Discontinued Operations (Schedule of Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash items	$ 11.3		$ 46.7
Total Current Assets	860.2	$ 926.2
Total Noncurrent Assets	0.0	1,042.3
Total Assets	860.2	1,968.5
Total Current Liabilities	89.2	211.8
Total Noncurrent Liabilities	0.0	1,095.5
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash items	11.3	208.1
Trade receivables, net	149.5	293.7
Inventories	222.2	364.9
Plant and equipment, net	317.8	18.2
Goodwill, net	122.4
Intangible assets, net	23.1
Other receivables and current assets	13.9	41.3
Total Current Assets	860.2	926.2
Plant and equipment, net		593.0
Goodwill, net		305.0
Intangible assets, net		100.1
Other noncurrent assets		44.2
Total Noncurrent Assets		1,042.3
Total Assets	860.2	1,968.5
Payables and accrued liabilities	70.2	177.3
Accrued income taxes	11.2	28.7
Current portion of long-term debt		5.8
Other current liabilities	7.8
Total Current Liabilities	89.2	211.8
Long-term debt		981.8
Deferred income taxes		56.7
Other noncurrent liabilities		57.0
Total Noncurrent Liabilities		1,095.5
Total Liabilities	89.2	1,307.3
Discontinued Operations [Member] | Electronic Materials Division [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash items		170.6
Trade receivables, net		134.7
Inventories		138.1
Plant and equipment, net		0.0
Other receivables and current assets		34.5
Total Current Assets		477.9
Plant and equipment, net		296.5
Goodwill, net		180.0
Intangible assets, net		75.1
Other noncurrent assets		37.5
Total Noncurrent Assets		589.1
Total Assets		1,067.0
Payables and accrued liabilities		85.8
Accrued income taxes		22.7
Current portion of long-term debt		5.8
Total Current Liabilities		114.3
Long-term debt		981.8
Deferred income taxes		50.3
Other noncurrent liabilities		47.4
Total Noncurrent Liabilities		1,079.5
Total Liabilities		1,193.8
Discontinued Operations [Member] | Performance Materials Division [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash items	11.3	37.5
Trade receivables, net	149.5	159.0
Inventories	222.2	226.8
Plant and equipment, net	306.8	0.0
Goodwill, net	122.4
Intangible assets, net	23.1
Other receivables and current assets	12.5	5.6
Total Current Assets	847.8	428.9
Plant and equipment, net		296.5
Goodwill, net		125.0
Intangible assets, net		25.0
Other noncurrent assets		6.7
Total Noncurrent Assets		453.2
Total Assets	847.8	882.1
Payables and accrued liabilities	59.3	72.5
Accrued income taxes	11.2	6.0
Current portion of long-term debt		0.0
Other current liabilities	7.8
Total Current Liabilities	78.3	78.5
Long-term debt		0.0
Deferred income taxes		6.4
Other noncurrent liabilities		9.6
Total Noncurrent Liabilities		16.0
Total Liabilities	78.3	94.5
Discontinued Operations [Member] | Energy-from-Waste [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash and cash items	0.0	0.0
Trade receivables, net	0.0	0.0
Inventories	0.0	0.0
Plant and equipment, net	11.0	18.2
Goodwill, net	0.0
Intangible assets, net	0.0
Other receivables and current assets	1.4	1.2
Total Current Assets	12.4	19.4
Plant and equipment, net		0.0
Goodwill, net		0.0
Intangible assets, net		0.0
Other noncurrent assets		0.0
Total Noncurrent Assets		0.0
Total Assets	12.4	19.4
Payables and accrued liabilities	10.9	19.0
Accrued income taxes	0.0	0.0
Current portion of long-term debt		0.0
Other current liabilities	0.0
Total Current Liabilities	10.9	19.0
Long-term debt		0.0
Deferred income taxes		0.0
Other noncurrent liabilities		0.0
Total Noncurrent Liabilities		0.0
Total Liabilities	$ 10.9	$ 19.0