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Summary of Significant Accounting Policies - Schedule of fair value on a recurring basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Fair Value, Inputs, Level 1 [Member]    
Assets:    
Money market funds $ 1,010 $ 16,775
Mutual funds 15,841 14,264
Fair Value, Inputs, Level 2 [Member]    
Assets:    
Short-term investments $ 104,870 $ 74,510