Investments - Available-For-Sale Securities in a Gross Unrealized Loss Position by Length of Time (Details) $ in Thousands	Jun. 30, 2025 USD ($) holding	Dec. 31, 2024 USD ($) holding
Investment grade
Fair value
Less than 12 months	$ 140,575	$ 280,332
12 months or longer	219,609	260,480
Total	360,184	540,812
Unrealized losses
Less than 12 months	1,259	3,701
12 months or longer	16,996	22,664
Total	$ 18,255	$ 26,365
No. of holdings | holding	450	616
Non-investment grade
Fair value
Less than 12 months	$ 30,247	$ 28,972
12 months or longer	21,713	27,561
Total	51,960	56,533
Unrealized losses
Less than 12 months	1,236	702
12 months or longer	1,211	2,080
Total	$ 2,447	$ 2,782
No. of holdings | holding	360	370
Corporate debt securities
Fair value
Less than 12 months	$ 75,033	$ 197,619
12 months or longer	125,187	156,059
Total	200,220	353,678
Unrealized losses
Less than 12 months	1,430	2,486
12 months or longer	3,315	6,199
Total	$ 4,745	$ 8,685
No. of holdings | holding	461	567
Collateralized debt obligations
Fair value
Less than 12 months	$ 40,941	$ 33,686
12 months or longer	7,390	11,762
Total	48,331	45,448
Unrealized losses
Less than 12 months	108	71
12 months or longer	160	316
Total	$ 268	$ 387
No. of holdings | holding	78	77
Commercial mortgage-backed securities
Fair value
Less than 12 months	$ 12,656	$ 28,333
12 months or longer	20,000	24,966
Total	32,656	53,299
Unrealized losses
Less than 12 months	110	407
12 months or longer	1,797	2,578
Total	$ 1,907	$ 2,985
No. of holdings | holding	79	131
Residential mortgage-backed securities
Fair value
Less than 12 months	$ 36,998	$ 38,003
12 months or longer	84,737	90,209
Total	121,735	128,212
Unrealized losses
Less than 12 months	784	1,289
12 months or longer	12,645	15,173
Total	$ 13,429	$ 16,462
No. of holdings | holding	162	169
Other debt securities
Fair value
Less than 12 months	$ 3,169	$ 11,663
12 months or longer	4,008	5,045
Total	7,177	16,708
Unrealized losses
Less than 12 months	37	150
12 months or longer	290	478
Total	$ 327	$ 628
No. of holdings | holding	28	42
U.S. Treasury
Fair value
Less than 12 months	$ 2,025
12 months or longer	0
Total	2,025
Unrealized losses
Less than 12 months	26
12 months or longer	0
Total	$ 26
No. of holdings | holding	2
Available-for-sale securities
Fair value
Less than 12 months	$ 170,822	$ 309,304
12 months or longer	241,322	288,041
Total	412,144	597,345
Unrealized losses
Less than 12 months	2,495	4,403
12 months or longer	18,207	24,744
Total	$ 20,702	$ 29,147
No. of holdings | holding	810	986