Nature of Business (Details)	Dec. 31, 2011 drillingunit	Oct. 31, 2011 drillingunit
Nature of Business
Number of mobile offshore drilling units	135
Number of High-Specification Floaters (in drilling units)	50
Number of Midwater Floaters (in drilling units)	25
Number of High-Specification Jackups (in drilling units)	9
Number of Standard Jackups (in drilling units)	50
Number of swamp barges (in drilling units)	1
Number of Ultra-Deepwater Floaters under construction (in drilling units)	2	2
Number of High-Specification Jackups under construction (in drilling units)	4

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Number of High-Specification Floaters, which includes Ultra-Deepwater, Deepwater and Harsh Environment semisubmersibles and drillships. High-Specification Floaters are specialized offshore drilling units with a water depth capacity of 4,500 feet or greater.

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- Definition

Number of High-Specification Jackups. High-Specification Jackups are harsh environment and high-performance jackups. Jackups are self-elevating drilling platforms that have legs that can be lowered to the ocean floor to establish a foundation to support the drilling platform. These units are generally suited for water depths of 400 feet or less.

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- Definition

Number of High-Specification Jackups under construction.

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- Definition

Number of Midwater Floaters. Midwater Floaters are non-high-specification semisubmersibles with a water depth capacity of less than 4,500 feet.

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No definition available.

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- Definition

Number of mobile offshore drilling units we own, had partial ownership interests in or operated at the measurement date.

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- Definition

Number of Standard Jackups. Standard Jackups are all other jackups other than High-Specification Jackups. Jackups are self-elevating drilling platforms that have legs that can be lowered to the ocean floor to establish a foundation to support the drilling platform. These units are generally suited for water depths of 400 feet or less.

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No definition available.

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- Definition

Number of swamp barge drilling rigs.

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No definition available.

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- Definition

Number of Ultra-Deepwater Floaters under construction.

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