Quarterly Financial Information Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 3,672	$ 3,826	$ 4,024	$ 3,624	$ 3,645	$ 3,817	$ 4,131	$ 3,781	$ 15,146	$ 15,374	$ 14,748
Cost of sales, exclusive of depreciation and amortization	2,111	2,181	2,288	2,073	2,188	2,253	2,379	2,181	8,653	9,001	8,209
Income from continuing operations, net of tax	295	366	270	312	256	368	371	328	1,243	1,323	1,369
Income from discontinued operations, net of tax	(3)	1	2	0	2	10	0	6	0	18	225
Net income (loss) attributable to parent	$ 292	$ 367	$ 272	$ 312	$ 258	$ 378	$ 371	$ 334	$ 1,243	$ 1,341	$ 1,594
Continuing operations (in dollars per share)	$ 1.24	$ 1.55	$ 1.14	$ 1.32	$ 1.07	$ 1.52	$ 1.51	$ 1.32	$ 5.25	$ 5.43	$ 5.34
Discontinued operations (in dollars per share)	(0.01)	0	0.01	0	0.01	0.04	0	0.02	0	0.07	0.88
Net Income (attributable to PPG) (in dollars per share)	1.23	1.55	1.15	1.32	1.08	1.56	1.51	1.34	5.25	5.50	6.22
Continuing operations (in dollars per share)	1.23	1.54	1.13	1.31	1.07	1.51	1.51	1.31	5.22	5.40	5.31
Discontinued operations (in dollars per share)	(0.01)	0	0.01	0	0.01	0.04	0	0.02	0	0.07	0.87
Earnings per common share - assuming dilution (in dollars per share)	$ 1.22	$ 1.54	$ 1.14	$ 1.31	$ 1.08	$ 1.55	$ 1.51	$ 1.33	$ 5.22	$ 5.47	$ 6.18