Balance Sheet Details - Schedule of Fixed Assets and Accrued Liabilities (Detail) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Fixed Assets
Machinery and equipment	$ 2,818,583	$ 2,818,583
Furniture and office equipment	157,391	157,391
Computer equipment and software	1,552,891	1,437,408
Leasehold improvements	570,173	570,173
Financed equipment		2,573,955
Construction in process	103,915	116,640
Total fixed assets, gross	5,202,953	7,674,150
Less accumulated depreciation and amortization	(3,910,892)	(4,934,728)
Total fixed assets, net	1,292,061	2,739,422
Accrued Liabilities
Accrued payroll	419,259	255,426
Accrued vacation	561,340	535,682
Accrued bonuses	971,918	712,574
Accrued sales commissions	89,671	62,767
Current portion of deferred rent		158,342
Accrued other	95,608	203,602
Total accrued liabilities	$ 2,137,796	$ 1,928,393