Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Common Class A [Member]
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	15,000,000	15,000,000
Common stock, shares issued (in shares)	8,073,993	7,855,381
Treasury stock, shares (in shares)	1,669,131	1,611,371
Allowance for doubtful accounts	$ 2,509	$ 1,794
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	71,228,023	70,989,426
Treasury stock, shares (in shares)	4,943,223	4,882,705