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Subsequent Events - Additional Information (Detail) - Office Space [Member] $ in Millions |  | 1 Months Ended
--- | --- | ---
Jan. 17, 2018 USD ($) ft² Option | Aug. 31, 2015
Subsequent Event [Line Items] |  |
Term of lease |  | 5 years
Lease renewal term |  | 5 years
Subsequent Event [Member] | Lease Agreements [Member] | Cambridge, Massachusetts [Member] | U.S. REIF Central Plaza Massachusetts, LLC [Memebr] |  |
Subsequent Event [Line Items] |  |
Area of office space | ft² | 7,800 |
Term of lease | 7 years |
Lease expiration date | Dec. 01, 2018 |
Lease renewal term | 5 years |
Number of renewal options | Option | 2 |
Operating lease, option to extend | the Company has two consecutive options to extend the Lease Term for an additional period of five years (the “Option Terms”), subject to certain conditions, upon notice to the Landlord. |
Operating leases annual base rent initial | $ 0.5 |
Operating leases annual base rent final | $ 0.6 |
Operating lease percentage of annual base rent | 100.00% |

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- Definition Operating lease percentage of annual base rent. + References No definition available. + Details
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- Definition Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980 + Details
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- Definition Description of terms and conditions of option to extend lessee's operating lease. Includes, but is not limited to, information about option recognized as part of right-of-use asset and lease liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980 + Details
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- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
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