Consolidated Balance Sheet - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Construction in Progress, Gross	[1]	$ 5,721		$ 5,721		$ 12,906
Depreciation		1,800	$ 1,300	5,200	$ 3,900
Furniture And Fixture [Member]
Construction in Progress, Gross		6,500		6,500
Software Development [Member]
Construction in Progress, Gross						2,100
Marlborough facility [Member]
Construction in Progress, Gross						$ 7,300
Waltham And Rancho Facilities [Member]
Construction in Progress, Gross		$ 4,900		$ 4,900

[1] Construction in progress as of September 30, 2019, includes $4.9 million, which is primarily related to various manufacturing expansion projects at our Waltham, Massachusetts and Rancho Dominguez, California facilities. Construction in progress as of December 31, 2018 includes $2.1 million of capitalized internal-use software development costs and $7.3 million for the buildout of our Marlborough, Massachusetts facility. Both projects have since been placed into service and as a result, $6.5 million of internal-use software development costs are now included in furniture and fixtures as of September 30, 2019.