Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details) - USD ($)		1 Months Ended		3 Months Ended				9 Months Ended		12 Months Ended
	Nov. 29, 2019	Jan. 31, 2020	Oct. 31, 2019	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Mar. 31, 2016	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Concentration Risk [Line Items]
Sale of common stock (in shares)								539,152
Exercise price of common stock (in dollars per share)				$ 3.50				$ 3.50
Proceeds from issuance of warrants								$ 1,900,000
Issuance of warrants, January 2020				$ 1,555,000	$ 103,000			197,394
Proceeds from the exercise of warrants								676,000	$ 0
Amount paid for clearing fees		$ 231,000
Offering costs		474,000
Proceeds from sale of common stock		$ 2,300,000
Percentage of gross proceeds used to make payments on note		10.00%
Gross proceeds		$ 275,000
Payments on the Iliad Note								$ 976,000	$ 0
Note Purchase Agreement
Concentration Risk [Line Items]
Percentage of gross proceeds used to make payments on note	10.00%
Payments on the Iliad Note		$ 226,000
Institutional Investor
Concentration Risk [Line Items]
Sale of common stock (in shares)		688,360		497,472
Exercise price of common stock (in dollars per share)		$ 3.37
Purchase price (in usd per share)		0.625
Private Placement
Concentration Risk [Line Items]
Sale of common stock (in shares)				41,680				48,185
Exercise price of common stock (in dollars per share)		$ 4.99		$ 4.9940				$ 4.9940
Amount paid for placement agent commissions		$ 193,000
Amount paid related to expenses for registered direct offering and concurrent private placement		$ 50,000
All Other Products
Concentration Risk [Line Items]
Warranty service periods			5 years
LEDFL Tubular LED Lamps (Excluding Red Caps)
Concentration Risk [Line Items]
Warranty service periods			10 years
Common Stock
Concentration Risk [Line Items]
Securities excluded from net loss per share calculation (in shares)						0
Equity Option
Concentration Risk [Line Items]
Securities excluded from net loss per share calculation (in shares)				117,000				57,000	0
Restricted Stock Units
Concentration Risk [Line Items]
Securities excluded from net loss per share calculation (in shares)				13,000				7,000	31,000
Warrant
Concentration Risk [Line Items]
Securities excluded from net loss per share calculation (in shares)				321,000				152,000	507,000
Convertible securities
Concentration Risk [Line Items]
Securities excluded from net loss per share calculation (in shares)				519,000		514,000		531,000
Minimum
Concentration Risk [Line Items]
Warranty service periods							1 year
Maximum
Concentration Risk [Line Items]
Warranty service periods							5 years
Customer concentration risk
Concentration Risk [Line Items]
Concentration risk (less than for one percent)				10.00%				10.00%
Customer concentration risk | Distributor To The U.S. Navy | Revenue
Concentration Risk [Line Items]
Concentration risk (less than for one percent)				67.00%		27.00%		52.00%	20.00%
Customer concentration risk | Distributor To The U.S. Navy | Accounts receivable
Concentration Risk [Line Items]
Concentration risk (less than for one percent)								73.00%		10.00%
Customer concentration risk | Distributor for the U.S. Navy and a Regional Commercial Lighting Retrofit Company | Revenue
Concentration Risk [Line Items]
Concentration risk (less than for one percent)				12.00%		14.00%		14.00%	23.00%
Customer concentration risk | Distributor for the U.S. Navy and a Regional Commercial Lighting Retrofit Company | Accounts receivable
Concentration Risk [Line Items]
Concentration risk (less than for one percent)										41.00%
Customer concentration risk | U.S. Navy and Shipbuilders | Revenue
Concentration Risk [Line Items]
Concentration risk (less than for one percent)						30.00%		58.00%	27.00%
Customer concentration risk | Global Healthcare Provider | Revenue
Concentration Risk [Line Items]
Concentration risk (less than for one percent)						15.00%
Customer concentration risk | Distributor To The U.S. Navy Combined With Sales To Shipbuilders | Revenue
Concentration Risk [Line Items]
Concentration risk (less than for one percent)				68.00%
Customer concentration risk | Two Offshore Suppliers | Accounts receivable | Minimum
Concentration Risk [Line Items]
Concentration risk (less than for one percent)				20.00%				14.00%
Customer concentration risk | Two Offshore Suppliers | Accounts receivable | Maximum
Concentration Risk [Line Items]
Concentration risk (less than for one percent)				25.00%				19.00%
Customer concentration risk | Two Offshore Suppliers | Accounts Payable | Minimum
Concentration Risk [Line Items]
Concentration risk (less than for one percent)								24.00%
Customer concentration risk | Two Offshore Suppliers | Accounts Payable | Maximum
Concentration Risk [Line Items]
Concentration risk (less than for one percent)								35.00%
Customer concentration risk | One Offshore Supplier | Accounts receivable
Concentration Risk [Line Items]
Concentration risk (less than for one percent)						18.00%			20.00%
Customer concentration risk | One Offshore Supplier | Accounts Payable
Concentration Risk [Line Items]
Concentration risk (less than for one percent)								36.70%
Customer concentration risk | One Domestic Supplier | Accounts Payable
Concentration Risk [Line Items]
Concentration risk (less than for one percent)								16.00%
Geographic concentration risk | Revenue | Countries outside of the United States
Concentration Risk [Line Items]
Concentration risk (less than for one percent)						0.00%			1.00%