Investments - Maturity Table (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 2,487,749	$ 2,554,332
Estimated Fair Value	2,311,062	$ 2,342,089
2023
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	114,993
Estimated Fair Value	113,061
2024
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	698,346
Estimated Fair Value	670,601
2025
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	298,066
Estimated Fair Value	286,613
2026
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	548,319
Estimated Fair Value	499,306
2027
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	98,309
Estimated Fair Value	95,902
2038
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	71
Estimated Fair Value	73
2039
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	718
Estimated Fair Value	719
2042
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,528
Estimated Fair Value	2,227
2043
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,434
Estimated Fair Value	4,055
2044
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,412
Estimated Fair Value	5,057
2045
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,443
Estimated Fair Value	4,940
2046
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,963
Estimated Fair Value	7,165
2047
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,386
Estimated Fair Value	7,586
2048
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,056
Estimated Fair Value	2,001
2049
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	16,374
Estimated Fair Value	14,836
2050
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	114,601
Estimated Fair Value	93,786
2051
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	161,035
Estimated Fair Value	130,855
2052
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	56,605
Estimated Fair Value	50,153
2053
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	109,892
Estimated Fair Value	100,141
2054
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	83,670
Estimated Fair Value	75,428
2055
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	98,051
Estimated Fair Value	94,030
2058
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	52,477
Estimated Fair Value	$ 52,527