Employee Benefit Plans (Additional Information) (Detail) $ in Millions		1 Months Ended	2 Months Ended	9 Months Ended	12 Months Ended
	Oct. 01, 2016 USD ($)	Aug. 31, 2016 USD ($) insurance_company purchase_agreement retiree	Sep. 30, 2016 USD ($) plan	Sep. 30, 2015 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jul. 31, 2016
Pension and Other Postretirement Benefits Disclosure [Line Items]
Pension Settlement Charges						$ 60	$ 968	$ 0
Discount rate used to calculate benefit obligation						3.20%	3.70%
Defined benefit pension expense						$ 65	$ 85	$ 88
ABO for all defined benefit pension plans						3,382	$ 3,171
Net actuarial loss (gain) arising during the year						$ 3
Return on plan assets assumption						5.40%	6.10%	6.10%
Impact on net periodic pension expense						$ 11
Weighted-average healthcare cost trend rate assumed for next fiscal year						6.10%
Assumed ultimate health care cost trend rate						4.50%
Assumed year that ultimate health care cost trend rate will be reached						2024
Accrued pensions						$ 729	$ 740
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						$ 46	48	$ 44
Deductible dividends on PPG shares held by the ESOP						14	14	13
Expense (income) of the deferred compensation plan						19	7	5
Increase (Decrease) in fair value of investments						18	5	3
Obligations under the deferred compensation plan						121	124
Investments in marketable securities by the deferred compensation plan						83	82
Aggregate PBO for the pension plans with PBO in excess of plan assets						2,544	2,406
Aggregate fair value of plan assets for the pension plans with PBO in excess of plan assets						1,792	1,609
Aggregate ABO for the pension plans with ABO in excess of plan assets						2,434	2,302
Fair value of plan assets for the pension plans with ABO in excess of plan assets						1,749	1,575
Pensions
Pension and Other Postretirement Benefits Disclosure [Line Items]
Recognized expense for defined contribution pension plans						57	70	60
Accrued pensions						15	11
Pittsburgh Glass Works L L C [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Liabilities for pension and post-employment benefits earned for service up to the time of sale						369	342
Costs related to the pension and other postemployment benefit liabilities of the divested business						$ 2	20	17
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 Plans of US Entity, Defined Benefit
Pension and Other Postretirement Benefits Disclosure [Line Items]
Number of Definitive Purchase Agreements | purchase_agreement		2
Number of insurance companies to service future benefit obligations | insurance_company		2
Number of Company's retirees affected by annuity purchase | retiree		13,200
Increase (decrease) in benefit obligation due to settlements						$ (1,600)
Noncash Pension Settlement Charge - after tax						535
Pension Settlement Charges						857
Contributions to defined benefit pension plans						54	$ 134	224
Discount rate used to calculate benefit obligation							4.50%		3.60%
Increase (decrease) in benefit obligation due to U.S. Plan Merger and Remeasurement						306
Increase (decrease) in pension expense						$ 10
Return on plan assets assumption						7.50%
Foreign Pension Plan
Pension and Other Postretirement Benefits Disclosure [Line Items]
Noncash Pension Settlement Charge - after tax							$ 47
Pension Settlement Charges							64
Contributions to defined benefit pension plans			$ 1			$ 33	54	39
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)	$ (7)
Foreign Pension Plan | Canada
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to defined benefit pension plans							7
U.S. Qualified Pension Plan [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Noncash Pension Settlement Charge - after tax						22
Pension Settlement Charges						35
Benefits paid						87
U.S. Non-qualified Plan [Member]
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 Charges						22
Pensions
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to defined benefit pension plans						87	204
Pension assets transferred						0	(3)
Plan settlements						95	2,338
Net actuarial loss (gain) arising during the year						38
Estimated amounts of accumulated net actuarial loss that will be amortized from AOCI into net periodic benefit cost in 2012						68
Impact on net periodic pension expense						22
Benefits paid						167	233
Accrued pensions						729	740
Estimated future benefit payments in 2018						147
Estimated future benefit payments in 2019						147
Estimated future benefit payments in 2020						156
Estimated future benefit payments in 2021						161
Estimated future benefit payments in 2022						166
Estimated aggregate future benefits payments for the five years thereafter						901
Pensions | Pensions
Pension and Other Postretirement Benefits Disclosure [Line Items]
Estimated amounts of accumulated net actuarial loss that will be amortized from AOCI into net periodic benefit cost in 2012						$ (75)	(110)	(119)
Welfare Benefits - U.S. and Canada
Pension and Other Postretirement Benefits Disclosure [Line Items]
Percentage of defined benefit pension plan assets market value						85.00%
Postretirement Health Coverage
Pension and Other Postretirement Benefits Disclosure [Line Items]
Increase (decrease) in benefit obligation due to U.S. Plan Merger and Remeasurement		$ (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						$ (35)
Estimated amounts of accumulated net actuarial loss that will be amortized from AOCI into net periodic benefit cost in 2012						17
Estimated amounts of accumulated prior service cost that will be amortized from AOCI into net periodic benefit cost in 2012						(60)
Impact on net periodic pension expense						26
Benefits paid						48	53
Accrued pensions						0	0
Estimated future benefit payments in 2018						54
Estimated future benefit payments in 2019						54
Estimated future benefit payments in 2020						53
Estimated future benefit payments in 2021						53
Estimated future benefit payments in 2022						52
Estimated aggregate future benefits payments for the five years thereafter						231
Retained U.S. Pension Plans [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to defined benefit pension plans						$ 146	29
Flat Glass Business [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Settlement charge	$ 11
Flat Glass Business [Member] | Pensions
Pension and Other Postretirement Benefits Disclosure [Line Items]
Increase (decrease) in benefit obligation due to settlements	(100)
Pension assets transferred							55
European Fiber Glass [Member]
Pension and Other Postretirement Benefits Disclosure [Line Items]
Pension Settlement Charges							46
Settlement charge	46
European Fiber Glass [Member] | Pensions
Pension and Other Postretirement Benefits Disclosure [Line Items]
Increase (decrease) in benefit obligation due to settlements	$ (340)
Pension assets transferred							250
Glass Segment [Member] | United States Pension Plans of US Entity, Defined Benefit
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to defined benefit pension plans							12	$ 26
Glass Segment [Member] | Foreign Pension Plan
Pension and Other Postretirement Benefits Disclosure [Line Items]
Contributions to defined benefit pension plans							$ 4
United States, Canada, Netherlands and United Kingdom
Pension and Other Postretirement Benefits Disclosure [Line Items]
Percentage of defined benefit pension plan assets market value						93.00%
Scenario, Forecast
Pension and Other Postretirement Benefits Disclosure [Line Items]
Weighted-average healthcare cost trend rate assumed for next fiscal year					5.80%
Assumed ultimate health care cost trend rate					4.50%
Scenario, Forecast | United States Pension Plans of US Entity, Defined Benefit
Pension and Other Postretirement Benefits Disclosure [Line Items]
Return on plan assets assumption					7.40%
Scenario, Forecast | Foreign Pension Plan
Pension and Other Postretirement Benefits Disclosure [Line Items]
Return on plan assets assumption					5.30%
Scenario, Forecast | Flat Glass Business [Member] | Pensions | Minimum
Pension and Other Postretirement Benefits Disclosure [Line Items]
Pension assets transferred					$ 5
Scenario, Forecast | Flat Glass Business [Member] | Pensions | Maximum
Pension and Other Postretirement Benefits Disclosure [Line Items]
Pension assets transferred					$ 10