Commitments and contingent liabilities - Significant Industry Concentrations Related to Credit Exposure (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	$ 69,829	$ 67,787
Financial institutions
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	11,105	$ 10,232
Unfunded commitments	33,200
Total exposure	44,300
Financial institutions | Securities industry
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	1,700
Unfunded commitments	18,800
Total exposure	20,500
Financial institutions | Asset managers
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	1,600
Unfunded commitments	8,000
Total exposure	9,600
Financial institutions | Banks
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	7,300
Unfunded commitments	1,500
Total exposure	8,800
Financial institutions | Insurance
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	100
Unfunded commitments	3,700
Total exposure	3,800
Financial institutions | Government
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	0
Unfunded commitments	300
Total exposure	300
Financial institutions | Other
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	400
Unfunded commitments	900
Total exposure	1,300
Commercial
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	2,100
Unfunded commitments	11,600
Total exposure	13,700
Commercial | Manufacturing
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	800
Unfunded commitments	4,100
Total exposure	4,900
Commercial | Services and other
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	1,000
Unfunded commitments	3,100
Total exposure	4,100
Commercial | Energy and utilities
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	200
Unfunded commitments	3,700
Total exposure	3,900
Commercial | Media and telecom
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	100
Unfunded commitments	700
Total exposure	$ 800