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Shareholders' Equity (Schedule Of Weighted Average Assumptions) (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Shareholders' Equity [Abstract]
Expected life (in years)	4 years 9 months 18 days	3 years 1 month 6 days	2 years 9 months 18 days
Risk-free interest rate	0.72%	1.47%	1.39%
Expected volatility	42.00%	44.00%	78.00%
Dividend yield	0.00%	0.00%	0.00%

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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