Employee Benefit Plans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	1 Months Ended
Mar. 31, 2013 D	Feb. 28, 2013 Restricted Stock	Feb. 28, 2013 Restricted Stock Units	Feb. 28, 2013 Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employer contribution to tax-qualified defined benefit pension plans	$ 41
Number of days used to compute performance period average closing price of restricted stock units	20
Share-Based Compensation, award granted		0.5	0.5	1.3
Share-Based Compensation, vesting period		3 years	3 years	3 years
Share-Based Compensation, vesting date				Dec. 31, 2015
Percentage of pre-tax earnings paid for profit sharing plan	15.00%
Share-based compensation program pre-tax profits excluding special items, profit sharing expense and share-based compensation program expense threshold	$ 10

Pre-tax profit threshold applicable to profit sharing.

No definition available.

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- Definition

Number of days used to compute performance period average closing price of restricted stock units

+ References

No definition available.

+ Details

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- Definition

Profit Sharing Plan, Percentage of Pre-Tax Earnings Paid

+ References

No definition available.

+ Details

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Vesting Date

+ 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 Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: 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=21915506&loc=d3e1928-114920

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)(iii)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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