|
Stock-Based Awards - Additional Information (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified |
3 Months Ended | 0 Months Ended |
|---|---|---|
|
Mar. 31, 2015
|
Jan. 01, 2015
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Unrecognized stock-based compensation cost | $ 26,317us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized | |
| Stock-based compensation recognized weighted average period | 3 years 8 months 12 days | |
| Nonemployee Service Based Options [Member] | ||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Number of outstanding unvested shares held by nonemployees | 10,683us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares / us-gaap_AwardTypeAxis = zfgn_NonemployeeServiceBasedOptionsMember |
|
| 2014 Employee Stock Purchase Plan [Member] | ||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Shares available for grant | 262,136us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross / us-gaap_PlanNameAxis = zfgn_TwoThousandAndFourteenEmployeeStockPurchasePlanMember |
|
| 2014 Stock Option and Incentive Plan [Member] | ||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Shares available for grant | 1,970,599us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_PlanNameAxis = zfgn_TwoThousandFourteenStockOptionMember |
|
| Shares added to plan | 915,166us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOtherIncreasesDecreasesInPeriod / us-gaap_PlanNameAxis = zfgn_TwoThousandFourteenStockOptionMember |
| X | ||||||||||
|
- Definition
Unrecognized cost of unvested share-based compensation awards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Definition
The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Definition
Gross number of share options (or share units) granted during the period. No definition available.
|
| X | ||||||||||
|
- Definition
Number of non-vested options outstanding. No definition available.
|
| X | ||||||||||
|
- Definition
The addition or reduction in the number of reserved shares that could potentially be issued under the option plan attributable to reasons other than grants, exercises, forfeitures, and expirations during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Details
|
| X | ||||||||||
|
- Details
|