Discontinued Operations (Carrying Amount of Accrual) (Details) - Energy-from-Waste (EfW) - Discontinued Operations, Held-for-sale or Disposed of by Sale - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal of business	$ 59.3	$ 945.7	$ 59.3	$ 945.7
Noncash expenses			(6.3)	(913.5)
Cash expenditures			(1.4)	(18.6)
Currency translation adjustment			7.3	(1.4)
Amount reflected in other noncurrent liabilities			(65.3)
Accrual for actions to dispose of business			5.8	12.2
Asset Actions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal of business	6.3		6.3	913.5
Noncash expenses			(6.3)	(913.5)
Cash expenditures			0.0	0.0
Currency translation adjustment			0.0	0.0
Amount reflected in other noncurrent liabilities			0.0
Accrual for actions to dispose of business			0.0	0.0
Contract Actions/ Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal of business	$ 53.0		53.0	32.2
Noncash expenses			0.0	0.0
Cash expenditures			(1.4)	(18.6)
Currency translation adjustment			7.3	(1.4)
Amount reflected in other noncurrent liabilities			(65.3)
Accrual for actions to dispose of business			$ 5.8	$ 12.2