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Note 8 - Geographic Information (Details) - Summary of Geographic Sales (USD $)
In Thousands, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Note 8 - Geographic Information (Details) - Summary of Geographic Sales [Line Items]    
Net Sales $ 13,145us-gaap_SalesRevenueNet $ 4,919us-gaap_SalesRevenueNet
UNITED STATES    
Note 8 - Geographic Information (Details) - Summary of Geographic Sales [Line Items]    
Net Sales 12,603us-gaap_SalesRevenueNet
/ us-gaap_StatementGeographicalAxis
= country_US		 4,283us-gaap_SalesRevenueNet
/ us-gaap_StatementGeographicalAxis
= country_US
International [Member]    
Note 8 - Geographic Information (Details) - Summary of Geographic Sales [Line Items]    
Net Sales $ 542us-gaap_SalesRevenueNet
/ us-gaap_StatementGeographicalAxis
= efoi_InternationalMember		 $ 636us-gaap_SalesRevenueNet
/ us-gaap_StatementGeographicalAxis
= efoi_InternationalMember