Background and Basis of Presentation - EPS (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) segment $ / shares shares	Mar. 31, 2016 USD ($) $ / shares shares
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of primary operations | segment	2
Potentially dilutive stock-based compensation awards excluded from computation of dilutive common shares | shares	72,000	140,000
Earnings (Loss) Per Basic Common Share
Income from continuing operations	$ 17.6	$ 19.2
Amounts attributable to participating securities	(0.1)	(0.2)
Net income available to common stockholders	$ 17.5	$ 19.0
Weighted-average basic shares outstanding (in shares) | shares	16,779,000	16,778,000
Basic earnings (loss) per share
Basic (in dollars per share) | $ / shares	$ 1.04	$ 1.13
Earnings (Loss) Per Diluted Common Share
Income from continuing operations	$ 17.6	$ 19.2
Amounts attributable to participating securities	(0.1)	(0.2)
Net income available to common stockholders	$ 17.5	$ 19.0
Weighted-average basic shares outstanding (in shares) | shares	16,779,000	16,778,000
Add: Assumed incremental shares under stock compensation plans (in shares) | shares	246,000	273,000
Weighted-average diluted shares (in shares) | shares	17,025,000	17,051,000
Diluted earnings (loss) per share
Diluted (in dollars per share) | $ / shares	$ 1.03	$ 1.11