Note 4 - Deferred Compensation Plan (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Deferred Compensation Arrangement with Individual, Compensation Expense	$ 7,000	$ 16,300
Deferred Compensation Liability, Current and Noncurrent, Total	5,592,167		$ 5,248,656
Deferred Compensation Share-based Arrangements, Liability, Current and Noncurrent	$ 4,150,000		$ 3,967,000
Share Price	$ 1,396		$ 1,333
Deferred Share and Phantom Shares [Member]
Deferred Compensation Arrangement with Individual, Compensation Expense	$ 336,000	$ 56,000