Quarterly report pursuant to Section 13 or 15(d)

Financial Instruments - Summary of Estimated Fair Value and Related Valuation Input Hierarchy of Available-for-Sale Securities (Detail)

v3.21.2
Financial Instruments - Summary of Estimated Fair Value and Related Valuation Input Hierarchy of Available-for-Sale Securities (Detail) - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]    
Total Fair Value $ 367,998 $ 499,345
Fair Value, Measurements, Recurring    
Schedule of Available-for-sale Securities [Line Items]    
Total Amortized Cost 367,935 499,049
Total Unrealized Gain 106 311
Total Unrealized Loss (43) (15)
Total Fair Value 367,998 499,345
Fair Value, Measurements, Recurring | Money Market Funds | Level 1    
Schedule of Available-for-sale Securities [Line Items]    
Total Amortized Cost 104,974 168,343
Total Unrealized Gain 0 0
Total Unrealized Loss 0 0
Total Fair Value 104,974 168,343
Fair Value, Measurements, Recurring | U.S. Treasury Obligations | Level 2    
Schedule of Available-for-sale Securities [Line Items]    
Total Amortized Cost 134,243 230,239
Total Unrealized Gain 23 113
Total Unrealized Loss (16) (6)
Total Fair Value 134,250 230,346
Fair Value, Measurements, Recurring | Government Agency Obligations | Level 2    
Schedule of Available-for-sale Securities [Line Items]    
Total Amortized Cost 21,429 22,537
Total Unrealized Gain 12 22
Total Unrealized Loss (5) (3)
Total Fair Value 21,436 22,556
Fair Value, Measurements, Recurring | Corporate Debt Obligations | Level 2    
Schedule of Available-for-sale Securities [Line Items]    
Total Amortized Cost 57,364 50,080
Total Unrealized Gain 63 166
Total Unrealized Loss (13) (1)
Total Fair Value 57,414 50,245
Fair Value, Measurements, Recurring | Commercial Paper | Level 2    
Schedule of Available-for-sale Securities [Line Items]    
Total Amortized Cost 39,972 17,990
Total Unrealized Gain 0 0
Total Unrealized Loss 0 0
Total Fair Value 39,972 17,990
Fair Value, Measurements, Recurring | Asset-Backed Securities | Level 2    
Schedule of Available-for-sale Securities [Line Items]    
Total Amortized Cost 9,953 9,860
Total Unrealized Gain 8 10
Total Unrealized Loss (9) (5)
Total Fair Value 9,952 9,865
Fair Value, Measurements, Recurring | Amounts Classified As Cash Equivalents    
Schedule of Available-for-sale Securities [Line Items]    
Total Amortized Cost (118,474) (199,090)
Total Unrealized Gain 0 0
Total Unrealized Loss 0 0
Total Fair Value (118,474) (199,090)
Fair Value, Measurements, Recurring | Amounts Classified As Short-Term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Total Amortized Cost 249,461 299,959
Total Unrealized Gain 106 311
Total Unrealized Loss (43) (15)
Total Fair Value $ 249,524 $ 300,255