The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

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+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35755396&loc=d3e33749-111570

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.12)

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

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- Definition

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.

+ References

No definition available.

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Equity Method Investments (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Feb. 27, 2014
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 717	$ 735
USG Boral Building Products
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 673	$ 689	$ 676
Ownership percentage	50.00%	50.00%	50.00%
Other equity method investments
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 44	$ 46
Other equity method investments \| Minimum
Schedule of Equity Method Investments [Line Items]
Ownership percentage	33.00%	33.00%
Other equity method investments \| Maximum
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%	50.00%