Inventories (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Inventory Disclosure [Abstract]
Raw materials and supplies	$ 194.4		$ 194.4		$ 216.0
Work-in-process	851.6		851.6		990.3
Finished goods	164.7		164.7		184.1
Total inventories at current cost	1,210.7		1,210.7		1,390.4
Adjustment from current cost to LIFO cost basis	131.8		131.8		136.4
Inventory valuation reserves	(204.1)		(204.1)		(206.3)
Progress payments	(44.1)		(44.1)		(48.9)
Total inventories, net	1,094.3		1,094.3		$ 1,271.6
Inventory [Line Items]
LIFO benefit (charge)			(4.6)	$ 4.5
NRV benefit (charge)			5.0	(4.3)
Net cost of sales impact	$ 0.4	$ 0.2	0.4	0.2
Inventory Valuation Reserve \| Titanium products [Member]
Inventory [Line Items]
Inventory valuation charges			$ 17.7	$ 11.4

Inventory, Net Realizable Value Reserve, Period Charge

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Lifo Provision Benefit and Change in Debit LIFO NRV reserve, net

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Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

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Gross amount, as of the balance sheet date, of merchandise, goods, commodities, or supplies held for future sale or to be used in manufacturing, servicing or production process.

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Amount of difference between inventory at lower of LIFO cost or market and inventory at lower of other inventory accounting method cost or market, for example, but not limited to, FIFO or average cost.

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The change in the inventory reserve representing the cumulative difference in cost between the first in, first out and the last in, first out inventory valuation methods, which change has been reflected in the statement of income during the period.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Gross amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed.

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Amount of valuation reserve for inventory.

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Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer.

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Amount of advances received from customers under long-term contracts which have been offset against inventories accounts at the balance sheet date.

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Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, charged to costs and expenses.

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