PENSION PLAN AND OTHER BENEFIT PLANS - Changes in Projected Benefit Obligation and Plan Assets, and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Plan
Changes in projected benefit obligation [Roll Forward]
Benefit obligation at beginning of year	$ 45,544	$ 36,186
Service cost	1,231	1,045	$ 1,195
Interest cost	1,806	1,738	1,587
Actuarial (gain) loss	(3,199)	8,064
Benefits paid	(1,585)	(1,489)
Benefit obligation at end of year	43,797	45,544	36,186
Changes in plan assets [Roll Forward]
Fair value of plan assets at beginning of year	43,336	41,782
Actual return on plan assets	(1,800)	3,043
Employer contributions	0	0
Benefits paid	(1,585)	(1,489)
Fair value of plan assets at end of year	39,951	43,336	41,782
Funded status of plan	(3,846)	(2,208)
Defined Benefit Health Care Plan
Changes in projected benefit obligation [Roll Forward]
Benefit obligation at beginning of year	1,663	1,490
Service cost	46	39	44
Interest cost	70	72	66
Participant contributions	83	84
Actuarial (gain) loss	215	177
Benefits paid	(413)	(199)
Benefit obligation at end of year	1,664	1,663	1,490
Changes in plan assets [Roll Forward]
Fair value of plan assets at beginning of year	0	0
Employer contributions	330	115
Participant contributions	83	84
Benefits paid	(413)	(199)
Fair value of plan assets at end of year	0	0	0
Funded status of plan	(1,664)	(1,663)
Executive Supplemental Pension Plan
Changes in projected benefit obligation [Roll Forward]
Benefit obligation at beginning of year	1,244	1,116
Service cost	44	38	40
Interest cost	49	55	48
Actuarial (gain) loss	(52)	110
Benefits paid	(75)	(75)
Benefit obligation at end of year	1,210	1,244	1,116
Changes in plan assets [Roll Forward]
Fair value of plan assets at beginning of year	0	0
Employer contributions	75	75
Benefits paid	(75)	(75)
Fair value of plan assets at end of year	0	0	$ 0
Funded status of plan	$ (1,210)	$ (1,244)