Earnings Per Common Share (Calculations) (Details) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings per common share - assuming dilution (attributable to PPG)
Weighted average common shares outstanding	138.2	143.2	138.7	144.4
Effect of dilutive securities:
Stock options	0.7	0.9	0.7	0.8
Other stock compensation plans	0.8	0.8	0.7	0.8
Potentially dilutive common shares	1.5	1.7	1.4	1.6
Adjusted weighted average common shares outstanding	139.7	144.9	140.1	146.0