Stock Plans (Schedule Of Fair Value Weighted Average Assumptions For Options Granted) (Details) (USD $)	12 Months Ended
Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2009 years
Stock Plans [Abstract]
Fair value per option	$ 9.94	$ 7.21	$ 5.80
Risk-free interest rate	2.60%	3.00%	2.20%
Expected dividend yield	3.60%	3.90%	3.00%
Expected volatility	40.00%	40.00%	42.00%
Expected life (years)	6.1	6.1	6.1

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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