Condensed Consolidated Statement of Shareholders' Equity (Unaudited) Statement - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive (Loss)/Income	Total PPG	Non-controlling Interests
Beginning balance at Dec. 31, 2018	$ 4,732	$ 969	$ 788	$ 18,131	$ (12,958)	$ (2,300)	$ 4,630	$ 102
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	317			312			312	5
Other comprehensive income, net of tax	75					76	76	(1)
Cash dividends	(113)			(113)			(113)
Purchase of treasury stock	(175)				(175)		(175)
Issuance of treasury stock	184		121		63		184
Stock-based compensation activity	(10)		(10)				(10)
Ending balance at Mar. 31, 2019	5,010	969	899	18,330	(13,070)	(2,224)	4,904	106
Beginning balance at Dec. 31, 2018	4,732	969	788	18,131	(12,958)	(2,300)	4,630	102
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	969
Other comprehensive income, net of tax	(33)
Ending balance at Sep. 30, 2019	5,355	969	925	18,735	(13,054)	(2,328)	5,247	108
Beginning balance at Mar. 31, 2019	5,010	969	899	18,330	(13,070)	(2,224)	4,904	106
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	279			272			272	7
Other comprehensive income, net of tax	(4)					(6)	(6)	2
Cash dividends	(114)			(114)			(114)
Issuance of treasury stock	16		7		9		16
Stock-based compensation activity	7		7				7
Dividends paid on subsidiary common stock to noncontrolling interests	(5)							(5)
Reductions in noncontrolling interests	(2)							(2)
Ending balance at Jun. 30, 2019	5,187	969	913	18,488	(13,061)	(2,230)	5,079	108
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	373			367			367	6
Other comprehensive income, net of tax	(104)					(98)	(98)	(6)
Cash dividends	(120)			(120)			(120)
Issuance of treasury stock	12		5		7		12
Stock-based compensation activity	7		7				7
Ending balance at Sep. 30, 2019	5,355	969	925	18,735	(13,054)	(2,328)	5,247	108
Beginning balance at Dec. 31, 2019	5,403	969	950	18,906	(13,191)	(2,350)	5,284	119
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	248			243			243	5
Other comprehensive income, net of tax	(702)					(692)	(692)	(10)
Cash dividends	(120)			(120)			(120)
Issuance of treasury stock	16		12		4		16
Stock-based compensation activity	(8)		(8)				(8)
Ending balance at Mar. 31, 2020	4,837	969	954	19,029	(13,187)	(3,042)	4,723	114
Beginning balance at Dec. 31, 2019	5,403	969	950	18,906	(13,191)	(2,350)	5,284	119
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	796
Other comprehensive income, net of tax	(444)
Ending balance at Sep. 30, 2020	5,424	969	980	19,325	(13,176)	(2,788)	5,310	114
Beginning balance at Mar. 31, 2020	4,837	969	954	19,029	(13,187)	(3,042)	4,723	114
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	100			102			102	(2)
Other comprehensive income, net of tax	119					117	117	2
Cash dividends	(121)			(121)			(121)
Issuance of treasury stock	5		2		3		5
Stock-based compensation activity	6		6				6
Dividends paid on subsidiary common stock to noncontrolling interests	(3)							(3)
Reductions in noncontrolling interests	(5)							(5)
Ending balance at Jun. 30, 2020	4,938	969	962	19,010	(13,184)	(2,925)	4,832	106
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	448			442			442	6
Other comprehensive income, net of tax	139					137	137	2
Cash dividends	(127)			(127)			(127)
Issuance of treasury stock	18		10		8		18
Stock-based compensation activity	8		8				8
Dividends paid on subsidiary common stock to noncontrolling interests	(1)							(1)
Reductions in noncontrolling interests	1							1
Ending balance at Sep. 30, 2020	$ 5,424	$ 969	$ 980	$ 19,325	$ (13,176)	$ (2,788)	$ 5,310	$ 114