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PENSION AND OTHER POSTRETIREMENT BENEFITS - FAIR VALUE OF PLAN ASSETS (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2017
Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets $ 189,542 $ 184,824 $ 216,065
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 189,542 184,824  
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year $ 216,065 189,542  
Pension Benefits | Minimum      
Defined Benefit Plan Disclosure [Line Items]      
Fund Valuations Lag Period 90 days    
Pension Benefits | Maximum      
Defined Benefit Plan Disclosure [Line Items]      
Fund Valuations Lag Period 120 days    
Pension Benefits | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets $ 23,674 23,674 19,049
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 23,674    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 19,049 23,674  
Pension Benefits | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 141,859 141,859 170,881
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 141,859    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 170,881 141,859  
Pension Benefits | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 24,009 26,946 $ 26,135
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 24,009 26,946  
Actual return on plan assets:      
Relating to assets still held at the reporting date 649 1,014  
Relating to assets sold during the period 503 259  
Purchases, Sales and Settlements 974 (4,210)  
Fair Value of Plan Assets at End of Year 26,135 24,009  
Pension Benefits | U.S. equity securities | Minimum      
Actual return on plan assets:      
Target plan allocation     28.00%
Pension Benefits | U.S. equity securities | Maximum      
Actual return on plan assets:      
Target plan allocation     48.00%
Pension Benefits | Common/Collective Trust Funds - U.S.      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 51,902 51,902 $ 75,699
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 51,902    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 75,699 51,902  
Pension Benefits | Common/Collective Trust Funds - U.S. | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds - U.S. | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 51,902 51,902 75,699
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 51,902    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 75,699 51,902  
Pension Benefits | Common/Collective Trust Funds - U.S. | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | U.S. Large-Cap      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 17,792 17,792 13,526
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 17,792    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 13,526 17,792  
Pension Benefits | U.S. Large-Cap | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 17,792 17,792 13,526
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 17,792    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 13,526 17,792  
Pension Benefits | U.S. Large-Cap | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | U.S. Large-Cap | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | U.S. Mid-Cap      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 2,479 2,479 1,701
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 2,479    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 1,701 2,479  
Pension Benefits | U.S. Mid-Cap | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 2,479 2,479 1,701
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 2,479    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 1,701 2,479  
Pension Benefits | U.S. Mid-Cap | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | U.S. Mid-Cap | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | U.S. Small-Cap      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 490   490
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 490    
Pension Benefits | U.S. Small-Cap | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 490   490
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 490    
Pension Benefits | U.S. Small-Cap | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0   0
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0    
Pension Benefits | U.S. Small-Cap | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0   0
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0    
Pension Benefits | International equity securities      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 3,340 3,340 $ 3,260
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 3,340    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 3,260 3,340  
Pension Benefits | International equity securities | Minimum      
Actual return on plan assets:      
Target plan allocation     13.00%
Pension Benefits | International equity securities | Maximum      
Actual return on plan assets:      
Target plan allocation     25.00%
Pension Benefits | International equity securities | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 3,340 3,340 $ 3,260
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 3,340    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 3,260 3,340  
Pension Benefits | International equity securities | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | International equity securities | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds - International      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 33,096 33,096 39,077
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 33,096    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 39,077 33,096  
Pension Benefits | Common/Collective Trust Funds - International | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds - International | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 33,096 33,096 39,077
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 33,096    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 39,077 33,096  
Pension Benefits | Common/Collective Trust Funds - International | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 54,970 54,970 54,106
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 54,970    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 54,106 54,970  
Pension Benefits | Common/Collective Trust Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 54,970 54,970 54,106
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 54,970    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 54,106 54,970  
Pension Benefits | Common/Collective Trust Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Guaranteed Insurance Contract      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 9,714 9,714 9,211
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 9,714    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 9,211 9,714  
Pension Benefits | Guaranteed Insurance Contract | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Guaranteed Insurance Contract | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Guaranteed Insurance Contract | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 9,714 9,960 $ 9,211
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 9,714 9,960  
Actual return on plan assets:      
Relating to assets still held at the reporting date 245 541  
Relating to assets sold during the period 12 14  
Purchases, Sales and Settlements (760) (801)  
Fair Value of Plan Assets at End of Year 9,211 9,714  
Pension Benefits | Other investments | Minimum      
Actual return on plan assets:      
Target plan allocation     0.00%
Pension Benefits | Other investments | Maximum      
Actual return on plan assets:      
Target plan allocation     7.00%
Pension Benefits | Private Equity Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 5,100 5,100 $ 7,111
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 5,100    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 7,111 5,100  
Pension Benefits | Private Equity Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Private Equity Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Private Equity Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 5,100 4,312 7,111
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 5,100 4,312  
Actual return on plan assets:      
Relating to assets still held at the reporting date (214) (140)  
Relating to assets sold during the period 491 245  
Purchases, Sales and Settlements 1,734 683  
Fair Value of Plan Assets at End of Year 7,111 5,100  
Pension Benefits | Real Estate      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 9,195 9,195 9,813
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 9,195    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 9,813 9,195  
Pension Benefits | Real Estate | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Real Estate | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Real Estate | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 9,195 8,515 9,813
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 9,195 8,515  
Actual return on plan assets:      
Relating to assets still held at the reporting date 618 680  
Relating to assets sold during the period 0 0  
Purchases, Sales and Settlements 0 0  
Fair Value of Plan Assets at End of Year 9,813 9,195  
Pension Benefits | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 63 63 72
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 63    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 72 63  
Pension Benefits | Cash | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 63 63 72
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 63    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 72 63  
Pension Benefits | Cash | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Cash | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 460 460 477
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 460    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 477 460  
Pension Benefits | Common/Collective Trust Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Common/Collective Trust Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 460 460 477
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 460    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 477 460  
Pension Benefits | Common/Collective Trust Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | STIF-Type Instrument      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,431 1,431 1,522
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,431    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 1,522 1,431  
Pension Benefits | STIF-Type Instrument | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | STIF-Type Instrument | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,431 1,431 1,522
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,431    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 1,522 1,431  
Pension Benefits | STIF-Type Instrument | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Pension Benefits | Fixed Income, Hedge Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 4,159 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0 4,159  
Actual return on plan assets:      
Relating to assets still held at the reporting date (67)  
Relating to assets sold during the period 0 0  
Purchases, Sales and Settlements (4,092)  
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 50,532 47,759 57,922
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 50,532 47,759  
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 57,922 50,532  
Other Postretirement Benefits | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 864
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 864 0  
Other Postretirement Benefits | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 50,532 50,532 57,058
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 50,532    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 57,058 50,532  
Other Postretirement Benefits | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 $ 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | U.S. equity securities | Minimum      
Actual return on plan assets:      
Target plan allocation     30.00%
Other Postretirement Benefits | U.S. equity securities | Maximum      
Actual return on plan assets:      
Target plan allocation     43.00%
Other Postretirement Benefits | Common/Collective Trust Funds - U.S.      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 14,878 14,878 $ 15,101
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 14,878    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 15,101 14,878  
Other Postretirement Benefits | Common/Collective Trust Funds - U.S. | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Common/Collective Trust Funds - U.S. | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 14,878 14,878 15,101
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 14,878    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 15,101 14,878  
Other Postretirement Benefits | Common/Collective Trust Funds - U.S. | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Fund - U.S.      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Fund - U.S. | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Fund - U.S. | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Fund - U.S. | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 $ 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | International equity securities | Minimum      
Actual return on plan assets:      
Target plan allocation     20.00%
Other Postretirement Benefits | International equity securities | Maximum      
Actual return on plan assets:      
Target plan allocation     30.00%
Other Postretirement Benefits | Common/Collective Trust Funds - International      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 8,674 8,674 $ 11,378
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 8,674    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 11,378 8,674  
Other Postretirement Benefits | Common/Collective Trust Funds - International | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Common/Collective Trust Funds - International | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 8,674 8,674 11,378
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 8,674    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 11,378 8,674  
Other Postretirement Benefits | Common/Collective Trust Funds - International | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Funds - International      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Funds - International | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Funds - International | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Funds - International | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 $ 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Fixed income investments | Minimum      
Actual return on plan assets:      
Target plan allocation     32.00%
Other Postretirement Benefits | Fixed income investments | Maximum      
Actual return on plan assets:      
Target plan allocation     42.00%
Other Postretirement Benefits | Common/Collective Trust Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 13,537 13,537 $ 15,272
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 13,537    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 15,272 13,537  
Other Postretirement Benefits | Common/Collective Trust Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Common/Collective Trust Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 13,537 13,537 15,272
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 13,537    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 15,272 13,537  
Other Postretirement Benefits | Common/Collective Trust Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Funds - Bonds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Funds - Bonds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Funds - Bonds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Funds - Bonds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 $ 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Other investments | Minimum      
Actual return on plan assets:      
Target plan allocation     0.00%
Other Postretirement Benefits | Other investments | Maximum      
Actual return on plan assets:      
Target plan allocation     7.00%
Other Postretirement Benefits | Mutual Funds - REITS      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 $ 864
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 864 0  
Other Postretirement Benefits | Mutual Funds - REITS | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 864
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 864 0  
Other Postretirement Benefits | Mutual Funds - REITS | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Mutual Funds - REITS | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Company Owned Life Insurance      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 13,443 13,443 15,307
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 13,443    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 15,307 13,443  
Other Postretirement Benefits | Company Owned Life Insurance | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Company Owned Life Insurance | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 13,443 13,443 15,307
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 13,443    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 15,307 13,443  
Other Postretirement Benefits | Company Owned Life Insurance | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Cash | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Cash | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
Other Postretirement Benefits | Cash | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | U.S. Small-Cap | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 154,729 149,032 174,277
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 154,729 149,032  
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 174,277 154,729  
South Jersey Gas Company | Pension Benefits | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 19,326 19,326 15,364
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 19,326    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 15,364 19,326  
South Jersey Gas Company | Pension Benefits | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 115,803 115,803 137,829
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 115,803    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 137,829 115,803  
South Jersey Gas Company | Pension Benefits | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 19,600 21,727 21,084
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 19,600 21,727  
Actual return on plan assets:      
Relating to assets still held at the reporting date 293 1,097  
Relating to assets sold during the period 405 212  
Purchases, Sales and Settlements 786 (3,436)  
Fair Value of Plan Assets at End of Year 21,084 19,600  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds - U.S.      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 42,369 42,369 61,057
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 42,369    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 61,057 42,369  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds - U.S. | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds - U.S. | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 42,369 42,369 61,057
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 42,369    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 61,057 42,369  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds - U.S. | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | U.S. Large-Cap      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 14,523 14,523 10,910
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 14,523    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 10,910 14,523  
South Jersey Gas Company | Pension Benefits | U.S. Large-Cap | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 14,523 14,523 10,910
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 14,523    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 10,910 14,523  
South Jersey Gas Company | Pension Benefits | U.S. Large-Cap | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | U.S. Large-Cap | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | U.S. Mid-Cap      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 2,024 2,024 1,372
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 2,024    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 1,372 2,024  
South Jersey Gas Company | Pension Benefits | U.S. Mid-Cap | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 2,024 2,024 1,372
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 2,024    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 1,372 2,024  
South Jersey Gas Company | Pension Benefits | U.S. Mid-Cap | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | U.S. Mid-Cap | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | U.S. Small-Cap      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 2,727 2,727 395
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 2,727    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 395 2,727  
South Jersey Gas Company | Pension Benefits | U.S. Small-Cap | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 2,727 2,727 395
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 2,727    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 395 2,727  
South Jersey Gas Company | Pension Benefits | U.S. Small-Cap | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | International equity securities      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 2,629   2,629
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 2,629    
South Jersey Gas Company | Pension Benefits | International equity securities | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 2,629   2,629
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 2,629    
South Jersey Gas Company | Pension Benefits | International equity securities | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0   0
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0    
South Jersey Gas Company | Pension Benefits | International equity securities | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0   0
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0    
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds - International      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 27,017 27,017 31,519
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 27,017    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 31,519 27,017  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds - International | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds - International | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 27,017 27,017 31,519
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 27,017    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 31,519 27,017  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds - International | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 44,873 44,873 43,640
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 44,873    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 43,640 44,873  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 44,873 44,873 43,640
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 44,873    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 43,640 44,873  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Guaranteed Insurance Contract      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 7,930 7,930 7,429
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 7,930    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 7,429 7,930  
South Jersey Gas Company | Pension Benefits | Guaranteed Insurance Contract | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Guaranteed Insurance Contract | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Guaranteed Insurance Contract | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 7,930 8,031 7,429
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 7,930 8,031  
Actual return on plan assets:      
Relating to assets still held at the reporting date 103 541  
Relating to assets sold during the period 9 12  
Purchases, Sales and Settlements (613) (654)  
Fair Value of Plan Assets at End of Year 7,429 7,930  
South Jersey Gas Company | Pension Benefits | Private Equity Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 4,164 4,164 5,735
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 4,164    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 5,735 4,164  
South Jersey Gas Company | Pension Benefits | Private Equity Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Private Equity Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Private Equity Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 4,164 3,477 5,735
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 4,164 3,477  
Actual return on plan assets:      
Relating to assets still held at the reporting date (224) (71)  
Relating to assets sold during the period 396 200  
Purchases, Sales and Settlements 1,399 558  
Fair Value of Plan Assets at End of Year 5,735 4,164  
South Jersey Gas Company | Pension Benefits | Real Estate      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 7,506 7,506 7,920
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 7,506    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 7,920 7,506  
South Jersey Gas Company | Pension Benefits | Real Estate | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Real Estate | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Real Estate | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 7,506 6,866 7,920
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 7,506 6,866  
Actual return on plan assets:      
Relating to assets still held at the reporting date 414 640  
Relating to assets sold during the period 0 0  
Purchases, Sales and Settlements 0 0  
Fair Value of Plan Assets at End of Year 7,920 7,506  
South Jersey Gas Company | Pension Benefits | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 52 52 58
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 52    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 58 52  
South Jersey Gas Company | Pension Benefits | Cash | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 52 52 58
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 52    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 58 52  
South Jersey Gas Company | Pension Benefits | Cash | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Cash | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 376 376 385
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 376    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 385 376  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 376 376 385
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 376    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 385 376  
South Jersey Gas Company | Pension Benefits | Common/Collective Trust Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | STIF-Type Instrument      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,168 1,168 1,228
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,168    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 1,228 1,168  
South Jersey Gas Company | Pension Benefits | STIF-Type Instrument | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | STIF-Type Instrument | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 1,168 1,168 1,228
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 1,168    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 1,228 1,168  
South Jersey Gas Company | Pension Benefits | STIF-Type Instrument | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Pension Benefits | Fixed Income, Hedge Funds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 3,353 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0 3,353  
Actual return on plan assets:      
Relating to assets still held at the reporting date 0 (13)  
Relating to assets sold during the period 0 0  
Purchases, Sales and Settlements 0 (3,340)  
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 45,948 43,428 52,663
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 45,948 43,428  
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 52,663 45,948  
South Jersey Gas Company | Other Postretirement Benefits | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 777
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 777 0  
South Jersey Gas Company | Other Postretirement Benefits | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 45,948 45,948 51,886
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 45,948    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 51,886 45,948  
South Jersey Gas Company | Other Postretirement Benefits | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Common/Collective Trust Funds - U.S.      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 13,372 13,372 13,572
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 13,372    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 13,572 13,372  
South Jersey Gas Company | Other Postretirement Benefits | Common/Collective Trust Funds - U.S. | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Common/Collective Trust Funds - U.S. | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 13,372 13,372 13,572
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 13,372    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 13,572 13,372  
South Jersey Gas Company | Other Postretirement Benefits | Common/Collective Trust Funds - U.S. | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Fund - U.S.      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Fund - U.S. | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Fund - U.S. | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Fund - U.S. | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Common/Collective Trust Funds - International      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 7,796 7,796 10,226
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 7,796    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 10,226 7,796  
South Jersey Gas Company | Other Postretirement Benefits | Common/Collective Trust Funds - International | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Common/Collective Trust Funds - International | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 7,796 7,796 10,226
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 7,796    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 10,226 7,796  
South Jersey Gas Company | Other Postretirement Benefits | Common/Collective Trust Funds - International | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - International      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - International | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - International | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - International | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - Bonds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - Bonds | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - Bonds | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - Bonds | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - REITS      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 777
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 777 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - REITS | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 777
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 777 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - REITS | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Mutual Funds - REITS | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Company Owned Life Insurance      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 12,613 12,613 14,362
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 12,613    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 14,362 12,613  
South Jersey Gas Company | Other Postretirement Benefits | Company Owned Life Insurance | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Company Owned Life Insurance | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 12,613 12,613 14,362
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 12,613    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 14,362 12,613  
South Jersey Gas Company | Other Postretirement Benefits | Company Owned Life Insurance | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Cash      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Cash | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Cash | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Cash | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Corporate Debt Securities      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 12,167 12,167 13,726
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 12,167    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 13,726 12,167  
South Jersey Gas Company | Other Postretirement Benefits | Corporate Debt Securities | Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 0 0  
South Jersey Gas Company | Other Postretirement Benefits | Corporate Debt Securities | Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 12,167 12,167 13,726
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 12,167    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year 13,726 12,167  
South Jersey Gas Company | Other Postretirement Benefits | Corporate Debt Securities | Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value of Plan Assets 0 0 $ 0
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value of Plan Assets at Beginning of Year 0    
Actual return on plan assets:      
Fair Value of Plan Assets at End of Year $ 0 $ 0