Note 3 - Goodwill and Acquired Intangible Assets- Summary of Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill	$ 13,074	$ 13,074	$ 13,074
Balance, IPR&D	28,700	28,700
Impairment, IP&D	(23,200)
Reclassification, IPR&D	(4,900)
Balance, IPR&D	600	28,700	28,700
Balance, Finite-lived Intangible Assets	1,669	1,881
Amortization expense, Finite-lived Intangible Assets	(503)	(212)	(212)
Reclassification, Finite-lived Intangible Assets	4,900
Balance, Finite-lived Intangible Assets	$ 6,066	$ 1,669	$ 1,881