Stock-Based Compensation (Schedule of ESPP Granted Black Scholes) (Details) (1999 ESPP [Member])	12 Months Ended
Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2009 years
1999 ESPP [Member]
Expected life (years)	0.5	0.5	0.5
Risk free interest rate (%)	0.10%	0.20%	0.40%
Expected volatility (%)	43.70%	51.20%	69.20%
Dividend yield (%)	0.00%	0.00%	0.00%

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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