Property and Equipment - Narrative (Details) (USD $)	3 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment
Asset impairment	$ 60,777,000	$ 0
Proceeds from sale of assets	1,348,000	13,277,000
(Gain) loss on sale of equipment	9,806,000	(1,637,000)
Atwood Southern Cross
Property, Plant and Equipment
Impairment, Net of Tax	7,100,000
Impairment Effect on Earnings Per Share, after Tax	$ 0.11
Proceeds from sale of assets	2,100,000
Other Operating Income (Expense), Net	2,000,000
(Gain) loss on sale of equipment	8,000,000
Construction in Progress, Newbuild Drilling Units
Property, Plant and Equipment
Expenditure towards construction of drilling units currently under construction	418,000,000
Capital Addition Purchase Commitments \| Construction in Progress, Newbuild Drilling Units
Property, Plant and Equipment
Commitments on drilling units under construction	704,000,000
Atwood Hunter
Property, Plant and Equipment
Asset impairment	60,800,000
Impairment, Net of Tax	56,100,000
Impairment Effect on Earnings Per Share, after Tax	$ 0.86
Atwood Hunter \| Equipment
Property, Plant and Equipment
Asset impairment	48,000,000
Atwood Hunter \| Inventory
Property, Plant and Equipment
Asset impairment	$ 8,400,000

Impairment of Long-Lived Assets to be Disposed of, Net of Tax

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- Definition

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

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After tax earnings per share or per unit impact arising from asset impairment.

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The aggregate amount of write-downs for impairments recognized during the period for long-lived assets held for abandonment, exchange or sale.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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The minimum amount the entity agreed to spend under the long-term purchase commitment.

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The net amount of other operating income and expenses, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operations.

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The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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