Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Allowance for doubtful accounts	$ 32.6	$ 35.9
Accumulated depreciation	1,230.1	1,234.8
Intangible assets, accumulated amortization	$ 552.3	$ 498.0
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	7,500,000	7,500,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.15	$ 0.15
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	397,200,000	397,200,000
Common stock, shares outstanding	257,600,000	262,000,000
Treasury stock, shares	139,600,000	135,200,000