Commitments and contingent liabilities - Narrative (Details) $ in Millions							2 Months Ended	9 Months Ended
	Jun. 07, 2022 USD ($)	May 09, 2022 USD ($)	Aug. 04, 2021 claim investmentFund	May 20, 2021 USD ($) claim	Sep. 09, 2020 USD ($) director claim	Dec. 17, 2015 lawsuit	Dec. 31, 2020 USD ($)	Sep. 30, 2022 USD ($) claim	Jun. 30, 2022 USD ($)	Feb. 28, 2022 claim	Dec. 31, 2021 USD ($) claim	Oct. 31, 2021 claim	Sep. 30, 2021 USD ($) claim	May 31, 2016 claim	Dec. 31, 2009 claim	Nov. 30, 2009 claim
Commitments and Contingencies Disclosure [Line Items]
Lending commitment maturing in less than one year								$ 29,800
Lending commitment maturing in one to five years								19,400
Lending commitment maturing over five years								859
Allowance for credit losses on lending related commitments								$ 72	$ 62		$ 45		$ 40
Collateralization percentage generally required for a securities lending transaction with indemnification against broker default								102.00%
Securities lending indemnifications, secured amount of collateral								$ 506,000			511,000
Securities lending indemnifications, joint venture								71,000			67,000
Securities lending indemnifications, collateral joint venture								76,000			71,000
Unsettled Repurchase Agreements
Commitments and Contingencies Disclosure [Line Items]
Unsettled repurchase and reverse repurchase agreements								2,500			2,600
Unsettled Reverse Repurchase Agreements
Commitments and Contingencies Disclosure [Line Items]
Unsettled repurchase and reverse repurchase agreements								$ 6,100			$ 9,100
Mortgage-Securitization Trusts Proceedings | Federal Court
Commitments and Contingencies Disclosure [Line Items]
Number of lawsuits or class actions (claim) | claim								3
Mortgage-Securitization Trusts Proceedings | State Court
Commitments and Contingencies Disclosure [Line Items]
Number of lawsuits or class actions (claim) | claim								7		3	3	3	3	1
Matters Related to R. Allen Stanford
Commitments and Contingencies Disclosure [Line Items]
Number of lawsuits or class actions (claim) | claim				1											2	1
New claims filed, number (in claims) | claim								3
Brazilian Postalis Litigation
Commitments and Contingencies Disclosure [Line Items]
New claims filed, number (in claims)			3			3
Claims settled, number (in claims) | claim					1
Number of directors held liable (in directors) | director					2
Damages awarded, value	$ 2	$ 20		$ 3	$ 50
Number of investment funds | investmentFund			3
Damages sought, value					$ 2
German Tax Matters | Foreign Tax Authority
Commitments and Contingencies Disclosure [Line Items]
Damages sought, value							$ 150
Maximum
Commitments and Contingencies Disclosure [Line Items]
Loss contingency, aggregate range of reasonable loss (up to)								$ 520
Standby letters of credit
Commitments and Contingencies Disclosure [Line Items]
Standby letters of credit (SBLC) collateralized with cash and securities								161			$ 172
SBLC expiring within one year								1,400
SBLC expiring within one to five years								621
SBLC expiring over five years								0
Off-balance sheet credit risks								2,013			1,971
Commercial letters of credit
Commitments and Contingencies Disclosure [Line Items]
Off-balance sheet credit risks								$ 46			$ 56