Discontinued Operations (Schedule of Assets and Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Current Assets	$ 19.4		$ 1.8
Total Noncurrent Assets	0.0		891.8
Total Current Liabilities	19.0		17.0
Total Noncurrent Liabilities	0.0		2.5
Energy From Waste [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Plant and equipment	18.2	$ 20.0	0.0
Other current assets	1.2		1.8
Total Current Assets	19.4		1.8
Plant and equipment, net	0.0		891.8
Total Noncurrent Assets	0.0		891.8
Payables and accrued liabilities	19.0		17.0
Total Current Liabilities	19.0		17.0
Other noncurrent liabilities	0.0		2.5
Total Noncurrent Liabilities	$ 0.0		$ 2.5