Commitments, Contingent Liabilities and Guarantees - Additional Information (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Mar. 31, 2025	Dec. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2019	Jun. 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	$ 22		$ 22			$ 16
Visa
Loss Contingencies
Fair value of liability	150		150			170
Visa IPO, shares of Visa's Class B common stock received (in shares)																				10.1
Visa Class B shares carryover basis																				$ 0
Escrow deposit	500	$ 1,500	500	$ 1,500	$ 375		$ 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	8		8
Make-whole payments	0	0	0	0
Repurchased outstanding principal	3	2	13	17
Repurchase demand request	10	$ 8	27	$ 36
Outstanding repurchase demand inventory	9		9			7
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	$ 8		$ 8			$ 12
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	78.00%		78.00%			76.00%
Other Liabilities
Loss Contingencies
Reserve for unfunded commitments	$ 151		$ 151			$ 134
Other Liabilities | Residential mortgage loans
Loss Contingencies
Outstanding balances on residential mortgage loans sold with representation and warranty provisions	$ 5		$ 5			$ 5