Consolidated Statement of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss	Total PPG	Non-controlling Interests
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	1,358			1,341			1,341	17
Other comprehensive loss, 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)							(12)
Reclassifications of Temporary to Permanent Equity				(107)		107
Stockholders' Equity, Other	4			4			4
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]
Net income attributable to the controlling and noncontrolling interests	1,269			1,243			1,243	26
Other comprehensive loss, net of tax	(51)					(50)	(50)	(1)
Cash dividends	(468)			(468)			(468)
Purchase of treasury stock	(325)				(325)		(325)
Issuance of treasury stock	243		151		92		243
Stock-based compensation activity	10		10				10
Dividends paid on subsidiary common stock to noncontrolling interests	(8)							(8)
Stockholders' Equity, Other	1		1				1
Ending 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	1,074			1,059			1,059	15
Other comprehensive loss, net of tax	(249)					(249)	(249)
Cash dividends	(496)			(496)			(496)
Issuance of treasury stock	78		45		33		78
Stock-based compensation activity	13		13				13
Dividends paid on subsidiary common stock to noncontrolling interests	(4)							(4)
Reductions in noncontrolling interests	(4)							(4)
Ending balance at Dec. 31, 2020	$ 5,815	$ 969	$ 1,008	$ 19,469	$ (13,158)	$ (2,599)	$ 5,689	$ 126