Investment securities available for sale - Additional Information (Details)	3 Months Ended	6 Months Ended
Jun. 30, 2024 USD ($) item	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) item	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Investment securities available for sale
Debt securities	$ 0		$ 0		$ 24,926,000
Proceeds from the sale of available-for-sale securities	$ 0	$ 0	$ 0	$ 0
Number of positions, total months \| item	58		58
Total fair value	$ 54,285,000		$ 54,285,000		66,969,000
Total unrealized losses	$ 8,114,000		$ 8,114,000		$ 7,766,000

Amount, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity), and investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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