Note 7 - Accounts and Other Receivables and Concentrations of Credit Risk (Tables)
|12 Months Ended|
Dec. 31, 2017
|Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]||
Tabular disclosure of the various types of trade accounts and notes receivable and for each the gross carrying value, allowance, and net carrying value as of the balance sheet date. Presentation is categorized by current, noncurrent and unclassified receivables.
Reference 1: http://www.xbrl.org/2003/role/presentationRef