Basic and Diluted Earnings (Loss) Per Common Share - Components of Basic and Diluted Earnings Per Share (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator:
Income from continuing operations, net of taxes	$ 14.2	$ 11.0	$ 37.3	$ 33.6
Income (loss) from discontinued operations, net of taxes	0.4	(1.5)	0.9	(6.3)
Net income	$ 14.6	$ 9.5	$ 38.2	$ 27.3
Denominator:
Weighted average common shares outstanding - Basic (shares)	52,356,798	52,356,798	52,356,798	52,356,798
Effect of dilutive restricted stock (shares)	58,165	0	33,137	0
Weighted average common shares outstanding - Diluted (shares)	52,414,963	52,356,798	52,389,935	52,356,798
Basic earnings (loss) per common share:
Continuing operations (usd per share)	$ 0.27	$ 0.21	$ 0.71	$ 0.64
Discontinued operations (usd per share)	$ 0.01	$ (0.03)	$ 0.02	$ (0.12)
Basic earnings per share (usd per share)	$ 0.28	$ 0.18	$ 0.73	$ 0.52
Diluted earnings (loss) per common share:
Continuing operations (usd per share)	$ 0.27	$ 0.21	$ 0.71	$ 0.64
Discontinued operations (usd per share)	$ 0.01	$ (0.03)	$ 0.02	$ (0.12)
Diluted earnings per share (usd per share)	$ 0.28	$ 0.18	$ 0.73	$ 0.52