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, 2015	$ 405.6	$ 64.8	$ 195.6	$ 274.9	$ (40.9)	$ (88.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	31.2			31.2
Total other comprehensive income	10.1					10.1	[1]
Cash dividends declared	(12.8)			(12.8)
Stock-based payments:
Stock-based compensation	2.9		2.9
Stock option exercises and other	0.7	0.2	0.7		(0.2)
Performance share unit transactions	(2.4)	0.4	(0.4)		(2.4)
Stock repurchase program	(33.8)				(33.8)
Ending Balance at Sep. 30, 2016	401.5	65.4	198.8	293.3	(77.3)	(78.7)
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	31.2			31.2
Total other comprehensive income	9.9					9.9	[1]
Cash dividends declared	(12.6)			(12.6)
Stock-based payments:
Stock-based compensation	2.9		2.9
Stock option exercises and other	1.6	0.4	2.7		(1.5)
Performance share unit transactions	(1.9)	0.2	(0.2)		(1.9)
Ending Balance at Sep. 30, 2017	$ 425.2	$ 66.0	$ 205.7	$ 320.4	$ (84.8)	$ (82.1)

[1] Amounts in parentheses indicate debits.