Note 4 - Leases - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating lease expense	$ 455	$ 470
Short-term lease and variable lease expense	147	111
Total lease expense	$ 602	$ 581
Weighted average remaining lease term under operating ROU leases (in years) (Year)	7 years 14 days	7 years 73 days
Weighted average discount rate for operating lease liabilities	5.25%	5.25%
Operating lease ROU assets obtained (in thousands)		$ 333