Commitments and Contingencies - Environmental Matters (Details) $ in Millions	Dec. 31, 2016 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Environmental remediation accrual, discounted basis	$ 15
Portion of environmental remediation costs recorded in other current liabilities	2
Portion of environmental remediation costs recorded in deferred credits and other liabilities	$ 13
Weighted average discount rate	2.40%
Environmental remediation accrual, undiscounted basis	$ 18
Expected payments of environmental remediation costs, 2017	2
Expected payments of environmental remediation costs, 2018	1
Expected payments of environmental remediation costs, 2019	1
Expected payments of environmental remediation costs, 2020	1
Expected payments of environmental remediation costs, 2021	1
Expected payments of environmental remediation costs, thereafter	$ 12