Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Finance Lease, Interest Payment on Liability		$ 1
Total finance lease costs	$ 3	5
General and administrative expense [Member]
Operating lease costs	14	29
Amortization of leased assets	2	4
Interest Expense [Member]
Finance Lease, Interest Expense	$ 1	$ 1