EMPLOYEE BENEFITS - Change in Projected Benefit Obligation and Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Pension Plan
Change in Projected Benefit Obligation:
Benefit obligation at end of prior year	$ 85,992	$ 94,276	$ 88,071
Service cost	1,420	1,548	1,398
Interest cost	3,654	3,392	3,601
Actuarial loss (gain)	12,763	(9,399)	5,404
Benefits Paid	(3,703)	(3,622)	(4,128)
Expenses paid	(114)	(203)	(70)
Settlements	0	0	0
Benefit obligation at end of year	100,012	85,992	94,276
Change in Plan Assets:
Fair value of plan assets at end of prior year	84,911	91,233	85,293
Actual return	12,724	(4,497)	8,138
Employer contributions	0	2,000	2,000
Benefits paid	(3,703)	(3,622)	(4,128)
Expenses paid	(114)	(203)	(70)
Settlements	0	0	0
Fair value of plan assets at end of year	93,818	84,911	91,233
(Un)Funded status at end of year	(6,194)	(1,081)	(3,043)
Accrued benefit (liability) asset recognized	(6,194)	(1,081)	(3,043)
Accumulated benefit obligation at end of year	88,247	77,888	83,802
Defined Benefit Pension Plan Acquired
Change in Projected Benefit Obligation:
Benefit obligation at end of prior year	3,873	4,392	4,238
Service cost	0	0	0
Interest cost	169	163	177
Actuarial loss (gain)	943	(480)	418
Benefits Paid	(68)	(183)	(43)
Expenses paid	(47)	(19)	(47)
Settlements	0	0	(351)
Benefit obligation at end of year	4,870	3,873	4,392
Change in Plan Assets:
Fair value of plan assets at end of prior year	4,070	4,031	2,993
Actual return	808	(259)	479
Employer contributions	0	500	1,000
Benefits paid	(68)	(183)	(43)
Expenses paid	(47)	(19)	(47)
Settlements	0	0	(351)
Fair value of plan assets at end of year	4,763	4,070	4,031
(Un)Funded status at end of year	(107)	197	(361)
Accrued benefit (liability) asset recognized	(107)	197	(361)
Accumulated benefit obligation at end of year	4,870	3,873	4,392
Restoration Plan
Change in Projected Benefit Obligation:
Benefit obligation at end of prior year	15,300	14,642	12,723
Service cost	339	293	247
Interest cost	713	597	567
Actuarial loss (gain)	3,319	344	1,751
Benefits Paid	(573)	(576)	(646)
Expenses paid	0	0	0
Settlements	0	0	0
Benefit obligation at end of year	19,098	15,300	14,642
Change in Plan Assets:
Fair value of plan assets at end of prior year	0	0	0
Actual return	0	0	0
Employer contributions	573	576	646
Benefits paid	(573)	(576)	(646)
Expenses paid	0	0	0
Settlements	0	0	0
Fair value of plan assets at end of year	0	0	0
(Un)Funded status at end of year	(19,098)	(15,300)	(14,642)
Accrued benefit (liability) asset recognized	(19,098)	(15,300)	(14,642)
Accumulated benefit obligation at end of year	$ 16,258	$ 13,403	$ 13,246