v3.21.2
Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents $ 201,220 $ 234,492
Investments 99,805 131,352
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level I)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 176,144 188,469
Investments 0 0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level II)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 25,076 46,023
Investments 99,805 131,352
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level III)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 0 0
Investments 0 0
Corporate bonds and commercial paper | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 36,466 31,239
Corporate bonds and commercial paper | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level I)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Corporate bonds and commercial paper | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level II)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 36,466 31,239
Corporate bonds and commercial paper | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level III)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Certificates of deposit | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 12,161 10,007
Certificates of deposit | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level I)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Certificates of deposit | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level II)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 12,161 10,007
Certificates of deposit | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level III)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
U.S. government securities | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 51,178 90,106
U.S. government securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level I)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
U.S. government securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level II)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 51,178 90,106
U.S. government securities | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level III)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Money market funds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 176,144 188,469
Money market funds | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 176,144 188,469
Money market funds | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level I)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 176,144 188,469
Money market funds | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level II)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 0 0
Money market funds | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level III)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 0 0
Certificates of deposit    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 25,076 25,028
Certificates of deposit | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 25,076 25,028
Certificates of deposit | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level I)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 0 0
Certificates of deposit | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level II)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 25,076 25,028
Certificates of deposit | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level III)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents $ 0 0
Corporate bonds and commercial paper    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents   996
Corporate bonds and commercial paper | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents   996
Corporate bonds and commercial paper | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level I)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents   0
Corporate bonds and commercial paper | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level II)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents   996
Corporate bonds and commercial paper | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level III)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents   0
U.S. government securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents   19,999
U.S. government securities | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents   19,999
U.S. government securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level I)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents   0
U.S. government securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level II)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents   19,999
U.S. government securities | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level III)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents   $ 0