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Pension Plan (Details) - Weighted average asset allocations by asset category
Dec. 31, 2019
Dec. 31, 2018
Pension Plan (Details) - Weighted average asset allocations by asset category [Line Items]    
Total pension plan assets 100.00% 100.00%
Equity And Index Funds [Member]    
Pension Plan (Details) - Weighted average asset allocations by asset category [Line Items]    
Total pension plan assets 69.30% 64.70%
Fixed Income Funds [Member]    
Pension Plan (Details) - Weighted average asset allocations by asset category [Line Items]    
Total pension plan assets 30.70% 35.30%