Income Taxes (Net Deferred Income Tax Assets and Liabilities) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) jurisdiction	Dec. 31, 2018 USD ($)
Income Tax Examination [Line Items]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount	$ 158	$ 164
Undistributed Earnings of Foreign Subsidiaries	$ 3,600	3,000
Number of PPG Subsidiaries	290
Number of taxable jurisdictions | jurisdiction	75
Income Tax, Potential U.S. Tax Cost for Repatriation of Foreign Earnings	$ 32	19
Deferred income tax assets related to
Employee benefits	382	366
Contingent and accrued liabilities	148	149
Operating loss and other carry-forwards	225	251
Inventories	4	7
Other	87	82
Valuation allowance	(158)	(164)
Total	688	691
Deferred income tax liabilities related to
Property	277	262
Intangibles	594	545
Employee benefits	65	46
Other	2	15
Total	938	868
Deferred income tax liabilities – net	$ (250)	$ (177)
Minimum
Income Tax Examination [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2020
Tax Credit Carryforward, Expiration Date	Dec. 31, 2020
Maximum
Income Tax Examination [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2039
Tax Credit Carryforward, Expiration Date	Dec. 31, 2039