Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions										1 Months Ended	3 Months Ended
	May 01, 2024	May 01, 2024	Apr. 30, 2024	Mar. 12, 2024	Feb. 01, 2024	Jan. 31, 2024	Aug. 01, 2023	Jul. 31, 2023	Apr. 30, 2023	Mar. 31, 2024	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										2,990,375	2,990,375		2,740,375
Carrying value										$ 29,900	$ 29,900		$ 27,404
Liquidation value and redemption price per share (in dollars per share)										$ 10,000	$ 10,000
Aggregate liquidation value										$ 30,200	$ 30,200
Subsequent Event
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock redeemed	$ 6,000
Series DD
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										169,625	169,625		169,625
Carrying value										$ 1,696	$ 1,696		$ 1,696
Issue date											Sep. 21, 2018
Contractual rate in effect											5.75%
Dividend declared per share (in dollars per share)											$ 143.75	$ 143.75
Series DD | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Dec. 01, 2023
Series EE
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										185,000	185,000		185,000
Carrying value										$ 1,850	$ 1,850		$ 1,850
Issue date											Jan. 24, 2019
Contractual rate in effect											6.00%
Dividend declared per share (in dollars per share)											$ 150.00	150.00
Series EE | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Mar. 01, 2024
Series GG
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										90,000	90,000		90,000
Carrying value										$ 900	$ 900		$ 900
Issue date											Nov. 07, 2019
Contractual rate in effect											4.75%
Dividend declared per share (in dollars per share)											$ 118.75	118.75
Series GG | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Dec. 01, 2024
Series JJ
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										150,000	150,000		150,000
Carrying value										$ 1,500	$ 1,500		$ 1,500
Issue date											Mar. 17, 2021
Contractual rate in effect											4.55%
Dividend declared per share (in dollars per share)											$ 113.75	113.75
Series JJ | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Jun. 01, 2026
Series LL
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										185,000	185,000		185,000
Carrying value										$ 1,850	$ 1,850		$ 1,850
Issue date											May 20, 2021
Contractual rate in effect											4.625%
Dividend declared per share (in dollars per share)											$ 115.63	115.63
Series LL | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Jun. 01, 2026
Series MM
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										200,000	200,000		200,000
Carrying value										$ 2,000	$ 2,000		$ 2,000
Issue date											Jul. 29, 2021
Contractual rate in effect											4.20%
Dividend declared per share (in dollars per share)											$ 105.00	105.00
Series MM | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Sep. 01, 2026
Series Q, R and S | Subsequent Event
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock redeemed		$ 5,000
Series Q
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										150,000	150,000		150,000
Carrying value										$ 1,500	$ 1,500		$ 1,500
Issue date											Apr. 23, 2013
Contractual rate in effect									5.15%
Dividend declared per share (in dollars per share)									$ 257.50		$ 220.45	128.75
Series Q | SOFR
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate, variable, basis spread							3.25%				3.25%
Series Q | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											May 01, 2023
Series R
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										150,000	150,000		150,000
Carrying value										$ 1,500	$ 1,500		$ 1,500
Issue date											Jul. 29, 2013
Contractual rate in effect								6.00%
Dividend declared per share (in dollars per share)								$ 300.00			$ 221.70	150.00
Series R | SOFR
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate, variable, basis spread							3.30%				3.30%
Series R | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Aug. 01, 2023
Series S
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										200,000	200,000		200,000
Carrying value										$ 2,000	$ 2,000		$ 2,000
Issue date											Jan. 22, 2014
Contractual rate in effect						6.75%
Dividend declared per share (in dollars per share)						$ 337.50					$ 233.70	168.75
Series S | SOFR
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate, variable, basis spread					3.78%						3.78%
Series S | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Feb. 01, 2024
Series U
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										100,000	100,000		100,000
Carrying value										$ 1,000	$ 1,000		$ 1,000
Issue date											Mar. 10, 2014
Contractual rate in effect											6.125%
Dividend declared per share (in dollars per share)											$ 153.13	153.13
Series U | Subsequent Event
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock redeemed			$ 1,000
Series U | SOFR
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate, variable, basis spread											3.33%
Series U | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Apr. 30, 2024
Series X
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										160,000	160,000		160,000
Carrying value										$ 1,600	$ 1,600		$ 1,600
Issue date											Sep. 23, 2014
Contractual rate in effect											6.10%
Dividend declared per share (in dollars per share)											$ 152.50	152.50
Series X | SOFR
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate, variable, basis spread											3.33%
Series X | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Oct. 01, 2024
Series CC
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										125,750	125,750		125,750
Carrying value										$ 1,258	$ 1,258		$ 1,258
Issue date											Oct. 20, 2017
Dividend declared per share (in dollars per share)											$ 203.70	182.79
Series CC | SOFR
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate, variable, basis spread											2.58%
Series CC | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Nov. 01, 2022
Series FF
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										225,000	225,000		225,000
Carrying value										$ 2,250	$ 2,250		$ 2,250
Issue date											Jul. 31, 2019
Contractual rate in effect											5.00%
Dividend declared per share (in dollars per share)											$ 125.00	125.00
Series FF | SOFR
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate, variable, basis spread											3.38%
Series FF | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Aug. 01, 2024
Series HH
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										300,000	300,000		300,000
Carrying value										$ 3,000	$ 3,000		$ 3,000
Issue date											Jan. 23, 2020
Contractual rate in effect											4.60%
Dividend declared per share (in dollars per share)											$ 115.00	115.00
Series HH | SOFR
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate, variable, basis spread											3.125%
Series HH | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Feb. 01, 2025
Series II
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										150,000	150,000		150,000
Carrying value										$ 1,500	$ 1,500		$ 1,500
Issue date											Feb. 24, 2020
Contractual rate in effect											4.00%
Dividend declared per share (in dollars per share)											$ 100.00	100.00
Series II | SOFR
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate, variable, basis spread											2.745%
Series II | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Apr. 01, 2025
Series KK
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										200,000	200,000		200,000
Carrying value										$ 2,000	$ 2,000		$ 2,000
Issue date											May 12, 2021
Contractual rate in effect											3.65%
Dividend declared per share (in dollars per share)											$ 91.25	$ 91.25
Series KK | Five-year CMT
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate, variable, basis spread											2.85%
Series KK | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Jun. 01, 2026
Series NN
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Shares (in shares)										250,000	250,000
Carrying value										$ 2,496	$ 2,496
Issue date											Mar. 12, 2024
Contractual rate in effect											6.875%
Dividend declared per share (in dollars per share)										$ 0	$ 0
Preferred stock issued				$ 2,500
Series NN | Five-year CMT
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock dividend rate, variable, basis spread											2.737%
Series NN | Minimum
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Earliest Redemption Date											Jun. 01, 2029