Share-Based Compensation (Summary Of Weighted-Average Assumptions Used In The Black-Scholes Option-Pricing Model) (Details) (USD $)	12 Months Ended
Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009 years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated fair value	$ 12.64		$ 5.83
Risk-free interest rate	2.20%		2.00%
Expected term (years)	4.73		4.30
Expected volatility	48.00%		39.00%
Expected dividend yield	1.24%		1.97%
Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated fair value		10.78
Risk-free interest rate		2.40%
Expected term (years)		4.30
Expected volatility		48.00%
Expected dividend yield		1.38%

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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