Investments - Maturity Table (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 2,563,984	$ 2,554,332
Estimated Fair Value	2,411,622	$ 2,342,089
2024
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	699,496
Estimated Fair Value	686,762
2025
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	298,815
Estimated Fair Value	289,794
2026
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	548,686
Estimated Fair Value	506,438
2027
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	98,612
Estimated Fair Value	95,746
2038
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	68
Estimated Fair Value	69
2039
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	646
Estimated Fair Value	639
2042
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,296
Estimated Fair Value	2,002
2043
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,156
Estimated Fair Value	3,773
2044
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,837
Estimated Fair Value	4,483
2045
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,107
Estimated Fair Value	4,596
2046
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,725
Estimated Fair Value	6,897
2047
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,646
Estimated Fair Value	6,880
2048
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,027
Estimated Fair Value	1,971
2049
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	15,792
Estimated Fair Value	14,170
2050
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	107,611
Estimated Fair Value	87,112
2051
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	154,622
Estimated Fair Value	124,399
2052
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	53,653
Estimated Fair Value	46,966
2053
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	245,209
Estimated Fair Value	236,537
2054
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	71,439
Estimated Fair Value	63,426
2055
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	86,199
Estimated Fair Value	81,892
2056
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	102,609
Estimated Fair Value	100,728
2058
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	46,733
Estimated Fair Value	$ 46,342