Commitments and Contingencies - Environmental Matters (Details) $ in Millions	Dec. 31, 2015 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Environmental remediation accrual, discounted basis	$ 14
Portion of environmental remediation costs recorded in other current liabilities	2
Portion of environmental remediation costs recorded in deferred credits and other liabilities	$ 12
Weighted average discount rate	1.80%
Environmental remediation accrual, undiscounted basis	$ 17
Expected payments of environmental remediation costs, 2016	2
Expected payments of environmental remediation costs, 2017	1
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, thereafter	$ 11