Derivative instruments (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Notional Amount	$ 670,470		$ 638,667
Asset Derivatives Fair Value	55,810		36,812
Liabilities Derivatives Fair Value	(593)		(212)
Derivative gain (loss)
Net Realized Gain (Loss)	$ 4,392	$ 3,686
Net Realized gain (loss) - Statement of Income	Realized Investment Gains (Losses)	Realized Investment Gains (Losses)
Unrealized Gain (Loss)	$ 6,886	$ (8,921)
Unrealized gain (loss) - Statement of Income	Net unrealized gain (loss) on financial instruments	Net unrealized gain (loss) on financial instruments
Total change in OCI for period	$ 6,245	$ (3,805)
Designated as Hedging
Derivative gain (loss)
Derivatives - effective portion reclassified from AOCI to income	(283)	(298)
Total income statement impact	(283)	(298)
Derivatives- effective portion recorded in OCI	5,962	(4,103)
Total change in OCI for period	6,245	(3,805)
Interest rate swaps
Asset Derivatives Fair Value	54,799		36,812
Derivative gain (loss)
Net Realized Gain (Loss)	4,392	3,686
Unrealized Gain (Loss)	6,886	(8,459)
Interest rate swaps \| Not Designated as Hedging \| Interest Rate Risk
Notional Amount	40,500		183,081
Asset Derivatives Fair Value	10,882		12,349
Interest rate swaps \| Designated as Hedging \| Interest Rate Risk
Notional Amount	564,620		416,139
Asset Derivatives Fair Value	43,917		24,463
FX forwards
Asset Derivatives Fair Value	1,011
Liabilities Derivatives Fair Value	(593)		(212)
Derivative gain (loss)
Unrealized Gain (Loss)		$ (462)
FX forwards \| Foreign Exchange Rate Risk
Notional Amount	65,350		39,447
Asset Derivatives Fair Value	1,011
Liabilities Derivatives Fair Value	$ (593)		$ (212)

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