,453,105	1,286,300	1,228,726
Assuming dilution (in shares)	897,292,233	892,839,745	895,756,850	892,527,357
Net income on which basic earnings per share is calculated
Income from continuing operations	$ 1,698	$ 1,673	$ 4,237	$ 5,766
Income/(loss) from discontinued operations, net of tax	(1)	(1)	(2)	(5)
Net income on which basic earnings per share is calculated	1,698	1,672	4,234	5,761
Net income on which diluted earnings per share is calculated
Income from continuing operations	1,698	1,673	4,237	5,766
Net income applicable to contingently issuable shares			(2)	0
Income from continuing operations on which diluted earnings per share is calculated	1,698	1,673	4,234	5,766
Income/(loss) from discontinued operations, net of tax, on which basic and diluted earnings per share is calculated	(1)	(1)	(2)	(5)
Net income on which diluted earnings per share is calculated	$ 1,698	$ 1,672	$ 4,232	$ 5,762
Assuming dilution
Continuing operations (in dollars per share)	$ 1.89	$ 1.87	$ 4.72	$ 6.46
Discontinued operations (in dollars per share)	0.00	0.00	0.00	(0.01)
Total (in dollars per share)	1.89	1.87	4.72	6.45
Basic
Continuing operations (in dollars per share)	1.90	1.89	4.76	6.50
Discontinued operations (in dollars per share)	0.00	0.00	0.00	(0.01)
Total (in dollars per share)	$ 1.90	$ 1.89	$ 4.76	$ 6.49