PENSION PLAN AND OTHER BENEFIT PLANS - Amounts Recognized, Assumptions Used, Target and Actual Allocation, Fair Value, Estimated Future Benefit Payments, and Other Disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net periodic benefit cost [Abstract]
Recognized loss	$ (1,484)	$ (681)	$ (1,624)
Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss): [Abstract]
Net actuarial (gain) loss	2,052	8,481	(6,487)
Recognized loss	1,484	681	1,624
Amortization of prior service cost	90	90	83
Total before tax effect	(658)	(7,890)	$ 8,028
Pension Plan
Amount recognized in accumulated other comprehensive income [Abstract]
Net actuarial loss	17,863	17,388
Prior service cost	7	15
Total before tax effects	17,870	17,403
Accumulated benefit obligation	$ 37,700	$ 38,700
Principal actuarial assumptions used in determining projected benefit obligation [Abstract]
Discount rate	4.39%	4.09%	4.92%
Assumed rate of future compensation increase	5.00%	5.00%	5.00%
Net periodic benefit cost [Abstract]
Service cost	$ 1,231	$ 1,045	$ 1,195
Interest cost	1,806	1,738	1,587
Expected return on plan assets	(3,287)	(3,174)	(2,824)
Amortization of net loss	1,414	649	1,579
Amortization of prior service cost	7	7	14
Recognized loss	(1,414)	(649)	(1,579)
Net periodic cost	1,171	265	1,551
Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss): [Abstract]
Net actuarial (gain) loss	1,888	8,195	(6,367)
Recognized loss	1,414	649	1,579
Amortization of prior service cost	(7)	(7)	(14)
Total before tax effect	(467)	(7,539)	7,960
Total recognized in net benefit cost and other comprehensive income (loss) (before tax effect)	1,638	$ 7,804	$ (6,409)
Amounts expected to be recognized in net periodic cost during next fiscal year [Abstract]
Loss recognition	1,534
Prior service cost recognition	$ 7
Weighted-average assumptions for net periodic cost [Abstract]
Discount rate	4.09%	4.92%	4.26%
Expected long-term rate of return on assets	7.75%	7.75%	7.75%
Assumed rate of future compensation increase	5.00%	5.00%	5.00%
Target allocations of plan assets [Abstract]
Percentage of plan assets (in hundredths)	100.00%	100.00%
Expected long-term rate of return on assets	7.75%	7.75%	7.75%
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 39,951	$ 43,336	$ 41,782
Estimated benefit payments for each of next five years and aggregate amount expected to be paid [Abstract]
2016	1,913
2017	1,963
2018	2,058
2019	2,105
2020	2,172
2021-2025	$ 12,037
Pension Plan | Minimum
Weighted-average assumptions for net periodic cost [Abstract]
Evaluation period of expected long-term return on plan assets	3 years
Pension Plan | Maximum
Weighted-average assumptions for net periodic cost [Abstract]
Evaluation period of expected long-term return on plan assets	5 years
Pension Plan | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 39,951	43,336
Pension Plan | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	34,735	39,305
Pension Plan | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	5,216	4,031
Pension Plan | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 0	$ 0
Pension Plan | Cash
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	2.50%
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	0.00%
Target allocation, maximum (in hundredths)	20.00%
Percentage of plan assets (in hundredths)	4.00%	1.00%
Expected long-term rate of return on assets	2.50%
Pension Plan | Cash | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 1,486	$ 626
Pension Plan | Cash | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	1,486	626
Pension Plan | Cash | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Cash | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 0	$ 0
Pension Plan | Alternative Assets
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	7.50%
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	0.00%
Target allocation, maximum (in hundredths)	10.00%
Percentage of plan assets (in hundredths)	2.00%	2.00%
Expected long-term rate of return on assets	7.50%
Pension Plan | Equity Securities - U.S. Companies | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 23,424	$ 28,011
Pension Plan | Equity Securities - U.S. Companies | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	23,424	28,011
Pension Plan | Equity Securities - U.S. Companies | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Equity Securities - U.S. Companies | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Equity Securities - International Companies | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	1,277	856
Pension Plan | Equity Securities - International Companies | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	1,277	856
Pension Plan | Equity Securities - International Companies | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Equity Securities - International Companies | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | U.S. Treasuries/Government Bonds | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	2,468	2,701
Pension Plan | U.S. Treasuries/Government Bonds | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	2,701
Pension Plan | U.S. Treasuries/Government Bonds | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	2,468	0
Pension Plan | U.S. Treasuries/Government Bonds | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Corporate bonds and notes | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	2,748	3,775
Pension Plan | Corporate bonds and notes | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Corporate bonds and notes | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	2,748	3,775
Pension Plan | Corporate bonds and notes | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Foreign Bonds, Notes & Debentures | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets		256
Pension Plan | Foreign Bonds, Notes & Debentures | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets		0
Pension Plan | Foreign Bonds, Notes & Debentures | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets		256
Pension Plan | Foreign Bonds, Notes & Debentures | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets		0
Pension Plan | Mutual Funds | Carrying Value
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	8,548	7,111
Pension Plan | Mutual Funds | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	8,548	7,111
Pension Plan | Mutual Funds | Fair Value | Significant Other Observable Inputs (Level 2)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	0	0
Pension Plan | Mutual Funds | Fair Value | Significant Unobservable Inputs (Level 3)
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 0	$ 0
Pension Plan | Large-Cap Domestic Equities
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	10.30%
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	30.00%
Target allocation, maximum (in hundredths)	60.00%
Percentage of plan assets (in hundredths)	58.00%	50.00%
Expected long-term rate of return on assets	10.30%
Pension Plan | Mid-Cap Domestic Equities
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	10.60%
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	0.00%
Target allocation, maximum (in hundredths)	20.00%
Percentage of plan assets (in hundredths)	4.00%	14.00%
Expected long-term rate of return on assets	10.60%
Pension Plan | Small-Cap Domestic Equities
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	10.80%
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	0.00%
Target allocation, maximum (in hundredths)	15.00%
Percentage of plan assets (in hundredths)	3.00%	3.00%
Expected long-term rate of return on assets	10.80%
Pension Plan | International Equities
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	10.30%
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	0.00%
Target allocation, maximum (in hundredths)	25.00%
Percentage of plan assets (in hundredths)	6.00%	4.00%
Expected long-term rate of return on assets	10.30%
Pension Plan | Intermediate Fixed Income
Weighted-average assumptions for net periodic cost [Abstract]
Expected long-term rate of return on assets	4.70%
Target allocations of plan assets [Abstract]
Target allocation, minimum (in hundredths)	20.00%
Target allocation, maximum (in hundredths)	50.00%
Percentage of plan assets (in hundredths)	23.00%	26.00%
Expected long-term rate of return on assets	4.70%
Defined Benefit Health Care Plan
Amount recognized in accumulated other comprehensive income [Abstract]
Net actuarial loss	$ 517	$ 322
Prior service cost	(434)	(531)
Total before tax effects	$ 83	$ (209)
Principal actuarial assumptions used in determining projected benefit obligation [Abstract]
Discount rate	4.39%	4.09%	4.92%
Health care cost trend: Initial (in hundredths)	7.00%	7.00%	8.00%
Year ultimate cost trend reached	2019	2018	2018
Net periodic benefit cost [Abstract]
Service cost	$ 46	$ 39	$ 44
Interest cost	70	72	66
Amortization of prior service cost	(97)	(97)	(97)
Recognized loss	20	3	10
Net periodic cost	39	17	23
Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss): [Abstract]
Net actuarial (gain) loss	(216)	(177)	61
Recognized loss	(20)	(3)	(10)
Amortization of prior service cost	(97)	(97)	(97)
Total before tax effect	293	271	26
Total recognized in net benefit cost and other comprehensive income (loss) (before tax effect)	332	288	49
Increase in unrecognized net loss	$ 196
Unrecognized net gain or loss increase threshold percentage for amortization of obligation (in hundredths)	10.00%
Average future working lifetime of active participants	15 years 7 months 6 days
Amounts expected to be recognized in net periodic cost during next fiscal year [Abstract]
Loss recognition	$ (23)
Prior service cost recognition	(97)
Effect of a 1% increase in health care trend rate on:
Benefit obligation	3	5	15
Total service and interest cost	0	0	0
Effect of a 1% decrease in health care trend rate on:
Benefit obligation	(3)	(6)	(23)
Total service and interest cost	$ 0	$ 0	$ (2)
Weighted-average assumptions for net periodic cost [Abstract]
Discount rate	4.09%	4.92%	4.26%
Health care cost trend: Initial	7.00%	8.00%	9.00%
Health care cost tread: Ultimate	5.00%	5.00%	5.00%
Year ultimate reached	2018	2018	2018
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 0	$ 0	$ 0
Estimated benefit payments for each of next five years and aggregate amount expected to be paid [Abstract]
2016	217
2017	170
2018	180
2019	168
2020	150
2021-2025	645
Estimated employer contributions in next fiscal year	217
Executive Supplemental Pension Plan
Amount recognized in accumulated other comprehensive income [Abstract]
Net actuarial loss	173	275
Prior service cost	0	0
Total before tax effects	173	275
Accumulated benefit obligation	$ 1,200	$ 1,200
Principal actuarial assumptions used in determining projected benefit obligation [Abstract]
Discount rate	4.39%	4.09%	4.92%
Assumed rate of future compensation increase	5.00%	5.00%	5.00%
Net periodic benefit cost [Abstract]
Service cost	$ 44	$ 38	$ 40
Interest cost	49	55	48
Amortization of net loss	50	29	34
Recognized loss	50	29	34
Net periodic cost	143	122	122
Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss): [Abstract]
Net actuarial (gain) loss	52	(110)	59
Recognized loss	(50)	(29)	(34)
Total before tax effect	(102)	81	(93)
Total recognized in net benefit cost and other comprehensive income (loss) (before tax effect)	41	$ 203	$ 29
Amounts expected to be recognized in net periodic cost during next fiscal year [Abstract]
Loss recognition	(26)
Prior service cost recognition	$ 0
Weighted-average assumptions for net periodic cost [Abstract]
Discount rate	4.09%	4.92%	4.26%
Assumed rate of future compensation increase	5.00%	5.00%	5.00%
Fair value plan assets by asset class [Abstract]
Fair value of plan assets	$ 0	$ 0	$ 0
Estimated benefit payments for each of next five years and aggregate amount expected to be paid [Abstract]
2016	74
2017	73
2018	112
2019	111
2020	108
2021-2025	498
Estimated employer contributions in next fiscal year	$ 75