Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Allowance for doubtful accounts receivable	$ 9,043	$ 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)	$ 1	$ 1
Common stock, shares authorized (in shares)	125,000,000	125,000,000
Common stock, shares issued (in shares)	30,941,394	31,922,409
Common stock, shares outstanding (in shares)	30,941,394	31,922,409