Discontinued Operations (Schedule of Discontinued Operations) (Details) - Designed Structures And Solutions - Discontinued Operations, Disposed of by Sale - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales	$ 0.0	$ 15.8	$ 0.0	$ 222.1
Gain (loss) on sale	0.0	0.5	(1.5)	(295.4)
Loss from operations	0.0	(3.3)	0.0	(8.6)
Loss before taxes	0.0	(2.8)	(1.5)	(304.0)
Income tax benefit	0.0	1.4	0.4	70.2
Loss from discontinued operations, net of taxes	$ 0.0	$ (1.4)	$ (1.1)	$ (233.8)

Amount before tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

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