Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Per Share data	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Allowance for doubtful accounts	$ 20,073	$ 18,632
Accumulated depreciation on property, plant and equipment	$ 737,037	$ 682,715
Shareholders' equity:
Common shares, par value	$ 1.25	$ 1.25
Common shares, shares authorized	120,000	120,000
Common shares, shares issued	58,931	58,931
Treasury shares, shares	3,779	3,872