XML 42 R32.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Nature of the Business and Basis of Presentation - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified | 9 Months Ended | 12 Months Ended | 0 Months Ended |
--- | --- | --- | --- | ---
Sep. 30, 2014 | Dec. 31, 2013 | Jun. 24, 2014 | Dec. 31, 2012
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items] |  |  |  |
Entity incorporation date | Nov. 22, 2005 | Nov. 22, 2005 |  |
Accumulated deficit | $ (94,454)us-gaap_RetainedEarningsAccumulatedDeficit | $ (68,907)us-gaap_RetainedEarningsAccumulatedDeficit |  | $ (54,880)us-gaap_RetainedEarningsAccumulatedDeficit
Net proceeds from initial public offering | 102,672 us-gaap_ProceedsFromIssuanceInitialPublicOffering |  |  |
Maximum [Member] |  |  |  |
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items] |  |  |  |
Net proceeds from initial public offering |  | 35,000 us-gaap_ProceedsFromIssuanceInitialPublicOffering / us-gaap_RangeAxis = us-gaap_MaximumMember |  |
Common Stock [Member] | IPO [Member] |  |  |  |
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items] |  |  |  |
Net proceeds from initial public offering |  |  | 102,672 us-gaap_ProceedsFromIssuanceInitialPublicOffering / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_IPOMember |
Initial public offering, common stock issued, shares |  |  | 6,900,000 us-gaap_StockIssuedDuringPeriodSharesNewIssues / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_IPOMember |
Initial public offering, common stock issued per share |  |  | $ 16.00 us-gaap_SharesIssuedPricePerShare / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_IPOMember |
Offering costs incurred |  |  | $ 2,508 zfgn_InitialPublicOfferingCost / us-gaap_StatementEquityComponentsAxis = us-gaap_CommonStockMember / us-gaap_StatementScenarioAxis = us-gaap_IPOMember |

X
- Definition Date when an entity was incorporated + References No definition available. + Details
Name: | dei_EntityIncorporationDateOfIncorporation
Namespace Prefix: | dei_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition The cash inflow associated with the amount received from entity's first offering of stock to the public. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceInitialPublicOffering
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cumulative amount of the reporting entity's undistributed earnings or deficit. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 31 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.31(a)(3)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_RetainedEarningsAccumulatedDeficit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount per share or per unit of equity securities issued by non-development stage entity. + References No definition available. + Details
Name: | us-gaap_SharesIssuedPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of new stock issued during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Initial Public Offering Cost + References No definition available. + Details
Name: | zfgn_InitialPublicOfferingCost
Namespace Prefix: | zfgn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | zfgn_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems
Namespace Prefix: | zfgn_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |