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Business Segments - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0.0	$ 488.6			$ 0.0	$ 498.6
Restructuring reserve	9.1				9.1		$ 33.1
Long-lived asset impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges		471.3
Facility shudown, idling and employee benefit costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges		17.3
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 1.0	$ 9.0
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	6.0				6.0
Employee benefit costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	$ 3.1				$ 3.1
Inventory Valuation Reserve | Titanium sponge inventory
Restructuring Cost and Reserve [Line Items]
Inventory valuation charges		$ 11.3

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+ References

No definition available.

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Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b))
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

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Amount of restructuring charges, remediation cost, and asset impairment loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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Amount of increase in the allowances and reserves, which consist of the valuation and qualifying accounts that are either netted against the cost of an asset or that reflect a liability established to represent expected future costs, from charges to costs and expenses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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