Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares	Jun. 30, 2016	Dec. 31, 2015
Common Class A [Member]
Common stock, shares authorized (in shares)	60,000,000	60,000,000
Common stock, shares outstanding (in shares)	29,615,609	30,303,818
Treasury stock, shares (in shares)	934,171
Common Class B [Member]
Common stock, shares authorized (in shares)	20,000,000	20,000,000
Common stock, shares outstanding (in shares)	10,167,314	10,093,305
Treasury stock, shares (in shares)	2,728,624	2,616,657
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01