CONDENSED CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Accounts receivable, allowance	$ 4,855	$ 4,866
Preferred stock par value	$ 1.00	$ 1.00
Preferred stock shares authorized	1,000,000	1,000,000
Preferred stock shares issued	0	0
Preferred stock shares outstanding	0	0
Common stock par value	$ 0.666	$ 0.666
Common stock shares authorized	70,000,000	70,000,000
Common stock shares issued	51,450,808	51,206,969
Common stock shares outstanding	51,450,808	51,206,969
Treasury stock shares issued	1,480,840	1,457,206
Treasury stock shares outstanding	1,480,840	1,457,206