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Stock-Based Compensation (Details 2) (Employee Stock Purchase Plan [Member])	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010 Y	Dec. 31, 2009 Y
Employee Stock Purchase Plan [Member]
Weighted average assumptions:
Expected term	0.50	0.50	0.50
Volatility	45.00%	46.00%	76.00%
Risk-free interest rate	0.20%	0.40%	0.50%
Expected dividend	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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