Retirement Benefits (Details 10)	12 Months Ended
Dec. 31, 2010
Domestic Equity Securities
Plan Asset Allocation Ranges (Table Amounts) [Abstract]
Asset allocation ranges, equity, minimum	10.00%
Asset allocation ranges, equity, maximum	30.00%
International Equity Securities
Plan Asset Allocation Ranges (Table Amounts) [Abstract]
Asset allocation ranges, equity, minimum	10.00%
Asset allocation ranges, equity, maximum	30.00%
Fixed Income Securities
Plan Asset Allocation Ranges (Table Amounts) [Abstract]
Asset allocation ranges, fixed income, minimum	30.00%
Asset allocation ranges, fixed income, maximum	50.00%
Real Estate and Other Securities
Plan Asset Allocation Ranges (Table Amounts) [Abstract]
Asset allocation ranges, real estate and other, minimum	10.00%
Asset allocation ranges, real estate and other, maximum	30.00%

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

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

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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.

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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)

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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.

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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.

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