Income Taxes (Reconciliation of Statutory U.S. Corporate Federal Income Tax Rate to Effective Income Tax Rate) (Detail)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
U.S. federal income tax rate	35.00%	35.00%	35.00%
Changes in rate due to:
U.S. State and local taxes	0.64%	0.67%	1.14%
U.S. tax benefit on foreign dividends	(1.49%)	(0.96%)	0.17%
Taxes on non-U.S. earnings	(9.70%)	(10.88%)	(8.13%)
PPG dividends paid to the ESOP	(0.18%)	(0.41%)	(0.57%)
U.S. tax incentives	(1.92%)	(1.79%)	(1.75%)
Significant audit settlements		(1.42%)
Other	(1.45%)	1.07%	(1.18%)
One-time charge, tax law change			6.64%
Effective income tax rate	20.90%	21.28%	31.32%

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate is the regular tax rate if there are alternative tax systems.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit that is attributable to changes in the income tax laws or rates.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to the deduction for dividends paid or received under enacted tax laws.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to the deduction for dividends paid to employee stock ownership plans received under enacted tax laws.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to the deduction for qualified production activities received under enacted tax laws.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to all other items not otherwise listed in the existing taxonomy.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to the repatriation of foreign earnings under enacted tax laws.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the state and local income tax expense or benefit, net of the federal tax benefit (expense) thereon, recorded during the period.

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The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate attributable to domestic income tax settlements during the period.

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