Investments in debt and equity securities - Debt Securities According to Contractual Terms (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Amortized costs
In one year or less	$ 88,203
After one year through five years	355,367
After five years through ten years	155,555
After ten years	25,147
Amortized costs	624,272	$ 578,165
Fair values
In one year or less	87,384
After one year through five years	333,584
After five years through ten years	140,592
After ten years	20,901
Fair values	$ 582,461	$ 589,772