High estimate of anticipated cash outlays for environmental remediation costs.

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Low estimate of anticipated cash outlays for environmental remediation costs.

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Environmental Matters [Abstract]

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Historical Environmental Remediation Expense, Lower Limit

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Historical Environmental Remediation Expense, Upper Limit

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Total number of PPG sites to be remediated under the 1990 administrative consent order.

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Percentage Of Total Remaining Reserve

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Remediation Period

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Total costs accrued as of the balance sheet date for environmental loss contingencies.

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Carrying value of the obligation (known or estimated) arising from requirements to perform activities to remediate one or more sites, payable in twelve months or in the next operating cycle if longer.

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Estimate of reasonably possible loss exposure in excess of amount accrued for remediation, site restoration, postclosure, monitoring commitments, or other exit costs associated with the sale, disposal or abandonment of a particular property resulting from unanticipated contamination of the assets.

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Cash outflows made during the period for environmental remediation activities.

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Commitments and Contingent Liabilities (Additional Information - Environmental Matters) (Detail) $ in Millions	12 Months Ended				48 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) Location	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2024 USD ($)	Jun. 30, 2009 Location
Environmental Matters [Abstract]
Reserves for environmental contingencies		$ 304	$ 291
Reserves for environmental contingencies classified as current liabilities		62	105
Pretax charges for environmental remediation costs		77	78	$ 10
Cash outlays related to environmental remediation		77	64	44
Historical low end of range of annual environmental remediation expense over the past 15 years		5
Historical high end of range of annual environmental remediation expense over the past 15 years		$ 35
Remediation Period		10 years
Scenario, Forecast \| Maximum
Environmental Matters [Abstract]
Cash For Environmental Loss Contingencies High Estimate	$ 100				$ 50
Unreserved loss contingencies related to environmental matters, high estimate	200
Scenario, Forecast \| Minimum
Environmental Matters [Abstract]
Cash For Environmental Loss Contingencies Low Estimate	80				$ 20
Unreserved loss contingencies related to environmental matters, high estimate	$ 100
Excavation of Soil
Environmental Matters [Abstract]
Percentage of the total remaining reserve		20.00%
Soil Treatment Transportation And Disposal Of Excavated Soil
Environmental Matters [Abstract]
Percentage of the total remaining reserve		14.00%
Construction Services
Environmental Matters [Abstract]
Percentage of the total remaining reserve		28.00%
Jersey City Manufacturing Plant
Environmental Matters [Abstract]
Reserves for environmental contingencies		$ 134	151
Pretax charges for environmental remediation costs		43	62	4
Glass and Chemical Sites
Environmental Matters [Abstract]
Reserves for environmental contingencies		96	90
Other Environmental Contingencies
Environmental Matters [Abstract]
Reserves for environmental contingencies		74	50
Pretax charges for environmental remediation costs		$ 34	$ 16	$ 6
Judicial Consent Order
Environmental Matters [Abstract]
Number Of Sites Involved For Environmental Remediation \| Location		19				20