Total Equity and Other Comprehensive Income (Rollforward of Total Equity) (Details) $ / shares in Units, shares in Thousands, $ in Millions		3 Months Ended		9 Months Ended
	Feb. 07, 2023 $ / shares shares	Sep. 30, 2024 USD ($) shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2024 USD ($) shares	Sep. 30, 2023 USD ($) shares	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance		$ 52,681.0	$ 49,346.0	$ 51,141.0	$ 45,812.0
Net income		1,505.0	1,570.0	4,326.0	4,764.0
Other comprehensive income (loss), net of tax		2,356.0	(736.0)	2,622.0	(89.0)
Cash dividends declared - Common		(646.0)	(624.0)	(1,893.0)	(1,837.0)
Cash dividends declared - Preferred		(82.0)	(104.0)	(258.0)	(299.0)
Preferred stock discount accretion
Preferred stock issuance					1,487.0
Common stock activity				16.0	17.0
Treasury stock activity		(114.0)	12.0	(206.0)	(349.0)
Other		29.0	17.0	(19.0)	(51.0)
Equity, Ending Balance		55,729.0	49,481.0	55,729.0	49,481.0
Preferred stock, par value		$ 0.5	$ 0.5	$ 0.5	0.5	$ 0.5	$ 0.5	$ 0.5	$ 0.5
Series W
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock activity (shares) | shares	1,500
Depositary shares conversion ratio	0.01
Fixed interest rate	6.25%
Preferred stock, par or stated value per share (in dollars per share) | $ / shares	$ 1
Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance					26.0
Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance					$ 45,838.0
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares) | shares		398,000	398,000	398,000	401,000
Equity, Beginning Balance		$ 2,716.0	$ 2,715.0	$ 2,716.0	$ 2,714.0
Common stock activity					$ 1.0
Treasury stock activity, shares | shares		(1,000)		(1,000)	(3,000)
Ending Balance, (in shares) | shares		397,000	398,000	397,000	398,000
Equity, Ending Balance		$ 2,716.0	$ 2,715.0	$ 2,716.0	$ 2,715.0
Common Stock | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares) | shares					401,000
Equity, Beginning Balance					$ 2,714.0
Capital Surplus - Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance		6,245.0	7,237.0	6,241.0	5,746.0
Preferred stock discount accretion		2.0	2.0	6.0	6.0
Preferred stock issuance					1,487.0
Equity, Ending Balance		6,247.0	7,239.0	6,247.0	7,239.0
Capital Surplus - Preferred Stock | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance					5,746.0
Capital Surplus - Common Stock and Other
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance		12,853.0	12,697.0	12,779.0	12,630.0
Common stock activity				16.0	16.0
Treasury stock activity		7.0	3.0	84.0	76.0
Other		43.0	32.0	24.0	10.0
Equity, Ending Balance		12,903.0	12,732.0	12,903.0	12,732.0
Capital Surplus - Common Stock and Other | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance					12,630.0
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance		57,652.0	55,346.0	56,290.0	53,572.0
Net income		1,490.0	1,554.0	4,279.0	4,714.0
Cash dividends declared - Common		(646.0)	(624.0)	(1,893.0)	(1,837.0)
Cash dividends declared - Preferred		(82.0)	(104.0)	(258.0)	(299.0)
Preferred stock discount accretion		(2.0)	(2.0)	(6.0)	(6.0)
Equity, Ending Balance		58,412.0	56,170.0	58,412.0	56,170.0
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance					26.0
Retained Earnings | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance					53,598.0
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance		(7,446.0)	(9,525.0)	(7,712.0)	(10,172.0)
Other comprehensive income (loss), net of tax		2,356.0	(736.0)	2,622.0	(89.0)
Equity, Ending Balance		(5,090.0)	(10,261.0)	(5,090.0)	(10,261.0)
Accumulated Other Comprehensive Income (Loss) | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance					(10,172.0)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance		(19,378.0)	(19,150.0)	(19,209.0)	(18,716.0)
Treasury stock activity		(121.0)	9.0	(290.0)	(425.0)
Equity, Ending Balance		(19,499.0)	(19,141.0)	(19,499.0)	(19,141.0)
Treasury Stock | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance					(18,716.0)
Non- controlling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance		39.0	26.0	36.0	38.0
Net income		15.0	16.0	47.0	50.0
Other		(14.0)	(15.0)	(43.0)	(61.0)
Equity, Ending Balance		$ 40.0	$ 27.0	$ 40.0	27.0
Non- controlling Interests | Cumulative Effect, Period of Adoption, Adjusted Balance
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, Beginning Balance					$ 38.0