Shareholders' Equity and Regulatory Matters - Accumulated other comprehensive income (loss) (Details) - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Shareholders' Equity and Regulatory Matters    
Net unrealized gains on securities $ 73 $ 466
Net unrecognized losses on defined benefit plan (32) (36)
Total accumulated other comprehensive income $ 41 $ 430