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Stock-Based Compensation - Fair Value of Stock Appreciation Rights Estimated, Monte Carlo Simulation Model (Detail) (Performance Units [Member], USD $)
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]    
Risk-free interest rate, Minimum 0.09% 0.13%
Risk-free interest rate, Maximum 0.79%  
Risk-free interest rate   0.35%
Estimated volatility factor   40.00%
Expected dividends      
Maximum [Member]
   
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]    
Estimated volatility factor 45.00%  
Minimum [Member]
   
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]    
Estimated volatility factor 40.00%