Leases (Schedule of Right-of-use Assets and Lease Liabilities) (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Right-of-use assets, finance lease		$ 220	$ 229
Finance lease liabilities:
Current lease liabilities, finance lease	[1]	8	7
Long-term lease liabilities, finance lease		244	240
Total lease liabilities, finance lease		252	247
Right-of-use assets, operating lease		$ 3	$ 14
Operating lease liabilities:
Operating Lease, Liability, Current		us-gaap:OtherCurrentLiabilitiesMember	us-gaap:OperatingLeaseLiabilityCurrent
Current lease liabilities, operating lease	[1]	$ 1	$ 10
Operating Lease, Liability, Noncurrent		us-gaap:OtherNoncurrentLiabilitiesMember	us-gaap:OperatingLeaseLiabilityNoncurrent
Long-term lease liabilities, operating lease		$ 2	$ 4
Operating Lease, Liability		us-gaap:OtherLiabilitiesMember	us-gaap:OperatingLeaseLiability
Total lease liabilities, operating lease		$ 3	$ 14
Right-of-use assets		223	243
Lease liabilities:
Current lease liabilities	[1]	9	17
Long-term lease liabilities		246	244
Total lease liabilities		$ 255	$ 261

[1] Current lease liabilities are included in other current liabilities on the consolidated balance sheets.