Note 7 - Leases (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Lessee, Operating Lease, Lease Not yet Commenced, Future Lease Obligations	$ 0
Operating Lease, Lease Income, Lease Payments	$ 2,200	$ 1,900	$ 1,800
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset				$ 2,300
Maximum [Member]
Lessee, Operating Lease, Renewal Term (Year)	2 years
Lessor, Operating Lease, Remaining Lease Term (Year)	4 years
Lessor, Operating Lease, Renewal Term (Year)	5 years
Minimum [Member]
Lessor, Operating Lease, Remaining Lease Term (Year)	1 year