Consolidated Balance Sheet - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019	Dec. 31, 2018
Construction in Progress, Gross	[1]	$ 6,826			$ 12,906
Depreciation		$ 1,600	$ 1,300
Software Development [Member]
Construction in Progress, Gross				$ 2,100
Casting Machine [Member]
Construction in Progress, Gross				$ 2,100
Marlborough facility [Member]
Construction in Progress, Gross					$ 7,300

[1] Construction in progress as of December 31, 2018 included $7.3 million for the buildout of our Marlborough facility, which was put into service and began depreciating on January 1, 2019, $2.1 million in capitalized internal-use software development costs and $2.1 million for a casting machine, among other projects.