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Stock-Based Compensation - Assumptions Used for Computing Stock-Based Employee Compensation Expense (Detail)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract]      
Risk-free interest rate, Minimum 1.95% 1.74% 1.97%
Risk-free interest rate, Maximum 3.15% 1.95% 3.61%
Dividend yield 2.00% 2.00% 2.00%
Stock price volatility, Minimum 18.35% 21.71% 25.26%
Stock price volatility, Maximum 20.21% 38.75% 38.43%
Expected term 10 years 10 years 10 years