EMPLOYEE BENEFIT PLANS (Tables)  | 
3 Months Ended | 
|---|---|
Mar. 31, 2021  | |
| Defined Benefit Plan Disclosure [Line Items] | |
| Schedule of Net Benefit Costs | 
 Three Months Ended March 31,  
(Dollars in Thousands)  
2021  
2020  
Service Cost  
$  
1,743 
$  
1,457 
Interest Cost  
1,221 
1,411 
Expected Return on Plan Assets  
(2,787) 
(2,748) 
Prior Service Cost Amortization  
4 
4 
Net Loss Amortization  
1,691 
1,011 
Special Termination 
- 
61 
Net Periodic Benefit Cost  
$  
1,872 
$  
1,196 
Discount Rate Used for Benefit Cost  
2.88% 
3.53% 
Long-term Rate of Return on Assets  
6.75% 
7.00% 
 | 
| Supplemental Executive Retirement Plan [Member] | |
| Defined Benefit Plan Disclosure [Line Items] | |
| Schedule of Net Benefit Costs | 
 The components of the net periodic benefit cost for the Company's 
Three Months Ended March 31,  
(Dollars in Thousands)  
2021  
2020  
Service Cost  
$  
9 
$  
- 
Interest Cost  
$  
59 
$  
72 
Prior Service Cost Amortization  
19 
- 
Net Loss Amortization  
198 
247 
Net Periodic Benefit Cost  
$  
285 
$  
319 
Discount Rate Used for Benefit Cost  
2.38% 
3.16% 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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- Definition Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Details 
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