Share-Based Compensation (Estimate Fair Value Of Share-Based Awards With Weighted-Average Assumptions) (Details) (USD $)	12 Months Ended
Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2009 years
Share-Based Compensation [Abstract]
Expected dividends	2.20%	2.30%	2.10%
Expected volatility	30.50%	31.40%	24.20%
Risk-free interest rate	3.40%	3.70%	4.50%
Expected term (in years)	5.7	6.0	7.0
Weighted-average grant-date fair value	$ 16.43	$ 16.55	$ 15.45

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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