Schedule I (Details)		12 Months Ended
	Jul. 01, 2021 USD ($) option	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Oct. 16, 2020 shares	Dec. 31, 2018 USD ($) shares
Income Statement [Abstract]
Operating Revenues		$ 1,991,996,000	$ 1,541,383,000	$ 1,628,626,000
Operating Expenses:
Operations		265,140,000	272,171,000	276,093,000
Depreciation		131,778,000	118,715,000	99,753,000
Energy and Other Taxes		1,435,000	11,918,000	11,996,000
Total Operating Expenses		1,642,876,000	1,259,161,000	1,427,421,000
Operating Income (Loss)		349,120,000	282,222,000	201,205,000
Other Income:
Total Other Income		4,592,000	7,979,000	4,208,000
Interest Charges		127,130,000	118,534,000	114,477,000
Income Taxes		47,107,000	22,664,000	21,061,000
Income from Continuing Operations		88,514,000	157,297,000	77,189,000
Equity in Earnings of Discontinued Operations - Net of taxes		51,000	(255,000)	(272,000)
Net Income		88,565,000	157,042,000	76,917,000
Subtract/Add: Income (Loss) Attributable to Noncontrolling Interests		474,000	(42,000)	0
Net Income		88,091,000	157,084,000	76,917,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net Income		88,565,000	157,042,000	76,917,000
Other Comprehensive Income (Loss) - Net of Tax
Postretirement Liability Adjustment		11,455,000	(5,692,000)	(6,498,000)
Losses reclassified from AOCL into income		32,000	34,000	35,000
Other Comprehensive Income (Loss) - Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Comprehensive Income		100,052,000	151,384,000	70,454,000
Subtract/Add: Comprehensive Income (Loss) Attributable to Noncontrolling Interests		474,000	(42,000)	0
Comprehensive Income Attributable to South Jersey Industries, Inc.		99,578,000	151,426,000	70,454,000
Postretirement Liability Adjustment, tax		(4,426,000)	2,316,000	2,539,000
Reclassification of Unrealized Gain on Derivatives - Other to Net Income, tax		(14,000)	(12,000)	(11,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		1,666,876,000	1,423,785,000	1,267,022,000
Net Income		88,565,000	157,042,000	76,917,000
Other Comprehensive Income (Loss), Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Common Stock Issued or Granted Through Equity Offering or Stock Plans		431,507,000	200,313,000	193,247,000
Cash Dividends Declared - Common Stock		(133,336,000)	(114,643,000)	(106,938,000)
Ending balance		$ 1,999,441,000	$ 1,666,876,000	$ 1,423,785,000
Cash Dividends Declared - Common Stock (in USD per share) | $ / shares		$ 1.22	$ 1.19	$ 1.16
Statement of Cash Flows [Abstract]
CASH USED IN OPERATING ACTIVITIES		$ 273,113,000	$ 311,639,000	$ 121,052,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital Expenditures		(532,026,000)	(486,451,000)	(504,212,000)
Proceeds from Company-Owned Life Insurance		0	0	1,694,000
Net Cash Used in Investing Activities		(645,497,000)	(507,751,000)	(477,648,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from Issuance of Long-Term Debt		460,000,000	1,050,000,000	429,657,000
Principal Repayments of Long-Term Debt		(117,909,000)	(667,909,000)	(733,909,000)
Payments for Issuance of Long-Term Debt		(17,632,000)	(8,191,000)	(2,744,000)
Net (Repayments of) Borrowings from Short-Term Credit Facilities		(262,400,000)	(252,300,000)	578,200,000
Dividends on Common Stock		(133,336,000)	(114,643,000)	(106,938,000)
Proceeds from Sale of Common Stock		429,772,000	200,000,000	189,032,000
Payments for the Issuance of Common Stock		(2,322,000)	(2,409,000)	0
Capital Contributions of Noncontrolling Interests in Subsidiary		3,820,000	6,037,000	0
Other		0	(1,023,000)	0
Net Cash Provided by Financing Activities		359,993,000	209,562,000	353,298,000
Net (Decrease) Increase in Cash, Cash Equivalents and Restricted Cash		(12,391,000)	13,450,000	(3,298,000)
Cash, Cash Equivalents and Restricted Cash at Beginning of Year		41,831,000	28,381,000	31,679,000
Cash, Cash Equivalents and Restricted Cash at End of Year		29,440,000	41,831,000	28,381,000
Property Plant and Equipment:
Nonutility Property, Plant and Equipment, at cost		240,503,000	147,764,000
Accumulated Depreciation		35,367,000	35,069,000
Investments:
Debt Securities, Available-for-sale		37,000	32,000
Total Investments		39,232,000	114,048,000
Current Assets:
Cash and Cash Equivalents		28,754,000	34,045,000
Other		25,269,000	29,081,000
Total Current Assets		638,962,000	506,828,000
Other		206,699,000	143,650,000
Total Assets		7,308,672,000	6,689,148,000
Equity [Abstract]
Common Stock		146,675,000	125,740,000
Premium on Common Stock		1,559,060,000	1,218,000,000
Treasury Stock (at par)		(287,000)	(321,000)
Accumulated Other Comprehensive Loss		(26,729,000)	(38,216,000)
Retained Earnings		310,433,000	355,678,000
Total South Jersey Industries, Inc. Equity		1,989,152,000	1,660,881,000
Noncontrolling Interests		10,289,000	5,995,000
Total Equity		1,999,441,000	1,666,876,000	$ 1,423,785,000		$ 1,267,022,000
Long-Term Debt		3,189,009,000	2,776,400,000
Current Liabilities:
Notes Payable - Banks		334,000,000	596,400,000
Current Portion of Long-Term Debt		66,076,000	142,801,000
Accounts Payable		330,164,000	256,589,000
Other Current Liabilities		54,311,000	31,369,000
Total Current Liabilities		955,682,000	1,163,632,000
Other Noncurrent Liabilities		188,971,000	147,501,000
Total Capitalization and Liabilities		$ 7,308,672,000	$ 6,689,148,000
Common stock, par value (in USD per share) | $ / shares		$ 1.25	$ 1.25
Common stock, authorized (in shares) | shares		220,000,000	220,000,000	120,000,000	220,000,000
Common Stock, outstanding (in shares) | shares		117,340,493	100,591,940	92,394,155		85,506,218
Operating lease right-of-use asset		$ 16,733,000	$ 1,929,000
Long-term lease liabilities		$ 16,059,000
Weighted-average discount rate - operating leases		4.00%	3.00%
Total South Jersey Industries, Inc. Equity
Other Income:
Net Income		$ 88,091,000	$ 157,084,000	$ 76,917,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net Income		88,091,000	157,084,000	76,917,000
Other Comprehensive Income (Loss) - Net of Tax
Other Comprehensive Income (Loss) - Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		1,660,881,000	1,423,785,000	1,267,022,000
Net Income		88,091,000	157,084,000	76,917,000
Other Comprehensive Income (Loss), Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Common Stock Issued or Granted Through Equity Offering or Stock Plans		431,507,000	200,313,000	193,247,000
Cash Dividends Declared - Common Stock		(133,336,000)	(114,643,000)	(106,938,000)
Ending balance		1,989,152,000	1,660,881,000	1,423,785,000
Equity [Abstract]
Total Equity		1,989,152,000	1,660,881,000	1,423,785,000		$ 1,267,022,000
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		125,740,000	115,493,000	106,883,000
Common Stock Issued or Granted Through Equity Offering or Stock Plans		20,935,000	10,247,000	8,610,000
Ending balance		146,675,000	125,740,000	115,493,000
Equity [Abstract]
Total Equity		146,675,000	125,740,000	115,493,000		106,883,000
Premium on Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		1,218,000,000	1,027,902,000	843,268,000
Common Stock Issued or Granted Through Equity Offering or Stock Plans		410,538,000	190,098,000	184,634,000
Ending balance		1,559,060,000	1,218,000,000	1,027,902,000
Equity [Abstract]
Total Equity		1,559,060,000	1,218,000,000	1,027,902,000		843,268,000
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		(321,000)	(289,000)	(292,000)
Common Stock Issued or Granted Through Equity Offering or Stock Plans		34,000	(32,000)	3,000
Ending balance		(287,000)	(321,000)	(289,000)
Equity [Abstract]
Total Equity		(287,000)	(321,000)	(289,000)		(292,000)
AOCL
Other Comprehensive Income (Loss) - Net of Tax
Other Comprehensive Income (Loss) - Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		(38,216,000)	(32,558,000)	(26,095,000)
Other Comprehensive Income (Loss), Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Ending balance		(26,729,000)	(38,216,000)	(32,558,000)
Equity [Abstract]
Total Equity		(26,729,000)	(38,216,000)	(32,558,000)		(26,095,000)
Retained Earnings
Other Income:
Net Income		88,091,000	157,084,000	76,917,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net Income		88,091,000	157,084,000	76,917,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		355,678,000	313,237,000	343,258,000
Net Income		88,091,000	157,084,000	76,917,000
Cash Dividends Declared - Common Stock		(133,336,000)	(114,643,000)	(106,938,000)
Ending balance		310,433,000	355,678,000	313,237,000
Equity [Abstract]
Total Equity		310,433,000	355,678,000	313,237,000		343,258,000
NCI
Other Income:
Net Income		474,000	(42,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net Income		474,000	(42,000)
Other Comprehensive Income (Loss) - Net of Tax
Other Comprehensive Income (Loss) - Net of Tax			0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		5,995,000	0	0
Net Income		474,000	(42,000)
Other Comprehensive Income (Loss), Net of Tax			0
Ending balance		10,289,000	5,995,000	0
Equity [Abstract]
Total Equity		10,289,000	5,995,000	0		0
Parent Company
Income Statement [Abstract]
Operating Revenues		48,220,000	44,410,000	34,757,000
Operating Expenses:
Operations		46,870,000	47,241,000	42,481,000
Depreciation		1,020,000	801,000	646,000
Energy and Other Taxes		2,194,000	1,992,000	1,842,000
Total Operating Expenses		50,084,000	50,034,000	44,969,000
Operating Income (Loss)		(1,864,000)	(5,624,000)	(10,212,000)
Other Income:
Equity in Earnings of Subsidiaries		121,324,000	190,245,000	118,910,000
Other		6,236,000	18,191,000	10,863,000
Total Other Income		127,560,000	208,436,000	129,773,000
Interest Charges		55,192,000	56,692,000	58,956,000
Income Taxes		(18,010,000)	(11,177,000)	(16,584,000)
Income from Continuing Operations		88,514,000	157,297,000	77,189,000
Equity in Earnings of Discontinued Operations - Net of taxes		51,000	(255,000)	(272,000)
Net Income		88,565,000	157,042,000	76,917,000
Subtract/Add: Income (Loss) Attributable to Noncontrolling Interests		474,000	(42,000)	0
Net Income		88,091,000	157,084,000	76,917,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net Income		88,565,000	157,042,000	76,917,000
Other Comprehensive Income (Loss) - Net of Tax
Postretirement Liability Adjustment		11,455,000	(5,692,000)	(6,498,000)
Losses reclassified from AOCL into income		32,000	34,000	35,000
Other Comprehensive Income (Loss) - Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Comprehensive Income		100,052,000	151,384,000	70,454,000
Subtract/Add: Comprehensive Income (Loss) Attributable to Noncontrolling Interests		474,000		0
Comprehensive Income Attributable to South Jersey Industries, Inc.		99,578,000	151,426,000	70,454,000
Postretirement Liability Adjustment, tax		(4,426,000)	2,316,000	2,539,000
Reclassification of Unrealized Gain on Derivatives - Other to Net Income, tax		(14,000)	(12,000)	(11,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		1,666,876,000	1,423,785,000	1,267,022,000
Net Income		88,565,000	157,042,000	76,917,000
Other Comprehensive Income (Loss), Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Common Stock Issued or Granted Through Equity Offering or Stock Plans		431,507,000	200,313,000	193,247,000
Capital Contributions of Noncontrolling Interests in Subsidiaries		3,820,000	6,037,000
Income from Equity Method Investments		69,478,000
Cash Dividends Declared - Common Stock		(133,336,000)	(114,643,000)	(106,938,000)
Ending balance		$ 1,999,441,000	$ 1,666,876,000	$ 1,423,785,000
Cash Dividends Declared - Common Stock (in USD per share) | $ / shares		$ 1.22	$ 1.19	$ 1.16
Statement of Cash Flows [Abstract]
CASH USED IN OPERATING ACTIVITIES		$ (118,847,000)	$ (246,530,000)	$ (12,039,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Net (Advances to) Repayments from Associated Companies		(51,572,000)	124,140,000	(42,084,000)
Capital Expenditures		(19,230,000)	(12,961,000)	(29,944,000)
Proceeds from Company-Owned Life Insurance		0	56,000	1,865,000
Net Cash Used in Investing Activities		(70,802,000)	111,235,000	(70,163,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from Issuance of Long-Term Debt		335,000,000	400,000,000	194,657,000
Principal Repayments of Long-Term Debt		(90,000,000)	(250,000,000)	(715,000,000)
Payments for Issuance of Long-Term Debt		(14,255,000)	(2,054,000)	(876,000)
Net (Repayments of) Borrowings from Short-Term Credit Facilities		(332,000,000)	(98,100,000)	496,100,000
Dividends on Common Stock		(133,336,000)	(114,643,000)	(106,938,000)
Proceeds from Sale of Common Stock		429,772,000	200,000,000	189,032,000
Payments for the Issuance of Common Stock		(2,322,000)	(2,409,000)	0
Capital Contributions of Noncontrolling Interests in Subsidiary		3,820,000	6,037,000	0
Other		0	(1,023,000)	0
Net Cash Provided by Financing Activities		196,679,000	137,808,000	56,975,000
Net (Decrease) Increase in Cash, Cash Equivalents and Restricted Cash		7,030,000	2,513,000	(25,227,000)
Cash, Cash Equivalents and Restricted Cash at Beginning of Year		2,620,000	107,000	25,334,000
Cash, Cash Equivalents and Restricted Cash at End of Year		9,650,000	2,620,000	107,000
Property Plant and Equipment:
Nonutility Property, Plant and Equipment, at cost		8,126,000	6,649,000
Accumulated Depreciation		2,414,000	2,614,000
Property, Plant and Equipment - Net		5,712,000	4,035,000
Investments:
Investments in Subsidiaries		3,166,214,000	2,958,076,000
Debt Securities, Available-for-sale		37,000	32,000
Total Investments		3,166,251,000	2,958,108,000
Current Assets:
Cash and Cash Equivalents		9,650,000	2,620,000
Receivable from Associated Companies		240,217,000	190,829,000
Accounts Receivable, after Allowance for Credit Loss, Current		44,000	43,000
Other		22,974,000	19,365,000
Total Current Assets		272,885,000	212,857,000
Other		96,940,000	65,933,000
Total Assets		3,541,788,000	3,240,933,000
Equity [Abstract]
Common Stock		146,675,000	125,740,000
Premium on Common Stock		1,559,060,000	1,218,000,000
Treasury Stock (at par)		(287,000)	(321,000)
Accumulated Other Comprehensive Loss		(26,729,000)	(38,216,000)
Retained Earnings		310,433,000	355,678,000
Total South Jersey Industries, Inc. Equity		1,989,152,000	1,660,881,000
Noncontrolling Interests		10,289,000	5,995,000
Total Equity		1,999,441,000	1,666,876,000	1,423,785,000		1,267,022,000
Long-Term Debt		1,255,089,000	964,602,000
Current Liabilities:
Notes Payable - Banks		143,000,000	475,000,000
Current Portion of Long-Term Debt		35,000,000	90,000,000
Payable to Associated Companies		1,121,000	3,305,000
Accounts Payable		5,675,000	6,112,000
Other Current Liabilities		47,893,000	23,396,000
Total Current Liabilities		232,689,000	597,813,000
Other Noncurrent Liabilities		54,569,000	11,642,000
Total Capitalization and Liabilities		$ 3,541,788,000	$ 3,240,933,000
Common stock, authorized (in shares) | shares			220,000,000
Common Stock, outstanding (in shares) | shares		117,340,493	100,591,940
Dividends received from subsidiaries		$ 0	$ 0	0
Total lease period	10 years
Term of contract	5 years
Renewal term	5 years
Number of options to renew | option	9
Additional term of contract, if renewed	45 years
Operating lease right-of-use asset	$ 16,800,000
Long-term lease liabilities	$ 16,800,000
Weighted-average discount rate - operating leases		3.00%
Parent Company | Total South Jersey Industries, Inc. Equity
Other Income:
Net Income		$ 88,091,000	157,084,000	76,917,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net Income		88,091,000	157,084,000	76,917,000
Other Comprehensive Income (Loss) - Net of Tax
Other Comprehensive Income (Loss) - Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		1,660,881,000	1,423,785,000	1,267,022,000
Net Income		88,091,000	157,084,000	76,917,000
Other Comprehensive Income (Loss), Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Common Stock Issued or Granted Through Equity Offering or Stock Plans		431,507,000	200,313,000	193,247,000
Capital Contributions of Noncontrolling Interests in Subsidiaries		0
Income from Equity Method Investments		69,478,000
Cash Dividends Declared - Common Stock		(133,336,000)	(114,643,000)	(106,938,000)
Ending balance		1,989,152,000	1,660,881,000	1,423,785,000
Equity [Abstract]
Total Equity		1,989,152,000	1,660,881,000	1,423,785,000		1,267,022,000
Parent Company | Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		125,740,000	115,493,000	106,883,000
Common Stock Issued or Granted Through Equity Offering or Stock Plans		20,935,000	10,247,000	8,610,000
Ending balance		146,675,000	125,740,000	115,493,000
Equity [Abstract]
Total Equity		146,675,000	125,740,000	115,493,000		106,883,000
Parent Company | Premium on Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		1,218,000,000	1,027,902,000	843,268,000
Common Stock Issued or Granted Through Equity Offering or Stock Plans		410,538,000	190,098,000	184,634,000
Income from Equity Method Investments		69,478,000
Ending balance		1,559,060,000	1,218,000,000	1,027,902,000
Equity [Abstract]
Total Equity		1,559,060,000	1,218,000,000	1,027,902,000		843,268,000
Parent Company | Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		(321,000)	(289,000)	(292,000)
Common Stock Issued or Granted Through Equity Offering or Stock Plans		34,000	(32,000)	3,000
Ending balance		(287,000)	(321,000)	(289,000)
Equity [Abstract]
Total Equity		(287,000)	(321,000)	(289,000)		(292,000)
Parent Company | AOCL
Other Comprehensive Income (Loss) - Net of Tax
Other Comprehensive Income (Loss) - Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		(38,216,000)	(32,558,000)	(26,095,000)
Other Comprehensive Income (Loss), Net of Tax		11,487,000	(5,658,000)	(6,463,000)
Ending balance		(26,729,000)	(38,216,000)	(32,558,000)
Equity [Abstract]
Total Equity		(26,729,000)	(38,216,000)	(32,558,000)		(26,095,000)
Parent Company | Retained Earnings
Other Income:
Net Income		88,091,000	157,084,000	76,917,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net Income		88,091,000	157,084,000	76,917,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		355,678,000	313,237,000	343,258,000
Net Income		88,091,000	157,084,000	76,917,000
Cash Dividends Declared - Common Stock		(133,336,000)	(114,643,000)	(106,938,000)
Ending balance		310,433,000	355,678,000	313,237,000
Equity [Abstract]
Total Equity		310,433,000	355,678,000	313,237,000		343,258,000
Parent Company | NCI
Other Income:
Net Income		474,000	(42,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net Income		474,000	(42,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		5,995,000	0	0
Net Income		474,000	(42,000)
Capital Contributions of Noncontrolling Interests in Subsidiaries		3,820,000	6,037,000
Ending balance		10,289,000	5,995,000	0
Equity [Abstract]
Total Equity		$ 10,289,000	$ 5,995,000	$ 0		$ 0