Quarterly report pursuant to sections 13 or 15(d)

Valuation Assumptions Used in Computation of Stock Option Expense (Detail)

v2.4.0.6
Valuation Assumptions Used in Computation of Stock Option Expense (Detail)
3 Months Ended
Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Expected volatility 81.10%
Weighted-average volatility 81.10%
Risk-free interest rate 0.40%
Expected dividend 0.00%
Minimum
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Expected life in years 3 years 6 months
Maximum
 
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Expected life in years 8 years 7 months 6 days