v3.20.2
Leases​ (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Dec. 31, 2019
Leases [Abstract]          
Lease cost $ 14 $ 15 $ 43 $ 47  
Right-of-use asset obtained in exchange for operating lease liability $ 6   $ 38    
Weighted-average remaining lease term 6 years 8 months 12 days   6 years 8 months 12 days   6 years 8 months 12 days
Weighted-average discount rate 5.90%   5.90%   6.00%
Operating Lease Obligation          
2020 $ 11   $ 11   $ 38
2021 38   38   29
2022 31   31   22
2023 24   24   17
2024 19   19   14
Thereafter 53   53   38
Total lease payments 176   176   158
Less: imputed interest 33   33   29
Present value of lease liabilities $ 143   $ 143   $ 129