Fair Value Measurements - Schedule of Fair Value of Financial Instruments (Detail) - Recurring - USD ($) $ in Thousands | Jun. 30, 2020 | Dec. 31, 2019 |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | $ 470,167 | $ 282,686 |
Total liabilities measured at fair value | 3,101 | 2,952 |
Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 339,635 | 136,258 |
U.S. treasury securities | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 25,243 | 48,355 |
Commercial paper | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 61,295 | 77,082 |
Overnight repurchase agreements | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | | 15,001 |
U.S. government agency obligations | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 43,994 | 5,990 |
Derivative liability | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total liabilities measured at fair value | 3,101 | 2,952 |
Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 364,878 | 184,613 |
Total liabilities measured at fair value | 0 | 0 |
Level 1 | Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 339,635 | 136,258 |
Level 1 | U.S. treasury securities | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 25,243 | 48,355 |
Level 1 | Commercial paper | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 0 | 0 |
Level 1 | Overnight repurchase agreements | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | | 0 |
Level 1 | U.S. government agency obligations | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 0 | 0 |
Level 1 | Derivative liability | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total liabilities measured at fair value | 0 | 0 |
Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 105,289 | 98,073 |
Total liabilities measured at fair value | 0 | 0 |
Level 2 | Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 0 | 0 |
Level 2 | U.S. treasury securities | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 0 | 0 |
Level 2 | Commercial paper | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 61,295 | 77,082 |
Level 2 | Overnight repurchase agreements | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | | 15,001 |
Level 2 | U.S. government agency obligations | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 43,994 | 5,990 |
Level 2 | Derivative liability | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total liabilities measured at fair value | 0 | 0 |
Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 0 | 0 |
Total liabilities measured at fair value | 3,101 | 2,952 |
Level 3 | Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 0 | 0 |
Level 3 | U.S. treasury securities | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 0 | 0 |
Level 3 | Commercial paper | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 0 | 0 |
Level 3 | Overnight repurchase agreements | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | | 0 |
Level 3 | U.S. government agency obligations | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total assets measured at fair value | 0 | 0 |
Level 3 | Derivative liability | | |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | | |
Total liabilities measured at fair value | $ 3,101 | $ 2,952 |