Condensed Consolidated Statements of Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Treasury Stock	Performance Shares Common Stock
Balance at beginning of period at Dec. 31, 2017		$ 0.4	$ 577.6	$ (97.4)	$ 256.7	$ (59.8)
Balance (in shares) at Dec. 31, 2017		35,273,864
Increase (Decrease) in Stockholders' Equity
Stock options exercised and issuance of other stock awards			(1.0)			2.9
Stock options exercised (in shares)		95,019
Restricted stock, net (in shares)		165,404
Performance shares issued (in shares)							54,546
Stock-based compensation			8.2
Other comprehensive loss				(19.2)
Net income (loss)					(67.1)
Balance (in shares) at Dec. 31, 2018		35,588,833
Balance at end of period at Dec. 31, 2018	$ 601.3	$ 0.4	584.8	(116.6)	189.6	(56.9)
Increase (Decrease) in Stockholders' Equity
Stock options exercised and issuance of other stock awards			(2.1)			2.1
Stock options exercised (in shares)		36,479
Restricted stock, net (in shares)		141,916
Performance shares issued (in shares)							54,860
Common stock repurchases (in shares)		(473,042)
Common stock repurchases		$ 7.4				(7.4)
Stock-based compensation			8.3
Other comprehensive loss				(14.4)
Net income (loss)	37.3				37.3
Balance (in shares) at Sep. 30, 2019		35,349,046
Balance at end of period at Sep. 30, 2019	$ 625.1	$ 0.4	$ 591.0	$ (131.0)	$ 226.9	$ (62.2)