Investments - Maturity Table (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 2,113,257	$ 2,563,984
Estimated Fair Value	2,022,605	$ 2,411,622
2024
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	49,998
Estimated Fair Value	49,922
2025
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	299,564
Estimated Fair Value	296,634
2026
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	549,052
Estimated Fair Value	522,070
2027
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	98,916
Estimated Fair Value	97,582
2038
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	66
Estimated Fair Value	68
2039
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	561
Estimated Fair Value	563
2042
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,152
Estimated Fair Value	1,914
2043
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,813
Estimated Fair Value	3,512
2044
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,125
Estimated Fair Value	3,867
2045
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,567
Estimated Fair Value	4,170
2046
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,014
Estimated Fair Value	6,318
2047
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	6,980
Estimated Fair Value	6,339
2048
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,706
Estimated Fair Value	1,597
2049
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	14,973
Estimated Fair Value	13,648
2050
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	102,417
Estimated Fair Value	84,272
2051
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	146,699
Estimated Fair Value	119,429
2052
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	59,033
Estimated Fair Value	53,601
2053
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	312,243
Estimated Fair Value	310,480
2054
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	132,881
Estimated Fair Value	128,397
2055
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	75,043
Estimated Fair Value	73,470
2056
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	200,334
Estimated Fair Value	202,800
2058
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	41,120
Estimated Fair Value	$ 41,952