Stock Compensation Plans (Details 1) (Stock Option Plan [Member])	12 Months Ended
Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Stock Option Plan [Member]
Assumptions Relating To The Valuation of Stock Options (Table Amounts)
Dividend yield	2.90%	3.60%	1.80%
Volatility rate	25.00%	25.00%	20.00%
Risk-free interest rate	2.20%	1.70%	2.80%
Expected option life (years)	6	5-6	6

The period of time a share-based award is expected to be outstanding.

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph A240
-Subparagraph e(2)(c)

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- Definition

The estimated measure of the percentage amount by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph A240
-Subparagraph e(2)(b)

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- Definition

The risk-free interest rate assumption that is used in valuing an option on its own shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph A240
-Subparagraph e(2)(d)

+ Details

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