Investments (Net Realized Investment Gains (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Debt Securities, Available-for-Sale [Line Items]
Total impairment losses:	$ (1,861)	$ (1,801)	$ (1,134)	$ (3,302)
Corporate debt	605	0	503	102
Net impairment losses recognized in earnings	(1,256)	(1,801)	(631)	(3,200)
Gross realized gains, available-for-sale fixed maturities	248	484	1,352	1,156
Gross realized (losses), available-for-sale fixed maturities	(238)	(1,567)	(5,179)	(3,636)
Net realized gains (losses), trading fixed maturities	20	5	32	18
Net realized gains (losses), equity investments	590	176	(968)	2,115
Net realized gains (losses), other investments	0	(245)	(158)	(826)
Change in unrealized holding gains (losses), trading fixed maturities	17	(5)	(85)	165
Change in unrealized holding gains (losses), equity investments	1,370	4,979	4,797	1,762
Change in unrealized holding gains (losses), convertible securities, carried at fair value	90	267	214	873
Other	0	(41)	0	6,719
Net investment gains (losses)	841	2,252	(626)	5,146
NORCAL Group
Debt Securities, Available-for-Sale [Line Items]
Gain on fair value of contingent consideration		6,500		6,500
Corporate Debt
Debt Securities, Available-for-Sale [Line Items]
Total impairment losses:	(1,868)	(1,398)	(1,408)	(2,710)
Asset-backed securities
Debt Securities, Available-for-Sale [Line Items]
Total impairment losses:	$ 7	$ (403)	$ 274	$ (592)