Investments - Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Amortized Cost
Less than 12 months	$ 281,748	$ 1,045,120
12 months or greater	107,020	310,494
Amortized Cost	388,768	1,355,614
Fair Value
Less than 12 months	281,748	1,039,333
12 months or greater	107,020	293,610
Fair Value	388,768	1,332,943
Accrued interest income	$ 2,100	$ 3,000