Earnings Per Share Table (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Net income, basic EPS	$ 11.7	$ 10.1	$ 14.3	$ 13.7
Weighted-average shares outstanding, basic EPS	11.5	11.4	11.5	11.4
Net income per common share, basic EPS	$ 1.02	$ 0.89	$ 1.24	$ 1.20
Effect of dilutive common share equivalents: [Abstract]
Net income, diluted EPS	$ 11.7	$ 10.1	$ 14.3	$ 13.7
Weighted-average shares outstanding, diluted EPS	11.6	11.6	11.6	11.6
Net income per common share, diluted EPS	$ 1.01	$ 0.87	$ 1.23	$ 1.18
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	$ (0.01)
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)	$ (0.01)	$ (0.01)