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Stock-Based Compensation (Details 1)	12 Months Ended
Stock-Based Compensation (Details 1)	Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2009 years
Stock options [Member]
Black-Scholes option-pricing model assumptions used to calculate the fair value of employee stock options and ESPP purchases
Average risk-free interest rate	1.60%	1.80%	1.60%
Dividend yield	0.00%	0.00%	0.00%
Volatility factor	63.80%	62.70%	61.00%
Weighted average expected life	4.9	4.9	4.9
Employee Stock Purchase Plan [Member]
Black-Scholes option-pricing model assumptions used to calculate the fair value of employee stock options and ESPP purchases
Average risk-free interest rate	0.10%	0.20%	0.30%
Dividend yield	0.00%	0.00%	0.00%
Volatility factor	53.60%	47.80%	82.40%
Weighted average expected life	0.5	0.5	0.5

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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