Commitments, Contingent Liabilities and Guarantees - Additional Information (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2014	Sep. 30, 2012	Mar. 31, 2012	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Dec. 31, 2008
Loss Contingencies
Margin account balance held by the brokerage clearing agent	$ 13		$ 13		$ 6
Visa
Loss Contingencies
Fair value of liability	196		196		168
Visa IPO, shares of Visa's Class B common stock received (in shares)																		10.1
Visa Class B shares carryover basis																		$ 0
Escrow deposit	1,500	$ 150	1,500	$ 150		$ 500	$ 350	$ 600	$ 250	$ 300	$ 600	$ 450	$ 150	$ 1,565	$ 400	$ 800	$ 500	$ 3,000
Residential mortgage loans
Loss Contingencies
Fair value of liability	9		9
Make-whole payments	0	0	0	0
Repurchased outstanding principal	2	13	17	46
Repurchase demand request	8	$ 16	36	$ 76
Outstanding repurchase demand inventory	7		7		8
Secured Debt
Loss Contingencies
Fully and unconditionally guaranteed certain long-term borrowing obligations issued by wholly-owned issuing trust entities	62		62		62
Standby Letters of Credit
Loss Contingencies
Reserve for unfunded commitments	$ 15		$ 15		$ 20
Standby letters of credit as a percentage of total letters of credit	99.00%		99.00%		99.00%
Standby Letters of Credit | Secured Debt
Loss Contingencies
Standby letters of credit as a percentage of total letters of credit	75.00%		75.00%		72.00%
Variable Rate Demand Note
Loss Contingencies
Total variable rate demand notes	$ 365		$ 365		$ 400
Letters of credit issued related to variable rate demand notes	53		53		83
Variable Rate Demand Note | Available-for-sale debt and other securities
Loss Contingencies
Total variable rate demand notes	0		0		6
Other Liabilities
Loss Contingencies
Reserve for unfunded commitments	138		138		166
Other Liabilities | Residential mortgage loans
Loss Contingencies
Outstanding balances on residential mortgage loans sold with representation and warranty provisions	$ 6		$ 6		$ 7