Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Allowances for credit losses	$ 1,262	$ 1,424
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	1,000,000	1,000,000
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Class A [Member]
Common stock, authorized (in shares)	60,000,000	60,000,000
Common stock, outstanding (in shares)	42,208,299	41,930,472
Treasury stock (in shares)	0	7,583,674
Common Class B [Member]
Common stock, authorized (in shares)	20,000,000	20,000,000
Common stock, outstanding (in shares)	12,518,877	12,360,729
Treasury stock (in shares)	24,892	7,959,511