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, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable
Loan count	338	619	1,103	1,911
Reduction in interest rate
Financing Receivable
Loan count	38	61	124	302
Extension of maturity date
Financing Receivable
Loan count	73	71	207	257
Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	213	458	721	1,286
Other
Financing Receivable
Loan count	14	29	51	66
Mortgages
Financing Receivable
Loan count	277	507	852	1,426
Mortgages | Reduction in interest rate
Financing Receivable
Loan count	2	13	6	35
Mortgages | Extension of maturity date
Financing Receivable
Loan count	63	35	128	114
Mortgages | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	210	455	715	1,273
Mortgages | Other
Financing Receivable
Loan count	2	4	3	4
Commercial | Commercial multi-family
Financing Receivable
Loan count				2
Commercial | Commercial multi-family | Reduction in interest rate
Financing Receivable
Loan count		0		0
Commercial | Commercial multi-family | Extension of maturity date
Financing Receivable
Loan count		0		1
Commercial | Commercial multi-family | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count		0		1
Commercial | Commercial multi-family | Other
Financing Receivable
Loan count		0		0
Commercial | CRE non-owner occupied
Financing Receivable
Loan count	2	1	5	10
Commercial | CRE non-owner occupied | Reduction in interest rate
Financing Receivable
Loan count	0	0	0	0
Commercial | CRE non-owner occupied | Extension of maturity date
Financing Receivable
Loan count	0	0	1	9
Commercial | CRE non-owner occupied | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	2	1	2	1
Commercial | CRE non-owner occupied | Other
Financing Receivable
Loan count	0	0	2	0
Commercial | CRE owner occupied
Financing Receivable
Loan count	6	4	14	35
Commercial | CRE owner occupied | Reduction in interest rate
Financing Receivable
Loan count	1	0	2	3
Commercial | CRE owner occupied | Extension of maturity date
Financing Receivable
Loan count	3	0	9	23
Commercial | CRE owner occupied | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	0	0	1	3
Commercial | CRE owner occupied | Other
Financing Receivable
Loan count	2	4	2	6
Commercial | Commercial and Industrial
Financing Receivable
Loan count	3	11	23	26
Commercial | Commercial and Industrial | Reduction in interest rate
Financing Receivable
Loan count	0	1	3	2
Commercial | Commercial and Industrial | Extension of maturity date
Financing Receivable
Loan count	3	2	8	10
Commercial | Commercial and Industrial | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	0	0	1	0
Commercial | Commercial and Industrial | Other
Financing Receivable
Loan count	0	8	11	14
Consumer | Credit card
Financing Receivable
Loan count	17	31	63	148
Consumer | Credit card | Reduction in interest rate
Financing Receivable
Loan count	7	19	31	108
Consumer | Credit card | Extension of maturity date
Financing Receivable
Loan count	0	0	0	0
Consumer | Credit card | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	0	0	0	1
Consumer | Credit card | Other
Financing Receivable
Loan count	10	12	32	39
Consumer | Home equity lines of credit
Financing Receivable
Loan count				2
Consumer | Home equity lines of credit | Reduction in interest rate
Financing Receivable
Loan count		0		0
Consumer | Home equity lines of credit | Extension of maturity date
Financing Receivable
Loan count		0		1
Consumer | Home equity lines of credit | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count		0		1
Consumer | Home equity lines of credit | Other
Financing Receivable
Loan count		0		0
Consumer | Personal loans
Financing Receivable
Loan count	33	59	144	245
Consumer | Personal loans | Reduction in interest rate
Financing Receivable
Loan count	28	28	82	148
Consumer | Personal loans | Extension of maturity date
Financing Receivable
Loan count	4	31	60	94
Consumer | Personal loans | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	1	0	1	1
Consumer | Personal loans | Other
Financing Receivable
Loan count	0	0	1	2
Consumer | Auto Loan
Financing Receivable
Loan count		4	1	8
Consumer | Auto Loan | Reduction in interest rate
Financing Receivable
Loan count	0	0	0	0
Consumer | Auto Loan | Extension of maturity date
Financing Receivable
Loan count	0	3	1	5
Consumer | Auto Loan | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	0	1	0	3
Consumer | Auto Loan | Other
Financing Receivable
Loan count	0	0	0	0
Consumer | Other
Financing Receivable
Loan count		1		7
Consumer | Other | Reduction in interest rate
Financing Receivable
Loan count		0		6
Consumer | Other | Extension of maturity date
Financing Receivable
Loan count		0		0
Consumer | Other | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count		0		0
Consumer | Other | Other
Financing Receivable
Loan count		1		1
Leasing
Financing Receivable
Loan count		1	1	2
Leasing | Reduction in interest rate
Financing Receivable
Loan count	0	0	0	0
Leasing | Extension of maturity date
Financing Receivable
Loan count	0	0	0	0
Leasing | Combination of reduction in interest rate and extension of maturity date
Financing Receivable
Loan count	0	1	1	2
Leasing | Other
Financing Receivable
Loan count	0	0	0	0