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Cash and Cash Equivalents - Additional Information (Detail) - USD ($)
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Cash and Cash Equivalents [Abstract]        
Cash and cash equivalents $ 7,677,000 $ 2,981,000 $ 1,294,000 $ 2,478,000
Restrictions on the Company's cash balances $ 0 $ 0