Stock, Stock Options and Rights Fair Value Assumptions (Details)	12 Months Ended
Dec. 31, 2011 Y	Dec. 31, 2010 Y	Dec. 31, 2009 Y
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	2.20%	2.60%	1.60%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	4.99	4.79	4.14
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	60.18%	60.60%	57.80%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected , Estimated Annualized Forfeiture Rate	6.80%	7.50%	7.70%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	0.10%	0.20%	0.60%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	0.5	0.5	0.5
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	57.40%	56.30%	88.80%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected , Estimated Annualized Forfeiture Rate	4.00%	4.00%	4.00%

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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