Leases Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Schedule of Lease Assets and Liabilities [Line Items]
Guarantee Obligations	$ 80	$ 299	$ 187
Minimum [Member]
Schedule of Lease Assets and Liabilities [Line Items]
Lessee Operating and Finance Leases, Remaining Lease Term	1 year
Maximum [Member]
Schedule of Lease Assets and Liabilities [Line Items]
Lessee Operating and Finance Leases, Remaining Lease Term	49 years
Residual Value Guarantee [Member]
Schedule of Lease Assets and Liabilities [Line Items]
Guarantee Obligations	$ 247