Earnings Per Common Share (Calculations) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015 shares	Jun. 30, 2014 shares	Jun. 30, 2015 shares	Jun. 30, 2014 shares
Earnings Per Share [Abstract]
Stock Split, Conversion Ratio	2
Earnings per common share - assuming dilution (attributable to PPG)
Weighted average common shares outstanding	272,500,000	277,200,000	272,800,000	277,800,000
Effect of dilutive securities:
Stock options	1,100,000	1,400,000	1,100,000	1,400,000
Other stock compensation plans	1,100,000	1,600,000	1,200,000	1,600,000
Potentially dilutive common shares	2,200,000	3,000,000	2,300,000	3,000,000
Adjusted weighted average common shares outstanding	274,700,000	280,200,000	275,100,000	280,800,000
Outstanding stock options excluded from the computation of diluted earnings per share due to their antidilutive effect	0	0	0	0