Income Taxes (Net Deferred Income Tax Assets and Liabilities) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) jurisdiction	Dec. 31, 2016 USD ($)
Income Tax Examination [Line Items]
Valuation Allowances and Reserves, Balance	$ 170	$ 119
Number of PPG Subsidiaries	250
Number of taxable jurisdictions | jurisdiction	75
Undistributed Earnings of Foreign Subsidiaries	$ 3,400	5,000
Income Tax, Potential U.S. Tax Cost for Repatriation of Foreign Earnings	30	350
Deferred income tax assets related to
Employee benefits	399	604
Contingent and accrued liabilities	164	263
Operating loss and other carry-forwards	221	197
Inventories	6	14
Property	51	49
Other	135	100
Valuation allowance	(173)	(119)
Total	803	1,108
Deferred income tax liabilities related to
Property	314	349
Intangibles	578	647
Employee benefits	11	4
Derivatives	1	6
Undistributed foreign earnings	24	189
Other	20	146
Total	948	1,341
Deferred income tax (liabilities) assets – net	$ (145)	(233)
Minimum
Income Tax Examination [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2018
Tax Credit Carryforward, Expiration Date	Dec. 31, 2018
Maximum
Income Tax Examination [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2030
Tax Credit Carryforward, Expiration Date	Dec. 31, 2027
Undistributed earnings, permanently reinvested [Member]
Income Tax Examination [Line Items]
Undistributed Earnings of Foreign Subsidiaries		$ 3,500