Consolidated Statement of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income/(Loss)	Total PPG	Non-controlling Interests
Beginning balance at Dec. 31, 2014	$ 5,265	$ 484	$ 1,028	$ 14,498	$ (8,714)	$ (2,116)	$ 5,180	$ 85
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	1,427			1,406			1,406	21
Other comprehensive loss, net of tax	(599)					(586)	(586)	(13)
Cash dividends	(383)			(383)			(383)
2:1 Stock split	0	485	(485)	0	0	0	0	0
Purchase of treasury stock	(751)				(751)		(751)
Issuance of treasury stock	71		46		25		71
Stock-based compensation activity	46		46				46
Dividends paid on subsidiary common stock to noncontrolling interests	(4)							(4)
Reductions in noncontrolling interests	(3)							(3)
Ending balance at Dec. 31, 2015	5,069	969	635	15,521	(9,440)	(2,702)	4,983	86
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	895			873			873	22
Other comprehensive loss, net of tax	336					346	346	(10)
Cash dividends	(414)			(414)			(414)
Purchase of treasury stock	(1,050)				(1,050)		(1,050)
Issuance of treasury stock	55		37		18		55
Stock-based compensation activity	35		35				35
Dividends paid on subsidiary common stock to noncontrolling interests	(4)							(4)
Reductions in noncontrolling interests	(7)		0				0	(7)
Ending balance at Dec. 31, 2016	4,915	969	707	15,980	(10,472)	(2,356)	4,828	87
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	342						337	5
Other comprehensive loss, net of tax	287						280	7
Cash dividends	(103)						(103)	0
Issuance of treasury stock	34						34	0
Stock-based compensation activity	(21)						(21)	0
Ending balance at Mar. 31, 2017	5,286						5,192	94
Beginning balance at Dec. 31, 2016	4,915	969	707	15,980	(10,472)	(2,356)	4,828	87
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	843						833	10
Other comprehensive loss, net of tax	310						297	13
Cash dividends	(205)						(205)	0
Issuance of treasury stock	49						49	0
Stock-based compensation activity	(16)						(16)	0
Ending balance at Jun. 30, 2017	5,728						5,623	105
Beginning balance at Dec. 31, 2016	4,915	969	707	15,980	(10,472)	(2,356)	4,828	87
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	1,459						1,443	16
Other comprehensive loss, net of tax	308						293	15
Cash dividends	(321)						(321)	0
Issuance of treasury stock	75						75	0
Stock-based compensation activity	(8)						(8)	0
Dividends paid on subsidiary common stock to noncontrolling interests	(5)							(5)
Ending balance at Sep. 30, 2017	6,005						5,897	108
Beginning balance at Dec. 31, 2016	4,915	969	707	15,980	(10,472)	(2,356)	4,828	87
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	1,615			1,594			1,594	21
Other comprehensive loss, net of tax	316					299	299	17
Cash dividends	(434)			(434)			(434)
Purchase of treasury stock	(813)				(813)		(813)
Issuance of treasury stock	83		49		34		83
Dividends paid on subsidiary common stock to noncontrolling interests	(5)							(5)
Reductions in noncontrolling interests	(5)		0				0	(5)
Ending balance at Dec. 31, 2017	5,672	969	756	17,140	(11,251)	(2,057)	5,557	115
Beginning balance at Mar. 31, 2017	5,286						5,192	94
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	501
Other comprehensive loss, net of tax	23
Ending balance at Jun. 30, 2017	5,728						5,623	105
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	616
Other comprehensive loss, net of tax	(2)
Ending balance at Sep. 30, 2017	6,005						5,897	108
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	156
Ending balance at Dec. 31, 2017	$ 5,672	$ 969	$ 756	$ 17,140	$ (11,251)	$ (2,057)	$ 5,557	$ 115