Background and Basis of Presentation - EPS (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) primary_operation $ / shares shares	Mar. 31, 2018 USD ($) $ / shares shares
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of primary operations | primary_operation	2
Earnings (Loss) Per Basic Common Share
Income from continuing operations	$ 11.8	$ 16.2
Amounts attributable to participating securities	0.0	(0.1)
Net income available to common stockholders	$ 11.8	$ 16.1
Weighted-average basic shares outstanding (in shares) | shares	16,862,000	16,847,000
Basic earnings per share (in dollars per share) | $ / shares	$ 0.70	$ 0.96
Earnings (Loss) Per Diluted Common Share
Income from continuing operations	$ 11.8	$ 16.2
Amounts attributable to participating securities	0.0	(0.1)
Net income available to common stockholders	$ 11.8	$ 16.1
Weighted-average diluted shares
Weighted-average basic shares outstanding (in shares) | shares	16,862,000	16,847,000
Add: Assumed incremental shares under stock compensation plans (in shares) | shares	59,000	159,000
Weighted-average diluted shares (in shares) | shares	16,921,000	17,006,000
Diluted earnings per share (in dollars per share) | $ / shares	$ 0.69	$ 0.95
Potentially dilutive stock-based compensation awards excluded from computation of dilutive common shares (in shares) | shares	231,332	197,200