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v3.20.1

Subsequent Events (Details) $ in Millions | 1 Months Ended | 3 Months Ended | 6 Months Ended
--- | --- | --- | ---
May 04, 2020 USD ($) rig | Mar. 31, 2020 USD ($) | Mar. 31, 2019 USD ($) | Mar. 31, 2020 USD ($) | Mar. 31, 2019 USD ($)
Subsequent Event [Line Items] |  |  |  |  |
Early termination revenue | $ |  | $ 8.2 | $ 1.2 | $ 8.3 | $ 8.3
Subsequent Event |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |
Early termination revenue | $ | $ 27.0 |  |  |  |
Domestic Conventional Rigs Asset Group | Subsequent Event |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |
Number of rigs decommissioned | rig | 2 |  |  |  |
FlexRig3 Asset Group | Subsequent Event |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |
Number of rigs decommissioned | rig | 35 |  |  |  |

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- Definition Revenue related to early termination of contract. + References No definition available. + Details
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Namespace Prefix: | hp_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Number Of Rigs Decommissioned + References No definition available. + Details
Name: | hp_NumberOfRigsDecommissioned
Namespace Prefix: | hp_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=hp_DomesticConventionalAssetGroupMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=hp_FlexRig3AssetGroupMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |