Unaudited Condensed Consolidated Statement Of Shareholders' Equity (USD $) In Millions, except Share data	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
BALANCE at Dec. 31, 2011	$ 1,894.6	$ 1.6	$ 19.6	$ 2,646.6	$ (773.2)
BALANCE, shares at Dec. 31, 2011		163,562,149
Net income	233.2			233.2
Repurchases of common stock	(533.2)				(533.2)
Stock-based compensation expense	15.2		15.2
Shares awarded under stock-based compensation plans, including income tax benefit of $8.0	28.7		(10.2)		38.9
BALANCE at Sep. 30, 2012	$ 1,638.5	$ 1.6	$ 24.6	$ 2,879.8	$ (1,267.5)
BALANCE, shares at Sep. 30, 2012		163,562,149