Leases Lessee (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Capital Leases, Future Minimum Payments, Next Rolling Twelve Months	$ 1	$ 1
Finance Lease, Liability, Payment, Due [Abstract]
Finance Lease, Liability, Payment, Due	16	16
Finance Lease, Liability, Payments, Due Year Five	1	1
Finance Lease, Liability, Payments, Due Year Four	1	1
Finance Lease, Liability, Payments, Due Year Three	1	1
Finance Lease, Liability, Payments, Due Year Two	2	2
Finance Lease, Liability, Payments, Due after Year Five	10	10
Finance Lease, Liability, Payments, Due Next Twelve Months	1	1
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Lessee, Operating Lease, Liability, Payments, Due after Year Five	483	483
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	14	14
Lessee, Operating Lease, Liability, Payments, Due Year Three	26	26
Lessee, Operating Lease, Liability, Payments, Due Year Four	27	27
Lessee, Operating Lease, Liability, Payments, Due Year Two	28	28
Lessee, Operating Lease, Liability, Payments, Due Year Five	26	26
Lessee, Operating Lease, Liability, Payments, Due	604	604
Assets and Liabilities, Lessee [Abstract]
Lease Liability, Operating and Financing	289	289
Right-of-use Asset, Operating and Financing	261	261
Operating Lease, Right-of-Use Asset	253	253
Finance Lease, Right-of-Use Asset	8	8
Operating Lease, Liability, Current	16	16
Operating Lease, Liability, Noncurrent	263	263
Operating Lease, Liability	279	279
Finance Lease, Liability, Current	1	1
Finance Lease, Liability, Noncurrent	9	9
Finance Lease, Liability	$ 10	$ 10
Lease, Cost [Abstract]
Operating Lease, Weighted Average Discount Rate, Percent	6.90%	6.90%
Finance Lease, Weighted Average Discount Rate, Percent	9.20%	9.20%
Operating Lease, Weighted Average Remaining Lease Term	22 years 9 months 18 days	22 years 9 months 18 days
Finance Lease, Weighted Average Remaining Lease Term	15 years 10 months 24 days	15 years 10 months 24 days
Lease, Cost	$ 17	$ 31
Variable Lease, Cost	2	3
Operating Lease, Cost	14	27
Finance Lease, Right-of-Use Asset, Amortization	1	1
Operating Lease Liabilities, Gross Difference, Amount [Abstract]
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(325)	(325)
Finance Lease Liabilities, Gross Difference, Amount [Abstract]
Finance Lease, Liability, Undiscounted Excess Amount	(6)	(6)
Operating Leases, Future Minimum Payments Due, Next Twelve Months	74	74
Capital Leases, Future Minimum Payments, Due in Rolling Year Two	1	1
Operating Leases, Future Minimum Payments, Due in Two Years	38	38
Capital Leases, Future Minimum Payments, Due in Rolling Year Three	1	1
Operating Leases, Future Minimum Payments, Due in Three Years	25	25
Capital Leases, Future Minimum Payments, Due in Rolling Year Four	1	1
Operating Leases, Future Minimum Payments, Due in Four Years	26	26
Capital Leases, Future Minimum Payments, Due in Rolling Year Five	1	1
Operating Leases, Future Minimum Payments, Due in Five Years	25	25
Capital Leases, Future Minimum Payments, Due in Rolling after Year Five	7	7
Operating Leases, Future Minimum Payments, Due Thereafter	455	455
Capital Leases, Future Minimum Payments Due	12	12
Operating Leases, Future Minimum Payments Due	643	643
Capital Leases, Future Minimum Payments, Interest Included in Payments	(6)	(6)
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	6	6
Operating Lease, Payments	$ 12	$ 26
Lessee, Operating Lease, Term of Contract	12 months	12 months