Note 5 - Leasing Arrangements - Rental Income under Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Minimum rentals	$ 2,863	$ 2,720
Percentage rentals	1,779	1,544
Licensing fees	912	903
Other (primarily common area recoveries)	1,353	1,056
Leasing	8,148	7,266
Water System Sales [Member]
Leasing	$ 1,241	$ 1,043