Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares	Jun. 30, 2015	Dec. 31, 2014
Common Class A [Member]
Common stock, shares authorized (in shares)	60,000,000	60,000,000
Common stock, shares outstanding (in shares)	30,205,415	29,889,332
Common Class B [Member]
Common stock, shares authorized (in shares)	20,000,000	20,000,000
Common stock, shares outstanding (in shares)	10,093,305	9,999,122
Treasury stock, shares (in shares)	2,616,657	2,560,580
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01