Leases Assets and Liabilities, Lessee (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Assets and Liabilities, Lessee [Abstract]
Operating Lease, Right-of-Use Asset	$ 99	$ 0
Finance Lease, Right-of-Use Asset	9
Leases, Right of Use Asset	108
Operating Lease, Liability, Current	23	0
Finance Lease, Liability, Current	2
Operating Lease, Liability, Noncurrent	76	$ 0
Finance Lease, Liability, Noncurrent	7
Leases, Liability	108
Finance lease, Accumulated Amortization	$ 8