CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 1,501	$ 1,655
Property, plant and equipment, accumulated depreciation	$ 227,348	$ 222,189
Capital Stock, par value (in dollars per share)	$ 1	$ 1
Capital Stock, authorized shares (shares)	50,000,000	50,000,000
Capital Stock, shares outstanding (shares)	18,226,942	17,854,506