Note 10 - Shareholders' Equity (Details Textual)	Dec. 31, 2018 $ / shares shares	Dec. 31, 2017 shares	Sep. 30, 2017 shares
Preferred Stock, Shares Authorized	1,000,000	1,000,000
Common Class A [Member]
Common Stock, Shares Authorized	10,000,000	10,000,000
Common Stock, Capital Shares Reserved for Future Issuance	832,233		832,233
Common Stock, Voting Rights, per Share	1
Common Class A [Member] | Minimum [Member]
Dividends Payable, Amount Per Share | $ / shares	$ 0.10
Common Class B [Member]
Common Stock, Shares Authorized	2,500,000	2,500,000
Common Stock, Voting Rights, per Share	3