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Employee Benefit Plans - Weighted-Average Assumptions Used for Options Granted (Detail) (USD $)
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12 Months Ended | ||
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Dec. 31, 2013
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Dec. 31, 2012
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Dec. 31, 2011
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| Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract] | |||
| Expected term (years) | 6 years 6 months | 6 years 6 months | 6 years 6 months |
| Expected dividend yield | 0.44% | 0.58% | 0.62% |
| Expected volatility | 30.94% | 31.05% | 29.84% |
| Expected forfeiture rate | |||
| Risk-free interest rate | 1.19% | 1.18% | 1.97% |
| Fair value of options granted | $ 5.82 | $ 4.38 | $ 4.07 |