Condensed Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Accumulated Depreciation	$ 220,856	$ 202,648
Preferred stock, par value (in usd per share)	$ 1	$ 1
Preferred stock, shares authorized	200,000	200,000
Preferred stock, shares issued	0	0
Common stock, par value (in usd per share)	$ 1	$ 1
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	28,056,402	27,735,757
Common Stock held in treasury, at cost (in shares)	936,449	698,183