Annual report pursuant to Section 13 and 15(d)

Awards Granted Assumptions (Detail)

Awards Granted Assumptions (Detail)
12 Months Ended
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Risk-free interest rates, minimum 1.50%
Risk-free interest rates, maximum 5.10%
Expected option life (in years) 6 years
Dividend yield 0.00%
Expected volatility, minimum 49.00%
Expected volatility, maximum 60.00%