Consolidated Balance Sheet (Current Period Unaudited) (Parentheticals) - $ / shares $ / shares in Thousands	Mar. 31, 2021	Dec. 31, 2020
Common Class A [Member]
Class of common stock, par value (in dollars per share)	$ 0	$ 0
Class of common stock, shares authorized (in shares)	10,000,000	10,000,000
Class of common stock, shares issued (in shares)	2,678,787	2,678,787
Treasury shares, issued (in shares)	41,729	39,467
Common Class B [Member]
Class of common stock, par value (in dollars per share)	$ 0	$ 0
Class of common stock, shares authorized (in shares)	2,500,000	2,500,000
Class of common stock, shares issued (in shares)	954,283	954,283
Treasury shares, issued (in shares)	182,435	182,435