Investments in debt and equity securities - Debt Securities According Contractual Terms (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Amortized costs
In one year or less	$ 79,070
After one year through five years	359,153
After five years through ten years	183,456
After ten years	25,049
Amortized costs	646,728	$ 578,165
Fair values
In one year or less	78,241
After one year through five years	340,698
After five years through ten years	171,360
After ten years	21,635
Fair values	$ 611,934	$ 589,772