Allowance for credit losses - Financial effect of the modifications made to borrowers experiencing financial difficultie (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		$ 1,149		$ 3,531
Mortgages
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		1,032		3,143
Commercial | CRE non-owner occupied
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		10		15
Commercial | CRE owner occupied
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		(47)		(2,120)
Consumer | Credit card
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		1		8
Consumer | Personal loans
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		146		411
Consumer | Auto Loan
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis				5
Leasing
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		$ 0		$ 2
Interest Rate Reduction | Mortgages
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification	5.70%		5.70%
Weighted average contractual interest rate after modification	4.20%		4.20%
Interest Rate Reduction | Commercial | CRE non-owner occupied
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification	9.00%		9.00%
Weighted average contractual interest rate after modification	7.20%		7.20%
Interest Rate Reduction | Commercial | CRE owner occupied
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification	8.40%		8.40%
Weighted average contractual interest rate after modification	6.60%		6.60%
Interest Rate Reduction | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification	12.50%		14.00%
Weighted average contractual interest rate after modification	7.60%		7.70%
Interest Rate Reduction | Consumer | Credit card
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification	19.60%		18.00%
Weighted average contractual interest rate after modification	3.60%		4.30%
Interest Rate Reduction | Consumer | Personal loans
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification	17.00%		18.00%
Weighted average contractual interest rate after modification	9.10%		9.70%
Interest Rate Reduction | Consumer | Auto Loan
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification			12.64%
Weighted average contractual interest rate after modification			12.62%
Interest Rate Reduction | Consumer | Other
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification			18.00%
Weighted average contractual interest rate after modification			0.00%
Term Extension | Construction
Financing Receivable, Modifications [Line Items]
Weighted average term increase			6 months
Term Extension | Mortgages
Financing Receivable, Modifications [Line Items]
Weighted average term increase	11 years		11 years
Term Extension | Commercial | CRE non-owner occupied
Financing Receivable, Modifications [Line Items]
Weighted average term increase	28 months		19 months
Term Extension | Commercial | CRE owner occupied
Financing Receivable, Modifications [Line Items]
Weighted average term increase	1 year		1 year
Term Extension | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Weighted average term increase	3 years		2 years
Term Extension | Consumer | Personal loans
Financing Receivable, Modifications [Line Items]
Weighted average term increase	7 years		7 years
Term Extension | Consumer | Auto Loan
Financing Receivable, Modifications [Line Items]
Weighted average term increase			3 years
Principal Forgiveness | Commercial | CRE owner occupied
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis			$ 100
Other-Than-Insignificant Payment Delays | Mortgages
Financing Receivable, Modifications [Line Items]
Weighted average term increase			40 months
Other-Than-Insignificant Payment Delays | Commercial | CRE non-owner occupied
Financing Receivable, Modifications [Line Items]
Weighted average term increase	7 months		12 months
Other-Than-Insignificant Payment Delays | Commercial | CRE owner occupied
Financing Receivable, Modifications [Line Items]
Weighted average term increase	10 months		8 months
Other-Than-Insignificant Payment Delays | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Weighted average term increase	7 months		8 months
Other-Than-Insignificant Payment Delays | Consumer | Credit card
Financing Receivable, Modifications [Line Items]
Weighted average term increase	29 months		26 months
Other-Than-Insignificant Payment Delays | Consumer | Other
Financing Receivable, Modifications [Line Items]
Weighted average term increase			11 months