Note 5 - Revenues - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Balance	$ 602	$ 554
Unbilled	685	551
Billings	(474)	(433)
Balance	813	672
Balance	3,200
Balance	4,000
Deferred Membership Dues [Member]
Billings	2,387	1,739
Balance	3,153	2,899
Revenue recognized	(1,522)	(1,322)
Balance	4,018	3,316
Customer Advance Deposits [Member]
Billings	255	287
Balance	553	453
Revenue recognized	(178)	(204)
Balance	$ 630	$ 536