Leases Supplemental Lease Disclosures (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Leases [Abstract]
Operating Lease, Payments	$ 88
Finance Lease, Interest Payment on Liability	3
Finance Lease, Principal Payments	6
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	45
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability		$ 3
Sale and Leaseback Transaction, Gain (Loss), Net	$ 34
Operating Lease, Weighted Average Remaining Lease Term	6 years 10 months 24 days	6 years 10 months 24 days
Finance Lease, Weighted Average Remaining Lease Term	7 years 3 months 18 days	7 years 3 months 18 days
Operating Lease, Weighted Average Discount Rate, Percent	13.50%	13.50%
Finance Lease, Weighted Average Discount Rate, Percent	5.70%	5.70%