Background and Basis of Presentation - EPS (Details) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) $ / shares shares	Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2019 USD ($) primary_operation $ / shares shares	Jun. 30, 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 (loss) from continuing operations | $	$ 13.6	$ (4.8)	$ 25.4	$ 11.4
Amounts attributable to participating securities | $	(0.1)	(0.1)	(0.2)	(0.1)
Net income (loss) available to common stockholders | $	$ 13.5	$ (4.9)	$ 25.2	$ 11.3
Weighted-average basic shares outstanding (in shares) | shares	16,863,000	16,827,000	16,861,000	16,842,000
Basic earnings (loss) per share (in dollars per share) | $ / shares	$ 0.80	$ (0.29)	$ 1.50	$ 0.67
Earnings (Loss) Per Diluted Common Share
Income (loss) from continuing operations | $	$ 13.6	$ (4.8)	$ 25.4	$ 11.4
Amounts attributable to participating securities | $	(0.1)	(0.1)	(0.2)	(0.1)
Net income (loss) available to common stockholders | $	$ 13.5	$ (4.9)	$ 25.2	$ 11.3
Weighted-average diluted shares
Weighted-average basic shares outstanding (in shares) | shares	16,863,000	16,827,000	16,861,000	16,842,000
Add: Assumed incremental shares under stock compensation plans (in shares) | shares	47,000	0	53,000	147,000
Weighted-average diluted shares (in shares) | shares	16,910,000	16,827,000	16,914,000	16,989,000
Diluted earnings (loss) per share (in dollars per share) | $ / shares	$ 0.80	$ (0.29)	$ 1.49	$ 0.66
Potentially dilutive stock-based compensation awards excluded from computation of dilutive common shares (in shares) | shares	230,928	250,095	231,129	196,530
Incremental shares resulting from diluted options (in shares) | shares		126,000