Average Investment Term, Alternative Investments

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Number of days notice required to redeem an investment.

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Maximum percentage of funds permitted to be invested.

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Number of Real Estate and Private Equity Partnerships

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For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Accumulated Benefit Obligation
-URI http://asc.fasb.org/extlink&oid=6503844

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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- Definition

The increase in the fair value of plan assets from contributions made by the employer.

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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)(3)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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Amount of discretionary contributions made by an employer to a defined contribution plan.

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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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Percentage employer matches of the employee's percentage contribution matched.

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States the frequency (for example, annually, semi-annually, quarterly) with which the entity can redeem its investment, or portion thereof, for each of those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments), by major category.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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Retirement Benefits (Details 12) $ in Millions	12 Months Ended
Retirement Benefits (Details 12) $ in Millions	Dec. 31, 2015 USD ($) partnership	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Defined Contribution Plans Disclosure (Amounts in paragraphs)
Employer match for first 8% contributed by plan participant	50.00%
Maximum percentage of employee compensation eligible for 50% cash matching by employer	8.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 291	$ 282	$ 285
Pension and post-retirement benefits disclosures (Amounts in paragraphs)
Accumulated benefit obligation for all defined benefit pension plans	$ 29,000	30,300
Information About Plan Assets (Amounts in paragraphs) [Abstract]
Maximum percentage of funds permitted to be invested in trust accounts	5.00%
Number of real estate and private equity partnerships \| partnership	167
Entities that calculate net asset value per share, unfunded commitments	$ 1,500	833
Average investment term, alternative investments	10 years
Entities that calculate net asset value per share, investment redemption frequency	quarterly
Notice period for alternative investments redemptions, days	90 days
OPEB contributions
Defined Contribution Plans Disclosure (Amounts in paragraphs)
Expected 2016 employer contributions	$ 75
Pension employer required minimum contributions
Defined Contribution Plans Disclosure (Amounts in paragraphs)
Expected 2016 employer contributions	79
Pension Benefits
Information About Plan Assets (Amounts in paragraphs) [Abstract]
Defined Benefit Plan, Contributions by Employer	578	$ 78
Voluntary Contributions [Member] \| Pension Benefits
Information About Plan Assets (Amounts in paragraphs) [Abstract]
Defined Benefit Plan, Contributions by Employer	$ 500