Earnings Per Common Share (Calculations) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ 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
Earnings per common share (attributable to PPG)
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
Net income (attributable to PPG)	$ 314	$ 433	$ 337	$ 322	$ 83	$ 371	$ 386	$ 1,262	$ 1,406	$ 2,102	$ 3,231
Weighted average common shares outstanding									271.4	276.6	286.8
Effect of dilutive securities:
Stock options									1.0	1.4	1.6
Other stock compensation plans									1.2	1.6	1.8
Potentially dilutive common shares									2.2	3.0	3.4
Adjusted weighted average common shares outstanding									273.6	279.6	290.2
Earnings per common share (attributable to PPG):
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) (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
Earnings per common share - assuming dilution (attributable to PPG)
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
Net Income (attributable to PPG) (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