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Share-Based Compensation Arrangements (Share Options Fair Value Assumptions) (Details) (Share Options [Member])	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)	9 years	9 years	9 years
Expected dividend yield	3.45%	3.33%	3.16%
Weighted average expected volatility	42.97%	41.90%	41.95%
Weighted average risk-free interest rate	1.53%	3.05%	3.42%

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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