Earnings Per Share of Common Stock - Computation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Number of shares on which basic earnings per share is calculated:
Weighted-average shares outstanding during period (in shares)	886,018,372	911,152,848	887,291,199	915,632,501
Add - Incremental shares under stock-based compensation plans (in shares)	5,368,268	2,566,139	4,007,433	3,000,429
Add - Incremental shares associated with contingently issuable shares (in shares)	1,453,105	1,493,644	1,228,726	1,373,960
Number of shares on which diluted earnings per share is calculated (in shares)	892,839,745	915,212,631	892,527,357	920,006,890
Net income on which basic earnings per share is calculated
Income from continuing operations	$ 1,673	$ 2,692	$ 5,766	$ 6,770
Income/(loss) from discontinued operations, net of tax	(1)	2	(5)	7
Net income on which basic earnings per share is calculated	1,672	2,694	5,761	6,777
Net income on which diluted earnings per share is calculated
Income from continuing operations	1,673	2,692	5,766	6,770
Net income applicable to contingently issuable shares			0	(1)
Income from continuing operations on which diluted earnings per share is calculated	1,673	2,692	5,766	6,769
Income/(loss) from discontinued operations, net of tax, on which basic and diluted earnings per share is calculated	(1)	2	(5)	7
Net income on which diluted earnings per share is calculated	$ 1,672	$ 2,694	$ 5,762	$ 6,776
Assuming dilution
Continuing operations (in dollars per share)	$ 1.87	$ 2.94	$ 6.46	$ 7.36
Discontinued operations (in dollars per share)	0.00	0.00	(0.01)	0.01
Total (in dollars per share)	1.87	2.94	6.45	7.37
Basic
Continuing operations (in dollars per share)	1.89	2.95	6.50	7.39
Discontinued operations (in dollars per share)	0.00	0.00	(0.01)	0.01
Total (in dollars per share)	$ 1.89	$ 2.95	$ 6.49	$ 7.40