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Stock-Based Compensation (Details 1) (USD $)	12 Months Ended
Stock-Based Compensation (Details 1) (USD $)	Dec. 31, 2011 years	Dec. 31, 2010 years	Dec. 31, 2009 years
Employee Stock Option [Member]
Weighted average assumptions in fair value of option grant
Estimated grant date fair value per share	$ 2.14	$ 1.95	$ 1.42
Expected life (years)	4.51	4.30	4.26
Risk-free interest rate	1.83%	1.91%	1.80%
Volatility	47.00%	51.00%	67.00%
Employee Stock Purchase Plan [Member]
Weighted average assumptions in fair value of option grant
Estimated grant date fair value per share	$ 1.81	$ 1.49	$ 1.79
Expected life (years)	0.8	0.8	0.7
Risk-free interest rate	0.10%	0.20%	0.30%
Volatility	45.00%	36.00%	52.00%

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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