Investment securities available for sale - Summary of gross realized gains and losses to available for sale securities (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Investment securities available for sale        
Gross realized gains     $ 39 $ 101
Gross realized losses   $ 0 (27)  
Available-for-sale Securities, Gross Realized Gain (Loss), Total $ 0 $ 0 $ 12 $ 101