Investment securities available for sale - Additional Information (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($) item	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) item	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sale of Available-for-sale Securities, Debt	$ 0	$ 0	$ 0	$ 0
Number of positions, Total months | item	72		72
Total Fair Value	$ 128,952,000		$ 128,952,000		$ 126,603,000
Total Unrealized Losses	13,210,000		13,210,000		13,790,000
Investment Pledged As Security For Debt [Member] | FHLB advances
Schedule of Available-for-sale Securities [Line Items]
Pledged Financial Instruments, Not Separately Reported, Securities for Federal Home Loan Bank	$ 23,245,000		$ 23,245,000		$ 5,613,000