Fair Value Measurements - Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - USD ($)
$ in Thousands |
Jun. 30, 2019 |
Dec. 31, 2018 |
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Financial assets and liabilities at fair value |
$ 3,766
|
$ 511
|
| Recurring basis |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Financial assets and liabilities at fair value |
3,766
|
|
| Recurring basis | Common stock warrant liability |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Financial assets and liabilities at fair value |
3,766
|
|
| Recurring basis | Quoted Prices in Active Markets for Identical Items (Level 1) |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Financial assets and liabilities at fair value |
0
|
|
| Recurring basis | Quoted Prices in Active Markets for Identical Items (Level 1) | Common stock warrant liability |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Financial assets and liabilities at fair value |
0
|
|
| Recurring basis | Significant Other Observable Inputs (Level 2) |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Financial assets and liabilities at fair value |
0
|
|
| Recurring basis | Significant Other Observable Inputs (Level 2) | Common stock warrant liability |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Financial assets and liabilities at fair value |
0
|
|
| Recurring basis | Significant Unobservable Inputs (Level 3) |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Financial assets and liabilities at fair value |
3,766
|
|
| Recurring basis | Significant Unobservable Inputs (Level 3) | Common stock warrant liability |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Financial assets and liabilities at fair value |
$ 3,766
|
|