Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Allowance for doubtful accounts	$ 25,916	$ 21,491
Accumulated depreciation on property, plant and equipment	$ 837,476	$ 784,864
Shareholders’ equity:
Common shares, par value	$ 1.25	$ 1.25
Common shares, shares authorized	305,000,000	305,000,000
Common shares, shares issued	176,793,000	176,793,000
Treasury shares, shares	38,357,000	32,389,000