Working Capital Detail (Additional Information) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Disclosure Components Of Working Capital Detail [Abstract]
Allowance for Doubtful Accounts	$ 87	$ 74
Percentage of inventories valued using the LIFO method	40.00%us-gaap_PercentageOfLIFOInventory	38.00%us-gaap_PercentageOfLIFOInventory
FIFO adjustment	182ppg_DifferenceInInventoryCarryingValue	195ppg_DifferenceInInventoryCarryingValue
Effect of LIFO on earnings, income	$ 0.3ppg_LIFOIncomeExpense	$ 0.7ppg_LIFOIncomeExpense

For an unclassified balance sheet, a valuation allowance for receivables due a company that are expected to be uncollectible.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 4

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5074-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.4)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_AllowanceForDoubtfulAccountsReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant