Condensed Consolidated Balance Sheets (Unaudited Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Consolidated Balance Sheets [Abstract]
Allowance for doubtful accounts	$ 20,163	$ 16,916
Accumulated depreciation, depletion and amortization, property, plant, and equipment	$ 742,810	$ 732,390
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	450,000,000	450,000,000
Common stock, shares issued	155,909,884	155,651,116