Business and Basis of Presentation (Detail)		1 Months Ended	3 Months Ended	9 Months Ended		12 Months Ended
	May 12, 2017	Oct. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Organization And Basis Of Presentation [Line Items]
Accumulated deficit			$ 188,457,980	$ 188,457,980		$ 178,478,801
Cash and cash equivalents			3,969,218	3,969,218	$ 7,568,186	3,949,135	$ 12,462,872
Value of shipments made but not yet sold			2,272,736	2,272,736		1,247,545
Reduction to accounts receivable			1,346,942	1,346,942		619,309
Deferred revenue			925,794	925,794		628,236
Deferred costs of goods sold			1,466,230	1,466,230		910,595
Provision for expected returns recorded as accrued expense				454,730		488,200
Allowance for doubtful accounts			$ 25,000	$ 25,000		$ 25,000
Reverse stock split conversion ratio	0.125
Minimum
Organization And Basis Of Presentation [Line Items]
Product sales right of return term				30 days
Maximum
Organization And Basis Of Presentation [Line Items]
Product sales right of return term				60 days
2017 Offerings
Organization And Basis Of Presentation [Line Items]
Gross proceeds from issuance of equity				$ 14,000,000
Net proceeds from issuance of stock and warrants				$ 12,900,000
Customer Concentration Risk | One Customer | Revenue
Organization And Basis Of Presentation [Line Items]
Concentration risk, percentage			21.00%	18.00%
Customer Concentration Risk | One Different Customer | Revenue
Organization And Basis Of Presentation [Line Items]
Concentration risk, percentage					11.00%
Customer Concentration Risk | Two Customers | Accounts Receivable
Organization And Basis Of Presentation [Line Items]
Concentration risk, percentage				28.00%		41.00%
Scenario, Forecast | Q3 2017 Offering Tranche Two
Organization And Basis Of Presentation [Line Items]
Gross proceeds from issuance of equity		$ 3,500,000