Leases - Supplemental Operating Lease Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease right-of-use assets	$ 118	$ 0
Accrued liabilities	26
Operating lease liabilities	98	$ 0
Operating lease liabilities	124
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 8
Operating Lease, Weighted Average Remaining Lease Term	6 years
Weighted average discount rate	5.00%