Annual report pursuant to Section 13 and 15(d)

Cash Equivalents And Investments (Schedule Of Cash Equivalents And Available-For-Sale Securities) (Details)

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Cash Equivalents And Investments (Schedule Of Cash Equivalents And Available-For-Sale Securities) (Details) - USD ($)
Dec. 31, 2017
Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 11,735,000 $ 9,653,000
Gross Unrealized Gains   4,000
Gross Unrealized Losses (1,000) (1,000)
Fair Value 11,734,000 9,656,000
Cash Equivalents 6,193,000 3,851,000
Short-Term Investments 5,540,744 5,805,276
Long-Term Investments
Cash Equivalents [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 6,193,000 3,851,000
Fair Value 6,193,000 3,851,000
Cash Equivalents 6,193,000 3,851,000
Cash Equivalents [Member] | Money Market Funds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 6,193,000 3,851,000
Fair Value 6,193,000 3,851,000
Cash Equivalents 6,193,000 3,851,000
Investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 5,542,000 5,802,000
Gross Unrealized Gains   4,000
Gross Unrealized Losses (1,000) (1,000)
Fair Value 5,541,000 5,805,000
Short-Term Investments 5,541,000 5,805,000
Investments [Member] | Certificates Of Deposit [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost   4,291,000
Gross Unrealized Gains   4,000
Gross Unrealized Losses   (1,000)
Fair Value   4,294,000
Short-Term Investments   4,294,000
Investments [Member] | Commercial Paper [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 997,000  
Fair Value 997,000  
Short-Term Investments 997,000  
Investments [Member] | Corporate Notes/Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 4,545,000 1,511,000
Gross Unrealized Losses (1,000)  
Fair Value 4,544,000 1,511,000
Short-Term Investments $ 4,544,000 $ 1,511,000