Note 5 - Short-term Investments (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Cash, Cash Equivalents and Investments [Table Text Block]

	December 31, 2018
	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Time deposits	$	6,172	$	-	$	-	$	6,172

	December 31, 2017
	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Time deposits	$	17,601	$	-	$	-	$	17,601

Investments Classified by Contractual Maturity Date [Table Text Block]

	December 31, 2018
	Cost		Fair Value
Time deposits
Due within one year	$	6,172	$	6,172

	December 31, 2017
	Cost		Fair Value
Time deposits
Due within one year	$	17,601	$	17,601