Inventories (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Inventories
Finished goods	$ 858	$ 884	$ 1,037
Raw materials	109	110	121
Operating supplies	40us-gaap_InventorySuppliesNetOfReserves	41us-gaap_InventorySuppliesNetOfReserves	46us-gaap_InventorySuppliesNetOfReserves
Inventories	$ 1,007us-gaap_InventoryNet	$ 1,035us-gaap_InventoryNet	$ 1,204us-gaap_InventoryNet

Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of products used directly or indirectly in the manufacturing or production process, which may or may not become part of the final product. May also include items used in the storage, presentation or transportation of physical goods.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 330

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SAB TOPIC 5.BB)

-URI http://asc.fasb.org/extlink&oid=27011343&loc=d3e100047-122729

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(a)(5))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant