Changes in accumulated other comprehensive income - Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Benefit (expense) from income taxes	$ (45,131)	$ (46,694)	$ (90,739)	$ (92,337)
Reclassification out of Accumulated Other Comprehensive Income \| Amounts reclassified from accumulated other comprehensive income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net unrealized gains (losses) on investments	(2,284)	(7,546)	(8,094)	(10,674)
Benefit (expense) from income taxes	$ 480	$ 1,585	$ 1,700	$ 2,242

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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+ Details