Earnings Per Common Share (Calculations) (Details) shares in Millions	3 Months Ended
Mar. 31, 2016 shares	Mar. 31, 2015 shares
Earnings Per Share [Abstract]
Stock Split, Conversion Ratio	2
Earnings per common share - assuming dilution (attributable to PPG)
Weighted average common shares outstanding	267.6	273.2
Effect of dilutive securities:
Stock options	0.9	1.2
Other stock compensation plans	0.9	1.2
Potentially dilutive common shares	1.8	2.4
Adjusted weighted average common shares outstanding	269.4	275.6
Outstanding stock options excluded from the computation of diluted earnings per share due to their antidilutive effect	0.6	0.0

Incremental Common Shares Attributable To Other Stock Compensation Plans

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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-Publisher FASB
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Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

+ References

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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