Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Allowance for doubtful accounts receivable	$ 7,488	$ 9,695
Preferred stock, undesignated, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, undesignated, shares authorized (in shares)	2,000,000	2,000,000
Preferred stock, undesignated, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	125,000,000	125,000,000
Common stock, shares issued (in shares)	30,807,548	31,922,409
Common stock, shares outstanding (in shares)	30,807,548	31,922,409