Lessee Operating Lease, Number Of Options To Extend

No definition available.

Name:	hp_LesseeOperatingLeaseNumberOfOptionsToExtend
Namespace Prefix:	hp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

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

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of operating lease expense. Excludes sublease income.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918638-209977

+ Details

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

- Definition

Weighted average discount rate for operating lease calculated at point in time.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(4)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971

+ Details

Name:	us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_LeaseContractualTermAxis=hp_TulsaCorporateOfficeLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LeaseContractualTermAxis=hp_TulsaIndustrialFacilityLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LEASES - Narrative (Details) $ in Millions	12 Months Ended
LEASES - Narrative (Details) $ in Millions	Sep. 30, 2020 USD ($) renewal_option	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Oct. 01, 2019
Lessee, Lease, Description [Line Items]
Weighted average incremental borrowing rate applied to operating lease liabilities	2.70%			2.90%
Operating lease expense \| $	$ 18.6	$ 15.5	$ 13.7
Tulsa Corporate Office Lease
Lessee, Lease, Description [Line Items]
Number of renewal options	2
Renewal option term	5 years
Tulsa Industrial Facility Lease
Lessee, Lease, Description [Line Items]
Number of renewal options	2
Renewal option term	2 years