Investments - Available-for-sale Securities in a Gross Unrealized Loss Position by Length of Time (Details) $ in Thousands	Dec. 31, 2025 USD ($) holding	Dec. 31, 2024 USD ($) holding
Investment grade
Fair value
Less than 12 months	$ 144,472	$ 280,332
12 months or longer	144,604	260,480
Total	289,076	540,812
Unrealized losses
Less than 12 months	433	3,701
12 months or longer	12,773	22,664
Total	$ 13,206	$ 26,365
No. of holdings | holding	371	616
Non-investment grade
Fair value
Less than 12 months	$ 37,154	$ 28,972
12 months or longer	15,975	27,561
Total	53,129	56,533
Unrealized losses
Less than 12 months	1,426	702
12 months or longer	1,193	2,080
Total	$ 2,619	$ 2,782
No. of holdings | holding	376	370
Corporate debt securities
Fair value
Less than 12 months	$ 72,699	$ 197,619
12 months or longer	41,040	156,059
Total	113,739	353,678
Unrealized losses
Less than 12 months	1,555	2,486
12 months or longer	1,630	6,199
Total	$ 3,185	$ 8,685
No. of holdings | holding	418	567
Collateralized debt obligations
Fair value
Less than 12 months	$ 57,917	$ 33,686
12 months or longer	3,909	11,762
Total	61,826	45,448
Unrealized losses
Less than 12 months	120	71
12 months or longer	44	316
Total	$ 164	$ 387
No. of holdings | holding	83	77
Commercial mortgage-backed securities
Fair value
Less than 12 months	$ 16,103	$ 28,333
12 months or longer	19,956	24,966
Total	36,059	53,299
Unrealized losses
Less than 12 months	59	407
12 months or longer	1,724	2,578
Total	$ 1,783	$ 2,985
No. of holdings | holding	70	131
Residential mortgage-backed securities
Fair value
Less than 12 months	$ 17,675	$ 38,003
12 months or longer	92,019	90,209
Total	109,694	128,212
Unrealized losses
Less than 12 months	27	1,289
12 months or longer	10,353	15,173
Total	$ 10,380	$ 16,462
No. of holdings | holding	146	169
Other debt securities
Fair value
Less than 12 months	$ 3,936	$ 11,663
12 months or longer	3,655	5,045
Total	7,591	16,708
Unrealized losses
Less than 12 months	39	150
12 months or longer	215	478
Total	$ 254	$ 628
No. of holdings | holding	27	42
U.S. Treasury
Fair value
Less than 12 months	$ 13,296
12 months or longer	0
Total	13,296
Unrealized losses
Less than 12 months	59
12 months or longer	0
Total	$ 59
No. of holdings | holding	3
Available-for-sale securities
Fair value
Less than 12 months	$ 181,626	$ 309,304
12 months or longer	160,579	288,041
Total	342,205	597,345
Unrealized losses
Less than 12 months	1,859	4,403
12 months or longer	13,966	24,744
Total	$ 15,825	$ 29,147
No. of holdings | holding	747	986