Commitments and Contingent Liabilities PFOA / Leach Settlement (Details)	3 Months Ended	9 Months Ended	12 Months Ended	105 Months Ended
	Jun. 30, 2017 USD ($)	Sep. 30, 2020 USD ($) lawsuits	Dec. 31, 2004 USD ($)	Sep. 30, 2020 USD ($) lawsuits	Jan. 01, 2012
PFOA Matters: Drinking Water Actions [Member]
Loss Contingencies [Line Items]
Binding Settlement Agreement Class Size			80,000
Loss Contingency, Number Of Water Districts Receiving Water Treatment					6
Litigation Settlement, Liability For Medical Monitoring Program, Threshold			$ 235,000,000
Litigation Settlement, Medical Monitoring Program, Escrow Account, Disbursements To Date				$ 2,000,000
Escrow Balance		$ 1,000,000		$ 1,000,000
PFOA Matters: Drinking Water Actions [Member] | WEST VIRGINIA AND OHIO [Domain]
Loss Contingencies [Line Items]
Loss Contingency, Pending Claims, Number		58		58
Loss Contingency, Threatened Claims, Number		33		33
PFOA Matters: Drinking Water Actions [Member] | WEST VIRGINIA AND OHIO [Domain] | Scheduled for trial [Member]
Loss Contingencies [Line Items]
Loss Contingency, Pending Claims, Number		6		6
PFOA Matters: Drinking Water Actions [Member] | WEST VIRGINIA AND OHIO [Domain] | Compensatory damages [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount Awarded to Other Party		$ 40,000,000
PFOA Matters: Drinking Water Actions [Member] | WEST VIRGINIA AND OHIO [Domain] | Loss of consortium [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount Awarded to Other Party		$ 10,000,000
PFOA Matters: Multi-District Litigation [Member]
Loss Contingencies [Line Items]
Disease Categories for MDL		6		6
Lawsuits alleging personal injury filed | lawsuits		3,550		3,550
Litigation Settlement, Amount Awarded to Other Party	$ 670,700,000
Chemours [Member] | PFOA Matters [Member]
Loss Contingencies [Line Items]
Indemnification Asset for liabilities indemnified by Chemours		$ 21,000,000		$ 21,000,000
Indemnified Liabilities for liabilities indemnified by Chemours		$ 21,000,000		$ 21,000,000