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Defined Pension Plans (Narrative) (Details) - USD ($)
 3 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]    
Pension period 30 years  
Defined Benefit Pension Plan [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Pension costs $ 1,029,000 $ 1,179,000
Unfunded Supplemental Executive Retirement Plan [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Pension costs $ 145,000 $ 195,000