Investments - Maturity Table (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 2,554,332	$ 2,535,568
Estimated Fair Value	2,342,089	$ 2,517,956
2023
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	162,526
Estimated Fair Value	159,078
2024
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	697,970
Estimated Fair Value	663,206
2025
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	297,822
Estimated Fair Value	283,197
2026
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	548,199
Estimated Fair Value	489,551
2027
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	98,210
Estimated Fair Value	94,277
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	740
Estimated Fair Value	731
2042
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,699
Estimated Fair Value	2,331
2043
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	4,573
Estimated Fair Value	4,096
2044
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,464
Estimated Fair Value	5,012
2045
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,520
Estimated Fair Value	4,912
2046
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,110
Estimated Fair Value	7,151
2047
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	8,470
Estimated Fair Value	7,502
2048
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,149
Estimated Fair Value	2,070
2049
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	16,482
Estimated Fair Value	14,645
2050
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	117,659
Estimated Fair Value	94,680
2051
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	163,803
Estimated Fair Value	130,870
2052
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	56,910
Estimated Fair Value	49,518
2053
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	111,518
Estimated Fair Value	100,258
2054
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	88,335
Estimated Fair Value	79,101
2055
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	102,497
Estimated Fair Value	96,290
2058
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	54,605
Estimated Fair Value	$ 53,540