Stock Compensation Plans (Schedule Of Fair Value Options Granted Date Using Weighted-Average Assumptions) (Details)	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Stock Compensation Plans [Abstract]
Risk-free interest rate	1.92%	2.12%	1.73%
Expected life of option	4.70	4.66	4.55
Expected dividend yield	2.34%	2.22%	3.25%
Expected volatility	26.82%	26.42%	32.66%

The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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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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