Quarterly Financial Information (Unaudited) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 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	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly financial information [Line Items]
Net sales	$ 3,682	$ 3,776	$ 3,806	$ 3,486	$ 3,417	$ 3,660	$ 3,782	$ 3,411	$ 14,750	$ 14,270	$ 14,241
Cost of Sales	2,117	2,100	2,082	1,905	1,910	1,978	1,988	1,817	8,204	7,693	7,786
Continuing operations	147	392	504	328	91	(211)	339	328	1,371	547	1,311
Discontinued operations	0	217	(3)	6	253	27	31	19	220	330	95
Net income (attributable to PPG)	$ 147	$ 609	$ 501	$ 334	$ 344	$ (184)	$ 370	$ 347	$ 1,591	$ 877	$ 1,406
Continuing operations (in dollars per share)	$ 0.58	$ 1.53	$ 1.96	$ 1.28	$ 0.35	$ (0.79)	$ 1.26	$ 1.23	$ 5.35	$ 2.06	$ 4.83
Discontinued operations (in dollars per share)	0.00	0.85	(0.01)	0.02	0.96	0.10	0.12	0.07	0.86	1.24	0.35
Earnings per common share (in dollars per share)	0.58	2.38	1.95	1.30	1.31	(0.69)	1.38	1.30	6.21	3.30	5.18
Continuing operations (in dollars per share)	0.58	1.52	1.95	1.27	0.34	(0.79)	1.25	1.22	5.32	2.05	4.79
Discontinued operations (in dollars per share)	0.00	0.84	(0.01)	0.02	0.96	0.10	0.12	0.07	0.85	1.23	0.35
Earnings per common share - assuming dilution (in dollars per share)	$ 0.58	$ 2.36	$ 1.94	$ 1.29	$ 1.30	$ (0.69)	$ 1.37	$ 1.29	$ 6.17	$ 3.28	$ 5.14