Summary of Significant Accounting Policies - Additional Information (Detail) |
6 Months Ended | |
|---|---|---|
|
Jun. 30, 2015
USD ($)
Segment
|
Dec. 31, 2014
USD ($)
|
|
| Summary Of Significant Accounting Policy [Line Items] | ||
| Deferred offering costs | $ 3,053,000 | $ 549,000 |
| Number of operating segment | Segment | 1 | |
| Leasehold Improvements [Member] | ||
| Summary Of Significant Accounting Policy [Line Items] | ||
| Estimated useful lives of assets | 3 years | |
| Minimum [Member] | ||
| Summary Of Significant Accounting Policy [Line Items] | ||
| Estimated useful lives of assets | 3 years | |
| Maximum [Member] | ||
| Summary Of Significant Accounting Policy [Line Items] | ||
| Estimated useful lives of assets | 5 years | |
| Other Noncurrent Assets [Member] | ||
| Summary Of Significant Accounting Policy [Line Items] | ||
| Long-term portion of restricted cash | $ 200,000 | |
| Prepaid Expenses and Other Current Assets [Member] | ||
| Summary Of Significant Accounting Policy [Line Items] | ||
| Current portion of restricted cash | $ 25,000 |