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Available-for-Sale Securities - Schedule of Fair Value of Available-for-Sale Securities by Type of Security (Detail) - USD ($)
$ in Thousands
Mar. 31, 2020
Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 401 $ 7,480
Gross Unrealized Gain   1
Gross Unrealized Loss (1)  
Fair Value 400 7,481
Corporate Bond Securities [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost 401 1,502
Gross Unrealized Gain   1
Gross Unrealized Loss (1)  
Fair Value $ 400 1,503
Commercial Paper [Member]    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost   5,978
Fair Value   $ 5,978