Australia Research and Development Tax Incentive - Additional Information (Detail) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Research and Development Tax Incentive [Line Items] | |||
| Unrealized foreign currency transaction gains (losses) | $ (6,000) | $ (82,000) | $ (93,000) |
| Australia [Member] | |||
| Research and Development Tax Incentive [Line Items] | |||
| Tax incentive receivable | 300,000 | 1,300,000 | |
| Maximum [Member] | Zafgen Australia Pty Limited [Member] | |||
| Research and Development Tax Incentive [Line Items] | |||
| Unrealized foreign currency transaction gains (losses) | $ (100,000) | (100,000) | (100,000) |
| Research and Development [Member] | |||
| Research and Development Tax Incentive [Line Items] | |||
| Percentage of refundable tax incentive | 45.00% | ||
| Reduction to research and development expenses | $ 300,000 | $ 1,400,000 | $ 400,000 |
| Research and Development [Member] | Australia [Member] | |||
| Research and Development Tax Incentive [Line Items] | |||
| Percentage of reduction in research and development costs | 45.00% | ||