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Assumption Used to Estimate Fair Value of Stock Awards Granted (Detail)
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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] | |||
| Volatility | 44.40% | 40.10% | 34.60% |
| Expected term (years) | 8 years | 10 years | 10 years |
| Risk free interest rate | 2.00% | 2.10% | 2.70% |
| Expected dividend yield | 0.00% | 0.00% | 0.00% |