Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheets [Abstract]
Allowances for trade accounts receivable	$ 44.0	$ 43.3
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	124,126,624	124,126,624
Common stock, shares outstanding	102,339,587	106,269,919
Treasury stock, shares	21,772,037	17,841,705