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Weighted-Average Assumptions Used for Stock Options Granted (Detail) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term in years 4 years 3 months 4 years 3 months 4 years 3 months
Risk-free interest rate 0.82% 0.57% 1.12%
Expected volatility 24.56% 31.40% 32.59%
Expected dividend yield 2.20% 3.49% 3.48%
Grant date fair value $ 13.33 $ 12.90 $ 12.31