Fair Value Measurements - Schedule of Changes in Fair Value of Securities Using Level 3 Inputs (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 551,689
Fair value, ending balance	571,389
Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	551,689	$ 349,255
Purchases	40,266	98,299
Sales	0	0
Issuances	0	0
Settlements	(12,067)	(8,709)
Transfers into Level 3	48,433	19,234
Transfers out of Level 3	(58,958)	(3,579)
Fair value, ending balance	571,389	455,170
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	478	95
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	1,705	735
Investments | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	470	95
Investments | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	(502)	(171)
Investments | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	2,058	746
Obligations of states and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	7,834	6,661
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(68)	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair value, ending balance	7,654	6,716
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	0	62
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	(112)	(7)
Obligations of states and political subdivisions | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0	62
Obligations of states and political subdivisions | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0	0
Obligations of states and political subdivisions | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	(112)	(7)
Corporate securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	297,332	187,980
Purchases	5,261	58,586
Sales	0	0
Issuances	0	0
Settlements	(7,269)	(5,535)
Transfers into Level 3	28,896	2,238
Transfers out of Level 3	(31,434)	0
Fair value, ending balance	293,713	245,489
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	226	251
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	850	1,846
Corporate securities | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	218	251
Corporate securities | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	(494)	112
Corporate securities | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	1,203	1,857
CLO and other ABS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	245,313	153,342
Purchases	30,119	39,713
Sales	0	0
Issuances	0	0
Settlements	(4,726)	(3,153)
Transfers into Level 3	19,537	14,148
Transfers out of Level 3	(27,524)	(953)
Fair value, ending balance	263,720	201,926
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	39	17
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	969	(1,168)
CLO and other ABS | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	39	17
CLO and other ABS | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	(7)	(20)
CLO and other ABS | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	969	(1,168)
RMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	0
Purchases	4,886
Sales	0
Issuances	0
Settlements	0
Transfers into Level 3	0
Transfers out of Level 3	0
Fair value, ending balance	4,886
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	0
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	0
RMBS | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0
RMBS | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0
RMBS | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	0
CMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	356	375
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(4)	(21)
Transfers into Level 3	0	2,848
Transfers out of Level 3	0	(2,626)
Fair value, ending balance	349	377
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	0	0
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	(2)	64
CMBS | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0	0
CMBS | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	(1)	(263)
CMBS | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	(2)	64
Common stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	854	897
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair value, ending balance	1,067	662
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	213	(235)
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	0	0
Common stock | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	213	(235)
Common stock | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0	0
Common stock | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	$ 0	$ 0