Quarterly report pursuant to Section 13 or 15(d)

Weighted-Average Assumptions used to Estimate Fair Value of Stock Options and Restricted Stock Awards using Black-Scholes Valuation Model (Detail)

v2.4.0.6
Weighted-Average Assumptions used to Estimate Fair Value of Stock Options and Restricted Stock Awards using Black-Scholes Valuation Model (Detail)
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility 100.78% 102.40%
Expected dividends 2.05% 5.07%
Expected term (in years) 6 years 7 months 6 days 8 years 2 months 12 days
Risk-free interest rate 1.06% 1.66%