Leases (Lease Income Associated with Operating Leases) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Lessor, Lease, Description [Line Items]
Fixed payments	$ 65
Variable payments	128
Total lease income under operating leases	193
Operating Revenues
Lessor, Lease, Description [Line Items]
Total lease income under operating leases	130
Other Income
Lessor, Lease, Description [Line Items]
Total lease income under operating leases	$ 63