STOCK-BASED COMPENSATION PLAN (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Fair Value Per Share (in USD per share)	$ 26.89	$ 26.89		$ 24.96	$ 26.89
Expected volatility, measurement period	3 years
Service period of shares	3 years
Net Expense	$ 3,507	$ 1,681	$ 1,746
Capitalized	$ (385)	$ (216)	(147)
Unrecognized compensation cost of awards granted under the plan				$ 4,000
Weighted average period over which unrecognized compensation cost is to be recognized (in years)	1 year 8 months 12 days
Weighted Average Fair Value
Nonvested Shares Outstanding, beginning balance (in USD per share)	$ 26.89
Granted (in USD per share)	23.28
Vested (in USD per share)	25.69
Cancelled/Forfeited (in USD per share)	25.11
Nonvested Shares Outstanding, ending balance (in USD per share)	$ 24.96	$ 26.89
Total Cost
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Net Expense	$ 3,892	$ 1,897	1,893
EPS | Total Cost
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Net Expense	$ (100)	$ (1,200)	$ (1,100)
Officers and other key employees
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of awards granted (in shares)	194,347	158,929	136,526
Actual amount of shares that ultimately vest of the original share units granted, minimum	0.00%
Actual amount of shares that ultimately vest of the original share units granted, maximum	200.00%
Shares Outstanding (in shares)	226,191	226,191		295,515	226,191
Number of shares awarded during the period (in shares)	13,247	0	0
Market value of shares awarded (in shares)	$ 300
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested Shares Outstanding, beginning balance (in shares)	226,191
Granted (in shares)	194,347	158,929	136,526
Vested (in shares)	(113,917)
Cancelled/Forfeited (in shares)	(11,106)
Nonvested Shares Outstanding, ending balance (in shares)	295,515	226,191
Expected number of shares to be awarded (in shares)				29,044
Officers and other key employees | Total Cost
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Net Expense	$ 3,051	$ 1,128	$ 1,260
Officers and other key employees | 2015 - TSR
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares Outstanding (in shares)	33,537	33,537			33,537
Fair Value Per Share (in USD per share)	$ 26.31	$ 26.31			$ 26.31
Expected Volatility		16.00%
Risk-Free Interest Rate		1.10%
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested Shares Outstanding, beginning balance (in shares)	33,537
Nonvested Shares Outstanding, ending balance (in shares)		33,537
Weighted Average Fair Value
Nonvested Shares Outstanding, beginning balance (in USD per share)	$ 26.31
Nonvested Shares Outstanding, ending balance (in USD per share)		$ 26.31
Officers and other key employees | 2015 - EGR, ROE, Time
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares Outstanding (in shares)	73,118	73,118			73,118
Fair Value Per Share (in USD per share)	$ 29.47	$ 29.47			$ 29.47
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested Shares Outstanding, beginning balance (in shares)	73,118
Nonvested Shares Outstanding, ending balance (in shares)		73,118
Weighted Average Fair Value
Nonvested Shares Outstanding, beginning balance (in USD per share)	$ 29.47
Nonvested Shares Outstanding, ending balance (in USD per share)		$ 29.47
Officers and other key employees | 2016 - TSR
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares Outstanding (in shares)	66,101			66,101
Fair Value Per Share (in USD per share)	$ 22.53			$ 22.53
Expected Volatility	18.10%
Risk-Free Interest Rate	1.31%
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested Shares Outstanding, ending balance (in shares)	66,101
Weighted Average Fair Value
Nonvested Shares Outstanding, ending balance (in USD per share)	$ 22.53
Officers and other key employees | 2016 - CEGR, Time
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares Outstanding (in shares)	122,759			122,759
Fair Value Per Share (in USD per share)	$ 23.52			$ 23.52
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested Shares Outstanding, ending balance (in shares)	122,759
Weighted Average Fair Value
Nonvested Shares Outstanding, ending balance (in USD per share)	$ 23.52
Directors
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of awards granted (in shares)	35,197
Vesting period of shares	12 months
Shares Outstanding (in shares)	26,338	26,338		35,197	26,338
Market value of shares awarded (in shares)	$ 800	$ 800	600
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested Shares Outstanding, beginning balance (in shares)	26,338
Granted (in shares)	35,197
Vested (in shares)	(26,338)
Cancelled/Forfeited (in shares)	0
Nonvested Shares Outstanding, ending balance (in shares)	35,197	26,338
Directors | Total Cost
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Net Expense	$ 841	$ 769	$ 633
Directors | 2016
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares Outstanding (in shares)	35,197			35,197
Fair Value Per Share (in USD per share)	$ 23.88			$ 23.88
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested Shares Outstanding, ending balance (in shares)	35,197
Weighted Average Fair Value
Nonvested Shares Outstanding, ending balance (in USD per share)	$ 23.88
2015 Omnibus Equity Compensation Plan
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of options granted (in shares)	0	0	0
Number of options outstanding (in shares)			0	0	0
Performance-based restricted shares
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Return on equity award threshold		7.00%
Performance-based restricted shares | Officers and other key employees
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting period of shares	3 years
Stock appreciation rights
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of awards granted (in shares)	0	0	0
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Granted (in shares)	0	0	0
Restricted stock
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Return on equity award threshold	7.00%
Restricted stock | Officers and other key employees
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of awards granted (in shares)	58,304	47,678
Vesting period of shares		3 years
Payout limit, percentage		100.00%
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Granted (in shares)	58,304	47,678
Restricted stock | Directors
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of awards granted (in shares)	35,197	26,338	23,220
Percent of shares granted that generally vest				100.00%
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Granted (in shares)	35,197	26,338	23,220
Restricted stock | Tranche Two
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Service period of shares		2 years
Restricted stock | Tranche 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