INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Reduction in income tax expense for the amortization of the regulatory liability associated with excess ADIT that was returned to customers	$ 8,100	$ 10,100

Reduction in income tax expense for the amortization of the regulatory liability associated with excess ADIT that was returned to customers

No definition available.

Name:	ogs_ReductioninincometaxexpensefortheamortizationoftheregulatoryliabilityassociatedwithexcessADITthatwasreturnedtocustomers
Namespace Prefix:	ogs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration