INCOME TAXES INCOME TAXES (Details) $ in Millions	Jun. 30, 2020 USD ($)
Income Tax Disclosure [Abstract]
Kansas Gas Service tax reform regulatory liability	$ 81.5

Kansas Gas Service tax reform regulatory liability

No definition available.

Name:	ogs_KansasGasServicetaxreformregulatoryliability
Namespace Prefix:	ogs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant