Annual report pursuant to Section 13 and 15(d)

EMPLOYEE BENEFIT PLANS - major categories of assets in the Company's pension plan (Details)

v3.20.4
EMPLOYEE BENEFIT PLANS - major categories of assets in the Company's pension plan (Details) - Defined benefit pension plan [Member] - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]        
Fair Value of Plan Assets $ 171,775 $ 161,646 $ 134,535 $ 129,719
U.S. Treasury Securities [Member] | Level 1 Inputs [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Fair Value of Plan Assets 405 907    
Mutual Funds [Member] | Level 1 Inputs [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Fair Value of Plan Assets 155,192 142,127    
Cash and Cash Equivalents [Member] | Level 1 Inputs [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Fair Value of Plan Assets 12,789 13,943    
U.S. Government Agency [Member] | Level 2 Inputs [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Fair Value of Plan Assets 1,555 2,078    
DomesticCorporateDebtSecuritiesMember | Level 2 Inputs [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Fair Value of Plan Assets $ 1,834 $ 2,591