Note 5 - Revenues - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Balance	$ 813	$ 672	$ 602	$ 554
Unbilled	960	978	1,645	1,529
Billings	(664)	(549)	(1,138)	(982)
Balance	1,109	1,101	1,109	1,101
Balance			3,200
Billings	664	549	1,138	982
Balance	4,800		4,800
Deferred Membership Dues [Member]
Billings	(2,254)	(2,605)	(4,641)	(4,344)
Balance	4,018	3,316	3,153	2,899
Billings	2,254	2,605	4,641	4,344
Revenue recognized	(1,496)	(1,424)	(3,018)	(2,746)
Balance	4,776	4,497	4,776	4,497
Customer Advance Deposits [Member]
Billings	(140)	(375)	(395)	(662)
Balance	630	536	553	453
Billings	140	375	395	662
Revenue recognized	(118)	(355)	(296)	(559)
Balance	$ 652	$ 556	$ 652	$ 556