Leases Maturities of lease liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020	$ 41
2021	37
2022	31
2023	25
2024	21
Later years	125
Total lease payments	280
Less amounts representing interest	(36)
Total lease obligations	244
Finance Lease, Liability, Payment, Due [Abstract]
2020	43
2021	36
2022	31
2023	28
2024	24
Later years	122
Total lease payments	284
Less amounts representing interest	(83)
Total lease obligations	$ 201	$ 144