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Stock-Based Compensation - Fair Value of Date of Grant Using Black Scholes Option Pricing Model (Detail) (Stock Options [Member])
9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Stock Options [Member]
   
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]    
Dividend yield 2.20% 1.60%
Risk-free interest rate 0.50% 0.20%
Expected volatility 34.00% 51.00%
Expected life (in years) 5 years 2 months 12 days 4 years 7 months 6 days