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Reportable Segments - Results of Operations by Reportable Segment (Parenthetical) (Detail)
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12 Months Ended | |||||||||||
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Dec. 31, 2012
Customer
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Dec. 31, 2012
Exxon Neftegas Limited (ENL) [Member]
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Dec. 31, 2011
Exxon Neftegas Limited (ENL) [Member]
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Dec. 31, 2012
Exxon Neftegas Limited (ENL) [Member]
International Drilling [Member]
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Dec. 31, 2011
Exxon Neftegas Limited (ENL) [Member]
International Drilling [Member]
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Dec. 31, 2012
Dowell Schlumberger [Member]
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Dec. 31, 2012
Dowell Schlumberger [Member]
International Drilling [Member]
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Dec. 31, 2010
BP [Member]
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Dec. 31, 2010
BP [Member]
Construction Contract [Member]
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Dec. 31, 2010
ExxonMobil [Member]
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Dec. 31, 2010
ExxonMobil [Member]
Rental Tools [Member]
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Dec. 31, 2010
ExxonMobil [Member]
International Drilling [Member]
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| Segment Reporting Information [Line Items] | ||||||||||||
| Number of major customer | 2 | |||||||||||
| Percent of total revenues | 12.00% | 16.00% | 10.00% | 12.00% | 12.00% | |||||||
| Percent of segment revenues | 27.00% | 34.00% | 24.00% | 90.00% | 7.00% | 22.00% | ||||||