Quarterly report pursuant to Section 13 or 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
Mar. 31, 2019
Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Short-term investments $ 4,997 $ 40,000
Other asset – advance payment to supplier 2,617 2,649
Total 7,614 42,649
Level 1    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Short-term investments 4,997 40,000
Total 4,997 40,000
Level 3    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Other asset – advance payment to supplier 2,617 2,649
Total $ 2,617 $ 2,649