Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income attributable to the controlling and noncontrolling interests	$ 1,074	$ 1,269	$ 1,358
Defined benefit pension and other postretirement benefit adjustments	(213)	(156)	9
Unrealized foreign currency translation adjustments	(36)	106	(155)
Derivative financial instruments		(1)	(1)
Other comprehensive loss, net of tax	(249)	(51)	(147)
Total comprehensive income	825	1,218	1,211
Less: amounts attributable to noncontrolling interests:
Net income	(15)	(26)	(17)
Unrealized foreign currency translation adjustments		1	11
Comprehensive income attributable to PPG	$ 810	$ 1,193	$ 1,205