Note 4 - Fair Value Measurements - Summary of Activities in Financial Instruments With Level 3 Inputs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Balance	$ 11,900	$ 17,600	$ 11,000	$ 16,800
Fair value change included in net loss	916	1,300	1,816	2,100
Payments	(8,016)		(8,016)
Balance	4,800	18,900	4,800	18,900
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	$ 916	$ 1,300	$ 1,816	$ 2,100