Pension and Other Postemployment Benefits (Details 4) (Pensions, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Actual return on plan assets:
Ending balance	$ 5,732us-gaap_InvestmentsFairValueDisclosure	$ 6,258us-gaap_InvestmentsFairValueDisclosure
Private equity funds
Actual return on plan assets:
Ending balance	25	27
Real estate funds
Actual return on plan assets:
Ending balance	421	385
Level 3
Actual return on plan assets:
Ending balance	446	412
Level 3 \| Private equity funds
Reconciliation of changes in the fair value of pension investments
Beginning balance	27	33
Actual return on plan assets:
Unrealized gains (losses)	(2)	1
Realized gains (losses)	1	5
Transfers in (out)	(1)	(12)
Ending balance	25	27
Level 3 \| Real estate funds
Reconciliation of changes in the fair value of pension investments
Beginning balance	385	357
Actual return on plan assets:
Unrealized gains (losses)	17	17
Realized gains (losses)	14	13
Transfers in (out)	5	(2)
Ending balance	$ 421	$ 385

Defined Benefit Plan Actual Return On Plan Assets Realized Gains Losses.

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- Definition

Defined Benefit Plan Actual Return On Plan Assets Unrealized Gains Losses.

+ References

No definition available.

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- Definition

Transfers in and out of Level 3. For example, transfers due to changes in the observability of significant inputs.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(iv)(02)(C)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(iv)(02)(C)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

-URI http://asc.fasb.org/extlink&oid=6505594

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph a, f, g

-Article 7

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560

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