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Marketable Securities - Additional Information (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Investments, Debt and Equity Securities [Abstract]    
Fair market value of investment securities exceeds cost basis $ 120  
Gross unrealized holding gains 135  
Gross unrealized holding losses 15  
Unrealized gain (loss) on available-for-sale securities 69 $ 202
Estimated tax expense (benefit) of change in value of available-for-sale securities 19  
Accrued interest receivable balance $ 177