CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Accounts receivable, allowance for doubtful accounts	$ 1,784	$ 1,773
Property, plant and equipment, accumulated depreciation	$ 218,836	$ 205,575
Capital Stock, par value (dollars per share)	$ 1	$ 1
Capital Stock, authorized shares (shares)	50,000,000	50,000,000
Capital Stock, shares outstanding (shares)	17,715,820	16,904,441