Employee Retirement Plans (Details 7) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Purchases, sales and settlements:
Fair value as of December 31	$ 1,340	$ 1,262
Significant Unobservable Inputs (Level 3)
Change in Plan Assets:
Fair value as of January 1	75	82
Realized gains (losses)	1	6
Unrealized gains (losses)	(1)	1
Purchases, sales and settlements:
Purchases	67	0
Sales	(3)	(14)
Settlements	0	0
Net transfers into (out of) Level 3	0	0
Fair value as of December 31	139	75
Fixed income
Purchases, sales and settlements:
Fair value as of December 31	571	344
Fixed income \| Significant Unobservable Inputs (Level 3)
Change in Plan Assets:
Fair value as of January 1	1	1
Realized gains (losses)	0	0
Unrealized gains (losses)	0	0
Purchases, sales and settlements:
Purchases	0	0
Sales	0	0
Settlements	0	0
Net transfers into (out of) Level 3	0	0
Fair value as of December 31	1	1
Other real estate assets
Purchases, sales and settlements:
Fair value as of December 31	55	35
Other real estate assets \| Significant Unobservable Inputs (Level 3)
Change in Plan Assets:
Fair value as of January 1	35	36
Realized gains (losses)	1	1
Unrealized gains (losses)	1	2
Purchases, sales and settlements:
Purchases	0	0
Sales	(2)	(4)
Settlements	0	0
Net transfers into (out of) Level 3	0	0
Fair value as of December 31	35	35
Limited partnerships
Purchases, sales and settlements:
Fair value as of December 31	103	39
Limited partnerships \| Significant Unobservable Inputs (Level 3)
Change in Plan Assets:
Fair value as of January 1	39	45
Realized gains (losses)	0	5
Unrealized gains (losses)	(2)	(1)
Purchases, sales and settlements:
Purchases	67	0
Sales	(1)	(10)
Settlements	0	0
Net transfers into (out of) Level 3	0	0
Fair value as of December 31	$ 103	$ 39

Defined benefit plan recognized gain loss.

No definition available.

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- Definition

Defined Benefit Plan, Sales, Plan Assets

+ References

No definition available.

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- Definition

Purchases of plan assets that occurred during the period.

+ References

No definition available.

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- Definition

Defined benefit plan un recognized gain loss.

+ References

No definition available.

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- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ 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 (b)

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Section 35

-Paragraph 50

-URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930

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- Definition

The amount that relates to an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include (a) making lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and (b) purchasing nonparticipating annuity contracts.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Section 15

-Paragraph 6

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=7577095&loc=d3e8001-114927

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)(8)

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

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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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