Investments - Available-For-Sale Securities in a Gross Unrealized Loss Position by Length of Time (Details) $ in Thousands	Jun. 30, 2026 USD ($) holding	Dec. 31, 2025 USD ($) holding
Investment grade
Fair value
Less than 12 months	$ 725,388	$ 144,472
12 months or longer	106,979	144,604
Total	832,367	289,076
Unrealized losses
Less than 12 months	5,879	433
12 months or longer	12,807	12,773
Total	$ 18,686	$ 13,206
No. of holdings | holding	734	371
Non-investment grade
Fair value
Less than 12 months	$ 25,070	$ 37,154
12 months or longer	2,852	15,975
Total	27,922	53,129
Unrealized losses
Less than 12 months	648	1,426
12 months or longer	157	1,193
Total	$ 805	$ 2,619
No. of holdings | holding	28	376
Corporate debt securities
Fair value
Less than 12 months	$ 432,603	$ 72,699
12 months or longer	13,788	41,040
Total	446,391	113,739
Unrealized losses
Less than 12 months	4,186	1,555
12 months or longer	608	1,630
Total	$ 4,794	$ 3,185
No. of holdings | holding	273	418
Collateralized debt obligations
Fair value
Less than 12 months	$ 146,226	$ 57,917
12 months or longer	2,566	3,909
Total	148,792	61,826
Unrealized losses
Less than 12 months	463	120
12 months or longer	24	44
Total	$ 487	$ 164
No. of holdings | holding	144	83
Commercial mortgage-backed securities
Fair value
Less than 12 months	$ 36,406	$ 16,103
12 months or longer	16,335	19,956
Total	52,741	36,059
Unrealized losses
Less than 12 months	261	59
12 months or longer	1,454	1,724
Total	$ 1,715	$ 1,783
No. of holdings | holding	100	70
Residential mortgage-backed securities
Fair value
Less than 12 months	$ 99,078	$ 17,675
12 months or longer	73,795	92,019
Total	172,873	109,694
Unrealized losses
Less than 12 months	1,393	27
12 months or longer	10,662	10,353
Total	$ 12,055	$ 10,380
No. of holdings | holding	185	146
Other debt securities
Fair value
Less than 12 months	$ 25,741	$ 3,936
12 months or longer	3,347	3,655
Total	29,088	7,591
Unrealized losses
Less than 12 months	169	39
12 months or longer	216	215
Total	$ 385	$ 254
No. of holdings | holding	57	27
U.S. Treasury
Fair value
Less than 12 months	$ 10,404	$ 13,296
12 months or longer	0	0
Total	10,404	13,296
Unrealized losses
Less than 12 months	55	59
12 months or longer	0	0
Total	$ 55	$ 59
No. of holdings | holding	3	3
Available-for-sale securities
Fair value
Less than 12 months	$ 750,458	$ 181,626
12 months or longer	109,831	160,579
Total	860,289	342,205
Unrealized losses
Less than 12 months	6,527	1,859
12 months or longer	12,964	13,966
Total	$ 19,491	$ 15,825
No. of holdings | holding	762	747