Commitment and Contingencies - Additional Information (Details)
|
1 Months Ended |
3 Months Ended |
6 Months Ended |
|
Dec. 31, 2017
USD ($)
ft²
Phase
|
Sep. 30, 2016 |
Jun. 30, 2018
USD ($)
|
Jun. 30, 2017
USD ($)
|
Jun. 30, 2018
USD ($)
|
Jun. 30, 2017
USD ($)
|
| Commitment And Contingencies [Line Items] |
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|
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| Deferred rent incentives |
|
|
$ 1,100,000
|
|
$ 1,100,000
|
|
| Rent expense |
|
|
900,000
|
$ 200,000
|
1,800,000
|
$ 400,000
|
| Letters Of Credit And Secured By Restricted Cash |
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| Commitment And Contingencies [Line Items] |
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|
|
|
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| Security deposit |
$ 1,800,000
|
|
1,800,000
|
|
1,800,000
|
|
| Maximum |
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|
|
|
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| Commitment And Contingencies [Line Items] |
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|
|
|
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| Tenant improvement allowance |
|
|
$ 10,900,000
|
|
$ 10,900,000
|
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| Bedford, Massachusetts |
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| Commitment And Contingencies [Line Items] |
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|
|
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| Operating lease expiration year and month |
2027-02
|
2021-10
|
|
|
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| Operating lease agreements additional term |
|
3 years
|
|
|
|
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| Office space leased | ft² |
67,000
|
|
|
|
|
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| Lessee, operating lease, lease not yet commenced, renewal term |
5 years
|
|
|
|
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| Number of phases | Phase |
2
|
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|
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| Initial annual base rent per square foot |
$ 39.50
|
|
|
|
|
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| Percentage increase in initial annual base rent per square foot. |
3.00%
|
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| Bedford, Massachusetts | Phase One |
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| Commitment And Contingencies [Line Items] |
|
|
|
|
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| Office space leased | ft² |
46,000
|
|
|
|
|
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| Bedford, Massachusetts | Phase Two |
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|
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| Commitment And Contingencies [Line Items] |
|
|
|
|
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| Office space leased | ft² |
21,000
|
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