Consolidated Statements 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, Amount at Dec. 31, 2009	$ 2,303.2	$ 1.9	$ 480.2	$ 2,221.0	$ (399.9)
BALANCE, Shares at Dec. 31, 2009		193,562,149
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	226.6			226.6
Repurchases of common stock	(524.4)				(524.4)
Treasury stock cancellation, shares	(30,000,000)	(30,000,000)
Treasury stock cancellation, amount	0	(0.3)	(483.7)	(82.4)	566.4
Stock-based compensation expense	15.9		15.9
Shares awarded under stock-based compensation plans, including excess income tax benefit of $10.6 in 2012, $22.8 in 2011 and $7.7 in 2010	57.6		(10.4)		68.0
BALANCE, Amount at Dec. 31, 2010	2,078.9	1.6	2.0	2,365.2	(289.9)
BALANCE, Shares at Dec. 31, 2010		163,562,149
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	281.4			281.4
Repurchases of common stock	(584.9)				(584.9)
Stock-based compensation expense	18.4		18.4
Shares awarded under stock-based compensation plans, including excess income tax benefit of $10.6 in 2012, $22.8 in 2011 and $7.7 in 2010	100.8		(0.8)		101.6
BALANCE, Amount 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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	316.4			316.4
Repurchases of common stock	(582.3)				(582.3)
Stock-based compensation expense	18.6		18.6
Shares awarded under stock-based compensation plans, including excess income tax benefit of $10.6 in 2012, $22.8 in 2011 and $7.7 in 2010	41.2		(11.6)		52.8
BALANCE, Amount 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