Note I - Income Taxes (Details Textual) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016
Statute of Limitations	3 years
Income Tax Examination, Penalties and Interest Expense	$ 0	$ 0
Foreign Tax Authority [Member] \| Canada Revenue Agency [Member] \| Earliest Tax Year [Member]
Open Tax Year	2013

The sum of the amounts of estimated penalties and interest recognized in the period arising from income tax examinations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

Name:	us-gaap_IncomeTaxExaminationPenaltiesAndInterestExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration