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Summary of Significant Accounting Policies - Summary of Depreciable Lives for Different Categories of Property Plant and Equipment (Detail)
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12 Months Ended |
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Dec. 31, 2012
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Minimum [Member] | Land drilling equipment [Member]
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| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, useful life | 3 years |
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Minimum [Member] | Barge drilling equipment [Member]
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| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, useful life | 3 years |
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Minimum [Member] | Drill pipe, rental tools and other [Member]
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| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, useful life | 4 years |
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Minimum [Member] | Buildings and improvements [Member]
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| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, useful life | 15 years |
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Maximum [Member] | Land drilling equipment [Member]
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| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, useful life | 20 years |
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Maximum [Member] | Barge drilling equipment [Member]
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| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, useful life | 20 years |
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Maximum [Member] | Drill pipe, rental tools and other [Member]
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| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, useful life | 7 years |
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Maximum [Member] | Buildings and improvements [Member]
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| Property, Plant and Equipment [Line Items] | |
| Property, Plant and Equipment, useful life | 30 years |