Earnings Per Share and Common Stock (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share and Common Stock [Abstract]
Anti-dilutive Shares Excluded from Diluted EPS Computation	0	200,000	0	200,000
Earnings Per Share - Basic [Abstract]
Net Income	$ 25.2	$ 29.4	$ 71.7	$ 68.2
Average Common Shares	39,800,000	37,700,000	39,400,000	37,300,000
Earnings Per Share	$ 0.63	$ 0.78	$ 1.82	$ 1.83
Earnings Per Share - Diluted [Abstract]
Net Income	$ 25.2	$ 29.4	$ 71.7	$ 68.2
Average Common Shares	39,900,000	37,800,000	39,500,000	37,300,000
Earnings Per Share	$ 0.63	$ 0.78	$ 1.81	$ 1.83
Dilutive Securities (Shares)	100,000	100,000	100,000	0