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Schedule of Valuation Inputs for Fair Value of Awards (Detail)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Weighted average historical volatility (based on a statistical analysis of the share price on a weighted moving average basis for the expected term of the option) 45.20% 44.40%
Expected term (years) 3 years 3 years
3 Year [Member] | US Interest Rates [Member]    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Three year risk free interest rate (based on US interest rates) 1.50% 2.20%