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Share-Based Compensation - Summary of Weighted Average Assumptions Used for Options Granted (Detail)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]      
Expected life (in years) 6 years 4 months 24 days 6 years 8 months 12 days 6 years 8 months 12 days
Expected volatility 32.40% 32.60% 33.10%
Risk-free interest rate 1.40% 1.00% 1.70%
Expected forfeiture rate 3.00% 3.00% 3.00%