CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts receivable, allowances	$ 29.2	$ 28.9
Property and equipment, accumulated depreciation	$ 391.2	$ 375.7
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, shares authorized		1,000,000,000
Treasury stock, shares	129,218,814	128,941,621
Nonvoting Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	0	0
Common stock, shares outstanding	0	0
Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000
Common stock, shares issued	342,902,272	342,902,272