STOCK-BASED COMPENSATION PLANS (Details) - USD ($) $ / shares in Units, $ in Millions | 9 Months Ended | 12 Months Ended | |
Sep. 30, 2016 | Sep. 30, 2015 | Dec. 31, 2015 | Sep. 30, 2016 |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Service period of shares | 3 years | | | |
Granted (in shares) | 33,218 | | | |
Shares Outstanding (in shares) | 46,475 | | 46,475 | 74,256 |
Fair Value Per Share (in dollars per share) | $ 26.67 | | $ 26.67 | $ 25.04 |
Expected volatility, measurement period | 3 years | | | |
Unrecognized compensation cost of awards granted under the plan | | | | $ 0.9 |
Weighted average period over which unrecognized compensation cost is to be recognized | 1 year 11 months | | | |
Shares | | | | |
Nonvested Shares Outstanding, beginning balance (in shares) | 46,475 | | | |
Granted (in shares) | 33,218 | | | |
Canceled / Forfeited (in shares) | (2,827) | | | |
Vested (in shares) | (2,610) | | | |
Nonvested Shares Outstanding, ending balance (in shares) | 74,256 | | 46,475 | |
Weighted Average Grant Date Fair Value | | | | |
Nonvested Shares Outstanding, beginning balance (in dollars per share) | $ 26.67 | | | |
Granted (in dollars per share) | 23.17 | | | |
Canceled / Forfeited (in dollars per share) | 25.89 | | | |
Vested (in dollars per share) | 29.47 | | | |
Nonvested Shares Outstanding, ending balance (in dollars per share) | $ 25.04 | | $ 26.67 | |
Cash payments to SJI relating to stock awards | $ 0.2 | $ 0.2 | | |
2014 - TSR | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Shares Outstanding (in shares) | 9,692 | | | 9,692 |
Fair Value Per Share (in dollars per share) | $ 21.31 | | | $ 21.31 |
Expected Volatility | 20.00% | | | |
Risk-Free Interest Rate | 0.80% | | | |
Shares | | | | |
Nonvested Shares Outstanding, ending balance (in shares) | 9,692 | | | |
Weighted Average Grant Date Fair Value | | | | |
Nonvested Shares Outstanding, ending balance (in dollars per share) | $ 21.31 | | | |
2014 - EGR | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Shares Outstanding (in shares) | 9,692 | | | 9,692 |
Fair Value Per Share (in dollars per share) | $ 27.22 | | | $ 27.22 |
Shares | | | | |
Nonvested Shares Outstanding, ending balance (in shares) | 9,692 | | | |
Weighted Average Grant Date Fair Value | | | | |
Nonvested Shares Outstanding, ending balance (in dollars per share) | $ 27.22 | | | |
2015 - TSR | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Shares Outstanding (in shares) | 6,884 | | | 6,884 |
Fair Value Per Share (in dollars per share) | $ 26.31 | | | $ 26.31 |
Expected Volatility | 16.00% | | | |
Risk-Free Interest Rate | 1.10% | | | |
Shares | | | | |
Nonvested Shares Outstanding, ending balance (in shares) | 6,884 | | | |
Weighted Average Grant Date Fair Value | | | | |
Nonvested Shares Outstanding, ending balance (in dollars per share) | $ 26.31 | | | |
2015 - EGR, ROE, Time | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Shares Outstanding (in shares) | 15,211 | | | 15,211 |
Fair Value Per Share (in dollars per share) | $ 29.47 | | | $ 29.47 |
Shares | | | | |
Nonvested Shares Outstanding, ending balance (in shares) | 15,211 | | | |
Weighted Average Grant Date Fair Value | | | | |
Nonvested Shares Outstanding, ending balance (in dollars per share) | $ 29.47 | | | |
2016 - TSR | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Shares Outstanding (in shares) | 11,472 | | | 11,472 |
Fair Value Per Share (in dollars per share) | $ 22.53 | | | $ 22.53 |
Expected Volatility | 18.10% | | | |
Risk-Free Interest Rate | 1.31% | | | |
Shares | | | | |
Nonvested Shares Outstanding, ending balance (in shares) | 11,472 | | | |
Weighted Average Grant Date Fair Value | | | | |
Nonvested Shares Outstanding, ending balance (in dollars per share) | $ 22.53 | | | |
2016 - CEGR, Time | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Shares Outstanding (in shares) | 21,305 | | | 21,305 |
Fair Value Per Share (in dollars per share) | $ 23.52 | | | $ 23.52 |
Shares | | | | |
Nonvested Shares Outstanding, ending balance (in shares) | 21,305 | | | |
Weighted Average Grant Date Fair Value | | | | |
Nonvested Shares Outstanding, ending balance (in dollars per share) | $ 23.52 | | | |
Officers and key employees | 2015 - Time | | | | |
Weighted Average Grant Date Fair Value | | | | |
Number of shares awarded during the period (in shares) | 2,610 | | | |
Fair value of shares issued | $ 0.1 | | | |
Restricted stock | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Vesting period of shares | | | 3 years | |
Payout limit | | | 100.00% | |
Return on equity award threshold | | | 7.00% | |
Cost of restricted stock awards | $ 0.2 | $ 0.1 | | |
Cost of restricted stock awards, capitalized | 50.00% | 50.00% | | |
Restricted stock | Officers and key employees | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Granted (in shares) | 9,965 | 7,878 | | |
Shares | | | | |
Granted (in shares) | 9,965 | 7,878 | | |
Restricted stock | Year two | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Service period of shares | | | 2 years | |
Restricted stock | Year three | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Service period of shares | | | 3 years | |
Performance shares | 2012 and 2013 Grants | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Vesting period of shares | 3 years | | | |
Weighted Average Grant Date Fair Value | | | | |
Number of shares awarded during the period (in shares) | 0 | | 0 | |
Minimum | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Percentage of actual amount of shares that ultimately vest of original share units granted | 0.00% | | | |
Maximum | | | | |
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items] | | | | |
Percentage of actual amount of shares that ultimately vest of original share units granted | 200.00% | | | |