XML 41 R35.htm IDEA: XBRL DOCUMENT v3.19.3
Note 5 - Fair Value Measurements - Fair Value of Financial Instruments (Details) - USD ($)
$ in Thousands
Sep. 30, 2019
Dec. 31, 2018
Investments:    
Investments $ 69,825 $ 69,972
Money Market Funds [Member] | Estimate of Fair Value Measurement [Member]    
Cash equivalents:    
Cash equivalents 6,406 4,984
Money Market Funds [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]    
Cash equivalents:    
Cash equivalents 6,406 4,984
Money Market Funds [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]    
Cash equivalents:    
Cash equivalents
Money Market Funds [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]    
Cash equivalents:    
Cash equivalents
Money Market Funds [Member] | Reported Value Measurement [Member]    
Cash equivalents:    
Cash equivalents 6,406 4,984
US Treasury Securities [Member] | Estimate of Fair Value Measurement [Member]    
Investments:    
Investments 69,825 69,972
US Treasury Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]    
Investments:    
Investments 69,825 69,972
US Treasury Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]    
Investments:    
Investments
US Treasury Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]    
Investments:    
Investments
US Treasury Securities [Member] | Reported Value Measurement [Member]    
Investments:    
Investments $ 69,821 $ 69,972