Employee Benefits - Expected Future Benefit Payments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
2013	$ 161
2014	166
2015	174
2016	184
2017	190
2018 - 2022	1,096
Postretirement Welfare Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
2013	16
2014	16
2015	17
2016	17
2017	17
2018 - 2022	80
Medicare Part D Subsidy [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
2013	2
2014	2
2015	2
2016	2
2017	3
2018 - 2022	$ 14

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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

+ Details

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- Definition

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

+ References

+ Details

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- Definition

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

+ References

+ Details

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- Definition

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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- Definition

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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- Definition

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

+ References

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