Fair Value Measurement - Level 3 Assets & Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:
Beginning Balance	$ 97,154	$ 71,513
Total gains (losses) realized and unrealized:
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Gain (Loss) on Investments
Included in other comprehensive income (loss)	$ (138)	$ (192)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Asset, Gain (Loss), Statement of Other Comprehensive Income or Comprehensive Income [Extensible Enumeration]	Other comprehensive income (loss), after tax, net of reclassification adjustments	Other comprehensive income (loss), after tax, net of reclassification adjustments
Purchases	$ 25,076	$ 45,029
Sales	(3,352)	(9,932)
Transfers in	3,587	20,762
Transfers out	(31,534)	(29,591)
Ending Balance	90,842	97,154
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets and liabilities held at period-end	$ 37	$ (624)
Fair Value Asset Recurring Basis Still Held Unrealized Gain Loss Statement Of Income Extensible List Not Disclosed Flag	Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets and liabilities held at period-end	Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets and liabilities held at period-end
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ (6,500)	$ (15,000)
Total gains (losses) realized and unrealized:
Included in earnings	6,500	5,000
Operating expense		3,500
Purchases	0	0
Sales	0	0
Transfers in	0	0
Transfers out	0	0
Ending balance	0	(6,500)
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets and liabilities held at period-end	0	0
Net investment income (loss)
Total gains (losses) realized and unrealized:
Included in earnings	$ 2	$ (23)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net investment income	Net investment income
Net investment gains (losses)
Total gains (losses) realized and unrealized:
Included in earnings	$ 47	$ (412)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Gain (Loss) on Investments	Gain (Loss) on Investments
Corporate debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:
Beginning Balance	$ 82,377	$ 63,973
Total gains (losses) realized and unrealized:
Included in other comprehensive income (loss)	(85)	165
Purchases	18,508	34,311
Sales	(2,814)	(9,534)
Transfers in	3,587	14,666
Transfers out	(20,511)	(21,393)
Ending Balance	81,062	82,377
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets and liabilities held at period-end	0	0
Corporate debt | Net investment income (loss)
Total gains (losses) realized and unrealized:
Included in earnings	0	(23)
Corporate debt | Net investment gains (losses)
Total gains (losses) realized and unrealized:
Included in earnings	0	212
Asset-backed Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:
Beginning Balance	4,414	2,954
Total gains (losses) realized and unrealized:
Included in other comprehensive income (loss)	(53)	(357)
Purchases	6,248	3,253
Sales	(286)	(398)
Transfers in	0	3,988
Transfers out	(6,551)	(5,026)
Ending Balance	3,774	4,414
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets and liabilities held at period-end	0	0
Asset-backed Securities | Net investment income (loss)
Total gains (losses) realized and unrealized:
Included in earnings	2	0
Asset-backed Securities | Net investment gains (losses)
Total gains (losses) realized and unrealized:
Included in earnings	0	0
Equity Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:
Beginning Balance	5,237	2,803
Total gains (losses) realized and unrealized:
Included in earnings	(51)	(737)
Purchases	320	3,171
Sales	0	0
Transfers in	0	0
Transfers out	0	0
Ending Balance	5,506	5,237
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets and liabilities held at period-end	(51)	(737)
Other Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation:
Beginning Balance	5,126	1,783
Total gains (losses) realized and unrealized:
Included in earnings	98	113
Purchases	0	4,294
Sales	(252)	0
Transfers in	0	2,108
Transfers out	(4,472)	(3,172)
Ending Balance	500	5,126
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets and liabilities held at period-end	88	113
Other Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	(6,500)	(15,000)
Total gains (losses) realized and unrealized:
Included in earnings	6,500	5,000
Operating expense		3,500
Purchases	0	0
Sales	0	0
Transfers in	0	0
Transfers out	0	0
Ending balance	0	(6,500)
Change in unrealized gains (losses) included in earnings for the above period for Level 3 assets and liabilities held at period-end	$ 0	$ 0