LONG-TERM DEBT (Details) - USD ($)		9 Months Ended
Sep. 27, 2019	Sep. 30, 2019
Debt Instrument [Line Items]
Interest rate		7.50%
Debt discount		$ 5,300,000
Early repayment of senior debt		725,000,000.0
Series 2018D Senior Notes, Due 2019
Debt Instrument [Line Items]
Principal amount issued		475,000,000.0
Early repayment of senior debt		$ 475,000,000.0
Series 2014A-1 Senior Notes, Due 2019
Debt Instrument [Line Items]
Interest rate		3.30%
Repayments of senior debt		$ 60,000,000.0
Series 2014B-1 Senior Notes, Due June 26, 2019
Debt Instrument [Line Items]
Repayments of senior debt		40,000,000.0
Series 2014B-2 Senior Notes, Due 2019
Debt Instrument [Line Items]
Repayments of senior debt		$ 60,000,000.0
Junior Subordinated Notes, 5.65%, Due 2079
Debt Instrument [Line Items]
Interest rate		5.625%
Debt discount		$ 5,300,000
Net cash proceeds from issuance of debt		194,700,000
Principal amount issued		$ 200,000,000.0
Series 2014A-2 Senior Notes, Due 2019
Debt Instrument [Line Items]
Interest rate		3.30%
Repayments of senior debt		$ 30,000,000.0
Series 2014A-3 Senior Notes, Due 2019
Debt Instrument [Line Items]
Interest rate		3.30%
Repayments of senior debt		$ 50,000,000.0
SJG
Debt Instrument [Line Items]
Interest rate		5.587%
Repayments of First Mortgage Bond		$ 10,000,000.0
ETG Utility Operations \| Series 2019A-1, Due 2029
Debt Instrument [Line Items]
Interest rate		2.84%
First Mortgage bonds	$ 40,000,000.0
Unsecured Term Loan \| SJG \| Credit Agreement
Debt Instrument [Line Items]
Draw on term loan		$ 10,000,000.0
Total Facility		$ 400,000,000.0

Face (par) amount of debt instrument at time of issuance.

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