Leases (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Line Items]
Option To Extend Lease Term	15 years
Lease, Option to Terminate	1 year
Assets recorded under finance leases	$ 221
Finance Leases	95
Finance Lease, lease not yet commenced, amount	$ 1
Finance Lease, lease not yet commenced, term of contract	5 years
Accumulated Depreciation [Member]
Leases [Line Items]
Finance Leases	$ 128
Current Portion Of Long-Term Debt [Member]
Leases [Line Items]
Finance Leases	35
Long-term Debt [Member]
Leases [Line Items]
Finance Leases	$ 60
Maximum [Member]
Leases [Line Items]
Remaining Lease Term	23 years
Maximum [Member] | Vehicle Leases [Member]
Leases [Line Items]
Remaining Lease Term	8 years
Minimum [Member]
Leases [Line Items]
Remaining Lease Term	1 year
Minimum [Member] | Vehicle Leases [Member]
Leases [Line Items]
Remaining Lease Term	1 year