Basis of Presentation and Significant Accounting Policies and Practices - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Basic EPS:
Net income	$ 7,769	$ 5,595	$ 5,017
Income allocated to RSUs	(33)	(27)	(32)
Income allocated to common stock for basic EPS	$ 7,736	$ 5,568	$ 4,985
Weighted average number of shares outstanding, basic (in shares)	923	921	936
Basic earnings per common share (in dollars per share)	$ 8.38	$ 6.05	$ 5.33
Dilutive effect of stock compensation plans	13	12	16
Diluted EPS:
Net income	$ 7,769	$ 5,595	$ 5,017
Income allocated to RSUs	(33)	(27)	(31)
Income allocated to common stock for diluted EPS	$ 7,736	$ 5,568	$ 4,986
Weighted average number of shares outstanding, diluted (in shares)	936	933	952
Diluted earnings per common share (in dollars per share)	$ 8.26	$ 5.97	$ 5.24