Incentive Plans (Schedule Of Weighted-Average Assumptions To Estimate The Fair Value) (Details) (Stock Options [Member])	12 Months Ended
Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2009 years
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected option life - years	7	7	7
Volatility	47.60%	46.80%	43.00%
Risk-free interest rate	2.90%	3.40%	3.30%
Dividend yield	0.40%	0.40%	1.90%

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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