Leases Lessee (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
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	15	15
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	9	9
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	577	577
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	8	8
Lessee, Operating Lease, Liability, Payments, Due Year Three	29	29
Lessee, Operating Lease, Liability, Payments, Due Year Four	29	29
Lessee, Operating Lease, Liability, Payments, Due Year Two	30	30
Lessee, Operating Lease, Liability, Payments, Due Year Five	28	28
Lessee, Operating Lease, Liability, Payments, Due	701	701
Assets and Liabilities, Lessee [Abstract]
Lease Liability, Operating and Financing	338	338
Right-of-use Asset, Operating and Financing	308	308
Operating Lease, Right-of-Use Asset	300	300
Finance Lease, Right-of-Use Asset	8	8
Operating Lease, Liability, Current	17	17
Operating Lease, Liability, Noncurrent	312	312
Operating Lease, Liability	329	329
Finance Lease, Liability, Current	1	1
Finance Lease, Liability, Noncurrent	8	8
Finance Lease, Liability	$ 9	$ 9
Lease, Cost [Abstract]
Operating Lease, Weighted Average Discount Rate, Percent	4.63%	4.63%
Finance Lease, Weighted Average Discount Rate, Percent	9.15%	9.15%
Operating Lease, Weighted Average Remaining Lease Term	12 years	12 years
Finance Lease, Weighted Average Remaining Lease Term	16 years	16 years
Lease, Cost	$ 23	$ 72
Variable Lease, Cost	11	32
Operating Lease, Cost	11	38
Finance Lease, Right-of-Use Asset, Amortization	0	1
Finance Lease, Interest Expense	1	1
Operating Lease Liabilities, Gross Difference, Amount [Abstract]
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(372)	(372)
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	$ 11	$ 37
Lessee, Operating Lease, Term of Contract	12 months	12 months