Stock Repurchases (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012		Mar. 07, 2013
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	1,003,417
Common stock repurchased, shares	537,054		203,896
Common stock repurchased, value	$ 59.7		$ 19.9
Other [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased, shares	6,259	[1]	13,053	[1]
Common stock repurchased, value	0.7	[1]	1.2	[1]
Open Market [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased, shares	530,795		190,843
Common stock repurchased, value	$ 59.0		$ 18.7

[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.