Cash Flow Discount Rate

No definition available.

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Standardized measure Of Discontinued Future Net Cash Flows Relating To Proved Oil, Natural Gas And Natural Gas Liquids Reserves [Abstract]

No definition available.

Name:	hrst_StandardizedMeasureOfDiscontinuedFutureNetCashFlowsRelatingToProvedOilNaturalGasAndNaturalGasLiquidsReservesAbstract
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Amount of estimated future accumulated cash inflow from the sale of proved oil and gas reserves.

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Amount of estimated future accumulated cash outflow for costs to be incurred in developing proved oil and gas reserves.

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Amount of estimated future accumulated cash outflow for income tax, based on the future income less future expense derived from production and sale of proved oil and gas reserves.

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Amount, after future accumulated cash outflow for development and production costs and future income tax, of estimated future accumulated cash inflow from the sale of proved oil and gas reserves.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Form 20-F
-Section Item 18
-Subsection Instruction 2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62479-109447

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 55
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=34713648&loc=d3e63094-109448

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 31
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62455-109447

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62476-109447

Name:	srt_FutureNetCashFlowsRelatingToProvedOilAndGasReservesNetCashFlows
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Amount of discount on future accumulated cash inflow, after deducting future accumulated cash outflow for development and production costs and future income tax, from sale of proved oil and gas reserves, using a discount rate of ten percent a year.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of discounted future accumulated cash inflow relating to proved oil and gas reserves.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Form 20-F
-Section Item 18
-Subsection Instruction 2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 31
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62455-109447

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 30
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62424-109447

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 55
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=34713648&loc=d3e63094-109448

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62500-109447

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62479-109447