Loans and asset quality - Nonperforming Assets (Details) - Domestic - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Impaired [Line Items]
With an allowance	$ 68
Without an allowance	18
Total nonperforming loans	86	$ 86
With an allowance, Other assets owned	0
Without an allowance, Other assets owned	2
Other assets owned	2	3
With an allowance, Total nonperforming assets	68
Without an allowance, Total nonperforming assets	20
Total nonperforming assets	88	89
Other residential mortgages
Financing Receivable, Impaired [Line Items]
With an allowance	58
Without an allowance	0
Total nonperforming loans	58	62
Wealth management loans and mortgages
Financing Receivable, Impaired [Line Items]
With an allowance	10
Without an allowance	18
Total nonperforming loans	$ 28	$ 24