Stock Repurchases (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 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	676,788			676,788
Common stock repurchased, shares	326,629	1,094,559		863,683		1,298,455
Common stock repurchased, value	$ 36.2	$ 93.1	[1]	$ 95.9		$ 113.0	[1]
Tender offer, offering costs		0.3				0.3
Other [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased, shares				6,259	[2]	13,053	[2]
Common stock repurchased, value				0.7	[2]	1.2	[1],[2]
Open Market [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased, shares	326,629	94,559		857,424		285,402
Common stock repurchased, value	36.2	8.3	[1]	95.2		27.0	[1]
Tender Offer [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased, shares		1,000,000				1,000,000
Common stock repurchased, value		$ 84.8	[1]			$ 84.8	[1]

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

[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 and restricted stock units.