Unaudited Condensed Consolidated Statement Of Shareholders' Equity (USD $) In Millions, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
BALANCE at Dec. 31, 2012	$ 1,688.5	$ 1.6	$ 26.6	$ 2,963.0	$ (1,302.7)
BALANCE, shares at Dec. 31, 2012		163,562,149
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	265.5			265.5
Repurchases of common stock	(6.9)				(6.9)
Stock-based compensation expense	17.3		17.3
Shares awarded under stock-based compensation plans, including income tax benefit of $8.5	29.0		(5.1)		34.1
BALANCE at Sep. 30, 2013	$ 1,993.4	$ 1.6	$ 38.8	$ 3,228.5	$ (1,275.5)
BALANCE, shares at Sep. 30, 2013		163,562,149