Postretirement Benefit Plans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
Jun. 30, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Liability related to funded defined-benefit pension plans	$ 327	$ 322
Contributions to benefit plans	0
Insurance cash value and Rabbi Trust investments supporting supplemental pension plan liability	69	66
Non-qualified supplemental retirement pension plan liability	60	58
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions to benefit plans	$ 20

Funded Defined Benefit Plan Liability

No definition available.

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- Definition

Insurance cash value and Rabbi Trust investments supporting supplemental pension plan liability.

+ References

No definition available.

+ Details

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- Definition

Unqualified supplemental retirement pension plan liability.

+ References

No definition available.

+ Details

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- Definition

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

+ 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)(3)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

+ Details

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- Definition

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.

+ 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 (g)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

+ Details

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