Quarterly Financial Information - Quarterly Condensed Consolidated Statement of Comprehensive Income (unaudited) (As Restated) (Details) - USD ($) $ in Millions	3 Months Ended								6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Other Comprehensive Income [Abstract]
Net income attributable to the controlling and noncontrolling interests	$ 156	$ 616	$ 501	$ 342	$ 344	$ (179)	$ 376	$ 354	$ 843	$ 1,459	$ 1,615	$ 895	$ 1,427
Unrealized foreign currency translation gains/(losses)		(29)	(55)	21					(34)	(63)	248	(476)	(717)
Defined benefit pension and other postretirement benefit adjustments		26	82	279					361	387	78	808	113
Unrealized (losses)/gains – derivative financial instruments		1	(4)	(13)					(17)	(16)	(10)	4	5
Other comprehensive loss, net of tax		(2)	23	287					310	308	316	336	(599)
Total comprehensive income		614	524	629					1,153	1,767	1,931	1,231	828
Less: net income attributable to noncontrolling interests	$ 5	6	5	5	$ 4	$ 5	$ 6	$ 7	10	16	21	22	21
Unrealized foreign currency translation (losses)/gains		(2)	(6)	(7)					(13)	(15)	(17)	10	13
Comprehensive income attributable to PPG		$ 606	$ 513	$ 617					$ 1,130	$ 1,736	$ 1,893	$ 1,219	$ 820