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Summary of Significant Accounting Policies (Details)
3 Months Ended 6 Months Ended
Jun. 30, 2012
Jun. 30, 2011
Jun. 30, 2012
Jun. 30, 2011
Weighted average estimates used in the Black-Scholes option-pricing model        
Risk free interest rates 1.00% 1.70% 1.30% 2.20%
Expected life in years 5 years 9 months 18 days 5 years 6 months 5 years 10 months 24 days 6 years 3 months 18 days
Expected dividend yield 0.00% 0.00% 0.00% 0.00%
Expected volatility 71.60% 73.20% 70.70% 73.90%