| Contracts Receivable - Additional Information (Detail) (USD $) | 9 Months Ended | ||
|---|---|---|---|
| Sep. 30, 2012
 Customer | Dec. 31, 2011 | Jan. 14, 2011 | |
| Accounts, Notes, Loans and Financing Receivable [Line Items] | |||
| Contract receivable | $ 91,748,000 | $ 72,474,000 | |
| Number of customers account for 74.3% of contract receivable | 3 | ||
| Contract retainage | 11,000,000 | ||
| Contract retainage to be collected in twenty equal monthly installments | 12,500,000 | ||
| Contract retainage to be collected through January 2013 | 2,500,000 | ||
| Top 3 Customer | |||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | |||
| Contract receivable | 68,200,000 | ||
| Bluewater | |||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | |||
| Contract receivable | 32,100,000 | ||
| Contract receivables monthly payments | 200,000 | ||
| Contract receivables monthly payment end date | Feb. 28, 2013 | ||
| Amount billed on customers | $ 56,700,000 | 
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- Definition Contract Receivable, Collection Date, End No definition available. 
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- Definition Monthly payment due on long-term contract receivable. No definition available. 
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- Definition Amount billed to customers under long-term contracts or programs that have been withheld because of retainage provisions in a contract to be collected in the twenty month period following the latest balance sheet presented. No definition available. 
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- Definition Amount billed to customers under long-term contracts or programs that have been withheld because of retainage provisions in a contract to be collected by January 2013. No definition available. 
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- Definition Number of customers that make up significant concentrations within the accounts receivable balance. No definition available. 
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- Details 
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- Definition Amount billed to customers under long-term contracts or programs to be collected in the next fiscal year following the latest fiscal year. Excludes amounts due that have been withheld because of retainage provisions in a contract. No definition available. 
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- Definition Amount billed to customers under long-term contracts or programs that have been withheld because of retainage provisions in a contract. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Revenue earned during the period arising from products sold or services provided under the terms of a contract, not elsewhere specified in the taxonomy. May include government contracts, construction contracts, and any other contract related to a particular project or product. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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