Leases (Lease Income Associated with Operating Leases) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Lessor, Lease, Description [Line Items]
Fixed payments	$ 4	$ 14
Variable payments	16	17
Total lease income under operating leases	20	31
Operating revenues
Lessor, Lease, Description [Line Items]
Total lease income under operating leases	20	21
Other income
Lessor, Lease, Description [Line Items]
Total lease income under operating leases	$ 0	$ 10