XML 66 R53.htm IDEA: XBRL DOCUMENT v3.21.1
Investments and Fair Value Instruments - Summary of Amortized Cost and Fair Value of Investment Securities Portfolio (Detail) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]    
Amortized Cost $ 23,051 $ 24,678
Unrealized Gains 656 1
Unrealized Losses 0 0
Estimated Fair Value 23,707 24,679
Cash Equivalents [Member] | Money Market Funds [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Amortized Cost 12,082 6,864
Unrealized Gains 0 0
Unrealized Losses 0 0
Estimated Fair Value 12,082 6,864
Cash Equivalents [Member] | Commercial Paper [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Amortized Cost   900
Unrealized Gains   0
Unrealized Losses   0
Estimated Fair Value   900
Short-term Investments [Member] | Commercial Paper [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Amortized Cost   12,119
Unrealized Gains   0
Unrealized Losses   0
Estimated Fair Value   12,119
Short-term Investments [Member] | Treasury Bills [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Amortized Cost   1,495
Unrealized Gains   1
Unrealized Losses   0
Estimated Fair Value   1,496
Short-term Investments [Member] | Corporate Securities [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Amortized Cost 10,969 3,300
Unrealized Gains 656 0
Unrealized Losses 0 0
Estimated Fair Value $ 11,625 $ 3,300