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Stock-Based Compensation - Summary of Weighted Average Assumptions Used for Grants (Detail)
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12 Months Ended | ||
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Dividend yield | 0.00% | 0.00% | 0.00% |
| Expected volatility | 65.00% | 73.25% | 75.71% |
| Risk-free interest rate | 1.54% | 0.52% | 0.58% |
| Performance-Based Shares [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Expected term (in years) | 3 years 10 months 6 days | 3 years 10 months 6 days | |
| Time-based, Performance-based and Modified Time-based Restricted Stock Awards [Member] | |||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Expected term (in years) | 4 years 6 months | 9 years 2 months 16 days | 10 years 3 months 26 days |