Investments - Contractual Maturities of Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Cost
Due within one year	$ 223,933	$ 163,890
Due after one year through five years	371,060	242,958
Due after five years through ten years	62,679	68,659
Due after ten years	116,908	137,764
Total	774,580	613,271
Fair Value
Due within one year	222,307	164,635
Due after one year through five years	368,574	247,857
Due after five years through ten years	62,639	73,479
Due after ten years	118,918	144,749
Total	$ 772,438	$ 630,720