Stock-Based Compensation Expense (Schedule Of Fair Value Of Each Option Granted Estimated With Weighted-Average Assumptions) (Details) (USD $)	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Stock-Based Compensation Expense [Abstract]
Dividend yield	1.53%	1.66%	2.13%
Volatility	33.04%	33.13%	32.94%
Average expected life (years)	6	6	6
Risk-free interest rate	3.67%	3.92%	3.37%
Fair value of options granted	$ 18.42	$ 13.76	$ 6.70

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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