Derivative Instruments - Hedged assets and liabilities in fair value (Details) - Designated as hedging instruments - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Derivative Instruments
Notional amount	$ 600,000	$ 600,000
Carrying Amount of Hedged Assets / Liabilities	598,040	600,339
Cumulative Fair Value Hedging Adjustment in the Carrying Amount of Hedged Assets / Liabilities	(1,960)	339
Mortgage backed securities - Residential agency
Derivative Instruments
Notional amount	200,000	200,000
Carrying Amount of Hedged Assets / Liabilities	198,210	200,241
Cumulative Fair Value Hedging Adjustment in the Carrying Amount of Hedged Assets / Liabilities	(1,790)	241
Amortized cost	320,700	323,400
Mortgage Loan Pools
Derivative Instruments
Notional amount	400,000	400,000
Carrying Amount of Hedged Assets / Liabilities	399,830	400,098
Cumulative Fair Value Hedging Adjustment in the Carrying Amount of Hedged Assets / Liabilities	(170)	98
Amortized cost	$ 664,100	$ 687,500