Fair Value Measurements - Summary of Financial Assets Subject to Fair Value Measurements on Recurring Basis and Level of Inputs Used in Measurements (Details) - USD ($)
$ in Thousands |
Mar. 31, 2018 |
Dec. 31, 2017 |
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Short-term marketable securities |
$ 71,281
|
$ 79,212
|
| Long-term marketable securities |
|
5,118
|
| Total marketable securities |
|
84,330
|
| Fair Value, Measurements, Recurring |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Money market funds |
62,085
|
5,709
|
| Short-term marketable securities |
71,281
|
|
| Total marketable securities |
|
84,330
|
| Assets fair value disclosure |
133,366
|
90,039
|
| Fair Value, Measurements, Recurring | Level 1 |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Money market funds |
62,085
|
5,709
|
| Assets fair value disclosure |
62,085
|
5,709
|
| Fair Value, Measurements, Recurring | Level 2 |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Short-term marketable securities |
71,281
|
|
| Total marketable securities |
|
84,330
|
| Assets fair value disclosure |
71,281
|
84,330
|
| Money market funds | Fair Value, Measurements, Recurring |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Money market funds |
62,085
|
5,709
|
| Money market funds | Fair Value, Measurements, Recurring | Level 1 |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Money market funds |
62,085
|
5,709
|
| Commercial Paper | Fair Value, Measurements, Recurring |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Short-term marketable securities |
5,428
|
6,359
|
| Commercial Paper | Fair Value, Measurements, Recurring | Level 2 |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Short-term marketable securities |
5,428
|
6,359
|
| Corporate Debt Securities | Fair Value, Measurements, Recurring |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Short-term marketable securities |
10,140
|
16,149
|
| Corporate Debt Securities | Fair Value, Measurements, Recurring | Level 2 |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Short-term marketable securities |
10,140
|
16,149
|
| Asset-backed Securities | Fair Value, Measurements, Recurring |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Short-term marketable securities |
14,404
|
14,588
|
| Long-term marketable securities |
|
2,742
|
| Asset-backed Securities | Fair Value, Measurements, Recurring | Level 2 |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Short-term marketable securities |
14,404
|
14,588
|
| Long-term marketable securities |
|
2,742
|
| US Government Debt Securities | Fair Value, Measurements, Recurring |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Short-term marketable securities |
41,309
|
42,116
|
| Long-term marketable securities |
|
2,376
|
| US Government Debt Securities | Fair Value, Measurements, Recurring | Level 2 |
|
|
| Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |
|
|
| Short-term marketable securities |
$ 41,309
|
42,116
|
| Long-term marketable securities |
|
$ 2,376
|