Investments in debt and equity securities available-for-sale - Debt Securities According to Contractual Terms (Details) $ in Thousands	Sep. 30, 2016 USD ($)
Amortized costs
In one year or less	$ 45,531
After one year through five years	233,813
After five years through ten years	223,019
After ten years	80,604
Amortized costs, total	582,967
Fair values
In one year or less	45,904
After one year through five years	243,355
After five years through ten years	233,147
After ten years	86,860
Debt securities, fair values total	$ 609,266