Total Equity and Other Comprehensive Income (Rollforward of Total Equity) (Details) $ / shares in Units, $ in Millions				3 Months Ended		9 Months Ended
	Aug. 19, 2022 $ / shares shares	Apr. 26, 2022 $ / shares shares	Sep. 13, 2021 $ / shares shares	Sep. 30, 2022 USD ($) shares	Sep. 30, 2021 USD ($) shares	Sep. 30, 2022 USD ($) shares	Sep. 30, 2021 USD ($) shares	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Common Stock [Abstract]
Equity, Beginning Balance				$ 47,688.0	$ 54,685.0	$ 55,726.0	$ 54,041.0
Net income				1,640.0	1,490.0	4,565.0	4,419.0
Other comprehensive income (loss), net of tax				(2,128.0)	(384.0)	(10,895.0)	(1,691.0)
Dividends, Cash [Abstract]
Common				(622.0)	(538.0)	(1,779.0)	(1,523.0)
Preferred				(65.0)	(57.0)	(181.0)	(162.0)
Preferred stock discount accretion
Preferred stock issuance				1,239.0	1,489.0	2,231.0	1,489.0
Common stock activity						15.0	12.0
Treasury stock activity				(1,045.0)	(382.0)	(2,959.0)	(244.0)
Other				16.0	(6.0)		(44.0)
Equity, Ending Balance				46,723.0	56,297.0	46,723.0	56,297.0
Preferred stock, par value				$ 0.5	$ 0.5	$ 0.5	$ 0.5	$ 0.5	$ 0.5	$ 0.5	$ 0.5
Series U
Dividends, Cash [Abstract]
Depositary shares issued (shares) | shares		1,000,000
Depositary shares conversion ratio		0.01
Fixed interest rate		6.00%
Preferred stock, par or stated value per share (in dollars per share) | $ / shares		$ 1
Series T
Dividends, Cash [Abstract]
Depositary shares issued (shares) | shares			1,500,000
Depositary shares conversion ratio			0.01
Fixed interest rate			3.40%
Preferred stock, par or stated value per share (in dollars per share) | $ / shares			$ 1
Series V Preferred Stock
Dividends, Cash [Abstract]
Depositary shares issued (shares) | shares	1,250,000
Depositary shares conversion ratio	0.01
Fixed interest rate	6.20%
Preferred stock, par or stated value per share (in dollars per share) | $ / shares	$ 1
Common Stock
Common Stock [Abstract]
Beginning Balance (in shares) | shares				411,000,000	425,000,000	420,000,000	424,000,000
Treasury stock activity, shares | shares				(7,000,000)	(2,000,000)	(16,000,000)	(1,000,000)
Ending Balance, (in shares) | shares				404,000,000	423,000,000	404,000,000	423,000,000
Equity, Beginning Balance				$ 2,714.0	$ 2,713.0	$ 2,713.0	$ 2,713.0
Dividends, Cash [Abstract]
Common stock activity						1.0
Equity, Ending Balance				2,714.0	2,713.0	2,714.0	2,713.0
Capital Surplus - Preferred Stock
Common Stock [Abstract]
Equity, Beginning Balance				6,004.0	3,519.0	5,009.0	3,517.0
Dividends, Cash [Abstract]
Preferred stock discount accretion				1.0	1.0	4.0	3.0
Preferred stock issuance				1,239.0	1,489.0	2,231.0	1,489.0
Equity, Ending Balance				7,244.0	5,009.0	7,244.0	5,009.0
Capital Surplus - Common Stock and Other
Common Stock [Abstract]
Equity, Beginning Balance				12,527.0	12,409.0	12,448.0	12,367.0
Dividends, Cash [Abstract]
Common stock activity						14.0	12.0
Treasury stock activity				6.0	5.0	56.0	78.0
Other				33.0	30.0	48.0	(13.0)
Equity, Ending Balance				12,566.0	12,444.0	12,566.0	12,444.0
Retained Earnings
Common Stock [Abstract]
Equity, Beginning Balance				51,841.0	48,663.0	50,228.0	46,848.0
Net income				1,624.0	1,474.0	4,513.0	4,381.0
Dividends, Cash [Abstract]
Common				(622.0)	(538.0)	(1,779.0)	(1,523.0)
Preferred				(65.0)	(57.0)	(181.0)	(162.0)
Preferred stock discount accretion				(1.0)	(1.0)	(4.0)	(3.0)
Equity, Ending Balance				52,777.0	49,541.0	52,777.0	49,541.0
Accumulated Other Comprehensive Income (Loss)
Common Stock [Abstract]
Equity, Beginning Balance				(8,358.0)	1,463.0	409.0	2,770.0
Other comprehensive income (loss), net of tax				(2,128.0)	(384.0)	(10,895.0)	(1,691.0)
Dividends, Cash [Abstract]
Equity, Ending Balance				(10,486.0)	1,079.0	(10,486.0)	1,079.0
Treasury Stock
Common Stock [Abstract]
Equity, Beginning Balance				(17,076.0)	(14,140.0)	(15,112.0)	(14,205.0)
Dividends, Cash [Abstract]
Treasury stock activity				(1,051.0)	(387.0)	(3,015.0)	(322.0)
Equity, Ending Balance				(18,127.0)	(14,527.0)	(18,127.0)	(14,527.0)
Non- controlling Interests
Common Stock [Abstract]
Equity, Beginning Balance				36.0	58.0	31.0	31.0
Net income				16.0	16.0	52.0	38.0
Dividends, Cash [Abstract]
Other				(17.0)	(36.0)	(48.0)	(31.0)
Equity, Ending Balance				$ 35.0	$ 38.0	$ 35.0	$ 38.0