Stockholders' Equity (Share Repurchase Programs) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Stockholders' Equity Note [Abstract]
Shares of common stock repurchased	511,000	149,046	521,000	176,046
Value of common stock repurchased	$ 20.5	$ 6.1	$ 21.0	$ 7.2