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Share Options And Awards (Fair Value And Weighted Average Assumptions Of Share Options) (Details) (Share Options [Member], USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Share Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value per share option	$ 5.68	$ 5.42
Dividend yield	5.30%	5.30%
Expected volatility	39.60%	38.80%
Expected life (in years)	6 years 2 months	6 years 2 months
Risk-free interest rate	2.40%	2.90%

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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