Commitments and Contingencies - Additional Information (Detail)		1 Months Ended								48 Months Ended
	Mar. 06, 2018 USD ($)	Mar. 31, 2018 ft²	Dec. 31, 2017 USD ($) ft²	Oct. 31, 2017 USD ($)	Feb. 28, 2017 ft²	Oct. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	May 31, 2016	Sep. 30, 2015 Patent	Mar. 31, 2018 USD ($) ft²	Apr. 30, 2014 USD ($)
Commitments and Contingencies [Line Items]
Potential payments agreed under license agreements											$ 6,000,000
License agreement, milestones payments										$ 3,500,000
License agreement, upfront payment										$ 1,500,000
Magnetic Clutch Patents
Commitments and Contingencies [Line Items]
Patents allegedly infringed upon, number | Patent									2
European Pigtail Patent
Commitments and Contingencies [Line Items]
Patents allegedly infringed upon, number | Patent									1
German Pigtail Patent
Commitments and Contingencies [Line Items]
Patents allegedly infringed upon, number | Patent									1
Patent One
Commitments and Contingencies [Line Items]
Patent expiration period								2020-09
Patent Two
Commitments and Contingencies [Line Items]
Patent expiration period								2020-12
Patent Three
Commitments and Contingencies [Line Items]
Patent expiration period								2021-10
Settlement Agreement
Commitments and Contingencies [Line Items]
Litigation settlement agreement date	March 6, 2018
Settlement Agreement | Former Employee
Commitments and Contingencies [Line Items]
Litigation settlement, agreed to pay amount	$ 150,000
Settlement Agreement | U.S. Government
Commitments and Contingencies [Line Items]
Litigation settlement, agreed to pay amount	3,100,000
Litigation settlement, agreed to pay accrued interest	$ 30,000
Lease Agreements
Commitments and Contingencies [Line Items]
Corporate headquarters acquisition				$ 16,500,000
Lease Agreements | Massachusetts
Commitments and Contingencies [Line Items]
Additional office space | ft²		11,269	6,607		21,603					11,269
Lease expiration date					Jul. 31, 2022
Extend lease term		Aug. 31, 2025	Aug. 31, 2025
Annual rent expense			$ 400,000
Lease Agreements | Germany
Commitments and Contingencies [Line Items]
Annual rent expense							$ 300,000
Lease commencement period							2017-05
Lease expiration period							2024-05
Lease Agreements | Japan
Commitments and Contingencies [Line Items]
Annual rent expense						$ 900,000
Lease expiration period						2021-09