Earnings Per Common Share (Calculations) (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings per common share - assuming dilution (attributable to PPG)
Weighted average common shares outstanding	267.2	272.5	267.4	272.8
Effect of dilutive securities:
Stock options	0.9	1.1	0.9	1.1
Other stock compensation plans	1.0	1.1	0.9	1.2
Potentially dilutive common shares	1.9	2.2	1.8	2.3
Adjusted weighted average common shares outstanding	269.1	274.7	269.2	275.1
Outstanding stock options excluded from the computation of diluted earnings per share due to their antidilutive effect	0.6	0.0	0.6	0.0