v2.3.0.15

Segment Information (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2011
Segment Reporting Information [Line Items]
Number of drillships		7
Revenues provided by drilling operations in U.S. Gulf of Mexico	$ 251.3	$ 539.4
Percent of revenues provided by drilling operations in the U.S. Gulf of Mexico	27.00%	29.00%
Percent of drilling revenues provided by deepwater drilling operations in the U.S. Gulf of Mexico	74.00%	68.00%
Minimum [Member] | Deepwater [Member]
Segment Reporting Information [Line Items]
Rigs drilling capacity		4,500
Maximum [Member] | Midwater [Member]
Segment Reporting Information [Line Items]
Rigs drilling capacity		4,499
Maximum [Member] | Jackup [Member]
Segment Reporting Information [Line Items]
Rigs drilling capacity		400
Deepwater [Member] | Other [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs		2
Jackup [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs		48
Other [Member] | Barge Rig [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs		1
Semisubmersibles [Member]
Segment Reporting Information [Line Items]
Number of contract drilling rigs		20

X

- Definition

Number Of Contract Drilling Rig

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X

- Definition

Number of drillships.

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X

- Definition

Percent Of Drilling Revenues Provided By Deepwater Drilling Operations In The US Gulf Of Mexico

+ Details

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- Definition

Percent Of Revenues Provided By Drilling Operations In The US Gulf Of Mexico

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- Definition

Revenues Provided By Drilling Operation

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Balance Type:	credit
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X

- Definition

Rigs drilling capacity, feet.

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Period Type:	duration

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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