Note 11 - Financial Instruments and Fair Value Disclosures (Tables)

12 Months Ended

Dec. 31, 2018

Statement Line Items [Line Items]

Disclosure of fair value measurement of assets [text block]

	Year ended December 31, 2018
	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	130,180	$	–	$	–	$	130,180
Investments (Note 5) (1)		1,742		39		–		1,781
	$	131,922	$	39	$	–	$	131,961

	Year ended December 31, 2017
	Level 1		Level 2		Level 3		Total
Cash and cash equivalents	$	160,395	$	–	$	–	$	160,395
Investments (Note 5) (1)		2,435		661		–		3,096
	$	162,830	$	661	$	–	$	163,491