EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Defined contribution plan expense	$ 6,200	$ 5,400	$ 4,800
Defined contribution plan, employer matching contribution percent	4.00%
Deferred compensation liability	$ 45,689	40,338
Carrying value of shares held in trust for stock related compensation plans	7,507	7,289
Cash surrender value of bank-owned life insurance policies	192,100	177,500
Supplemental Retirement and Salary Contribution Plans [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation plans expense	3,400	2,300	$ 3,500
Deferred compensation liability	41,800	37,500
Deferred Compensation Plans and Rabbi Trusts [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation liability	10,900	9,000
Carrying value of shares held in trust for stock related compensation plans	$ 7,500	$ 7,300

Carrying amount as of the balance sheet date of amounts which could be received based on the terms of the insurance contract upon surrendering life policies owned by the entity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 4
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6812-107765

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Value of common stock issued to a trust (for example, but not limited to, rabbi trust) set up specifically to accumulate stock for the sole purpose of distribution to participating employees.

+ References

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The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 30
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363

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Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

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Amount of cost for defined contribution plan.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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