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Revenue (Details) - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Change in Contract with Customer, Asset [Abstract]    
Beginning balance $ 117 $ 106
Additions, net 78 63
Billings transferred to accounts receivable (74) (60)
Other 0 (2)
Ending balance 121 107
Change in Contract with Customer, Liability [Abstract]    
Beginning balance 166 135
Additions, net 99 85
Revenue recognized from opening balance (93) (70)
Other (1) (4)
Ending balance $ 171 $ 146