Loans and asset quality - Nonperforming Assets (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Nonperforming Assets [Line Items]
With an allowance	$ 40	$ 58
Without an allowance	64	60
Total nonperforming loans	104	118
With an allowance, Other assets owned	0	0
Without an allowance, Other assets owned	3	2
Other assets owned	3	2
With an allowance, Total nonperforming assets	40	58
Without an allowance, Total nonperforming assets	67	62
Total nonperforming assets	107	120
Commercial real estate
Nonperforming Assets [Line Items]
With an allowance	0	12
Without an allowance	51	42
Total nonperforming loans	51	54
Other residential mortgages
Nonperforming Assets [Line Items]
With an allowance	32	38
Without an allowance	1	1
Total nonperforming loans	33	39
Wealth management mortgages
Nonperforming Assets [Line Items]
With an allowance	8	8
Without an allowance	12	17
Total nonperforming loans	$ 20	$ 25