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Divestitures - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Divestitures - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2021	Sep. 30, 2020	Mar. 31, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Businesses, net of cash disposed	$ 0		$ 853
Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposal of discontinued operations	0		585
Income before income tax, discontinued operations	$ 0		576
Masco Cabinetry \| Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Businesses, net of cash disposed		$ 989
Gain (loss) on disposition of business			$ 585
Cash and Cash Equivalents \| Masco Cabinetry \| Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Businesses, net of cash disposed		853
ACProducts Preferred Stock \| Masco Cabinetry \| Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses		$ 136