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Employee Benefit Plans - Assumptions, Additional Information (Details)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]        
Expected long-term rate of return on plan assets   6.60% 6.60%  
Fixed income securities        
Defined Benefit Plan Disclosure [Line Items]        
Market return expectation rate   60.00%    
Equity securities        
Defined Benefit Plan Disclosure [Line Items]        
Market return expectation rate   40.00%    
Pension Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Discount rate   4.35% 3.73%  
Expected long-term rate of return on plan assets   6.60% 6.60% 6.70%
Pension Benefits | Scenario, Forecast        
Defined Benefit Plan Disclosure [Line Items]        
Expected long-term rate of return on plan assets 6.45%      
Other postretirement obligations        
Defined Benefit Plan Disclosure [Line Items]        
Discount rate   4.23% 3.55%  
Expected long-term rate of return on plan assets   6.60% 6.60% 6.60%
Other postretirement obligations | Scenario, Forecast        
Defined Benefit Plan Disclosure [Line Items]        
Expected long-term rate of return on plan assets 6.00%