Represents the number of idle conventional rigs that are decommissioned during the reporting period.

No definition available.

Name:	hp_NumberOfDecommissionedIdleConventionalRigs
Namespace Prefix:	hp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Loss recognized as a result of the initial and subsequent write-down of a long-lived asset's carrying amount to fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2921-110230

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=hp_ContractDrillingEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=hp_RealEstateBuildingsAndEquipmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_PropertyPlantAndEquipmentOtherTypesMember
Namespace Prefix:
Data Type:	na
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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, Property, plant and equipment (Details) $ in Millions	12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($) item
PROPERTY, PLANT AND EQUIPMENT
Abandonments \| $	$ 42.6	$ 39.3	$ 43.6
Number of idle conventional rigs decommissioned \| item			23
Contract drilling equipment \| Minimum
PROPERTY, PLANT AND EQUIPMENT
Estimated useful lives	4 years
Contract drilling equipment \| Maximum
PROPERTY, PLANT AND EQUIPMENT
Estimated useful lives	15 years
Real estate buildings and equipment \| Minimum
PROPERTY, PLANT AND EQUIPMENT
Estimated useful lives	10 years
Real estate buildings and equipment \| Maximum
PROPERTY, PLANT AND EQUIPMENT
Estimated useful lives	45 years
Other assets \| Minimum
PROPERTY, PLANT AND EQUIPMENT
Estimated useful lives	2 years
Other assets \| Maximum
PROPERTY, PLANT AND EQUIPMENT
Estimated useful lives	23 years