Stock Repurchases (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Equity, Class of Treasury Stock [Line Items]
Number of shares authorized for repurchase	534,212
Common stock repurchased, shares	1,740,372		1,979,444		4,047,311
Common stock repurchased, value	$ 152.5	[1]	$ 130.8	[1]	$ 202.2	[1]
Tender offer costs	0.3		0.2		0.3
Open Market [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased, shares	727,319		55,133
Common stock repurchased, value	66.5	[1]	4.2	[1]
Tender Offer [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased, shares	1,000,000		1,904,761		4,000,000
Common stock repurchased, value	84.8	[1]	125.2	[1]	200.3	[1]
Other [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased, shares	13,053	[2]	19,550	[2]	47,311	[2]
Common stock repurchased, value	$ 1.2	[1],[2]	$ 1.4	[1],[2]	$ 1.9	[1],[2]
Maximum [Member]
Equity, Class of Treasury Stock [Line Items]
Number of shares authorized for repurchase	1,000,000

[1] Tender Offer amounts include offering costs of $0.3 million, $0.2 million, and $0.3 million for 2012, 2011 and 2010, respectively.

[2] Represents shares of common stock released to us by team members as payment of tax withholdings due to us upon the vesting of restricted stock.