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Estimated Useful Lives of Property and Equipment (Detail)	12 Months Ended
	Dec. 31, 2011 Year
Drilling rigs and other equipment
Property, Plant and Equipment [Line Items]
Useful Lives, minimum	1.5
Useful Lives, maximum	15
Buildings
Property, Plant and Equipment [Line Items]
Useful Lives, minimum	15.0
Useful Lives, maximum	20
Other
Property, Plant and Equipment [Line Items]
Useful Lives, minimum	3.0
Useful Lives, maximum	12

X

- Details

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X

- Definition

The maximum useful life of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

+ References

No definition available.

+ Details

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X

- Definition

The minimum useful life of long lived, physical assets used in the normal conduct of business and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

+ References

No definition available.

+ Details

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