Shareholders' Equity and Regulatory Matters - Accumulated other comprehensive income (loss) (Details) - USD ($)
$ in Thousands
Sep. 30, 2020
Dec. 31, 2019
Shareholders' Equity and Regulatory Matters    
Net unrealized gains on securities $ 482 $ 186
Net unrecognized losses on defined benefit plan (38) (44)
Total accumulated other comprehensive income $ 444 $ 142