Stock Compensation Plans (Estimated Fair Value for Performance Share Grants) (Details) (USD $)	0 Months Ended
Mar. 08, 2011
Stock Compensation Plans
Grant Date Market Price	$ 96.70
Average Expected Term (Years)	2.81
Expected Volatility	94.40%
Risk-Free Interest Rate	1.17%
Dividend Yield	0.58%
Fair Value	$ 77.90
Fair Value (Percent of Grant Date Market Price)	80.60%

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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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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- Definition

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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