Investments - Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Amortized Cost
Less than 12 months	$ 308,430	$ 1,045,120
12 months or greater	144,384	310,494
Amortized Cost	452,814	1,355,614
Fair Value
Less than 12 months	301,187	1,039,333
12 months or greater	136,464	293,610
Fair Value	437,651	1,332,943
Accrued interest income	$ 2,400	$ 3,000