Leases Assets and Liabilities, Lessee (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Assets and Liabilities, Lessee [Abstract]
Operating Lease, Right-of-Use Asset	$ 95	$ 0
Finance Lease, Right-of-Use Asset	11
Leases, Right of Use Asset	106
Operating Lease, Liability, Current	21	0
Finance Lease, Liability, Current	3
Operating Lease, Liability, Noncurrent	74	$ 0
Finance Lease, Liability, Noncurrent	8
Leases, Liability	106
Finance lease, Accumulated Amortization	$ 9