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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustment to retained earnings - Adoption of ASU 2016-16	$ (4)						$ (4)
Beginning balance at Dec. 31, 2017	5,672	$ 969	$ 756	$ 17,140	$ (11,251)	$ (2,057)	5,557	$ 115
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	340			334			334	6
Other comprehensive loss, net of tax	161					159	159	2
Cash dividends	(112)			(112)			(112)
Purchase of treasury stock	(600)				(600)		(600)
Issuance of treasury stock	31		24		7		31
Stock-based compensation activity	(19)		(19)				(19)
Reductions in noncontrolling interests	(2)							(2)
Reclassification from other comprehensive income to retained earnings - Adoption of ASU 2018-02	0			107		(107)
Ending balance at Mar. 31, 2018	5,467	969	761	17,465	(11,844)	(2,005)	5,346	121
Beginning balance at Dec. 31, 2017	5,672	969	756	17,140	(11,251)	(2,057)	5,557	115
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	1,097
Other comprehensive loss, net of tax	(44)
Reclassification from other comprehensive income to retained earnings - Adoption of ASU 2018-02						(107)
Ending balance at Sep. 30, 2018	5,078	969	772	17,988	(12,552)	(2,197)	4,980	98
Beginning balance at Mar. 31, 2018	5,467	969	761	17,465	(11,844)	(2,005)	5,346	121
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	375			371			371	4
Other comprehensive loss, net of tax	(280)					(270)	(270)	(10)
Cash dividends	(110)			(110)			(110)
Purchase of treasury stock	(463)				(463)		(463)
Issuance of treasury stock	3		1		2		3
Stock-based compensation activity	7		7				7
Dividends paid on subsidiary common stock to noncontrolling interests	(2)							(2)
Reductions in noncontrolling interests	(14)							(14)
Ending balance at Jun. 30, 2018	4,983	969	769	17,726	(12,305)	(2,275)	4,884	99
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	382			378			378	4
Other comprehensive loss, net of tax	75					78	78	(3)
Cash dividends	(116)			(116)			(116)
Purchase of treasury stock	(250)				(250)		(250)
Issuance of treasury stock	4		1		3		4
Stock-based compensation activity	2		2				2
Dividends paid on subsidiary common stock to noncontrolling interests	(2)							(2)
Ending balance at Sep. 30, 2018	5,078	969	772	17,988	(12,552)	(2,197)	4,980	98
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 loss, 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 loss, 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 loss, 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 loss, 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