Allowance for credit losses - Financial effect of the modifications made to borrowers experiencing financial difficultie (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		$ (808)		$ 2,382
Mortgages
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		1,091		2,111
Commercial | CRE non-owner occupied
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		5		5
Commercial | CRE owner occupied
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		(2,073)		(2,073)
Consumer | Credit card
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		2		7
Consumer | Personal loans
Financing Receivable, Modifications [Line Items]
Reduced the amortized cost basis		135		265
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		$ 2		$ 2
Interest Rate Reduction | Mortgages
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification	5.60%		5.70%
Weighted average contractual interest rate after modification	4.10%		4.20%
Interest Rate Reduction | Commercial | CRE owner occupied
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification			6.00%
Weighted average contractual interest rate after modification			5.30%
Interest Rate Reduction | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification	21.70%		21.70%
Weighted average contractual interest rate after modification	8.00%		8.00%
Interest Rate Reduction | Consumer | Credit card
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification	17.60%		17.60%
Weighted average contractual interest rate after modification	4.70%		4.60%
Interest Rate Reduction | Consumer | Personal loans
Financing Receivable, Modifications [Line Items]
Weighted average contractual interest rate before modification	20.30%		18.90%
Weighted average contractual interest rate after modification	10.70%		10.30%
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		6 months
Term Extension | Mortgages
Financing Receivable, Modifications [Line Items]
Weighted average term increase	12 years		11 years
Term Extension | Commercial | CRE non-owner occupied
Financing Receivable, Modifications [Line Items]
Weighted average term increase	10 months		10 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	1 year		1 year
Term Extension | Consumer | Personal loans
Financing Receivable, Modifications [Line Items]
Weighted average term increase	6 years		6 years
Term Extension | Consumer | Auto Loan
Financing Receivable, Modifications [Line Items]
Weighted average term increase	3 years		3 years
Other-Than-Insignificant Payment Delays | Mortgages
Financing Receivable, Modifications [Line Items]
Weighted average term increase	40 months		40 months
Other-Than-Insignificant Payment Delays | Commercial | CRE non-owner occupied
Financing Receivable, Modifications [Line Items]
Weighted average term increase			12 months
Other-Than-Insignificant Payment Delays | Commercial | CRE owner occupied
Financing Receivable, Modifications [Line Items]
Weighted average term increase	24 months		8 months
Other-Than-Insignificant Payment Delays | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Weighted average term increase	24 months		9 months
Other-Than-Insignificant Payment Delays | Consumer | Credit card
Financing Receivable, Modifications [Line Items]
Weighted average term increase	24 months		24 months