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Leases - Narrative (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Lessee, Lease, Description [Line Items]      
Operating Lease, Expense $ 53 $ 93  
Operating Leases, Rent Expense     $ 30
Minimum      
Lessee, Lease, Description [Line Items]      
Lease terms of contract 1 year    
Maximum      
Lessee, Lease, Description [Line Items]      
Lease terms of contract 16 years