Earnings Per Share Table (Details) (USD $) In Millions, except Per 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, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Net income, basic EPS	$ 12.3	$ 10.5	$ 26.6	$ 24.2
Weighted-average shares outstanding, basic EPS	11.5	11.5	11.5	11.4
Net income per common share, basic EPS	$ 1.07	$ 0.92	$ 2.32	$ 2.12
Effect of dilutive common share equivalents: [Abstract]
Net income, diluted EPS	$ 12.3	$ 10.5	$ 26.6	$ 24.2
Weighted-average shares outstanding, diluted EPS	11.6	11.7	11.6	11.6
Net income per common share, diluted EPS	$ 1.06	$ 0.90	$ 2.29	$ 2.08
Restricted stock units [Member]
Effect of dilutive common share equivalents: [Abstract]
Incremental common shares attributable to share-based payment arrangements	0	0.1	0	0.1
Effect on basic net income per common share	$ 0.00	$ (0.01)	$ 0.00	$ (0.02)
Stock option [Member]
Effect of dilutive common share equivalents: [Abstract]
Incremental common shares attributable to share-based payment arrangements	0.1	0.1	0.1	0.1
Effect on basic net income per common share	$ (0.01)	$ (0.01)	$ (0.03)	$ (0.02)