Represents the number of subsidiaries.

No definition available.

Name:	hk_NumberOfSubsidiaries
Namespace Prefix:	hk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash inflow (outflow) to dispose of long-lived, physical assets and mineral interests in oil and gas properties used for normal oil and gas operations.

+ References

No definition available.

+ Details

Name:	hk_ProceedsPaymentsFromSaleOfOilAndGasPropertyAndEquipment
Namespace Prefix:	hk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentRepurchasedFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2443-110228

+ Details

Name:	us-gaap_GainLossOnDispositionOfAssets1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ 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)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

+ Details

Name:	us-gaap_GainLossOnSaleOfPropertyPlantEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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

- Definition

The cash inflow to dispose of long-lived, physical assets and mineral interests in oil and gas properties used for normal oil and gas operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

+ Details

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

- Definition

Amount of cash inflow for the sale of long-lived, physical assets used to produce goods and services and not intended for resale, classified as other.

+ References

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=hk_SeniorSecuredNotesTwoDue2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=hk_SeniorNotesDue2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_GainLossOnInvestmentsMember1
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=hk_WillistonBasinOperatedAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=hk_EagleFordFormationAssetsOfEastTexasElHalconAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=hk_NonOperatingOwnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

ACQUISITIONS AND DIVESTITURES - Divestitures (Details) $ in Thousands				3 Months Ended			6 Months Ended		12 Months Ended
	Sep. 19, 2017 USD ($)	Jul. 10, 2017 USD ($) subsidiary	Jan. 24, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Oct. 10, 2017 USD ($)	Sep. 07, 2017 USD ($)	Feb. 16, 2017 USD ($)
Divestitures
Proceeds received from sale of oil and natural gas properties							$ 1,779	$ 477,306
Aggregate principal amount				$ 625,005			625,005		$ 425,005
Proceeds received from sale of other operating property and equipment							1,899	10,352
Gain (loss) from sale of other operating property and equipment				$ (2,225)	$ 4,500		$ (5,904)	235,690
12.0% senior secured second lien notes due 2022
Divestitures
Interest rate (as a percent)		12.00%
6.75% senior notes due 2025
Divestitures
Principal amount repurchased										$ 425,000	$ 425,000
Aggregate principal amount											$ 850,000	$ 850,000
Interest rate (as a percent)				6.75%			6.75%		6.75%		6.75%	6.75%
Gain on sale of oil and natural gas assets
Divestitures
Gain (loss) from sale of other operating property and equipment		$ 0	$ 0
Williston Basin Assets
Divestitures
Gain (loss) from sale of other operating property and equipment		0					$ (5,900)		$ 485,900
Williston Basin Assets \| Other operating property and equipment
Divestitures
Proceeds received from sale of oil and natural gas properties		1,390,000
Proceeds received from sale of other operating property and equipment		$ 10,900
Williston Basin Assets \| 6.75% senior notes due 2025
Divestitures
Principal amount repurchased											$ 425,000
Williston Basin Assets \| Disposal Group Disposed of by Sale
Divestitures
Ownership percentage in subsidiaries		100.00%
Number of subsidiaries \| subsidiary		2
Proceeds received from sale of oil and natural gas properties		$ 1,400,000
El Halcon Assets
Divestitures
Gain (loss) from sale of other operating property and equipment			0
El Halcon Assets \| Other operating property and equipment
Divestitures
Proceeds received from sale of oil and natural gas properties			484,100
Proceeds received from sale of other operating property and equipment			10,200
El Halcon Assets \| Gain on sale of oil and natural gas assets
Divestitures
Gain (loss) from sale of other operating property and equipment						$ 231,200		$ 4,500
El Halcon Assets \| Disposal Group Disposed of by Sale
Divestitures
Proceeds from sales of interests			$ 491,100
Non-operating owner \| Williston Basin Assets
Divestitures
Proceeds from sales of interests	$ 103,400
Gain (loss) on sale	$ 0