Contingencies and Commitments - Loss Contingencies (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Environmental Remediation Contingency [Domain]
Environmental Contingencies
Liability recorded for projected environmental remediation costs	$ 5
Litigation [Member]
Litigation Contingencies
Aggregate reserves for claims deemed both probable and reasonably estimable	55	$ 53
Maximum [Member] | Environmental Remediation Contingency [Domain]
Litigation Contingencies
Loss Contingency, Estimate of Possible Loss ( Equal to or less than)	16
Maximum [Member] | Litigation [Member]
Litigation Contingencies
Loss Contingency, Estimate of Possible Loss ( Equal to or less than)	439
Minimum [Member] | Litigation [Member]
Litigation Contingencies
Loss Contingency, Estimate of Possible Loss ( Equal to or less than)	$ 79