Note 6 - Goodwill, In-process Research and Development, and Other Intangible Assets - Summary of Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Goodwill	$ 13,074	$ 13,074	$ 13,074	$ 13,074
Balance, IPR&D	28,700	28,700	$ 28,700	$ 28,700
Balance, Finite-lived Intangible Assets	1,669	1,881
Amortization expense, Finite-lived Intangible Assets	(53)	(53)
Balance, Finite-lived Intangible Assets	$ 1,616	$ 1,828