SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) number in Thousands, $ in Thousands	3 Months Ended
Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Significant Accounting Policies [Line Items]
Number of natural gas distribution services customers	2,300
Segment Reporting, Disclosure of Major Customers	no	no
Allowance for Doubtful Accounts, Premiums and Other Receivables	$ 17,200		$ 16,100
Capital Expenditures Incurred but Not yet Paid	$ 13,400	$ 5,300

Number of customers the natural gas distribution service segment services.

No definition available.

Name:	ogs_NumberOfNaturalGasDistributionServicesCustomers
Namespace Prefix:	ogs_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items for Significant accounting policies of the reporting entity.

+ References

No definition available.

+ Details

Name:	ogs_SignificantAccountingPoliciesLineItems
Namespace Prefix:	ogs_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The valuation allowance as of the balance sheet date to reduce the gross amount of receivables to estimated net realizable value, which would be presented in parentheses on the face of the balance sheet.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481962/310-10-50-4

+ Details

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

- Definition

Future cash outflow to pay for purchases of fixed assets that have occurred.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482913/230-10-50-4

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482913/230-10-50-3

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482913/230-10-50-5

+ Details

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

- Definition

Disclosure of the extent of enterprise reliance on its major customers. For example, includes revenues from transactions with a single external customer amounting to 10 percent or more of the entity's revenues, the total amount of revenues from each such customer, and the identity of the segment or segments reporting the revenues. A group of entities that the entity knows to be under common control generally will be considered a single customer for inclusion in this item. The federal government, a state government, a local government (for example, a county or municipality), or a foreign government each will generally be considered as a single customer for inclusion in this item.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

+ Details

Name:	us-gaap_SegmentReportingDisclosureOfMajorCustomers
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration