Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts receivable, allowance for doubtful accounts	$ 1,975	$ 1,638
Preferred stock, no par value (in dollars per share)	$ 0	$ 0
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	0	0
Common Class A [Member]
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	10,000,000	10,000,000
Common stock, shares outstanding (in shares)	2,144,912	2,174,912
Common stock, treasury shares (in shares)	1,072,769	1,072,769
Common Class B [Member]
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	30,000,000	30,000,000
Common stock, shares outstanding (in shares)	10,132,102	10,092,352
Common stock, treasury shares (in shares)	3,218,307	3,218,307