FINANCIAL INSTRUMENTS (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Inputs, Level 1 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restricted investments held in escrow	$ 1.3	$ 1.3
Margin accounts with selected counterparties to support risk management activities	16.6	17.3
Fair Value, Inputs, Level 2 [Member] | South Jersey Gas Company [Member] | Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Long-term receivables, net of unamortized discount	13.6	11.7
Imputed interest on long term receivables	$ 1.3	$ 1.2