SEGMENT INFORMATION (Details 2) (USD $)	12 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Revenues from external customers
Total operating revenue	$ 2,543,894,000	$ 1,875,162,000	$ 1,843,740,000
Total Long-Lived Assets	3,677,070,000	3,275,020,000	3,194,273,000
Receivables from customers	95,500,000	85,100,000
Contract Drilling
Revenues from external customers
Total operating revenue	2,528,774,000	1,862,408,000	1,832,965,000
U.S. Land
Revenues from external customers
Total operating revenue	2,100,508,000	1,412,495,000	1,441,164,000
Offshore
Revenues from external customers
Total operating revenue	201,417,000	202,734,000	204,702,000
International Land
Revenues from external customers
Total operating revenue	226,849,000	247,179,000	187,099,000
Other.
Revenues from external customers
Total operating revenue	15,120,000	12,754,000	10,775,000
Reportable and other
Revenues from external customers
Total operating revenue	2,543,894,000	1,875,162,000	1,843,740,000
United States
Revenues from external customers
Total operating revenue	2,276,118,000	1,572,139,000	1,613,940,000
Total Long-Lived Assets	3,423,185,000	2,973,712,000	2,879,222,000
Argentina
Revenues from external customers
Total operating revenue	44,205,000	55,855,000	42,087,000
Total Long-Lived Assets	78,221,000	91,322,000	99,896,000
Ecuador
Revenues from external customers
Total operating revenue	42,598,000	52,115,000	52,250,000
Total Long-Lived Assets	28,439,000	27,772,000	26,022,000
Colombia
Revenues from external customers
Total operating revenue	74,504,000	57,533,000	77,322,000
Total Long-Lived Assets	67,369,000	59,798,000	62,942,000
Other Foreign
Revenues from external customers
Total operating revenue	106,469,000	137,520,000	58,141,000
Total Long-Lived Assets	$ 79,856,000	$ 122,416,000	$ 126,191,000
One company
Revenues from external customers
Revenues from major customer (as a percent)	12.50%	12.50%	10.10%
Another company
Revenues from external customers
Revenues from major customer (as a percent)	11.50%	10.60%	12.40%

Represents the percentage of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues.

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Amount of revenue generated from a single external customer that accounts for 10 percent or more of an entity's revenues.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 39

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 42

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9054-108599

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- Definition

Tangible assets that are held by an entity for use in the production or supply of goods and services, for rental to others, or for administrative purposes and that are expected to provide economic benefit for more than one year; net of accumulated depreciation. 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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.13)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 7

-Section 03

-Paragraph 8

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 13

-Subparagraph a

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 12

-Paragraph 5

-Subparagraph b, c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

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- Definition

Amount of revenue from external customers for the reportable segment. Such disclosure is presented if the amount is: (a) included in the measure of segment profit or loss reviewed by the chief operating decision maker or (b) otherwise regularly provided to the chief operating decision maker, even if not included in that measure of segment profit or loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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