Discontinued Operations - Additional Information (Details) $ in Thousands		3 Months Ended			9 Months Ended
	Sep. 01, 2016 option	Sep. 30, 2019 USD ($)	Mar. 31, 2019	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contracts revenue		$ 29,201		$ 23,002	$ 81,075	$ 66,351
Cost of revenues		9,268		6,796	25,688	19,686
Supply agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contracts revenue		1,200		2,000	4,000	5,700
Cost of revenues		$ 1,100		$ 1,800	$ 3,700	$ 5,300
Discontinued operations, disposed of by sale | International Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Supply commitment term	3 years
Supply agreement, number of annual options to extend | option	2
Supply agreement, extended term			12 months
Supply agreement, extended period			2020-08