Stock Repurchases (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended				9 Months Ended				3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012		Mar. 07, 2013	Sep. 30, 2013 Other [Member]		Sep. 30, 2012 Other [Member]		Sep. 30, 2013 Open Market [Member]	Sep. 30, 2013 Open Market [Member]	Sep. 30, 2012 Open Market [Member]		Sep. 30, 2012 Tender Offer [Member]
Equity, Class of Treasury Stock [Line Items]
Increase in number of shares authorized for repurchase					1,000,000
Remaining number of shares authorized for repurchase		394,770
Common stock repurchased, shares		1,145,701	1,298,455			6,259	[1]	13,053	[1]	282,018	1,139,442	285,402		1,000,000
Common stock repurchased, value		$ 127.2	$ 113.0	[2]		$ 0.7	[1]	$ 1.2	[1],[2]	$ 31.3	$ 126.5	$ 27.0	[2]	$ 84.8	[2]
Tender offer, offering costs	$ 0.3		$ 0.3

[1] 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 and restricted stock units.

[2] Tender Offer amount includes offering costs of $0.3 million for 2012.