Share-Based Compensation Arrangements (Share Options Fair Value Assumptions) (Details) (Share Options [Member])	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011
Share Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (years)	9.0	9.0
Expected dividend yield	3.45%	3.33%
Weighted average expected volatility	42.97%	41.90%
Weighted average risk-free interest rate	1.53%	3.05%

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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