Note 6 - Lease - Impact of New Lease Standard (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Straight-line rent expense recognized for operating lease	$ 601,000	$ 601,000	$ 601,000
Variable rent expense recognized for operating lease	264,000
Total rent expense	$ 865,000
Weighted average remaining lease term (in years) (Year)	2 years
Weighted average discount rate	12.05%