XML 48 R37.htm IDEA: XBRL DOCUMENT v3.21.2
Marketable Securities - Components of Marketable Securities by Security Type (Detail) - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]    
Marketable Securities, Amortized Cost $ 80,359 $ 101,050
Marketable Securities, Gross Unrealized Gains 3 14
Marketable Securities, Gross Unrealized Losses (2) (3)
Marketable Securities, Fair Value 80,360 101,061
U.S. Treasury Securities (due within one year) [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Marketable Securities, Amortized Cost 77,358 74,066
Marketable Securities, Gross Unrealized Gains 3 10
Marketable Securities, Gross Unrealized Losses (2) (3)
Marketable Securities, Fair Value 77,359 74,073
U.S. Government Agency Bonds (due within one year) [Member]    
Schedule Of Available For Sale Securities [Line Items]    
Marketable Securities, Amortized Cost 3,001 26,984
Marketable Securities, Gross Unrealized Gains   4
Marketable Securities, Fair Value $ 3,001 $ 26,988