Condensed Consolidated Balance Sheets (Parentheticals) - $ / shares shares in Thousands	Mar. 31, 2018	Dec. 31, 2017
Common Stock, Par or Stated Value Per Share	$ 0.25
Preferred Stock, Shares Authorized	300	300
Preferred Stock, Shares Outstanding	0	0
Treasury Stock, Shares	3,751	3,701
Common Shares [Member]
Common Stock, Shares Authorized	100,000	100,000
Common Stock, Shares, Issued	36,872	36,532
Common Stock, Par or Stated Value Per Share	$ 0	$ 0
Class B Common Shares [Member]
Common Stock, Shares Authorized	12,000	12,000
Common Stock, Shares, Issued	6	6
Common Stock, Par or Stated Value Per Share	$ 0	$ 0