| Long-Term Debt (Parenthetical) (Detail) | 3 Months Ended | 12 Months Ended | 
|---|---|---|
| Mar. 31, 2013 | Dec. 31, 2012 | |
| Debt Instrument [Line Items] | ||
| Debt, maturity year | 2016 | |
| 9 5/8% Senior Secured Second Lien Notes | ||
| Debt Instrument [Line Items] | ||
| Debt, interest rate | 9.625% | 9.625% | 
| Debt, maturity year | 2016 | 2016 | 
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- Definition Debt Instrument Maturity Year No definition available. 
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- Definition The average effective interest rate during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
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