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Employee Benefits (Multiemployer Plans) (Details)
$ in Millions
12 Months Ended
Dec. 31, 2019
USD ($)
plan
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Multiemployer Plans [Line Items]      
Number of multiemployer plans | plan 2    
Foreign Plan [Member]      
Multiemployer Plans [Line Items]      
Contributions to multi-employer plans | $ $ 9 $ 7 $ 8