The amount of contribution receivable from general partner.

No definition available.

Name:	grnt_PartnersCapitalAccountContributionReceivable
Namespace Prefix:	grnt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage of allocation of net profit and losses to partners

+ References

No definition available.

+ Details

Name:	grnt_PercentageOfAllocationOfNetProfitsAndLossesToPartners
Namespace Prefix:	grnt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of cumulative distributions received by distributions.

+ References

No definition available.

+ Details

Name:	grnt_PercentageOfCumulativeAmountOfDistributions
Namespace Prefix:	grnt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of cumulative distributions received by partner

+ References

No definition available.

+ Details

Name:	grnt_PercentageOfCumulativeDistributionsReceivedByPartner
Namespace Prefix:	grnt_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of reallocation of distributions from Limited Partner to General Partner

+ References

No definition available.

+ Details

Name:	grnt_ReallocationOfDistributionsFromLimitedPartnerToGeneralPartner
Namespace Prefix:	grnt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The total amount of distributions to limited partners.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB TOPIC 4.F)
-URI https://asc.fasb.org/extlink&oid=120397183&loc=d3e187171-122770

+ Details

Name:	us-gaap_LimitedPartnersCapitalAccountDistributionAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_LimitedPartnersCapitalAccountLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage rate used to calculate dividend payments on preferred stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496158-112644

+ Details

Name:	us-gaap_PreferredStockDividendRatePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_StatementScenarioAxis=grnt_ScenarioThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PartnerTypeOfPartnersCapitalAccountAxis=us-gaap_GeneralPartnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=grnt_ScenarioFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PartnerTypeOfPartnersCapitalAccountAxis=us-gaap_LimitedPartnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=grnt_ScenarioOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=grnt_ScenarioTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Partners' capital (Details) - USD ($)	3 Months Ended		9 Months Ended
Partners' capital (Details) - USD ($)	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Partners' capital
Reallocation of distributions from Limited Partner to General Partner	$ 6,654		$ 25,623	$ 12,856,000
LPA distributions	0	$ 0	$ 0	$ 0
Scenario III
Partners' capital
Percentage of cumulative distributions received by distributions			20.00%
General Partner
Partners' capital
Contributions receivable	0		$ 0		$ 84,000
General Partner \| Scenario III
Partners' capital
Percentage of cumulative distributions received by partner			80.00%
General Partner \| Scenario IV
Partners' capital
Percentage of cumulative distributions received by partner			20.00%
Limited Partner
Partners' capital
Contributions receivable	$ 10,000		$ 10,000
Limited Partner \| Scenario I
Partners' capital
Percentage of allocation of net profit and losses to partners			100.00%
Limited Partner \| Scenario II
Partners' capital
Percentage of allocation of net profit and losses to partners			100.00%
Preferred return (as a percent)			8.00%
Limited Partner \| Scenario III
Partners' capital
Percentage of cumulative distributions received by partner			20.00%
Limited Partner \| Scenario IV
Partners' capital
Percentage of cumulative distributions received by partner			80.00%