Note 4 - Fair Value Measurements - Summary of Activities in Financial Instruments With Level 3 Inputs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Balance	$ 4,800	$ 18,900	$ 11,000	$ 16,800
Fair value change included in net loss	(500)	(8,000)	1,316	(5,900)
Payments			(8,016)
Balance	4,300	10,900	4,300	10,900
Changes in unrealized gains or losses for the period included in earnings (or changes in net assets) for liabilities held at the end of the reporting period	$ (500)	$ (8,000)	$ 1,316	$ (5,900)