Nature of Operations - Narrative (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($) position	Mar. 31, 2019 USD ($) position	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) product_family	Dec. 31, 2017 USD ($) position sales_agency region sales_agent	Dec. 31, 2016 position
Restructuring Cost and Reserve [Line Items]
Decrease in operating expense										$ 3,600	$ 8,400
Restructuring costs and asset impairment charges											$ 1,800
Number of geographic regions | region											6
Number of sales agencies | sales_agency											50
Number of sales agents | sales_agent											10
Provision for slow-moving and obsolete inventories									$ (14)	$ (17)	$ 1,400
Number of new product families | product_family										6
Change in revenue, percent	21.10%
Restructuring			$ 100	$ 100					196	$ 111	1,662
Net sales	$ 3,531	$ 2,915	$ 3,082	$ 3,177	$ 3,118	$ 5,158	$ 5,172	$ 4,659	$ 12,705	$ 18,107	$ 19,846
Number of positions eliminated | position			9	3							17	20
Flicker-Free TLEDs
Restructuring Cost and Reserve [Line Items]
Standard Product Warranty, Number of Years											10 years
Legacy Luminaire Product Line
Restructuring Cost and Reserve [Line Items]
Change in revenue, percent					17.00%					90.00%