Summary of Significant Accounting Policies - Inventories (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Inventories
Raw materials	$ 123,000	$ 69,000
Work-in-process	27,000	4,000
Finished goods	175,000	318,000
Inventories	325,000	$ 391,000
Impairment charge recorded to the obsolescence reserve	$ 173,000