Total Equity and Other Comprehensive Income (Rollforward of Total Equity) (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	$ 54,469.0	$ 51,141.0
Net income	1,499.0	1,344.0
Other comprehensive income (loss), net of tax	1,328.0	(330.0)
Cash dividends declared - Common	(639.0)	(624.0)
Cash dividends declared - Preferred	(71.0)	(81.0)
Preferred stock discount accretion	0.0
Treasury stock activity	(36.0)	1.0
Other	(99.0)	(77.0)
Equity, ending balance	56,451.0	51,374.0
Preferred stock, par value	$ 0.5	$ 0.5	$ 0.5	$ 0.5
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	396	398
Equity, beginning balance	$ 2,717.0	$ 2,716.0
Ending balance (in shares)	396	398
Equity, ending balance	$ 2,717.0	$ 2,716.0
Capital Surplus - Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	5,749.0	6,241.0
Preferred stock discount accretion	2.0	2.0
Equity, ending balance	5,751.0	6,243.0
Capital Surplus - Common Stock and Other
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	12,961.0	12,779.0
Treasury stock activity	102.0	71.0
Other	(83.0)	(61.0)
Equity, ending balance	12,980.0	12,789.0
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	59,282.0	56,290.0
Net income	1,481.0	1,330.0
Cash dividends declared - Common	(639.0)	(624.0)
Cash dividends declared - Preferred	(71.0)	(81.0)
Preferred stock discount accretion	(2.0)	(2.0)
Equity, ending balance	60,051.0	56,913.0
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	(6,565.0)	(7,712.0)
Other comprehensive income (loss), net of tax	1,328.0	(330.0)
Equity, ending balance	(5,237.0)	(8,042.0)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	(19,719.0)	(19,209.0)
Treasury stock activity	(138.0)	(70.0)
Equity, ending balance	(19,857.0)	(19,279.0)
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	44.0	36.0
Net income	18.0	14.0
Other	(16.0)	(16.0)
Equity, ending balance	$ 46.0	$ 34.0