Total Equity and Other Comprehensive Income (Rollforward of Total Equity) (Details) $ / shares in Units, $ in Millions			3 Months Ended		6 Months Ended
	Feb. 07, 2023 $ / shares shares	Apr. 26, 2022 $ / shares shares	Jun. 30, 2023 USD ($) shares	Jun. 30, 2022 USD ($) shares	Jun. 30, 2023 USD ($) shares	Jun. 30, 2022 USD ($) shares	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Common Stock [Abstract]
Equity, Beginning Balance				$ 49,216.0	$ 45,812.0	$ 55,726.0
Net income			$ 1,500.0	1,496.0	3,194.0	2,925.0
Other comprehensive income (loss), net of tax			(417.0)	(2,627.0)	647.0	(8,767.0)
Dividends, Cash [Abstract]
Common			(606.0)	(626.0)	(1,213.0)	(1,157.0)
Preferred			(127.0)	(71.0)	(195.0)	(116.0)
Preferred stock discount accretion
Preferred stock issuance				992.0	1,487.0	992.0
Treasury stock activity			(123.0)	(725.0)	(361.0)	(1,914.0)
Other			28.0	18.0	(68.0)	(16.0)
Equity, Ending Balance			49,346.0	47,688.0	49,346.0	47,688.0
Preferred stock, par value			0.5	0.5	0.5	0.5	$ 0.5	$ 0.5	$ 0.5	$ 0.5
Common stock activity			17.0	$ 15.0	17.0	$ 15.0
Cumulative Effect, Period of Adoption, Adjustment
Common Stock [Abstract]
Equity, Beginning Balance					26.0
Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance			$ 49,074.0		$ 45,838.0
Series U
Dividends, Cash [Abstract]
Depositary shares conversion ratio		0.01
Common stock activity (shares) | shares		1,000,000
Fixed interest rate		6.00%
Preferred stock, par or stated value per share (in dollars per share) | $ / shares		$ 1
Series W
Dividends, Cash [Abstract]
Depositary shares conversion ratio	0.01
Common stock activity (shares) | shares	1,500,000
Fixed interest rate	6.25%
Preferred stock, par or stated value per share (in dollars per share) | $ / shares	$ 1
Common Stock
Common Stock [Abstract]
Beginning Balance (in shares) | shares			399,000,000	415,000,000	401,000,000	420,000,000
Treasury stock activity, shares | shares			(1,000,000)	(4,000,000)	(3,000,000)	(9,000,000)
Ending Balance, (in shares) | shares			398,000,000	411,000,000	398,000,000	411,000,000
Equity, Beginning Balance			$ 2,714.0	$ 2,713.0	$ 2,714.0	$ 2,713.0
Dividends, Cash [Abstract]
Equity, Ending Balance			2,715.0	2,714.0	2,715.0	2,714.0
Common stock activity			$ 1.0	1.0	$ 1.0	1.0
Common Stock | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Beginning Balance (in shares) | shares			399,000,000		401,000,000
Equity, Beginning Balance			$ 2,714.0		$ 2,714.0
Capital Surplus - Preferred Stock
Common Stock [Abstract]
Equity, Beginning Balance			7,235.0	5,011.0	5,746.0	5,009.0
Dividends, Cash [Abstract]
Preferred stock discount accretion			2.0	1.0	4.0	3.0
Preferred stock issuance				992.0	1,487.0	992.0
Equity, Ending Balance			7,237.0	6,004.0	7,237.0	6,004.0
Capital Surplus - Preferred Stock | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance			7,235.0		5,746.0
Capital Surplus - Common Stock and Other
Common Stock [Abstract]
Equity, Beginning Balance			12,629.0	12,476.0	12,630.0	12,448.0
Dividends, Cash [Abstract]
Treasury stock activity			3.0	5.0	73.0	50.0
Other			49.0	32.0	(22.0)	15.0
Equity, Ending Balance			12,697.0	12,527.0	12,697.0	12,527.0
Common stock activity			16.0	14.0	16.0	14.0
Capital Surplus - Common Stock and Other | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance			12,629.0		12,630.0
Retained Earnings
Common Stock [Abstract]
Equity, Beginning Balance			54,598.0	51,058.0	53,572.0	50,228.0
Net income			1,483.0	1,481.0	3,160.0	2,889.0
Dividends, Cash [Abstract]
Common			(606.0)	(626.0)	(1,213.0)	(1,157.0)
Preferred			(127.0)	(71.0)	(195.0)	(116.0)
Preferred stock discount accretion			(2.0)	(1.0)	(4.0)	(3.0)
Equity, Ending Balance			55,346.0	51,841.0	55,346.0	51,841.0
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment
Common Stock [Abstract]
Equity, Beginning Balance					26.0
Retained Earnings | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance			54,598.0		53,598.0
Accumulated Other Comprehensive Income (Loss)
Common Stock [Abstract]
Equity, Beginning Balance			(9,108.0)	(5,731.0)	(10,172.0)	409.0
Other comprehensive income (loss), net of tax			(417.0)	(2,627.0)	647.0	(8,767.0)
Dividends, Cash [Abstract]
Equity, Ending Balance			(9,525.0)	(8,358.0)	(9,525.0)	(8,358.0)
Accumulated Other Comprehensive Income (Loss) | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance			(9,108.0)		(10,172.0)
Treasury Stock
Common Stock [Abstract]
Equity, Beginning Balance			(19,024.0)	(16,346.0)	(18,716.0)	(15,112.0)
Dividends, Cash [Abstract]
Treasury stock activity			(126.0)	(730.0)	(434.0)	(1,964.0)
Equity, Ending Balance			(19,150.0)	(17,076.0)	(19,150.0)	(17,076.0)
Treasury Stock | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance			(19,024.0)		(18,716.0)
Non- controlling Interests
Common Stock [Abstract]
Equity, Beginning Balance			30.0	35.0	38.0	31.0
Net income			17.0	15.0	34.0	36.0
Dividends, Cash [Abstract]
Other			(21.0)	(14.0)	(46.0)	(31.0)
Equity, Ending Balance			26.0	$ 36.0	26.0	$ 36.0
Non- controlling Interests | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance			$ 30.0		$ 38.0