Allowance for credit losses - Troubled debt restructurings loan count by type of modification (Details) - loans	3 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2022
Financing Receivable, Modifications [Line Items]
Loan count	338	1,103
Reduction in interest rate
Financing Receivable, Modifications [Line Items]
Loan count	38	124
Term Extension
Financing Receivable, Modifications [Line Items]
Loan count	73	207
Combination of reduction in interest rate and extension of maturity date
Financing Receivable, Modifications [Line Items]
Loan count	213	721
Other
Financing Receivable, Modifications [Line Items]
Loan count	14	51
Mortgages
Financing Receivable, Modifications [Line Items]
Loan count	277	852
Mortgages | Reduction in interest rate
Financing Receivable, Modifications [Line Items]
Loan count	2	6
Mortgages | Term Extension
Financing Receivable, Modifications [Line Items]
Loan count	63	128
Mortgages | Combination of reduction in interest rate and extension of maturity date
Financing Receivable, Modifications [Line Items]
Loan count	210	715
Mortgages | Other
Financing Receivable, Modifications [Line Items]
Loan count	2	3
Commercial | CRE non-owner occupied
Financing Receivable, Modifications [Line Items]
Loan count	2	5
Commercial | CRE non-owner occupied | Reduction in interest rate
Financing Receivable, Modifications [Line Items]
Loan count	0	0
Commercial | CRE non-owner occupied | Term Extension
Financing Receivable, Modifications [Line Items]
Loan count	0	1
Commercial | CRE non-owner occupied | Combination of reduction in interest rate and extension of maturity date
Financing Receivable, Modifications [Line Items]
Loan count	2	2
Commercial | CRE non-owner occupied | Other
Financing Receivable, Modifications [Line Items]
Loan count	0	2
Commercial | CRE owner occupied
Financing Receivable, Modifications [Line Items]
Loan count	6	14
Commercial | CRE owner occupied | Reduction in interest rate
Financing Receivable, Modifications [Line Items]
Loan count	1	2
Commercial | CRE owner occupied | Term Extension
Financing Receivable, Modifications [Line Items]
Loan count	3	9
Commercial | CRE owner occupied | Combination of reduction in interest rate and extension of maturity date
Financing Receivable, Modifications [Line Items]
Loan count	0	1
Commercial | CRE owner occupied | Other
Financing Receivable, Modifications [Line Items]
Loan count	2	2
Commercial | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Loan count	3	23
Commercial | Commercial and Industrial | Reduction in interest rate
Financing Receivable, Modifications [Line Items]
Loan count	0	3
Commercial | Commercial and Industrial | Term Extension
Financing Receivable, Modifications [Line Items]
Loan count	3	8
Commercial | Commercial and Industrial | Combination of reduction in interest rate and extension of maturity date
Financing Receivable, Modifications [Line Items]
Loan count	0	1
Commercial | Commercial and Industrial | Other
Financing Receivable, Modifications [Line Items]
Loan count	0	11
Consumer | Credit card
Financing Receivable, Modifications [Line Items]
Loan count	17	63
Consumer | Credit card | Reduction in interest rate
Financing Receivable, Modifications [Line Items]
Loan count	7	31
Consumer | Credit card | Term Extension
Financing Receivable, Modifications [Line Items]
Loan count	0	0
Consumer | Credit card | Combination of reduction in interest rate and extension of maturity date
Financing Receivable, Modifications [Line Items]
Loan count	0	0
Consumer | Credit card | Other
Financing Receivable, Modifications [Line Items]
Loan count	10	32
Consumer | Personal loans
Financing Receivable, Modifications [Line Items]
Loan count	33	144
Consumer | Personal loans | Reduction in interest rate
Financing Receivable, Modifications [Line Items]
Loan count	28	82
Consumer | Personal loans | Term Extension
Financing Receivable, Modifications [Line Items]
Loan count	4	60
Consumer | Personal loans | Combination of reduction in interest rate and extension of maturity date
Financing Receivable, Modifications [Line Items]
Loan count	1	1
Consumer | Personal loans | Other
Financing Receivable, Modifications [Line Items]
Loan count	0	1
Consumer | Auto Loan
Financing Receivable, Modifications [Line Items]
Loan count		1
Consumer | Auto Loan | Reduction in interest rate
Financing Receivable, Modifications [Line Items]
Loan count	0	0
Consumer | Auto Loan | Term Extension
Financing Receivable, Modifications [Line Items]
Loan count	0	1
Consumer | Auto Loan | Combination of reduction in interest rate and extension of maturity date
Financing Receivable, Modifications [Line Items]
Loan count	0	0
Consumer | Auto Loan | Other
Financing Receivable, Modifications [Line Items]
Loan count	0	0
Leasing
Financing Receivable, Modifications [Line Items]
Loan count	0	1
Leasing | Reduction in interest rate
Financing Receivable, Modifications [Line Items]
Loan count	0	0
Leasing | Term Extension
Financing Receivable, Modifications [Line Items]
Loan count	0	0
Leasing | Combination of reduction in interest rate and extension of maturity date
Financing Receivable, Modifications [Line Items]
Loan count	0	1
Leasing | Other
Financing Receivable, Modifications [Line Items]
Loan count	0	0