Long-Term Debt (Details) - USD ($) $ in Thousands		6 Months Ended
	Dec. 23, 2016	Jun. 30, 2017	Jun. 30, 2016	Jul. 31, 2017
Debt Instrument [Line Items]
Repayments of Long-term Debt		$ 1,278
Amortization of debt issuance costs		296	$ 307
Subsequent event
Debt Instrument [Line Items]
Increase in term loan facility				$ 20,000
NY Green Bank
Debt Instrument [Line Items]
Loan Amount	$ 25,000
Long-term borrowings	25,000	$ 23,800
Debt issuance costs	$ 1,200
Interest rate spread (as a percent)	6.00%
Effective interest rate (as a percent)		11.20%
Term of loan agreement	3 years
2017		$ 4,800
2018		9,000
2019		10,000
End of term charge		$ 1,800
NY Green Bank | Subsequent event
Debt Instrument [Line Items]
Loan Amount				45,000
Increase in term loan facility				$ 20,000