Share-Based Compensation (Schedule Of Fair Value Of PSUs Assumptions Using Monte Carlo Simulation) (Details) (USD $)	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Share-Based Compensation [Line Items]
Volatility	47.70%
Risk-free interest rate	0.06%
Performance Stock Units [Member]
Share-Based Compensation [Line Items]
Closing stock price on grant date	$ 28.16	$ 17.84
Performance period starting price	$ 24.94	$ 16.85
Term of award (in years)	2.99	2.99
Volatility	65.06%	69.75%
Risk-free interest rate	0.45%	1.19%
Expected dividend yield	0.00%	0.00%
Fair value per TSR PSU	$ 29.88
TSR Based PSUs [Member] \| Performance Stock Units [Member]
Share-Based Compensation [Line Items]
Fair value per TSR PSU	$ 45.37	$ 24.38

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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