Stockholders' Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended		1 Months Ended	3 Months Ended			6 Months Ended			0 Months Ended
	May 03, 2012	Feb. 03, 2012	May 31, 2011	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2012	Jun. 30, 2011	Feb. 02, 2010	Aug. 03, 2012 Subsequent Event [Member]
Class of Stock [Line Items]
Common stock, dividends, per share, declared	$ 0.17	$ 0.17								$ 0.17
Dividend declared and paid, common shares							$ 3.9	$ 0
Stock repurchase program, authorized amount			30
Line of credit facility, funds for future share repurchases									30
Common stock repurchased under repurchase program, shares				0	171,600	0	17,800	171,600
Common stock repurchased, average price per share					$ 34.68		$ 39.50	$ 34.68
Common stock repurchased, amount					6.0		0.7	6.0
Cash expended for repurchase of common stock							0.7	5.4
Common stock repurchased, unsettled trades					0.6			0.6
Common stock available for future share repurchases, amount							$ 10.3