Company Operations and Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	1 Months Ended	3 Months Ended					12 Months Ended					50 Months Ended
	Jul. 31, 2016 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) Segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2016 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Valuation Allowances and Reserves, Balance							$ 1.8	$ 1.8
Number of business segment | Segment								1
Cash and cash equivalents maximum maturity period								3 months
Product shipment costs						$ 3.9		$ 3.7	$ 3.8
Account receivable, reserves			$ 7.2				12.3	12.3	7.2			$ 7.2
Advertising cost expensed						0.7		0.5	0.3
Company's grant revenue		$ 0.0						$ 6.5	5.1			20.9
Prior period reclassification adjustment	$ 0.6		$ 6.5	$ 0.7	$ 0.7	$ 2.5	$ 2.6		$ 0.7	$ 6.3	$ 2.4	$ 0.6
Minimum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of the assets								3 years
Maximum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful lives of the assets								15 years