Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheets [Abstract]
Allowance for doubtful accounts receivable	$ 3,434	$ 3,346
Accumulated depreciation on property, plant and equipment	236,099	231,221
Accumulated amortization on other intangible assets	15,945	15,741
Deferred income taxes included in other long-term liabilities	$ 94,909	$ 92,448
Common stock, par value	$ 1	$ 1
Common stock, authorized	250,000,000	250,000,000
Common stock, issued	118,672,601	118,487,455
Treasury stock, shares	55,681,846	55,668,137