Retirement Benefits (Details 10) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Actual return on plan assets:
Fair value of plan assets at end of year	$ 26,279	$ 25,273
Level 3
Changes in Fair Value of Plan Assets, Significant Unobservable Inputs (Table Amounts) [Abstract]
Fair value of plan assets at beginning of year	5,670	5,028
Actual return on plan assets:
Unrealized (losses) gains, net	67	358
Realized gains, net	170	43
Purchases	513	1,629
Sales	(993)	(1,388)
Fair value of plan assets at end of year	5,427	5,670
High yield debt and Hedge funds \| Level 3
Changes in Fair Value of Plan Assets, Significant Unobservable Inputs (Table Amounts) [Abstract]
Fair value of plan assets at beginning of year	822	786
Actual return on plan assets:
Unrealized (losses) gains, net	(46)	(16)
Realized gains, net	89	43
Purchases	21	200
Sales	(254)	(191)
Fair value of plan assets at end of year	632	822
Private equities
Actual return on plan assets:
Fair value of plan assets at end of year	2,030	2,075
Private equities \| Level 3
Changes in Fair Value of Plan Assets, Significant Unobservable Inputs (Table Amounts) [Abstract]
Fair value of plan assets at beginning of year	2,075	1,980
Actual return on plan assets:
Unrealized (losses) gains, net	(60)	112
Realized gains, net	10	0
Purchases	431	666
Sales	(426)	(683)
Fair value of plan assets at end of year	2,030	2,075
Real estate
Actual return on plan assets:
Fair value of plan assets at end of year	2,759	2,767
Real estate \| Level 3
Changes in Fair Value of Plan Assets, Significant Unobservable Inputs (Table Amounts) [Abstract]
Fair value of plan assets at beginning of year	2,767	2,256
Actual return on plan assets:
Unrealized (losses) gains, net	173	262
Realized gains, net	71	0
Purchases	61	763
Sales	(313)	(514)
Fair value of plan assets at end of year	2,759	2,767
Other Investments \| Level 3
Changes in Fair Value of Plan Assets, Significant Unobservable Inputs (Table Amounts) [Abstract]
Fair value of plan assets at beginning of year	6	6
Actual return on plan assets:
Unrealized (losses) gains, net	0	0
Realized gains, net	0	0
Purchases	0	0
Sales	0	0
Fair value of plan assets at end of year	$ 6	$ 6

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Actual return on plan assets, separately identifying the amount related to assets sold during the period.

+ 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)(A)

-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 20

-Section 50

-Paragraph 5

-Subparagraph (c)(iv)(02)(A)

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

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Actual return on plan assets, separately identifying the amount related to assets still held at the reporting date.

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The amount of increase in the plan assets attributed to a business combination.

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The amount of decrease in the plan assets attributed to the sale, liquidation, spin-off or other divestiture of a corporate division or subsidiary.

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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

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-Section 35

-Paragraph 50

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

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