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Note 4 - Receivables (Tables)
12 Months Ended
Dec. 31, 2019
Notes Tables  
Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]
    December 31,
    2019   2018
Accounts receivable–trade   $
29,134
    $
28,885
 
Less allowance for doubtful receivables    
(486
)    
(564
)
Receivables, net   $
28,648
    $
28,321