Commitments and Contingent Liabilities Environmental (Details) $ in Millions	Sep. 30, 2018 USD ($)
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	$ 417
Accrual for Environmental Loss Contingencies, Potential Exposure in Excess of Accrual	825
Superfund Sites [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	58
Chemours [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	228
Accrual for Environmental Loss Contingencies, Potential Exposure in Excess of Accrual	395
Chemours [Member] | Indemnification Agreement [Member]
Loss Contingencies [Line Items]
Indemnification Assets	228
Chemours [Member] | Indemnification Agreement [Member] | Superfund Sites [Member]
Loss Contingencies [Line Items]
Indemnification Assets	$ 39