Commitment fee percentage

No definition available.

Name:	hpr_CommitmentFeePercentage
Namespace Prefix:	hpr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line of Credit, Upon Redetermination Maximum Borrowing Capacity Could Be Reduced By

+ References

No definition available.

+ Details

Name:	hpr_LineOfCreditMaximumBorrowingCapacityCouldBeReducedByUponRedetermination
Namespace Prefix:	hpr_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum Credit Amount, Maximum Commitments That Could Be Elected By Lenders

+ References

No definition available.

+ Details

Name:	hpr_MaximumCreditAmountMaximumCommitmentsThatCouldBeElectedByLenders
Namespace Prefix:	hpr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Permitted Debt Resulting in Accelerated Maturity Date

+ References

No definition available.

+ Details

Name:	hpr_PermittedDebtResultingInAcceleratedMaturityDate
Namespace Prefix:	hpr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Revolving Credit Facility Interest Rate Percent Above LIBOR.

+ References

No definition available.

+ Details

Name:	hpr_RevolvingCreditFacilityInterestRatePercentAboveLibor
Namespace Prefix:	hpr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Revolving credit facility interest rate percent above Libor alternate interest rate

+ References

No definition available.

+ Details

Name:	hpr_RevolvingCreditFacilityInterestRatePercentAboveLiborAlternateInterestRate
Namespace Prefix:	hpr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ 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://fasb.org/us-gaap/role/ref/legacyRef
-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

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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
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
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The effective interest rate during the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

Long-Term Debt - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Debt Instrument [Line Items]
Maximum credit amount	$ 1,500,000,000
Principal amount	$ 720,000,000		$ 765,000,000
Weighted average interest rate	3.40%	4.00%
Minimum
Debt Instrument [Line Items]
Interest rate margin	1.50%
Revolving credit facility interest rate percent above LIBOR alternate interest rate	0.50%
Commitment fee percentage	0.375%
Maximum
Debt Instrument [Line Items]
Interest rate margin	2.50%
Revolving credit facility interest rate percent above LIBOR alternate interest rate	1.50%
Commitment fee percentage	0.50%
Amended Credit Facility
Debt Instrument [Line Items]
Debt instrument, maturity date	Sep. 14, 2023
Line of credit facility, maximum borrowing capacity	$ 500,000,000.0
Principal amount	95,000,000		140,000,000
Letters of credit issued amount	26,000,000.0
Line of credit facility, remaining borrowing capacity	379,000,000.0
Permitted Debt Resulting in Accelerated Maturity Date	$ 100,000,000.0
Line of Credit Maximum Borrowing Capacity Could Be Reduced By Upon Redetermination	0.50
7.0% Senior Notes
Debt Instrument [Line Items]
Debt instrument, maturity date	Oct. 15, 2022
Principal amount	$ 350,000,000		350,000,000
Debt, stated interest rate	7.00%
8.75% Senior Notes
Debt Instrument [Line Items]
Debt instrument, maturity date	Jun. 15, 2025
Principal amount	$ 275,000,000		$ 275,000,000
Debt, stated interest rate	8.75%