Quarterly Financial Information (Unaudited) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly financial information [Line Items]
Net sales	$ 3,696	$ 3,872	$ 4,100	$ 3,662	$ 3,707	$ 3,935	$ 4,082	$ 3,636	$ 15,330	$ 15,360	$ 14,265
Cost of Sales	2,093	2,150	2,283	2,065	2,165	2,229	2,306	2,091	8,591	8,791	8,314
Continuing operations	314	433	337	321	86	377	393	277	1,405	1,133	950
Discontinued operations	$ 0	$ 0	$ 0	$ 1	$ (3)	$ (6)	$ (7)	$ 985	$ 1	$ 969	$ 2,281
Continuing operations (in dollars per share)	$ 1.17	$ 1.60	$ 1.24	$ 1.17	$ 0.32	$ 1.36	$ 1.41	$ 1.00	$ 5.18	$ 4.10	$ 3.31
Discontinued operations (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.01	$ (0.01)	$ (0.02)	$ (0.02)	$ 3.54	$ 0.00	$ 3.50	$ 7.96
Net income (attributable to PPG)	$ 314	$ 433	$ 337	$ 322	$ 83	$ 371	$ 386	$ 1,262	$ 1,406	$ 2,102	$ 3,231
Earnings per common share (in dollars per share)	$ 1.17	$ 1.60	$ 1.24	$ 1.18	$ 0.31	$ 1.34	$ 1.39	$ 4.54	$ 5.18	$ 7.60	$ 11.27
Continuing operations (in dollars per share)	1.16	1.59	1.23	1.16	0.31	1.35	1.40	0.98	5.14	4.05	3.27
Discontinued operations (in dollars per share)	0.00	0.00	0.00	0.01	(0.01)	(0.02)	(0.02)	3.50	0.00	3.47	7.86
Earnings per common share - assuming dilution (in dollars per share)	$ 1.16	$ 1.59	$ 1.23	$ 1.17	$ 0.30	$ 1.33	$ 1.38	$ 4.48	$ 5.14	$ 7.52	$ 11.13