Debt - Long-Term Debt (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Sep. 01, 2016
Debt Instrument [Line Items]
Notes payable	$ 200,000	$ 1,395,000
Total	42,874,000	49,268,000
Add: capital leases (See Note 7)	222,000	480,000
Less: debt discount	(2,023,000)	(3,543,000)
Total	41,073,000	46,205,000
Less: current portion of long-term debt	(3,306,000)	(3,113,000)
Total long-term debt, net of current portion	37,767,000	43,092,000
Globus facility agreement
Debt Instrument [Line Items]
Maximum borrowing capacity	30,000,000	30,000,000	$ 30,000,000
Less: debt discount	(800,000)
Amended Credit Facility With Mid Cap
Debt Instrument [Line Items]
Maximum borrowing capacity	12,674,000	$ 17,873,000
Less: debt discount	$ (1,200,000)