Financial Instruments, Hedging Activities and Fair Value Measurements (Additional Information) (Details) € in Millions	3 Months Ended	9 Months Ended		12 Months Ended
	Mar. 31, 2015 EUR (€)	Sep. 30, 2015 USD ($) shares	Sep. 30, 2015 EUR (€)	Dec. 31, 2014 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2015 EUR (€)
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Shares of PPG stock that are to be contributed to the asbestos settlement trust | shares		1,388,889
Total principal amount payable for PPG shares contributed to the asbestos settlement		$ 62,000,000
Fair value of the equity forward arrangement to mitigate the impact of changes in fair value of stock contributed to the asbestos settlement trust		192,000,000		$ 268,000,000
Fair value of foreign currency forward contracts designated as cash flow hedges, net asset		45,000,000		46,000,000
Notional amount		560,000,000
Fair value of nine U.S. dollar to euro cross currency swap contracts		29,000,000		(32,000,000)
Debt Instrument, Face Amount					$ 1,260,000,000	€ 1,200
Euro-denominated borrowings hedging a portion of PPG's net investment in European operations | €	€ 300		€ 300
Fair Value of Debt Instrument Designated as a Hedge of Net Investment in Foreign Operations		2,100,000,000		1,200,000,000
Accumulated pretax unrealized translation gains (losses) in AOCI, related to both the euro-denominated borrowings and the cross currency swaps that have been designated as hedges of net investments		(280,000,000)		(169,000,000)
Capital Lease Obligations		29,000,000		33,000,000
Short-term Debt		42,000,000		115,000,000
Long-term Debt		4,481,000,000		3,877,000,000
Long-lived assets fair value amount		4,588,000,000		4,164,000,000
Significant Fair Value Adjustments on Other Assets (Liabilities) Carried at Fair Value				0
Settlement Date 15 March 2018
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional amount		560,000,000
Net Investment Hedging [Member]
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Euro-denominated borrowings hedging a portion of PPG's net investment in European operations		$ 1,900,000,000		$ 1,000,000,000