Commitments and Contingencies - Environmental Matters (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Accrued expenses and other current liabilities	$ 8	$ 12
Deferred credits and other liabilities	29	28
Environmental remediation accrual, discounted basis	$ 37	$ 40
Weighted average discount rate	1.30%	2.90%
Expected payments of environmental remediation costs, 2019	$ 5
Expected payments of environmental remediation costs, 2020	5
Expected payments of environmental remediation costs, 2021	3
Expected payments of environmental remediation costs, 2022	3
Expected payments of environmental remediation costs, 2023	2
Expected payments of environmental remediation costs, thereafter	$ 17