Stock-Based Compensation - Share-Based Compensation Included in Unaudited Results of Operations (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock option expense, included in total operating expenses	$ 40,000	$ 77,000
Officer Compensation [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock option expense, included in total operating expenses	19,000	33,000
Non-employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock option expense, included in total operating expenses	9,000	16,000
Sales, General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock option expense, included in total operating expenses	$ 12,000	$ 28,000