Fair Value Measurements - Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands | Apr. 30, 2020 | Jan. 31, 2020 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | $ 80,843 |
Short-term investments | $ 12,571 | 17,967 |
Recurring Basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 61,158 | 70,468 |
Short-term investments | 12,571 | 17,967 |
Total cash equivalents and short-term investments | 73,729 | 88,435 |
Recurring Basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 44,781 | 45,654 |
Short-term investments | 0 | 5,000 |
Total cash equivalents and short-term investments | 44,781 | 50,654 |
Recurring Basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 16,377 | 24,814 |
Short-term investments | 12,571 | 12,967 |
Total cash equivalents and short-term investments | 28,948 | 37,781 |
Recurring Basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 0 | 0 |
Short-term investments | 0 | 0 |
Total cash equivalents and short-term investments | 0 | 0 |
Certificates of deposit | Recurring Basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 0 | |
Certificates of deposit | Recurring Basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 0 | |
Certificates of deposit | Recurring Basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 0 | |
Certificates of deposit | Recurring Basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 0 | |
Commercial paper | Recurring Basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 10,265 | 10,567 |
Commercial paper | Recurring Basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 0 | 0 |
Commercial paper | Recurring Basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 10,265 | 10,567 |
Commercial paper | Recurring Basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | | 0 |
U.S. treasury securities | Recurring Basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | | 5,000 |
U.S. treasury securities | Recurring Basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | | 5,000 |
U.S. treasury securities | Recurring Basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | | 0 |
U.S. treasury securities | Recurring Basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | | 0 |
Asset-backed securities | Recurring Basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 1,004 | 2,400 |
Asset-backed securities | Recurring Basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 0 | 0 |
Asset-backed securities | Recurring Basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 1,004 | 2,400 |
Asset-backed securities | Recurring Basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 0 | 0 |
Corporate debt securities | Recurring Basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 1,302 | |
Corporate debt securities | Recurring Basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 0 | |
Corporate debt securities | Recurring Basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 1,302 | |
Corporate debt securities | Recurring Basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Short-term investments | 0 | |
Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 44,781 | 45,654 |
Money market funds | Recurring Basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 44,781 | 45,654 |
Money market funds | Recurring Basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 44,781 | 45,654 |
Money market funds | Recurring Basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 0 | 0 |
Money market funds | Recurring Basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 0 | 0 |
Certificates of deposit | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 15,078 | 15,021 |
Certificates of deposit | Recurring Basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 15,078 | 15,021 |
Certificates of deposit | Recurring Basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 0 | 0 |
Certificates of deposit | Recurring Basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 15,078 | 15,021 |
Certificates of deposit | Recurring Basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 0 | 0 |
Reverse repurchase agreements | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | 4,200 |
Reverse repurchase agreements | Recurring Basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | 4,200 |
Reverse repurchase agreements | Recurring Basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | 0 |
Reverse repurchase agreements | Recurring Basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | 4,200 |
Reverse repurchase agreements | Recurring Basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | |
Commercial paper | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 1,299 | 4,093 |
Commercial paper | Recurring Basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 1,299 | 4,093 |
Commercial paper | Recurring Basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 0 | 0 |
Commercial paper | Recurring Basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | 1,299 | 4,093 |
Commercial paper | Recurring Basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | |
Corporate debt securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | 1,500 |
Corporate debt securities | Recurring Basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | 1,500 |
Corporate debt securities | Recurring Basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | 0 |
Corporate debt securities | Recurring Basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | 1,500 |
Corporate debt securities | Recurring Basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total cash equivalents | | $ 0 |