Leases (Schedule of Right-of-use Assets and Lease Liabilities) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Right-of-use assets, finance lease		$ 227	$ 229
Finance lease liabilities:
Current lease liabilities, finance lease	[1]	7	7
Long-term lease liabilities, finance lease		242	240
Total lease liabilities, finance lease		249	247
Right-of-use assets, operating lease		10	14
Operating lease liabilities:
Current lease liabilities, operating lease	[1]	7	10
Long-term lease liabilities, operating lease		3	4
Total lease liabilities, operating lease		10	14
Right-of-use assets		237	243
Lease liabilities:
Current lease liabilities	[1]	14	17
Long-term lease liabilities		245	244
Total lease liabilities		$ 259	$ 261

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