Business and Basis of Presentation (Detail)		3 Months Ended
	May 12, 2017	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($) $ / shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Organization And Basis Of Presentation [Line Items]
Proceeds from Collaborators		$ 5,000,000
Revenues		4,942,990	$ 4,306,122
Accounts receivable, net		1,588,720		$ 1,049,329
Net proceeds from issuance of stock and warrants		0	6,302,000
Accumulated deficit		189,873,944		191,338,054
Cash and cash equivalents		6,097,792	6,897,161	4,043,681	$ 3,949,135
Deferred revenue		0		820,031
Allowance for doubtful accounts		25,000
Reverse stock split conversion ratio	0.125
Prepaid expenses and other current assets		952,985		1,867,803
Assets, Current		10,498,149		9,103,374
Accrued Sales Return provisions		1,405,117		666,375
Liabilities, Current		4,150,439		4,581,835
Stockholders' Equity Attributable to Parent		6,822,524		5,017,389
Cost of revenues		2,955,260	2,697,602
Gross Profit		1,987,730	1,608,520
Net Income (Loss) Available to Common Stockholders, Diluted		1,166,252	$ (7,274,082)
Net loss per common share applicable to common stockholders, basic and diluted (in dollars per share) | $ / shares			$ (7.27)
Noninterest Income, Other		4,755,705
Compensation cost not yet recognized		$ 314,025
Compensation cost not yet recognized, period for recognition		2 years 4 months 24 days
Maximum
Organization And Basis Of Presentation [Line Items]
Future Milestone Payments Receivable [Line Items]		$ 21,500,000
Collaborator Payments Receivable		$ 26,500,000
Customer Concentration Risk | One Customer | Revenue
Organization And Basis Of Presentation [Line Items]
Concentration risk, percentage			17.00%
Customer Concentration Risk | Customers [Member] | Accounts Receivable
Organization And Basis Of Presentation [Line Items]
Concentration risk, percentage		46.00%	66.00%
Customer Concentration Risk | Two Customers | Revenue
Organization And Basis Of Presentation [Line Items]
Concentration risk, percentage		32.00%
ASU 2014-09 Adjustment [Member]
Organization And Basis Of Presentation [Line Items]
Revenues			$ 7,654
Accounts receivable, net				1,353,499
Accumulated deficit				(297,858)
Deferred revenue				(820,031)
Prepaid expenses and other current assets				(1,356,405)
Assets, Current				770,008
Accrued Sales Return provisions				1,292,181
Liabilities, Current				472,150
Stockholders' Equity Attributable to Parent				297,858
Cost of revenues			26,029
Gross Profit			(18,375)
Net Income (Loss) Available to Common Stockholders, Diluted			$ (18,375)
Net loss per common share applicable to common stockholders, basic and diluted (in dollars per share) | $ / shares			$ (0.02)
ASU 2014-09 Adjusted [Member]
Organization And Basis Of Presentation [Line Items]
Revenues			$ 4,313,776
Accounts receivable, net				2,402,828
Accumulated deficit				191,040,196
Deferred revenue				0
Prepaid expenses and other current assets				511,398
Assets, Current				9,873,382
Accrued Sales Return provisions				1,958,556
Liabilities, Current				5,053,985
Stockholders' Equity Attributable to Parent				$ 5,315,247
Cost of revenues			2,723,631
Gross Profit			1,590,145
Net Income (Loss) Available to Common Stockholders, Diluted			$ (7,292,457)
Net loss per common share applicable to common stockholders, basic and diluted (in dollars per share) | $ / shares			$ (7.29)