CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Common Stock in Treasury	Noncontrolling Interest
Total stockholders' equity, Beginning of Period at Dec. 31, 2017	$ 1,222.5	$ 1.3	$ 1,322.0	$ 1,995.9	$ (239.5)	$ (1,857.7)	$ 0.5
Shares oustanding, Beginning of Period (in shares) at Dec. 31, 2017		80.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	50.3			50.3
Other Comprehensive Income (Loss) – net of tax	28.8				28.8
Issuance of Common Stock	15.9		15.9
Issuance of Common Stock (in shares)		0.8
Compensation under Stock-based Plans - net	(21.3)		(23.0)			1.7
Compensation under Stock-based Plans - net (in shares)		0.1
Dividends	(7.8)		0.2	(8.0)
Acquisition of Treasury Stock (in shares)		(5.1)
Acquisition of Treasury Stock	(209.5)					(209.5)
Other				2.6	(2.6)
Shares outstanding, End of Period (in shares) at Mar. 31, 2018		76.0
Total stockholders' equity, End of Period at Mar. 31, 2018	1,078.9	$ 1.3	1,315.1	2,040.8	(213.3)	(2,065.5)	0.5
Total stockholders' equity, Beginning of Period at Dec. 31, 2017	1,222.5	$ 1.3	1,322.0	1,995.9	(239.5)	(1,857.7)	0.5
Shares oustanding, Beginning of Period (in shares) at Dec. 31, 2017		80.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 146.7
Acquisition of Treasury Stock (in shares)	(8.0)
Acquisition of Treasury Stock	$ (325.0)
Other	(2.6)
Shares outstanding, End of Period (in shares) at Sep. 30, 2018		73.0
Total stockholders' equity, End of Period at Sep. 30, 2018	974.7	$ 1.3	1,338.7	2,121.9	(304.3)	(2,183.5)	0.6
Total stockholders' equity, Beginning of Period at Mar. 31, 2018	1,078.9	$ 1.3	1,315.1	2,040.8	(213.3)	(2,065.5)	0.5
Shares oustanding, Beginning of Period (in shares) at Mar. 31, 2018		76.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	57.8			57.8
Other Comprehensive Income (Loss) – net of tax	(74.9)				(74.9)
Issuance of Common Stock	0.3		0.3
Compensation under Stock-based Plans - net	11.3		11.2			0.1
Dividends	(7.5)		0.2	(7.7)
Acquisition of Treasury Stock (in shares)		(2.9)
Acquisition of Treasury Stock	(117.8)					(117.8)
Shares outstanding, End of Period (in shares) at Jun. 30, 2018		73.1
Total stockholders' equity, End of Period at Jun. 30, 2018	948.1	$ 1.3	1,326.8	2,090.9	(288.2)	(2,183.2)	0.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	38.6			38.6
Other Comprehensive Income (Loss) – net of tax	(16.0)				(16.1)		0.1
Issuance of Common Stock	0.7		0.7
Compensation under Stock-based Plans - net	10.9		10.9
Dividends	(7.3)		0.3	(7.6)
Acquisition of Treasury Stock (in shares)		(0.1)
Acquisition of Treasury Stock	(0.3)					(0.3)
Shares outstanding, End of Period (in shares) at Sep. 30, 2018		73.0
Total stockholders' equity, End of Period at Sep. 30, 2018	$ 974.7	$ 1.3	1,338.7	2,121.9	(304.3)	(2,183.5)	0.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Acquisition of Treasury Stock (in shares)	(3.4)
Acquisition of Treasury Stock	$ (100.0)
Shares outstanding, End of Period (in shares) at Dec. 31, 2018		69.6
Total stockholders' equity, End of Period at Dec. 31, 2018	861.0	$ 0.8	797.3	749.0	(284.8)	(401.8)	0.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(66.6)			(66.6)
Other Comprehensive Income (Loss) – net of tax	(2.3)				(2.3)
Issuance of Common Stock	21.4		21.4
Issuance of Common Stock (in shares)		0.7
Compensation under Stock-based Plans - net	(23.0)		(24.7)			1.7
Compensation under Stock-based Plans - net (in shares)		0.1
Dividends	(7.9)		0.1	(8.0)
Acquisition of Treasury Stock	(0.3)					(0.3)
Shares outstanding, End of Period (in shares) at Mar. 31, 2019		70.4
Total stockholders' equity, End of Period at Mar. 31, 2019	782.3	$ 0.8	794.1	674.4	(287.1)	(400.4)	0.5
Total stockholders' equity, Beginning of Period at Dec. 31, 2018	861.0	$ 0.8	797.3	749.0	(284.8)	(401.8)	0.5
Shares oustanding, Beginning of Period (in shares) at Dec. 31, 2018		69.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	29.9
Other	0.0
Shares outstanding, End of Period (in shares) at Sep. 30, 2019		70.6
Total stockholders' equity, End of Period at Sep. 30, 2019	866.3	$ 0.8	812.6	754.9	(300.3)	(401.7)	0.0
Total stockholders' equity, Beginning of Period at Mar. 31, 2019	782.3	$ 0.8	794.1	674.4	(287.1)	(400.4)	0.5
Shares oustanding, Beginning of Period (in shares) at Mar. 31, 2019		70.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	75.1			75.1
Other Comprehensive Income (Loss) – net of tax	(0.2)				(0.2)
Issuance of Common Stock	1.5		1.5
Compensation under Stock-based Plans - net	11.8		11.7			0.1
Dividends	(7.8)		0.2	(8.0)
Acquisition of Treasury Stock	(2.1)					(2.1)
Shares outstanding, End of Period (in shares) at Jun. 30, 2019		70.4
Total stockholders' equity, End of Period at Jun. 30, 2019	860.6	$ 0.8	807.5	741.5	(287.3)	(402.4)	0.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	21.4			21.4
Other Comprehensive Income (Loss) – net of tax	(13.0)				(13.0)
Issuance of Common Stock	4.2		4.2
Issuance of Common Stock (in shares)		0.2
Compensation under Stock-based Plans - net	1.7		0.7			1.0
Dividends	(7.8)		0.2	(8.0)
Acquisition of Treasury Stock	(0.3)					(0.3)
Noncontrolling Interest, Decrease from Deconsolidation	(0.5)						(0.5)
Shares outstanding, End of Period (in shares) at Sep. 30, 2019		70.6
Total stockholders' equity, End of Period at Sep. 30, 2019	$ 866.3	$ 0.8	$ 812.6	$ 754.9	$ (300.3)	$ (401.7)	$ 0.0