Consolidated Balance Sheets (Paranthetical) Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 59.0	$ 55.4
Preferred stock, no par value	$ 0.00	$ 0.00
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	200,000	200,000
Preferred stock, shares outstanding	200,000	200,000
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	492,100,000	491,400,000
Common stock, shares outstanding	417,500,000	449,500,000
Treasury stock, shares	74,600,000	41,900,000