Retirement Benefits (Summary Of Target Assets Allocation) (Detail)	12 Months Ended
Dec. 31, 2012
Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of target assets allocation, Equity - minimum	60.00%
Percentage of target assets allocation, Equity - maximum	70.00%
U.S. Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of target assets allocation, Equity - minimum	18.00%
Percentage of target assets allocation, Equity - maximum	33.00%
International Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of target assets allocation, Equity - minimum	14.00%
Percentage of target assets allocation, Equity - maximum	24.00%
Emerging Markets [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of target assets allocation, Equity - minimum	5.00%
Percentage of target assets allocation, Equity - maximum	11.00%
Alternative Investment [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of target assets allocation, Equity - minimum	0.00%
Percentage of target assets allocation, Equity - maximum	18.00%
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of target assets allocation, Debt - minimum	30.00%
Percentage of target assets allocation, Debt - maximum	40.00%
U.S. Long Duration [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of target assets allocation, Debt - minimum	30.00%
Percentage of target assets allocation, Debt - maximum	40.00%
Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of target assets allocation, Other - minimum	0.00%
Percentage of target assets allocation, Other - maximum	5.00%
Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of target assets allocation, Other - minimum	0.00%
Percentage of target assets allocation, Other - maximum	5.00%

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Target allocation maximum percentage of investments in debt securities to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

+ References

No definition available.

+ Details

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- Definition

Target allocation minimum percentage of investments in debt securities to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph d(2)

-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 5

-Subparagraph (c)(i)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e2446-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(i)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

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- Definition

Target allocation maximum percentage of investments in equity securities to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

+ References

No definition available.

+ Details

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- Definition

Target allocation minimum percentage of investments in equity securities to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

+ References

No definition available.

+ Details

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- Definition

Target allocation maximum percentage in other than debt securities, equity securities, and real estate to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

+ References

No definition available.

+ Details

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- Definition

Target allocation minimum percentage in other than debt securities, equity securities, and real estate to total plan assets presented on a weighted-average basis as of the measurement date of the latest statement of financial position.

+ References

No definition available.

+ Details

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