SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

3 Months Ended

Mar. 31, 2021

Accounting Policies [Abstract]

Asset Retirement Obligation Activity

Accounting Standards Update and Change in Accounting Principle

NEW ACCOUNTING PRONOUNCEMENTS - Other than as described below, no new accounting pronouncement had, or is expected to have, a material impact on the condensed consolidated financial statements of SJI, or the condensed financial statements of SJG.

Recently Adopted Standards:

Standard	Description	Date of Adoption	Application	Effect on the Financial Statements of SJI and SJG
ASU 2019-12: Simplifying the Accounting for Income Taxes	This ASU removes exceptions related to the incremental approach for intraperiod tax allocation, the requirement to recognize a deferred tax liability for changes in ownership of a foreign subsidiary or equity method investment, and the general methodology for calculating income taxes in an interim period when the year-to-date loss exceeds the anticipated loss. The guidance also adds requirements to reflect changes to tax laws or rates in the annual effective tax rate computation in the interim period in which the changes were enacted, to recognize franchise or other similar taxes that are partially based on income as an income-based tax and any incremental amounts as non-income-based tax, and to evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction.	January 1, 2021	Modified retrospective for amendments related to changes in ownership of a foreign subsidiary or equity method investment; Modified retrospective or retrospective for amendments related to taxes partially based on income; Prospective for all other amendments	Adoption of this guidance did not have a material impact on the financial statement results of SJI or SJG.
ASU 2020-01: Clarifying the Interactions between Topic 321 (Investments - Equity Securities), Topic 323 (Investments - Equity Method and Joint Ventures), and Topic 815 (Derivatives and Hedging)	The amendments in this ASU clarify that an entity should consider observable transactions that require it to either apply or discontinue the equity method of accounting for the purposes of applying the measurement alternative in accordance with Topic 321 immediately before applying or upon discontinuing the equity method. The amendments in this ASU also clarify that for the purposes of applying Topic 815, an entity should not consider whether, upon the settlement of a forward contract or exercise of a purchased option, individually or with existing investments, the underlying securities would be accounted for under the equity method in Topic 323 or the fair value option in accordance with the financial instruments guidance in Topic 825.	January 1, 2021	Prospective	Adoption of this guidance did not have a material impact on the financial statement results of SJI or SJG.

Standards Not Yet Effective:

Standard	Description	Date of Adoption	Application	Effect on the Financial Statements of SJI and SJG
ASU 2020-04: Reference Rate Reform (Topic 848) - Facilitation of the Effects of Reference Rate Reform on Financial Reporting ASU 2021-01: Reference Rate Reform (Topic 848)	The amendments in ASU 2020-04 provide various optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The amendments apply only to contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. The expedients and exceptions provided by the amendments do not apply to contract modifications made and hedging relationships entered into or evaluated after December 31, 2022, except for hedging relationships existing as of December 31, 2022, that an entity has elected certain optional expedients for and that are retained through the end of the hedging relationship. The amendments in ASU 2021-01 clarify that certain optional expedients and exceptions in Topic 848 for contract modifications and hedge accounting apply to changes in the interest rates used for margining, discounting, or contract price alignment for derivative instruments that are being implemented as part of the market-wide transition to new reference rates (commonly referred to as the "discounting transition").	March 12, 2020 through December 31, 2022 An entity may elect to apply the amendments for contract modifications by Topic or Industry Subtopic as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020, up to the date that the financial statements are available to be issued.	Prospective for contract modifications and hedging relationships. Once elected for a Topic or an Industry Subtopic, the amendments in this Update must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic.	Management is currently determining the impact that adoption of this guidance will have on the financial statements of SJI and SJG, including forming an implementation team that is evaluating the impact of the guidance on our current contracts. Management is also evaluating timing of adoption.

ASU 2020-06: Accounting for Convertible Instruments and Contracts in an Entity's Own Equity The amendments in this ASU simplify the accounting for convertible instruments by removing certain separation models in Subtopic 470-20. Under the amendments, embedded conversion features are no longer separated from the host contract for convertible instruments with conversion features that are not required to be accounted for as derivatives under Topic 815, or that do not result in substantial premiums accounted for as paid-in capital. Consequently, a convertible debt instrument will be accounted for as a single liability measured at its amortized cost and a convertible preferred stock will be accounted for as a single equity instrument measured at its historical cost, as long as no other features require bifurcation and recognition as derivatives. The amendments also add new convertible instrument disclosure requirements. Additionally, the amendments in this ASU remove certain conditions from the settlement guidance within the derivative scope exception guidance contained in Subtopic 815-40 and further clarify the derivative scope exception guidance. Finally, the amendments in this ASU align the diluted EPS calculation for convertible instruments by requiring that an entity use the if-converted method instead of the treasury stock method when calculated diluted EPS for convertible instruments. January 1, 2022; early adoption permitted, but not before January 1, 2021. Retrospective or Modified Retrospective Management is currently determining the impact that adoption of this guidance will have on the financial statements of SJI and SJG