Discontinued Operations - Results of Operations (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating expenses:
Income (loss) from discontinued operations, net of taxes			$ 207.3	$ 19.5
Income from discontinued operations, net of taxes	$ 1.9	$ 6.9	207.3	19.5
Discontinued Operations, Disposed of by Sale \| Fairbanks Morse
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations
Net sales	0.0	74.7	7.6	203.1
Cost of sales	0.0	57.4	7.6	155.6
Gross profit	0.0	17.3	0.0	47.5
Operating expenses:
Selling, general, and administrative expenses	0.0	7.0	1.5	20.3
Other	0.0	0.8		0.8
Other			(0.1)
Total operating expenses	0.0	7.8	1.4	21.1
Income (loss) from discontinued operations before income taxes	0.0	9.5	(1.4)	26.4
Income tax benefit (expense)	0.0	(2.6)	0.3	(6.9)
Income (loss) from discontinued operations, net of taxes	0.0	6.9	(1.1)	19.5
Gain from sale of discontinued operations, net of taxes	1.9	0.0	208.4	0.0
Income from discontinued operations, net of taxes	$ 1.9	$ 6.9	$ 207.3	$ 19.5

Disposal Group, Including Discontinued Operation, Operating Expense [Abstract]

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