CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Accounts receivable, allowance for doubtful accounts	$ 1,095	$ 1,040
Property, plant and equipment, accumulated depreciation	$ 206,463	$ 198,075
Capital Stock, par value	$ 1	$ 1
Capital Stock, authorized shares	50,000,000	50,000,000
Capital Stock, shares outstanding	16,268,268	16,220,648