Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Redeemable convertible preferred stock, liquidation preference (usd per share)	$ 0	$ 50
Redeemable convertible preferred stock, shares outstanding	0	76,002
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, shares issued	49,598,653	49,693,532
Common stock, shares outstanding	49,598,653	49,693,532
Treasury stock, shares	9,211,857	8,738,094
Allowance for Doubtful Accounts [Member]
Allowances for receivables	$ 39.2	$ 38.3