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	151.6			151.6
Repurchases of common stock	(532.9)				(532.9)
Stock-based compensation expense	11.2		11.2
Shares awarded under stock-based compensation plans, including income tax benefit of $2.0	3.7		(3.8)		7.5
BALANCE at Jun. 30, 2012	$ 1,528.2	$ 1.6	$ 27.0	$ 2,798.2	$ (1,298.6)
BALANCE, shares at Jun. 30, 2012		163,562,149