Business and Basis of Presentation (Detail) - USD ($)	3 Months Ended		12 Months Ended	15 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Mar. 31, 2019	Dec. 31, 2017
Organization And Basis Of Presentation [Line Items]
Proceeds from Collaborators				$ 18,700,000
Accounts receivable, net	$ 972,352		$ 1,082,957	972,352
Accumulated deficit	188,966,084		191,016,591	188,966,084
Cash and cash equivalents	7,200,795		6,780,429	7,200,795
Allowance for doubtful accounts	25,000		25,000	25,000
Prepaid expenses and other current assets	962,727		860,915	962,727
Assets, Current	11,630,142		11,586,165	11,630,142
Accrued Sales Return provisions	726,892		1,101,658	726,892
Liabilities, Current	4,502,872		6,592,897	4,502,872
Operating Lease, Liability, Noncurrent	1,211,480		1,301,172	1,211,480
Stockholders' Equity Attributable to Parent	8,192,411	$ 6,822,524	6,097,811	8,192,411	$ 5,017,389
Cost of revenues	2,324,231	2,955,260
Gross Profit	798,704	1,987,730
Net Income (Loss) Available to Common Stockholders, Diluted	2,050,507	$ 1,166,252
Compensation cost not yet recognized	$ 208,741			208,741
Compensation cost not yet recognized, period for recognition	1 year 9 months 5 days
Earnings Per Share, Basic	$ 0.26	$ 0.18
Earnings Per Share, Diluted	$ 0.15	$ 0.08
Operating Lease, Right-of-Use Asset	$ 1,870,979		1,968,062	1,870,979
Other long-term assets	30,081		30,314	30,081
Assets	13,906,763		13,991,880	13,906,763
Accrued Liabilities, Current	3,036,301		2,236,633	3,036,301
Liabilities	$ 5,714,352		$ 7,894,069	5,714,352
Maximum
Organization And Basis Of Presentation [Line Items]
Future Milestone Payments Receivable [Line Items]				6,200,000
Two Customers | Revenue | Customer Concentration Risk
Organization And Basis Of Presentation [Line Items]
Concentration risk, percentage	32.00%	32.00%
Two Customers | Accounts Receivable | Customer Concentration Risk
Organization And Basis Of Presentation [Line Items]
Concentration risk, percentage	44.00%		45.00%
CalculatedUnderRevenueGuidanceInEffectBeforeTopic842 [Member]
Organization And Basis Of Presentation [Line Items]
Prepaid expenses and other current assets	$ 1,007,579		$ 905,767	1,007,579
Assets, Current	11,674,994		11,631,017	11,674,994
Liabilities, Current	3,922,588		6,015,437	3,922,588
Operating Lease, Liability, Noncurrent	0		0	0
Operating Lease, Right-of-Use Asset	0		0	0
Other long-term assets	64,444		74,892	64,444
Assets	12,114,999		12,113,248	12,114,999
Accrued Liabilities, Current	2,456,017		1,659,173	2,456,017
Liabilities	3,922,588		6,015,437	3,922,588
DifferenceBetweenRevenueGuidanceInEffectBeforeAndAfterTopic842 [Member]
Organization And Basis Of Presentation [Line Items]
Prepaid expenses and other current assets	44,852		44,852	44,852
Assets, Current	44,852		44,852	44,852
Liabilities, Current	(580,284)		(577,460)	(580,284)
Operating Lease, Liability, Noncurrent	(1,211,480)		(1,301,172)	(1,211,480)
Operating Lease, Right-of-Use Asset	(1,870,979)		(1,968,062)	(1,870,979)
Other long-term assets	34,363		44,578	34,363
Assets	(1,791,764)		(1,878,632)	(1,791,764)
Accrued Liabilities, Current	(580,284)		(577,460)	(580,284)
Liabilities	$ (1,791,764)		$ (1,878,632)	$ (1,791,764)