Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Beginning Balance at Dec. 31, 2016	$ 394.1	$ 65.4	$ 200.3	$ 301.8	$ (81.4)	$ (92.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	7.3			7.3
Total other comprehensive income	1.4					1.4	[1]
Cash dividends declared	(4.2)			(4.2)
Stock-based payments:
Stock-based compensation	0.4		0.4
Stock option exercises and other	0.6	0.1	0.5
Performance share unit transactions	(1.9)	0.2	(0.2)		(1.9)
Ending Balance at Mar. 31, 2017	397.7	65.7	201.0	304.9	(83.3)	(90.6)
Beginning Balance at Dec. 31, 2017	457.4	66.1	207.7	346.6	(86.1)	(76.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	12.9			12.9
Total other comprehensive income	2.9					2.9	[1]
Cash dividends declared	(4.2)			(4.2)
Stock-based payments:
Stock-based compensation	0.9		0.9
Stock option exercises and other	0.0		0.2		(0.2)
Ending Balance at Mar. 31, 2018	$ 469.9	$ 66.1	$ 208.8	$ 355.3	$ (86.3)	$ (74.0)

[1] Amounts in parentheses indicate losses.