Commitments and Contingent Liabilities (Environmental) (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Environmental Remediation [Line Items]
Accrual for environmental remediation activities	$ 455	$ 457
Potential environmental liability in excess of accrued amount	910
Chemours [Member]
Environmental Remediation [Line Items]
Accrual for environmental remediation activities	256
Potential environmental liability in excess of accrued amount	436
Chemours [Member] | Indemnification Agreement [Member]
Environmental Remediation [Line Items]
Indemnification Asset	256
Superfund Sites [Member]
Environmental Remediation [Line Items]
Accrual for environmental remediation activities	74	$ 17
Superfund Sites [Member] | Chemours [Member] | Indemnification Agreement [Member]
Environmental Remediation [Line Items]
Indemnification Asset	$ 54