Condensed Consolidated Balance Sheet (Unaudited) (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheet [Abstract]
Allowances for doubtful receivables	$ 23.4	$ 19.3
Accumulated depreciation	$ 1,992.8	$ 1,940.9
Common stock, par value in USD per share	$ 5	$ 5
Common stock, share authorized	200,000,000	200,000,000
Common stock, share issued	150,503,327	149,713,719
Common stock shares held by wholly owned subsidiary	14,000,000	14,000,000
Common stock held in treasury	24,583,946	24,422,527