Note 7 - Fair Value Measurements - Reconciles Net Loss to Unrealized Loss on Equity Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net loss recognized during the period on equity securities	$ (3,745)
Less: Net loss recognized during the period on equity securities sold during the period	(534)
Unrealized loss recognized during the reporting period on equity securities still held at the reporting date	$ (3,211)