Commitments and Contingencies - Respirator and Environmental (Details)	1 Months Ended					3 Months Ended				9 Months Ended										12 Months Ended
	Apr. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jul. 31, 2018 USD ($)	Apr. 30, 2018 USD ($)	Feb. 28, 2018 USD ($)	Sep. 30, 2019 USD ($) lawsuit $ / shares	Mar. 31, 2019 USD ($) $ / shares	Sep. 30, 2018 $ / shares	Mar. 31, 2018 USD ($)	Sep. 30, 2019 USD ($) lawsuit	Sep. 30, 2019 USD ($) lawsuit	Sep. 30, 2019 USD ($) lawsuit $ / shares	Sep. 30, 2019 USD ($) facility lawsuit	Sep. 30, 2019 USD ($) case lawsuit	Sep. 30, 2019 USD ($) individual lawsuit	Sep. 30, 2019 USD ($) lawsuit	Sep. 30, 2019 USD ($) item lawsuit	Sep. 30, 2019 USD ($) lawsuit defendant	Sep. 30, 2018 $ / shares	Dec. 31, 2018 item	Sep. 30, 2017 USD ($)
Loss contingencies
Diluted earnings per share | $ / shares						$ 2.72		$ 2.58				$ 6.15							$ 6.61
Respirator Mask/Asbestos Litigation
Loss contingencies
Total number of named claimants																	1,770			2,320
Number of years company has been the defendant in Respirator Mask/Asbestos Litigation										20 years
Number of total claims the Company prevailed after being taken to trial											2			14
Number of total claims taken to trial | case														15
Accrued loss contingency reserve | $						$ 620,000,000				$ 620,000,000	$ 620,000,000	$ 620,000,000	$ 620,000,000	$ 620,000,000	$ 620,000,000	$ 620,000,000	$ 620,000,000	$ 620,000,000
Increase (decrease) accrued loss contingency reserve | $																337,000,000
Increase in liabilities, gross | $							$ 313,000,000
Increase in liabilities, net | $							$ 238,000,000
Diluted earnings per share | $ / shares							$ 0.40
Payments for fees and settlements related to litigation | $																390,000,000
Insurance receivables | $						4,000,000				$ 4,000,000	$ 4,000,000	4,000,000	4,000,000	4,000,000	$ 4,000,000	4,000,000	4,000,000	4,000,000
Respirator Mask/Asbestos Litigation | State court of California
Loss contingencies
Number of total claims the Company prevailed after being taken to trial | lawsuit											1
Respirator Mask/Asbestos Litigation | State court of Kentucky
Loss contingencies
Number of unnamed defendant | individual															2
Litigation settlement awarded | $				$ 2,000,000
Amount of punitive damages awarded | $				63,000,000
Settlement amount paid | $				$ 65,000,000
Respirator Mask/Asbestos Litigation | Kentucky and West Virginia
Loss contingencies
Settlement amount paid | $	$ 340,000,000	$ 340,000,000
Respirator Mask/Asbestos Litigation - State of West Virginia
Loss contingencies
Number of additional defendants										two
Accrued loss contingency reserve | $						0				$ 0	$ 0	0	0	0	$ 0	0	0	0
Respirator Mask/Asbestos Litigation - Aearo Technologies
Loss contingencies
Accrued loss contingency reserve | $						24,000,000				24,000,000	24,000,000	24,000,000	24,000,000	24,000,000	24,000,000	24,000,000	24,000,000	24,000,000
Quarterly fee paid to Cabot to retain responsibility and liability for products manufactured before July 11, 1995 | $																100,000
Environmental Matters - Remediation
Loss contingencies
Accrued loss contingency reserve | $						20,000,000				$ 20,000,000	20,000,000	20,000,000	20,000,000	20,000,000	20,000,000	20,000,000	20,000,000	20,000,000
Number of years remediation payments expected to be paid for applicable sites										20 years
Environmental Matters - Other
Loss contingencies
Accrued loss contingency reserve | $						0				$ 0	0	0	0	0	0	0	0	0
Insurance receivables | $						33,000,000				$ 33,000,000	$ 33,000,000	33,000,000	$ 33,000,000	33,000,000	33,000,000	33,000,000	$ 33,000,000	$ 33,000,000
Increase (decrease) in insurance recovery receivable | $							$ 25,000,000
Environmental Matters - Regulatory Activities
Loss contingencies
Number of years after phase-out decision in May 2000 that the Company stopped manufacturing and using vast majority of perfluorooctanyl compounds										2 years
Amount of PFOA and PFOS found in drinking water, either individually or combined, that are allowed per the EPA's announced lifetime health advisory levels in parts per trillion																	70
Amount of PFOA in drinking water allowed per provisional health advisories in parts per trillion (superseded)																	400
Amount of PFOS in drinking water allowed per provisional health advisories in parts per trillion (superseded)																	200
Number of PFCs the EPA has required to have public water system suppliers monitor																	6
Number compounds EPA asked for public comment on draft toxicity assessments for PFAS compounds, including PFBS																	2
Number of public water supplies the EPA reported results																	4,920
Number of water supplies that reported above advisory level with PFOA																	13
Number of water supplies that reported above advisory level with PFOS																	46
Number of water supplies that reported above advisory level with both PFOA and PFOS under technical advisory issued by EPA in September 2016																	65
Environmental Matters - Regulatory Activities | Minimum
Loss contingencies
Number of water supply samples used to test for PFOA and PFOS under the EPA lifetime health advisory program																	1
Environmental Matters - Regulatory Activities | Alabama
Loss contingencies
Number of years covered by permit for sludge containing PFAS										20 years
Environmental Matters - Regulatory Activities | Minnesota Department of Health
Loss contingencies
Amount of PFOA in drinking water allowed per Minnesota Department of Health in parts per trillion																	35
Amount of PFOS in drinking water allowed per Minnesota Department of Health in parts per trillion																	27
Additional amounts of PFOS in drinking water allowed per Minnesota Department of Health in parts per trillion																	15
Amount of PFHxS in drinking water allowed per Minnesota Department of Health in parts per trillion																	47
Amount of PFBS in drinking water allowed per Minnesota Department of Health in parts per billion																	2
Environmental Matters - Litigation | State court in New York
Loss contingencies
Number of lawsuits filed | lawsuit											3
Environmental Matters - Litigation | State Court of Lawrence County, Alabama
Loss contingencies
Total number of named claimants																	200
Environmental Matters - Litigation | U.S. District Court for the Northern District of Alabama
Loss contingencies
Number of unnamed defendant | defendant																		3
Environmental Matters - Litigation | Alabama
Loss contingencies
Litigation settlement awarded | $	35,000,000
Number of local water works for whom the water authority supplies water																	5
Environmental Matters - Litigation | Morgan County, Alabama
Loss contingencies
Total number of named claimants																	3
Environmental Matters - Litigation | Decatur, Alabama
Loss contingencies
Number of closed municipal landfills																	3
Environmental Matters - Litigation | Minnesota
Loss contingencies
Litigation settlement awarded | $									$ 897,000,000
Settlement amount paid | $					$ 850,000,000
Amount the State's damages expert contended that the State incurred in damages | $																					$ 5,000,000,000
Environmental Matters - Litigation | Lake Elmo, Minnesota | Maximum
Loss contingencies
Settlement amount paid | $	$ 5,000,000
Environmental Matters - Litigation | New Jersey
Loss contingencies
Number of additional defendants										six
Number of lawsuits filed | lawsuit											2
Environmental Matters - Litigation | Salem County, New Jersey
Loss contingencies
Number of facilities related to the manufacture and disposal of PFAS | facility													2
Environmental Matters - Litigation | New Hampshire
Loss contingencies
Number of additional defendants										seven
Number of lawsuits filed | lawsuit											2
Environmental Matters - Litigation | Vermont
Loss contingencies
Number of additional defendants										ten
Number of lawsuits filed | lawsuit											2
Environmental Matters - Other Environmental Litigation
Loss contingencies
Accrued loss contingency reserve | $						$ 241,000,000				$ 241,000,000	$ 241,000,000	$ 241,000,000	$ 241,000,000	$ 241,000,000	$ 241,000,000	$ 241,000,000	$ 241,000,000	$ 241,000,000
Increase (decrease) accrued loss contingency reserve | $							235,000,000
Increase in liabilities, net | $							$ 186,000,000
Diluted earnings per share | $ / shares							$ 0.32
Number of landfills tested by the entity for environmental matters and litigation related to historical PFAS manufacturing operations																	4
Number of former disposal sites with PFC present in soil and groundwater in Washington County, Minnesota																	2
Environmental Matters - Other Environmental Litigation | New Jersey
Loss contingencies
Number of unnamed defendant | defendant																		120
Approximate number of miles of a river seeking to be cleaned																	8
The value the award the plaintiff seeks | $			$ 165,000,000
Number of chemicals of concern in the sediment																	8
Number of commercial drum conditioning facilities																	2
Environmental Matters - Aqueous Film Forming Foam Litigation
Loss contingencies
Number of lawsuits filed | lawsuit											8
Number of putative class action and other lawsuits																	130
Environmental Matters - Aqueous Film Forming Foam Litigation | Various state courts
Loss contingencies
Number of lawsuits pending | lawsuit						6				6	6	6	6	6	6	6	6	6
Environmental Matters - Aqueous Film Forming Foam Litigation | Federal court
Loss contingencies
Number of lawsuits pending | lawsuit						2				2	2	2	2	2	2	2	2	2
Environmental Matters - Aqueous Film Forming Foam Litigation | U.S. Judicial Panel on Multidistrict Litigation (MDL)
Loss contingencies
Number of lawsuits filed | lawsuit											119
Number of putative class action and other lawsuits | lawsuit											125
Environmental Matters - Other PFAS-related Environmental Litigation
Loss contingencies
Number of facilities related to the manufacture and disposal of PFAS | facility													5
Environmental Matters - Other PFAS-related Environmental Litigation | U.S. District Court of New York State
Loss contingencies
Number of lawsuits filed | lawsuit											47
Number of additional new claims filed | lawsuit											4
Number of putative class action and other lawsuits | lawsuit											1
Environmental Matters - Other PFAS-related Environmental Litigation | Alabama
Loss contingencies
Number of perfluorinated materials (FBSA and FBSEE) the company cannot release into "the waters of the United States."																	2
Number of putative class action and other lawsuits | lawsuit											2
Environmental Matters - Other PFAS-related Environmental Litigation | Delaware
Loss contingencies
Number of putative class action and other lawsuits | lawsuit											1
Environmental Matters - Other PFAS-related Environmental Litigation | Maine
Loss contingencies
Number of lawsuits filed | lawsuit											1
Environmental Matters - Other PFAS-related Environmental Litigation | Michigan
Loss contingencies
Number of lawsuits filed | lawsuit											254
Number of federal bellwether cases with trial-ready dates set | lawsuit											4
Number of putative class action and other lawsuits | lawsuit											1
Environmental Matters - Other PFAS-related Environmental Litigation | United States
Loss contingencies
Number of facilities related to the manufacture and disposal of PFAS | facility													3
Environmental Matters - Other PFAS-related Environmental Litigation | Europe
Loss contingencies
Number of facilities related to the manufacture and disposal of PFAS | facility													2