Pensions and Other Employee Benefits - Estimated Future Benefit Payments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Pension Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2013	$ 110
2014	116
2015	126
2016	134
2017	141
Years 2018-2022	868
Postretirement Benefit Plans [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2013	13
2014	14
2015	14
2016	15
2017	15
Years 2018-2022	82
Subsidy Receipts, 2013
Subsidy Receipts, 2014
Subsidy Receipts, 2015
Subsidy Receipts, 2016
Subsidy Receipts, 2017
Subsidy Receipts, Years 2018-2022	$ 1

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Amount of benefits expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year from a defined benefit plan.

+ 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 (f)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

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Amount of benefits expected to be paid in the next fiscal year following the latest fiscal year from a defined benefit plan.

+ References

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Amount of benefits expected to be paid in the fifth fiscal year following the latest fiscal year from a defined benefit plan.

+ References

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Amount of benefits expected to be paid in the fourth fiscal year following the latest fiscal year from a defined benefit plan.

+ References

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Amount of benefits expected to be paid in the third fiscal year following the latest fiscal year from a defined benefit plan.

+ References

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Amount of benefits expected to be paid in the second fiscal year following the latest fiscal year from a defined benefit plan.

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- Definition

Amount of the prescription drug subsidy receipts to be received after the fifth fiscal year following the latest fiscal year.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 60

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

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Amount of the prescription drug subsidy receipts to be received in the next fiscal year following the latest fiscal year.

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Amount of the prescription drug subsidy receipts to be received in the fifth fiscal year following the latest fiscal year.

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Amount of the prescription drug subsidy receipts to be received in the fourth fiscal year following the latest fiscal year.

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Amount of the prescription drug subsidy receipts to be received in the third fiscal year following the latest fiscal year.

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Amount of the prescription drug subsidy receipts to be received in the second fiscal year following the latest fiscal year.

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