Income from Continuing Operations Per Unrestricted Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Schedule of Basic and Diluted Earnings Per Share [Line Items]
Income from Continuing Operations	$ 55.6	$ 1.1	$ 93.5	$ 36.7
Dilutive Effect on Income of Equity-based Compensation Equivalent Shares	0	0	0	0
Diluted Income from Continuning Operations Attributed to Unrestricted Shares	55.3	1.1	93.0	36.5
Weighted-Average Unrestricted Shares Outstanding	58,299,700	60,141,400	59,155,500	60,312,600
Equity-based Compensation Equivalent Shares	171,900	88,000	146,600	106,200
Weighted-Average Unrestricted Shares and Equivalent Shares Outstanding Assuming Dilution	58,471,600	60,229,400	59,302,100	60,418,800
Basic Income from Continuing Operations Per Unrestricted Share	$ 0.95	$ 0.01	$ 1.57	$ 0.61
Diluted Income from Continuing Operations Per Untrestriced Share	$ 0.95	$ 0.01	$ 1.56	$ 0.61
Restricted Shares [Member]
Schedule of Basic and Diluted Earnings Per Share [Line Items]
Income from Continuing Operations	0.3	0	0.5	0.2
Unrestricted Shares [Member]
Schedule of Basic and Diluted Earnings Per Share [Line Items]
Income from Continuing Operations	$ 55.3	$ 1.1	$ 93.0	$ 36.5