Note 8 - Leases - Liabilities Related to Costs of Exit From Leased Premises (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Balance as of January 1, 2018		$ 233
Costs of exit from leased premises			359
Deferred rent on cease-use date			19
Impairment of property and equipment			(106)
Cash paid, net of receipts	$ (2,799)	$ (1,272)	(41)
Accretion charges, included in rent expense			2
Balance as of December 31, 2018			$ 233