Quarterly Financial Information Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 3,645	$ 3,817	$ 4,131	$ 3,781	$ 3,682	$ 3,776	$ 3,804	$ 3,486	$ 15,374	$ 14,748	$ 14,270
Cost of sales, exclusive of depreciation and amortization	2,188	2,253	2,379	2,181	2,120	2,104	2,083	1,902	9,001	8,209	7,665
Continuing operations	256	368	371	328	148	393	497	331	1,323	1,369	543
Discontinued operations	2	10	0	6	3	217	(1)	6	18	225	330
Net income (loss) attributable to parent	$ 258	$ 378	$ 371	$ 334	$ 151	$ 610	$ 496	$ 337	$ 1,341	$ 1,594	$ 873
Continuing operations (in dollars per share)	$ 1.07	$ 1.52	$ 1.51	$ 1.32	$ 0.59	$ 1.53	$ 1.93	$ 1.29	$ 5.43	$ 5.34	$ 2.05
Discontinued operations (in dollars per share)	0.01	0.04	0.00	0.02	0.01	0.85	0.00	0.02	0.07	0.88	1.24
Net Income (attributable to PPG) (in dollars per share)	1.08	1.56	1.51	1.34	0.60	2.38	1.93	1.31	5.50	6.22	3.29
Continuing operations (in dollars per share)	1.07	1.51	1.51	1.31	0.58	1.52	1.92	1.28	5.40	5.31	2.04
Discontinued operations (in dollars per share)	0.01	0.04	0.00	0.02	0.01	0.84	0.00	0.02	0.07	0.87	1.23
Earnings per common share - assuming dilution (in dollars per share)	$ 1.08	$ 1.55	$ 1.51	$ 1.33	$ 0.59	$ 2.36	$ 1.92	$ 1.30	$ 5.47	$ 6.18	$ 3.27