Leases - Supplemental Operating Lease Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Leases [Abstract]
Document Period End Date	Jun. 30, 2019
Operating lease right-of-use assets	$ 113	$ 0
Accrued liabilities	26
Operating lease liabilities	95	$ 0
Operating lease liabilities	121
Operating Lease, Right-of-Use Asset, in Exchange for Lease Obligations	5
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases for the six months period	$ 17
Operating Lease, Weighted Average Remaining Lease Term	6 years
Weighted average discount rate	5.00%