Annual report pursuant to Section 13 and 15(d)

Fair Value of Financial Assets and Liabilities (Schedule of Financial Assets Measured at Fair Value) (Details)

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Fair Value of Financial Assets and Liabilities (Schedule of Financial Assets Measured at Fair Value) (Details) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Short-term investments $ 40,000 $ 30,731
Other assets – advance payment to supplier 2,649 1,472
Total 42,649 32,203
Level 1    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Short-term investments 40,000 30,731
Total 40,000 30,731
Level 3    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Other assets – advance payment to supplier 2,649 1,472
Total $ 2,649 $ 1,472