Earnings Per Share of Common Stock - Computation (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Weighted-average number of shares on which earnings per share calculations are based
Weighted-average shares outstanding during period (in shares)	887,969,345	889,581,542
Add - Incremental shares under stock-based compensation plans (in shares)	5,740,415	3,372,460
Add - Incremental shares associated with contingently issuable shares (in shares)	1,329,477	956,524
Assuming dilution (in shares)	895,039,238	893,910,526
Net income on which basic earnings per share is calculated
Income from continuing operations	$ 1,176	$ 1,593
Income/(loss) from discontinued operations, net of tax	(1)	(2)
Net income on which basic earnings per share is calculated	1,175	1,591
Net income on which diluted earnings per share is calculated
Income from continuing operations	1,176	1,593
Net income applicable to contingently issuable shares	(2)
Income from continuing operations on which diluted earnings per share is calculated	1,174	1,593
Income/(loss) from discontinued operations, net of tax, on which basic and diluted earnings per share is calculated	(1)	(2)
Net income on which diluted earnings per share is calculated	$ 1,173	$ 1,591
Assuming dilution
Continuing operations (in dollars per share)	$ 1.31	$ 1.78
Discontinued operations (in dollars per share)	0.00	0.00
Total (in dollars per share)	1.31	1.78
Basic
Continuing operations (in dollars per share)	1.32	1.79
Discontinued operations (in dollars per share)	0.00	0.00
Total (in dollars per share)	$ 1.32	$ 1.79