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Credit Risk (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2020
Dec. 31, 2018
Dec. 31, 2019
Sep. 30, 2018
Concentration Risk [Line Items]        
Debt Instrument, Fair Value Disclosure $ 730   $ 390  
Ford And Affiliates [Member] | Accounts Receivable [Member] | Credit Concentration Risk [Member]        
Concentration Risk [Line Items]        
Entity-wide revenue, major customer, percentage 19.00% 22.00%    
Nissan\Renault [Member] | Accounts Receivable [Member] | Credit Concentration Risk [Member]        
Concentration Risk [Line Items]        
Entity-wide revenue, major customer, percentage 6.00% 13.00%    
Fair Value Measured at Net Asset Value Per Share [Member]        
Concentration Risk [Line Items]        
Investments, Fair Value Disclosure     $ 3 $ 15