Leases (Details) - Office and Laboratory Space in Needham, Massachusetts. $ in Millions	Feb. 15, 2018 USD ($) ft²	Apr. 15, 2014 ft²
Leases
Area of space \| ft²	27,810	15,197
Minimum
Leases
Operating lease expense	$ 0.7
Maximum
Leases
Operating lease expense	$ 1.1

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147478964/842-20-50-3

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