Note 16 - Revenue from Contracts With Customers (Details Textual) - USD ($)	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Revenue from Contract with Customer, Including Assessed Tax	$ 156,000	$ 136,000

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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+ Details