Financial Instruments, Hedging Activities and Fair Value Measurements (Additional Information) (Detail) € in Billions	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2018 EUR (€)	Dec. 31, 2016 USD ($)	Feb. 28, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2016 USD ($) shares	Dec. 31, 2015 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Forward Contract Indexed to Issuer's Equity, Indexed Shares | shares						2,777,778
Forward Contract Indexed To Issuers Equity Shares Principal Amount			$ 60,000,000
Interest Paid by PPG to Counter Party			10,000,000
Forward Contract Indexed To Issuers Equity Fair Value						$ 258,000,000
Foreign Currency Contracts, Liability, Fair Value Disclosure					$ 20,000,000
Notional Amount of Derivative Instruments Designated as Net Investment Hedges	$ 560,000,000
Derivative Instruments in Hedges, Net Investment in Foreign Operations, Assets, Fair Value, Net	35,000,000				2,000,000
Fair Value of Debt Instrument Designated as a Hedge of Net Investment in Foreign Operations	2,600,000,000				2,700,000,000
Derivative, Cash Received on Hedge	3,000,000
Foreign Currency Contracts, Liability, Fair Value Disclosure	36,000,000
Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss)	4,732,000,000		$ 4,915,000,000		5,672,000,000		$ 5,069,000,000
Cash Flow Hedging
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Foreign Currency Contracts, Liability, Fair Value Disclosure					3,000,000
Notional Amount of Derivative Instruments Designated as Net Investment Hedges	50,000,000				284,000,000
Foreign Currency Contracts, Liability, Fair Value Disclosure	1,000,000
Net Investment Hedging
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount of Nonderivative Instruments | €		€ 2.3
Interest Rate Swap
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount of Derivative Instruments Designated as Net Investment Hedges				$ 525,000,000
Interest Rate Derivatives, at Fair Value, Net				$ 8,000,000
Designated as Hedging Instrument | Foreign Currency Contracts | Cash Flow Hedging | Settlement Date 15 March 2018
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount of Derivative Instruments Designated as Net Investment Hedges					560,000,000
Designated as Hedging Instrument | Cross Currency Swaps
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount of Derivative Instruments Designated as Net Investment Hedges	575,000,000
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Unrealized Gain (Loss) on Interest Rate Cash Flow Hedges, Pretax, Accumulated Other Comprehensive Income (Loss)	$ 161,000,000				$ 16,000,000