Employee Plans (Fair Value Assumptions On Stock Options) (Details) (USD $)	12 Months Ended
Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2009 years
Employee Plans [Abstract]
Weighted-average fair value of grant	$ 20.10	$ 17.83	$ 2.82
Risk-free interest rate	1.71%	1.74%	1.57%
Expected volatility	71.31%	72.20%	58.28%
Expected life of options in years	3.62	3.63	3.77
Expected dividend yield

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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