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Share-Based Compensation - Other Award Types (Details) - Other Award Types - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based liabilities paid $ 6 $ 2 $ 2
Number of shares that became available under the Plan 17,207 20,393 45,781
Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period (not more than) 4 years