Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	$ 202,648	$ 183,829
Stockholders' Equity, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Par or Stated Value Per Share	$ 1	$ 1
Preferred Stock, Shares Authorized	200,000	200,000
Preferred Stock, Shares Issued	0	0
Common Stock, Par or Stated Value Per Share	$ 1	$ 1
Common Stock, Shares Authorized	50,000,000	50,000,000
Common Stock, Shares, Issued	27,735,757	27,518,226
Treasury Stock, shares	698,183	385,942