Investments - Schedule of Available For Sale Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Amortized Cost
Amortized Cost	$ 6,231,018	$ 5,586,730
Fair Value
Fair Value	5,876,721	5,263,739
U.S. Treasury securities
Amortized Cost
Due in 1 year	213,553
Due after 1 but within 5 years	301,532
Due after 5 but within 10 years	32,302
Due after 10 years	14,466
Subtotal	561,853
Amortized Cost	561,853	1,014,076
Fair Value
Due in 1 year	212,961
Due after 1 but within 5 years	292,711
Due after 5 but within 10 years	29,303
Due after 10 years	12,315
Subtotal	547,290
Fair Value	547,290	996,382
Municipal debt securities
Amortized Cost
Due in 1 year	16,767
Due after 1 but within 5 years	84,229
Due after 5 but within 10 years	144,143
Due after 10 years	385,876
Subtotal	631,015
Amortized Cost	631,015	585,047
Fair Value
Due in 1 year	16,624
Due after 1 but within 5 years	81,905
Due after 5 but within 10 years	134,741
Due after 10 years	350,231
Subtotal	583,501
Fair Value	583,501	547,258
Non-U.S. government securities
Amortized Cost
Due in 1 year	5,267
Due after 1 but within 5 years	32,032
Due after 5 but within 10 years	7,706
Due after 10 years	36,626
Subtotal	81,631
Amortized Cost	81,631	77,516
Fair Value
Due in 1 year	5,233
Due after 1 but within 5 years	30,792
Due after 5 but within 10 years	6,195
Due after 10 years	27,578
Subtotal	69,798
Fair Value	69,798	67,447
Corporate debt securities
Amortized Cost
Due in 1 year	164,458
Due after 1 but within 5 years	505,921
Due after 5 but within 10 years	1,014,720
Due after 10 years	202,548
Subtotal	1,887,647
Amortized Cost	1,887,647	1,380,533
Fair Value
Due in 1 year	163,676
Due after 1 but within 5 years	489,307
Due after 5 but within 10 years	959,079
Due after 10 years	170,984
Subtotal	1,783,046
Fair Value	1,783,046	1,297,055
U.S. agency mortgage-backed securities
Amortized Cost
Amortized Cost	1,249,259	922,907
Fair Value
Fair Value	1,125,436	821,346
Residential and commercial mortgage securities
Amortized Cost
Amortized Cost	519,613	571,163
Fair Value
Fair Value	478,086	517,940
Asset-backed securities
Amortized Cost
Amortized Cost	642,395	584,168
Fair Value
Fair Value	631,959	564,995
Money market funds
Amortized Cost
Amortized Cost	657,605	444,121
Fair Value
Fair Value	$ 657,605	$ 444,121

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Section 50
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-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
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-Paragraph 1
-Publisher FASB
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