Retirement Plans - Funded Status of Pension and Postretirement Medical Plans (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Change in benefit obligation
Actuarial (gain) loss	$ 125
Change in fair value of plan assets
Beginning balance	2,145
Ending balance	2,251
Funded Pension Plans [Member]
Change in benefit obligation
Beginning balance	1,957	2,110
Service cost	45	61
Interest cost	91	82
Actuarial (gain) loss	470	(139)
Benefit payments	(77)	(69)
Plan curtailments	(3)	(103)
Special termination benefits	2	5
Foreign currency exchange rate changes	(35)	10
Ending balance	2,450	1,957
Change in fair value of plan assets
Beginning balance	2,145	1,763
Actual return on plan assets	151	292
Employer contributions	68	146
Benefit payments	(77)	(69)
Foreign currency exchange rate changes	(36)	13
Ending balance	2,251	2,145
Funded status (plan assets greater (less) than benefit obligations) at December 31	(199)	188
Unrecognized net actuarial (gains) losses	859	405
Unfunded Pension Plan [Member]
Change in benefit obligation
Beginning balance	253	234
Service cost	12	12
Interest cost	9	7
Actuarial (gain) loss	61	28
Benefit payments	(57)	(20)
Plan curtailments		(8)
Ending balance	278	253
Change in fair value of plan assets
Employer contributions	56	20
Benefit payments	(56)	(20)
Funded status (plan assets greater (less) than benefit obligations) at December 31	(278)	(253)
Unrecognized net actuarial (gains) losses	135	108
Postretirement Medical Plan [Member]
Change in benefit obligation
Beginning balance	97	134
Service cost	4	4	7
Interest cost	3	3	5
Actuarial (gain) loss	(4)	(4)
Benefit payments	(6)	(5)
Plan curtailments		(35)
Ending balance	94	97	134
Change in fair value of plan assets
Employer contributions	6	5
Benefit payments	(6)	(5)
Funded status (plan assets greater (less) than benefit obligations) at December 31	(94)	(97)
Unrecognized net actuarial (gains) losses	$ (5)	$ (2)

Benefit payments fair value of plan asset.

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Unrecognized net actuarial gains losses.

+ References

No definition available.

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- Definition

The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Actual Return on Plan Assets (Component of Net Periodic Postretirement Benefit Cost)

-URI http://asc.fasb.org/extlink&oid=6504192

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)(1)

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-Glossary Actual Return on Plan Assets (Component of Net Periodic Pension Cost)

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- Definition

Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Gain or Loss

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- Definition

1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

+ References

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-Publisher FASB

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-Topic 715

-SubTopic 20

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-Paragraph 1

-Subparagraph (a)

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-Glossary Projected Benefit Obligation

-URI http://asc.fasb.org/extlink&oid=6522206

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Accumulated Postretirement Benefit Obligation

-URI http://asc.fasb.org/extlink&oid=6503904

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- Definition

The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Postretirement Benefits

-URI http://asc.fasb.org/extlink&oid=6521376

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-Topic 715

-SubTopic 60

-Section 50

-Paragraph 4

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-Publisher FASB

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-Topic 715

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- Definition

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

+ References

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- Definition

The amount of decrease that is related to an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services.

+ References

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-Glossary Plan Curtailment

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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

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- Definition

Amount of gain (loss) from foreign currency exchange rate changes for benefit obligation for plans of a foreign operation whose functional currency is not the reporting currency.

+ References

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The amount of increase or decrease in plan assets attributed to foreign currency changes. The effects of foreign currency exchange rate changes that are to be disclosed are those applicable to plans of a foreign operation whose functional currency is not the reporting currency.

+ References

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- Definition

The funded status is measured as the difference between the fair value of plan assets and the benefit obligation. Will normally be the same as the net Defined Benefit Plan, Amounts Recognized in Balance Sheet, Total.

+ References

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- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

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The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

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

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-Glossary Service Cost (Component of Net Periodic Pension Cost)

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The amount of increase related to special termination benefits offered to and accepted by employees in connection with their termination of employment that are only offered for a short period of time. A situation involving termination benefits may also involve a curtailment.

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