Discontinued Operations (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred tax assets, valuation allowance		$ 155.2	$ 103.6
Unrecognized tax benefits		106.9	97.5	$ 108.7	$ 124.3
Energy-from-Waste [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal, before tax	$ 945.7	945.7
Loss on disposat, net of tax	846.6	846.6	0.0	0.0
Plant and equipment, estimated net realizable value	20.0	18.2	0.0
Deferred tax assets, valuation allowance	58.0
Unrecognized tax benefits	7.9
Energy-from-Waste [Member] | Asset Impariment [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal, before tax	913.5	913.5
Energy-from-Waste [Member] | Contract Actions/Other [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal, before tax	$ 32.2	32.2
European Homecare Business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of business, net of tax		0.0	0.0	$ 3.9
Assets of discontinued operations		0.0	0.0
Liabilities of discontinued operations		$ 0.0	$ 0.0