Note 12 - Operating Leases (Details Textual)	6 Months Ended
Jun. 30, 2019 ft²
Operating Lease, Weighted Average Discount Rate, Percent	4.10%
Operating Lease, Weighted Average Lease Term	17 years 109 days
Administrative, Research and Development, and Manufacturing Space in Bedford, MA [Member]
Area of Real Estate Property	134,000
Office, Research and Development, Training, and Warehousing Space in Padova, Italy [Member]
Area of Real Estate Property	33,000

Weighted average discount rate for operating lease calculated at point in time.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(4)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918686-209980

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=77888399&loc=SL77918982-209971

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