Discontinued Operations and Assets Held for Sale - Components Reflected in Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on sale of California Discontinued Entities	$ 0.0	$ 0.0	$ 13.2	$ 0.0
Income from non-controlling interest	0.0	0.0	8.1	0.0
California Discontinued Entities | Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue	0.0	38.3	32.5	38.3
Cost of goods sold	0.0	(32.4)	3.8	(32.4)
Operating expenses	(0.6)	(8.4)	(9.4)	(8.4)
Total cost of sales	(0.6)	(40.8)	(5.6)	(40.8)
General and administrative expenses	0.0	(2.9)	(1.1)	(2.9)
Other operating income, net	0.0	0.0	0.3	0.0
Disposal Group, Including Discontinued Operation, Interest Expense	0.0	(1.0)	0.0	(1.0)
Interest income	0.0	0.0	3.0	0.0
Loss on sale of California Discontinued Entities	1.4	0.0	(39.8)	0.0
income (loss) from discontinued operations before taxes	0.8	(6.4)	(10.7)	(6.4)
Income tax expense (benefit)	0.3	(2.3)	(2.2)	(2.3)
Income (loss) from discontinued operations, net of tax	$ 0.5	$ (4.1)	$ (8.5)	$ (4.1)
Non-controlling interest					$ 10.5