Employee Benefit Plans (Additional Information) (Detail) $ in Millions		1 Months Ended		12 Months Ended
	Oct. 01, 2016 USD ($)	Oct. 31, 2016 USD ($)	Aug. 31, 2016 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) plan	Dec. 31, 2016 USD ($)	Jul. 31, 2016	Dec. 31, 2015
Pension and Other Postretirement Benefits Disclosure [Line Items]
Pension settlement charge					$ 0	$ 60	$ 968
Contributions to defined benefit pension plans					$ 75
Discount rate used to calculate benefit obligation					3.70%	3.20%
ABO for all defined benefit pension plans					$ 2,944	$ 3,382
Net actuarial loss (gain) arising during the year					$ 8
Return on plan assets assumption					5.40%	5.40%	6.10%
Impact on net periodic pension expense					$ 12
Weighted-average healthcare cost trend rate assumed for next fiscal year					5.80%
Assumed ultimate health care cost trend rate					4.50%
Recognized expense for defined contribution pension plans					$ 63	$ 57	$ 70
Defined contribution plan contribution rates as percentage of employee earnings					6.00%
Company-matching contribution, percent of match					100.00%
Compensation expense related to the ESOP					$ 47	46	48
Deductible dividends on PPG shares held by the ESOP					13	14	14
Expense (income) of the deferred compensation plan					(1)	19	7
Increase (Decrease) in fair value of investments					(2)	18	5
Obligations under the deferred compensation plan					110	121
Investments in marketable securities by the deferred compensation plan					73	83
Aggregate PBO for the pension plans with PBO in excess of plan assets					1,935	2,544
Aggregate fair value of plan assets for the pension plans with PBO in excess of plan assets					1,269	1,792
Aggregate ABO for the pension plans with ABO in excess of plan assets					1,883	2,434
Fair value of plan assets for the pension plans with ABO in excess of plan assets					1,269	1,749
Pittsburgh Glass Works L L C
Pension and Other Postretirement Benefits Disclosure [Line Items]
Liabilities for pension and post-employment benefits earned for service up to the time of sale					313	369
Costs related to the pension and other postemployment benefit liabilities of the divested business					$ 1	2	20
Minimum
Pension and Other Postretirement Benefits Disclosure [Line Items]
Company-matching contribution					2.00%
Maximum
Pension and Other Postretirement Benefits Disclosure [Line Items]
Company-matching contribution					5.00%
United States
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to defined benefit pension plans					$ 99	87
Plan settlements					24	95
Net actuarial loss (gain) arising during the year					39
Benefits paid					125	167
Estimated future benefit payments in 2019					136
Estimated future benefit payments in 2020					139
Estimated future benefit payments in 2021					145
Estimated future benefit payments in 2022					147
Estimated future benefit payments in 2023					153
Estimated aggregate future benefits payments for the five years thereafter					826
Postretirement Health Coverage
Pension and Other Postretirement Benefits Disclosure [Line Items]
Plan amendments			$ (306)
Amortization reduction period			5 years 7 months 6 days
Other Postretirement Benefits
Pension and Other Postretirement Benefits Disclosure [Line Items]
Net actuarial loss (gain) arising during the year					(47)
Benefits paid					49	48
Estimated future benefit payments in 2019					53
Estimated future benefit payments in 2020					53
Estimated future benefit payments in 2021					53
Estimated future benefit payments in 2022					52
Estimated future benefit payments in 2023					51
Estimated aggregate future benefits payments for the five years thereafter					228
Flat Glass Business
Pension and Other Postretirement Benefits Disclosure [Line Items]
Pre-tax gain (loss) due to settlements							(11)
Flat Glass Business | United States
Pension and Other Postretirement Benefits Disclosure [Line Items]
Settlement charge							100
Pension assets transferred					$ (20)		(55)
European Fiber Glass
Pension and Other Postretirement Benefits Disclosure [Line Items]
Pension settlement charge		$ 46
Pre-tax gain (loss) due to settlements							(46)
European Fiber Glass | United States
Pension and Other Postretirement Benefits Disclosure [Line Items]
Settlement charge	$ 340
Pension assets transferred							(250)
United States, Canada, Netherlands and United Kingdom
Pension and Other Postretirement Benefits Disclosure [Line Items]
Percentage of defined benefit pension plan assets market value					92.00%
Scenario, Forecast
Pension and Other Postretirement Benefits Disclosure [Line Items]
Weighted-average healthcare cost trend rate assumed for next fiscal year				5.60%
Assumed ultimate health care cost trend rate				4.40%
Scenario, Forecast | United States
Pension and Other Postretirement Benefits Disclosure [Line Items]
Impact on net periodic pension expense				$ 19
Scenario, Forecast | Other Postretirement Benefits
Pension and Other Postretirement Benefits Disclosure [Line Items]
Impact on net periodic pension expense				$ 22
United States
Pension and Other Postretirement Benefits Disclosure [Line Items]
Number of definitive purchase agreements			2
Number of insurance companies to service future benefit obligations			2
Number of Company's retirees affected by annuity purchase			13,200
Noncash Pension Settlement Charge - after tax							535
Pension settlement charge							857
Contributions to defined benefit pension plans					$ 75	54	134
Discount rate used to calculate benefit obligation								3.60%	4.50%
Increase (decrease) in benefit obligation due to U.S. Plan Merger and Remeasurement							306
Increase (decrease) in pension expense							10
Settlement charge							1,600
Return on plan assets assumption					7.40%
United States | Glass Segment
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to defined benefit pension plans						12
United States | Scenario, Forecast
Pension and Other Postretirement Benefits Disclosure [Line Items]
Return on plan assets assumption				7.40%
Foreign Plan
Pension and Other Postretirement Benefits Disclosure [Line Items]
Noncash Pension Settlement Charge - after tax							47
Pension settlement charge							64
Contributions to defined benefit pension plans					$ 24	$ 33	54
Increase (decrease) in benefit obligation due to U.S. Plan Merger and Remeasurement							200
Estimated future mandatory contributions, low end of range					20
Estimated future mandatory contributions, high end of range					$ 30
Number of legacy plan windups | plan						2
After-tax wind-up charges						$ (34)
Pre-tax gain (loss) due to settlements						47
Foreign Plan | Canada
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to defined benefit pension plans							7
Voluntary contributions						1
Foreign Plan | Glass Segment
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to defined benefit pension plans						4
Foreign Plan | Scenario, Forecast
Pension and Other Postretirement Benefits Disclosure [Line Items]
Return on plan assets assumption				5.40%
Retained U.S. Pension Plans
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to defined benefit pension plans						$ 29	$ 146
Welfare Benefits - U.S. and Canada
Pension and Other Postretirement Benefits Disclosure [Line Items]
Percentage of defined benefit pension plan assets market value					86.00%
U.S. Qualified Pension Plan
Pension and Other Postretirement Benefits Disclosure [Line Items]
Noncash Pension Settlement Charge - after tax					$ 22
Pension settlement charge					35
Benefits paid					87
U.S. Non-qualified Plan
Pension and Other Postretirement Benefits Disclosure [Line Items]
Noncash Pension Settlement Charge - after tax					14
Cash payment to retirees - U.S. Non-qualified Pension Plan					40
Pension settlement charge					$ 22