RATES AND REGULATORY ACTIONS (Details)			1 Months Ended																						3 Months Ended	12 Months Ended		336 Months Ended
	Jul. 01, 2018 USD ($)	Nov. 01, 2017 USD ($)	Dec. 31, 2019 USD ($) site customer	Nov. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jul. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	May 31, 2019 USD ($)	Apr. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jan. 31, 2019 USD ($)	Oct. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Aug. 31, 2018 USD ($)	Jul. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)	May 31, 2018 USD ($)	Mar. 31, 2018 USD ($)	Nov. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jul. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)	Apr. 30, 2017 USD ($)	Oct. 31, 2016 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) decatherm site customer	Jun. 30, 2017 USD ($)	Dec. 31, 2019 USD ($) site customer	Aug. 31, 2019 USD ($)	Jan. 31, 2017 USD ($)
Schedule of Capitalization [Line Items]
Approved rate of return on rate base, percentage											6.98%
Approved return on common equity, percentage											9.80%
Requested rate increase (decrease), amount											$ 90,000
Investment approved to be recovered through SHARP																	$ 100,300,000
Public utilities budget											$ 3,000,000.0
Amount of statewide funding approved																						$ 344,700,000					$ 344,700,000
Number of customers purchasing energy commodity from another entity | customer			21,693																							21,693		21,693
Unamortized remediation costs			$ 3,500,000																							$ 3,500,000		$ 3,500,000
Public utilities, funding level																$ 344,700,000
Disposal Group, Held-for-sale, Not Discontinued Operations
Schedule of Capitalization [Line Items]
Consideration received on sales or projects																									$ 228,100,000	$ 24,300,000
Elkton Gas | Disposal Group, Held-for-sale, Not Discontinued Operations
Schedule of Capitalization [Line Items]
Consideration received on sales or projects			$ 15,000,000.0
Weather
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount														$ (800,000)
Public utilities, annual revenue														6,300,000
New Jersey Board of Public Utilities
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount														1,300,000
Public utilities, annual revenue														2,200,000
South Jersey Gas Company
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)													$ (25,900,000)
Investment amount of SHARP																			$ 110,300,000
Investment requested to be recovered through SHARP, term																			3 years
Number of sites for environmental cleanup (in sites) | site			12																							12		12
Regulatory assets			$ 496,177,000																						492,365,000	$ 496,177,000		$ 496,177,000
Regulatory costs entity is expensing																						12,700,000					12,700,000
South Jersey Gas Company | Environmental Remediation Costs: Expended - Net
Schedule of Capitalization [Line Items]
Regulatory assets			$ 156,279,000																						136,227,000	$ 156,279,000		$ 156,279,000
South Jersey Gas Company | Storm Hardening and Reliability Program | Building
Schedule of Capitalization [Line Items]
Investments during the period																											35,700,000
South Jersey Gas Company | New Jersey Board of Public Utilities
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)		$ 39,500,000
Approved rate of return on rate base, percentage		6.80%
Approved return on common equity, percentage		9.60%
Requested rate increase (decrease), amount												$ 3,500,000						$ 195,400,000
Roll of AIRP investments into base rates									$ 63,000,000.0				60,400,000
Investment to be recovered by Sharp II					$ 27,400,000
Public utilities budget												81,300,000
Amount of statewide funding approved													3,700,000
Increase (decrease) in Universal Service Fund recoveries													900,000
South Jersey Gas Company | New Jersey Board of Public Utilities | SHARP Investments
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)																				$ 3,600,000
Public utilities, property, plant and equipment									28,300,000											33,300,000
South Jersey Gas Company | New Jersey Board of Public Utilities | Annual BGSS Filing
Schedule of Capitalization [Line Items]
Public utilities, bill credit																							$ 8,000,000.0
Requested rate increase (decrease), amount							$ (27,600,000)															(4,700,000)
South Jersey Gas Company | New Jersey Board of Public Utilities | EET Rate Adjustment Petition
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)																			$ 2,600,000
Requested rate increase (decrease), amount																						3,000,000.0
South Jersey Gas Company | New Jersey Board of Public Utilities | Storm Hardening and Reliability Program
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount									3,000,000.0														4,000,000.0
South Jersey Gas Company | New Jersey Board of Public Utilities | AIRP II Investments
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)																				5,000,000.0
Public utilities, property, plant and equipment																				46,100,000			42,000,000.0
Authorized replacement investments (up to)																								$ 302,500,000
South Jersey Gas Company | New Jersey Board of Public Utilities | Annual SBC Filing
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount						$ 3,900,000															$ 8,500,000
Annual BGSS Filing | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)													65,500,000
Stipulation of Settlement | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)								$ 65,500,000
Public utilities, bill credit								$ 24,000,000.0
Recovery period | decatherm																										2
Conservation Incentive Program | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount																						200,000
Conservation Incentive Program | South Jersey Gas Company | Non-weather
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount																						1,100,000
Conservation Incentive Program | South Jersey Gas Company | Weather
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount																						(900,000)
Annual CIP Filing | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount							(7,600,000)									(26,400,000)
Annual CIP Filing | South Jersey Gas Company | Non-weather
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount							(32,300,000)									(4,000,000.0)
Annual CIP Filing | South Jersey Gas Company | Weather
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount							24,700,000									(22,400,000)
Accelerated Infrastructure Replacement Program
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount																							$ 4,500,000
Accelerated Infrastructure Replacement Program | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount									6,500,000				6,600,000
Accelerated Infrastructure Replacement Program II | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)					6,700,000
Regulatory investment to be recovered by AIRP II					64,500,000
SHARP II | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)					2,900,000
EET
Schedule of Capitalization [Line Items]
Amount of regulatory costs available for recovery																														$ 36,300,000
EET | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount																(1,600,000)
Annual EET Rate Adjustments | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount							1,300,000
Societal Benefits Clause | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount															$ (3,400,000)
Societal Benefits Clause | South Jersey Gas Company | New Jersey Board of Public Utilities
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)										$ (2,200,000)
Remediation Adjustment Clause
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount														6,900,000
Number of sites for environmental cleanup (in sites) | site			12																							12		12
Amortization period																										7 years
Regulated costs recovered																												$ 154,200,000
Remediation Adjustment Clause | Environmental Remediation Costs: Expended - Net
Schedule of Capitalization [Line Items]
Regulatory assets			$ 156,300,000																						136,200,000	$ 156,300,000		156,300,000
New Jersey Clean Energy Program
Schedule of Capitalization [Line Items]
Amount of statewide funding approved																344,700,000													$ 344,700,000
New Jersey Clean Energy Program | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Regulatory costs entity is expensing																12,700,000													$ 13,200,000
Universal Service Fund
Schedule of Capitalization [Line Items]
Amount of statewide funding approved																				38,300,000
Amount of statewide costs proposed																						16,300,000					16,300,000
Universal Service Fund | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Amount of statewide funding approved							6,700,000									10,400,000
Amount of proposed impact of annual costs							1,000,000.0									900,000				(2,200,000)		$ (2,000,000.0)					$ (2,000,000.0)
Amount of increase (decrease) in regulatory costs approved																				$ 3,200,000
Annual USF Recoveries | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)					1,000,000.0
Annual Tax Rider | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount							6,800,000
OSMC Rate Adjustment
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount						200,000								1,100,000
State Gas Utilities
Schedule of Capitalization [Line Items]
Public utilities budget													45,500,000
Over Collected Tax
Schedule of Capitalization [Line Items]
Refund liability																5,200,000
Over Collected Tax | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Credits due to customers under conditions of approval													13,800,000
Unprotected Excess Deferred Income Tax | South Jersey Gas Company
Schedule of Capitalization [Line Items]
Credits due to customers under conditions of approval													$ 27,500,000
Public utilities, customer refund term													5 years
ETG Utility Operations
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount														1,200,000
Regulatory assets			169,231,000																						169,921,000	169,231,000		169,231,000
Public utilities, annual revenue													$ 2,200,000
Public utilities, funding level																11,500,000
ETG Utility Operations | Environmental Remediation Costs: Expended - Net
Schedule of Capitalization [Line Items]
Regulatory assets			16,955,000																						$ 10,875,000	16,955,000		16,955,000
ETG Utility Operations | Annual BGSS Filing
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount																	$ (7,100,000)
ETG Utility Operations | New Jersey Board of Public Utilities
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)	$ (12,100,000)			$ 34,000,000.0														$ (10,900,000)
Approved rate of return on rate base, percentage		6.50%
Approved return on common equity, percentage		9.60%
Approved common equity component, percentage		51.50%
Investment requested to be recovered through rider recovery mechanism, amount of IIP												$ 518,000,000.0
Requested recovery of investment costs not yet approved							300,000,000.0
ETG Utility Operations | Annual EEP Rate Adjustment
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)									$ 1,300,000
Requested rate increase (decrease), amount						1,000,000.0
ETG Utility Operations | Annual EEP Rate Adjustment | New Jersey Board of Public Utilities
Schedule of Capitalization [Line Items]
Public utilities budget			3,000,000.0																							3,000,000.0		3,000,000.0
ETG Utility Operations | WNC/OCP/OSMC Rate Adjustment Petition
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount						(7,800,000)
Public utilities, annual revenue						1,600,000
ETG Utility Operations | RAC Rate Adjustment Petition
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount						6,100,000
ETG Utility Operations | CEP Rate Adjustment
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount						$ (100,000)								(1,600,000)
Public utilities, annual revenue														$ 10,000,000.0
ETG Utility Operations | USF Filing
Schedule of Capitalization [Line Items]
Amount of statewide funding approved																7,200,000
Public utilities, annual revenue																$ 800,000
ETG Utility Operations | State Gas Utilities
Schedule of Capitalization [Line Items]
Requested rate increase (decrease), amount													800,000
Public utilities budget													4,800,000
ETG Utility Operations | Annual USF Petition
Schedule of Capitalization [Line Items]
Approved requested rate increase (decrease)					$ 800,000		$ 800,000
ETG Utility Operations
Schedule of Capitalization [Line Items]
Credits due to customers under conditions of approval			15,000,000.0																							15,000,000.0		15,000,000.0
Customer bill credit applied													15,000,000.0
Elkton Gas
Schedule of Capitalization [Line Items]
Credits due to customers under conditions of approval			$ 300,000																							$ 300,000		$ 300,000
Customer bill credit applied													$ 300,000