Earnings Per Share and Common Stock (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	0 Months Ended		3 Months Ended
	Mar. 04, 2014	Feb. 26, 2014	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share and Common Stock [Abstract]
Anti-dilutive Shares Excluded from Diluted EPS Computation			0	0.1
Earnings Per Share - Basic [Abstract]
Net Income			$ 33.5	$ 32.5
Average Common Shares			41.4	38.9
Earnings Per Share			$ 0.81	$ 0.83
Earnings Per Share - Diluted [Abstract]
Net Income			33.5	32.5
Average Common Shares			41.6	39.0
Earnings Per Share			$ 0.80	$ 0.83
Dilutive Securities (Shares)			0.2	0.1
Forward Contract Indexed to Issuer's Equity, Indexed Shares		2.8
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share		$ 48.01
Common Stock, Shares, Issued - Option Agreement	0.4
Proceeds from Issuance or Sale of Equity - Option Agreement	20.2
Forward Contract Indexed to Issuer's Equity, Dilutive effect			0
Forward Contract Indexed to Issuer's Equity, Initial Fair Value		0
Stock Issued During Period, Shares, Employee Benefit Plan			0.4
Stock Issued During Period, Value, Employee Benefit Plan			$ 19.5