XML 116 R99.htm IDEA: XBRL DOCUMENT
v3.10.0.1

EMPLOYEE BENEFIT PLANS - Plan Assets (Details) - USD ($) $ in Thousands | Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2016
--- | --- | --- | ---
PLAN ASSETS |  |  |
Fair value of plan assets | $ 94,897 | $ 92,816 | $ 90,748
(Level 1) |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 92,320 | 92,719 |
(Level 1) | Short-term investments. |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 2,745 | 3,488 |
(Level 1) | Mutual funds |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 68,804 | 69,539 |
(Level 1) | Domestic stock funds |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 18,361 | 18,377 |
(Level 1) | Bond funds |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 17,918 | 18,357 |
(Level 1) | Balanced funds |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 17,977 | 18,222 |
(Level 1) | International stock funds |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 14,548 | 14,583 |
(Level 1) | Domestic common stock |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 20,771 | 19,692 |
(Level 2) |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 2,461 |  |
(Level 2) | Domestic common stock |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 2,461 |  |
(Level 3) |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 116 | 97 | $ 177
(Level 3) | Oil and Gas Properties |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 116 | 97 |
Total Measure at Fair Value |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 94,897 | 92,816 |
Total Measure at Fair Value | Short-term investments. |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 2,745 | 3,488 |
Total Measure at Fair Value | Mutual funds |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 68,804 | 69,539 |
Total Measure at Fair Value | Domestic stock funds |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 18,361 | 18,377 |
Total Measure at Fair Value | Bond funds |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 17,918 | 18,357 |
Total Measure at Fair Value | Balanced funds |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 17,977 | 18,222 |
Total Measure at Fair Value | International stock funds |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 14,548 | 14,583 |
Total Measure at Fair Value | Domestic common stock |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | 23,232 | 19,692 |
Total Measure at Fair Value | Oil and Gas Properties |  |  |
PLAN ASSETS |  |  |
Fair value of plan assets | $ 116 | $ 97 |

X
- 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_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_MutualFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_PrivateEquityFundsDomesticMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_BondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_BalancedFundsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_PrivateEquityFundsForeignMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=hp_DomesticCommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_OilAndGasPropertiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |