Discontinued Operations - Additional Information (Details) $ in Thousands		3 Months Ended			6 Months Ended
	Sep. 01, 2016 option	Jun. 30, 2019 USD ($)	Mar. 31, 2019	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contracts revenue		$ 27,319		$ 22,042	$ 51,874	$ 43,349
Cost of revenues		8,433		6,488	16,420	12,890
Supply agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contracts revenue		1,200		1,600	2,800	3,700
Cost of revenues		$ 1,200		$ 1,500	$ 2,600	$ 3,500
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