Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
CURRENT ASSETS:
Allowance for doubtful accounts	$ 121.4	$ 118.6
OTHER ASSETS:
Accumulated amortization on intangible assets	$ 255.4	$ 247.9
SHAREHOLDERS' EQUITY:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	25,000,000	25,000,000
Preferred stock, issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	125,000,000	125,000,000
Common stock, issued (in shares)	112,463,899	112,014,673
Treasury stock at cost (in shares)	32,990,255	32,658,685