Total Equity and Other Comprehensive Income (Rollforward of Total Equity) (Details) $ / shares in Units, $ in Millions				3 Months Ended		9 Months Ended
	Feb. 07, 2023 $ / shares shares	Aug. 19, 2022 shares	Apr. 26, 2022 shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2022 USD ($) shares	Sep. 30, 2023 USD ($) shares	Sep. 30, 2022 USD ($) shares	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Common Stock [Abstract]
Equity, Beginning Balance					$ 47,688.0	$ 45,812.0	$ 55,726.0
Net income				$ 1,570.0	1,640.0	4,764.0	4,565.0
Other comprehensive income (loss), net of tax				(736.0)	(2,128.0)	(89.0)	(10,895.0)
Dividends, Cash [Abstract]
Common				(624.0)	(622.0)	(1,837.0)	(1,779.0)
Preferred				(104.0)	(65.0)	(299.0)	(181.0)
Preferred stock discount accretion
Preferred stock issuance					1,239.0	1,487.0	2,231.0
Treasury stock activity				12.0	(1,045.0)	(349.0)	(2,959.0)
Other				17.0	16.0	(51.0)
Equity, Ending Balance				49,481.0	46,723.0	49,481.0	46,723.0
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
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				$ 49,346.0		$ 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%
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
Series V
Dividends, Cash [Abstract]
Depositary shares conversion ratio		0.01
Common stock activity (shares) | shares		1,250,000
Fixed interest rate		6.20%
Common Stock
Common Stock [Abstract]
Beginning Balance (in shares) | shares				398,000,000	411,000,000	401,000,000	420,000,000
Treasury stock activity, shares | shares					(7,000,000)	(3,000,000)	(16,000,000)
Ending Balance, (in shares) | shares				398,000,000	404,000,000	398,000,000	404,000,000
Equity, Beginning Balance				$ 2,715.0	$ 2,714.0	$ 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
Common Stock | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Beginning Balance (in shares) | shares				398,000,000		401,000,000
Equity, Beginning Balance				$ 2,715.0		$ 2,714.0
Capital Surplus - Preferred Stock
Common Stock [Abstract]
Equity, Beginning Balance				7,237.0	6,004.0	5,746.0	5,009.0
Dividends, Cash [Abstract]
Preferred stock discount accretion				2.0	1.0	6.0	4.0
Preferred stock issuance					1,239.0	1,487.0	2,231.0
Equity, Ending Balance				7,239.0	7,244.0	7,239.0	7,244.0
Capital Surplus - Preferred Stock | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance				7,237.0		5,746.0
Capital Surplus - Common Stock and Other
Common Stock [Abstract]
Equity, Beginning Balance				12,697.0	12,527.0	12,630.0	12,448.0
Dividends, Cash [Abstract]
Treasury stock activity				3.0	6.0	76.0	56.0
Other				32.0	33.0	10.0	48.0
Equity, Ending Balance				12,732.0	12,566.0	12,732.0	12,566.0
Common stock activity						16.0	14.0
Capital Surplus - Common Stock and Other | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance				12,697.0		12,630.0
Retained Earnings
Common Stock [Abstract]
Equity, Beginning Balance				55,346.0	51,841.0	53,572.0	50,228.0
Net income				1,554.0	1,624.0	4,714.0	4,513.0
Dividends, Cash [Abstract]
Common				(624.0)	(622.0)	(1,837.0)	(1,779.0)
Preferred				(104.0)	(65.0)	(299.0)	(181.0)
Preferred stock discount accretion				(2.0)	(1.0)	(6.0)	(4.0)
Equity, Ending Balance				56,170.0	52,777.0	56,170.0	52,777.0
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				55,346.0		53,598.0
Accumulated Other Comprehensive Income (Loss)
Common Stock [Abstract]
Equity, Beginning Balance				(9,525.0)	(8,358.0)	(10,172.0)	409.0
Other comprehensive income (loss), net of tax				(736.0)	(2,128.0)	(89.0)	(10,895.0)
Dividends, Cash [Abstract]
Equity, Ending Balance				(10,261.0)	(10,486.0)	(10,261.0)	(10,486.0)
Accumulated Other Comprehensive Income (Loss) | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance				(9,525.0)		(10,172.0)
Treasury Stock
Common Stock [Abstract]
Equity, Beginning Balance				(19,150.0)	(17,076.0)	(18,716.0)	(15,112.0)
Dividends, Cash [Abstract]
Treasury stock activity				9.0	(1,051.0)	(425.0)	(3,015.0)
Equity, Ending Balance				(19,141.0)	(18,127.0)	(19,141.0)	(18,127.0)
Treasury Stock | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance				(19,150.0)		(18,716.0)
Non- controlling Interests
Common Stock [Abstract]
Equity, Beginning Balance				26.0	36.0	38.0	31.0
Net income				16.0	16.0	50.0	52.0
Dividends, Cash [Abstract]
Other				(15.0)	(17.0)	(61.0)	(48.0)
Equity, Ending Balance				27.0	$ 35.0	27.0	$ 35.0
Non- controlling Interests | Cumulative Effect, Period of Adoption, Adjusted Balance
Common Stock [Abstract]
Equity, Beginning Balance				$ 26.0		$ 38.0