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Investments and Fair Value Instruments - Summary of Fair Value of Investments Securities (Detail) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Assets at Fair Value    
Total Assets at Fair Value $ 23,707 $ 24,679
Treasury Bills [Member]    
Assets at Fair Value    
Short-term investments   1,496
Money Market Funds [Member]    
Assets at Fair Value    
Cash equivalents 12,082 6,864
Corporate Securities [Member]    
Assets at Fair Value    
Short-term investments 11,625 3,300
Commercial Paper [Member]    
Assets at Fair Value    
Cash equivalents   900
Short-term investments   12,119
Level 1 [Member]    
Assets at Fair Value    
Total Assets at Fair Value 23,707 8,360
Level 1 [Member] | Treasury Bills [Member]    
Assets at Fair Value    
Short-term investments   1,496
Level 1 [Member] | Money Market Funds [Member]    
Assets at Fair Value    
Cash equivalents 12,082 6,864
Level 1 [Member] | Corporate Securities [Member]    
Assets at Fair Value    
Short-term investments 11,625 0
Level 1 [Member] | Commercial Paper [Member]    
Assets at Fair Value    
Cash equivalents   0
Short-term investments   0
Level 2 [Member]    
Assets at Fair Value    
Total Assets at Fair Value 0 16,319
Level 2 [Member] | Treasury Bills [Member]    
Assets at Fair Value    
Short-term investments   0
Level 2 [Member] | Money Market Funds [Member]    
Assets at Fair Value    
Cash equivalents 0 0
Level 2 [Member] | Corporate Securities [Member]    
Assets at Fair Value    
Short-term investments 0 3,300
Level 2 [Member] | Commercial Paper [Member]    
Assets at Fair Value    
Cash equivalents   900
Short-term investments   12,119
Level 3 [Member]    
Assets at Fair Value    
Total Assets at Fair Value 0 0
Level 3 [Member] | Treasury Bills [Member]    
Assets at Fair Value    
Short-term investments   0
Level 3 [Member] | Money Market Funds [Member]    
Assets at Fair Value    
Cash equivalents 0 0
Level 3 [Member] | Corporate Securities [Member]    
Assets at Fair Value    
Short-term investments $ 0 0
Level 3 [Member] | Commercial Paper [Member]    
Assets at Fair Value    
Cash equivalents   0
Short-term investments   $ 0