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Stock Compensation (Valuation Assumptions Of Stock Option Plan) (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock Compensation [Abstract]
Expected volatility rate	31.20%	27.70%	27.30%
Risk free interest rate	2.30%	3.40%	3.70%
Expected holding period	6 years	6 years	7 years
Dividend yield	4.60%	4.20%	4.70%

The estimated measure of the percentage 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.

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