Leases Supplemental Lease Disclosures (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
Leases [Abstract]
Operating Lease, Payments	$ 57
Finance Lease, Interest Payment on Liability	2
Finance Lease, Principal Payments	4
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	35
Sale and Leaseback Transaction, Gain (Loss), Net	$ 36
Operating Lease, Weighted Average Remaining Lease Term	6 years 9 months 18 days
Finance Lease, Weighted Average Remaining Lease Term	7 years 6 months
Operating Lease, Weighted Average Discount Rate, Percent	13.60%
Finance Lease, Weighted Average Discount Rate, Percent	5.70%