Debt Instrument Borrowing Base Determination, Day and Month

No definition available.

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- Definition

Debt instrument covenant percentage of total value of mortgaged properties evaluated in reserve report.

+ References

No definition available.

+ Details

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- Definition

Debt instrument covenant percentage related to projected production volumes.

+ References

No definition available.

+ Details

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- Definition

Debt instrument ratio current consolidated assets to current consolidated liabilities.

+ References

No definition available.

+ Details

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- Definition

Amount of decrease in borrowing base of line of credit facility.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Financial covenant requirement amount of cash on hand of current borrowing base.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Financial covenant requirement percentage of cash on hand of current borrowing base.

+ References

No definition available.

+ Details

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- Definition

Line of Credit Maturity Month and Year

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Pro rata share percentage of new common stock for predecessor unitholders.

+ References

No definition available.

+ Details

Name:	hrst_ProRataSharePercentageOfNewCommonsTockForPredecessorUnitholders
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Ratio of Indebtedness to Earnings.

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
Balance Type:	na
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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ 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))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

States whether the entity was in compliance with the debt covenants throughout the reporting period, and describes facts and circumstances of any compliance failure.

+ References

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

+ Details

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Data Type:	num:percentItemType
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

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

+ Details

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value amount of debt instrument that was repurchased.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentRepurchaseAmount
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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) from the difference between the repurchase price of a debt instrument initially issued by the entity and the net carrying amount of the debt at the time of its repurchase.

+ References

No definition available.

+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective interest rate at the end of the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Long-Term Debt, Net (Narrative) (Details) - USD ($) $ in Thousands			12 Months Ended
	Jun. 04, 2018	May 31, 2018	Dec. 31, 2018	Dec. 31, 2016	Mar. 31, 2019	Aug. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	$ 1,000,000
Line of credit facility amount outstanding			$ 115,000
Senior Note Holders
Debt Instrument [Line Items]
Pro rata share percentage of new common stock for predecessor unitholders	95.00%
Predecessor
Debt Instrument [Line Items]
Line of credit facility amount outstanding							$ 263,000
8.0% Senior Notes due 2019 \| Predecessor
Debt Instrument [Line Items]
Senior unsecured notes, stated interest rate		8.00%
Senior notes maturity date		Apr. 15, 2019
Debt instrument, repurchased face amount				$ 82,700
Debt instrument, repurchased amount				35,000
Gain (loss) on repurchase of debt instrument				$ 47,700
Senior notes, carrying amount							343,348
Standby Letters of Credit \| Predecessor
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity		$ 100,000
Letters of credit outstanding, amount		200					$ 200
Standby Letters of Credit \| Successor
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	$ 50,000
Letters of credit outstanding, amount			$ 200
Secured Debt \| Predecessor
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity		$ 1,000,000
Weighted average effective interest rate		5.47%					4.82%
Line of credit, borrowing base		$ 325,000					$ 325,000
Credit facility, expiration date		2020-02
Secured Debt \| Revolving Credit Facility
Debt Instrument [Line Items]
Weighted average effective interest rate			5.10%
Reduction in borrowing base			$ 2,400			$ 60,300
Line of credit, borrowing base			$ 262,300			$ 264,700
Ratio of indebtedness to earnings			4.0
Debt instrument ratio current consolidated assets to current consolidated liabilities			1.0
Debt instrument covenant percentage of total value of mortgaged properties evaluated in reserve report			95.00%
Debt instrument covenant percentage related to projected production volumes			70.00%
Percentage of cash, per current borrowing base			5.00%
Amount of cash, equivalent to percentage			$ 30,000
Debt instrument, covenant compliance			As of December 31, 2018, the Company was in compliance with all of these financial covenants.
Secured Debt \| Revolving Credit Facility \| Successor
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	$ 1,000,000
Senior credit facility, expiration date			Feb. 26, 2021
Secured Debt \| Revolving Credit Facility \| Borrowing Base Determination, Period One
Debt Instrument [Line Items]
Borrowing base scheduled redetermination date			--04-01
Secured Debt \| Revolving Credit Facility \| Borrowing Base Determination, Period Two
Debt Instrument [Line Items]
Borrowing base scheduled redetermination date			--10-01
Subsequent Event [Member] \| Secured Debt \| Revolving Credit Facility
Debt Instrument [Line Items]
Reduction in borrowing base					$ 2,000