Consolidated Statement of Shareholders' Equity - 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, 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 income, 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)							(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	1,615			1,594			1,594	21
Other comprehensive income, 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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to the controlling and noncontrolling interests	1,358			1,341			1,341	17
Other comprehensive income, net of tax	(147)					(136)	(136)	(11)
Cash dividends	(453)			(453)			(453)
Purchase of treasury stock	(1,721)				(1,721)		(1,721)
Issuance of treasury stock	42		28		14		42
Stock-based compensation activity	4		4				4
Dividends paid on subsidiary common stock to noncontrolling interests	(7)							(7)
Reductions in noncontrolling interests	(12)		0				0	(12)
Ending 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]
Reclassifications of Temporary to Permanent Equity	$ 0	$ 0	$ 0	$ 107	$ 0	$ (107)	$ 0	$ 0