Basic and Diluted Earnings Per Common Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Numerator
Income from continuing operations	$ 10.7	$ 5.9	$ 19.2	$ 16.3
Income from discontinued operations, net of taxes	0.4	0.6	0.4	0.6
Net income	$ 11.1	$ 6.5	$ 19.6	$ 16.9
Denominator
Weighted average common shares outstanding - Basic	52,349,583	52,175,628	52,340,463	52,164,735
Effect of dilutive restricted stock	7,580	154,469	16,541	141,600
Weighted Average Number of Shares Outstanding, Diluted	52,357,163	52,330,097	52,357,004	52,306,335
Basic income per common share:
Continuing operations	$ 0.20	$ 0.11	$ 0.36	$ 0.31
Discontinued operations	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Net income	$ 0.21	$ 0.12	$ 0.37	$ 0.32
Diluted income per common share:
Continuing operations	$ 0.20	$ 0.11	$ 0.36	$ 0.31
Discontinued operations	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Net income	$ 0.21	$ 0.12	$ 0.37	$ 0.32