Earnings Per Common Share (Calculations) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings per common share (attributable to PPG)
Net income (attributable to PPG)	$ 339	$ 311	$ 714	$ 879
Weighted average common shares outstanding	153.7	156.8	153.2	158.5
Earnings per common share (attributable to PPG)	$ 2.21	$ 1.98	$ 4.66	$ 5.55
Earnings per common share - assuming dilution (attributable to PPG)
Net income (attributable to PPG)	$ 339	$ 311	$ 714	$ 879
Weighted average common shares outstanding	153.7	156.8	153.2	158.5
Effect of dilutive securities:
Stock options	0.9	1.0	0.8	1.2
Other stock compensation plans	0.9	0.8	0.8	0.8
Potentially dilutive common shares	1.8	1.8	1.6	2.0
Adjusted weighted average common shares outstanding	155.5	158.6	154.8	160.5
Earnings per common share - assuming dilution (attributable to PPG)	$ 2.18	$ 1.96	$ 4.61	$ 5.48