Commitments and Contingent Liabilities (Litigation Settlements Disclosure) (Detail) $ in Millions	1 Months Ended	12 Months Ended
	May 14, 2002 shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2008 USD ($)
Forward Contract Indexed To Issuers Equity Fair Value					$ 258
Prepayment of future pre-tax cash payments to the trust					$ 764
Cash Paid for Asbestos Settlement Funding		$ 0	$ 813	$ 0
Change in fair value:
Investment in equity affiliates		(134)	(46)	(94)
Other Reserves		$ 180
Asbestos Issue
Loss Contingency, Pending Claims, Number		625
Change in fair value:
Other Reserves		$ 162
Asbestos Settlement Liability, Current
Beginning balance/Prior year activity			796
Change in fair value:
PPG stock			(34)
Equity forward instrument			0
Accretion of asbestos liability			0
Company Stock To Be Contributed To Asbestos Trust			(308)
Reclassification			1
Ending balance/Activity during year				796
Asbestos Settlement Liability, Long-term
Beginning balance/Prior year activity			252
Change in fair value:
PPG stock			0
Accretion of asbestos liability			6
Reclassification			0
Ending balance/Activity during year				252
Equity Forward (Asset) Liability
Forward Contract Indexed To Issuers Equity Fair Value				(223)
Change in fair value:
PPG stock			0
Equity forward instrument			35
Accretion of asbestos liability			0
Settlement of equity forward instrument with counterparty			(49)
Company Stock To Be Contributed To Asbestos Trust			(308)
Reclassification			1
Pre-tax Charge
Beginning balance/Prior year activity		$ 5	12
Change in fair value:
PPG stock			(34)
Equity forward instrument			35
Accretion of asbestos liability			6
Reclassification			0
Ending balance/Activity during year			5	$ 12
Pittsburgh Corning Corporation
Change in fair value:
Investment in equity affiliates			(15)
Other Current Liabilities
Change in fair value:
Cash Contributed to the PC Trust			(506)
Other Noncurrent Liabilities
Change in fair value:
Cash Contributed to the PC Trust			$ (258)
Pittsburgh Corning Corporation | Asbestos Issue
Agreement to convey assets to the PC asbestos settlement trust (the Trust), shares of PPG common stock | shares	2,777,778
Change in fair value:
Future cash payments to the Trust by PPG's participating historical insurance carriers						$ 1,700
Future PPG cash payments to the Trust, prepayment discount rate	5.50%