Purification Solutions Goodwill and Long-Lived Assets Impairment Charges - Impairment Charges and Associated Tax Benefit (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2018		Jun. 30, 2018	Jun. 30, 2017
Goodwill And Intangible Assets [Line Items]
Purification Solutions goodwill impairment charge	$ 92	[1]	$ 92
Purification Solutions long-lived assets impairment charge			162
Deferred tax provision (benefit)			131	$ (25)
Purification Solutions [Member]
Goodwill And Intangible Assets [Line Items]
Purification Solutions goodwill impairment charge	92	[1]	92
Purification Solutions long-lived assets impairment charge	162		$ 162
Deferred tax provision (benefit)	(30)
Impairment charges, after tax	$ 224

[1] Refer to Note E for details on the Purification Solutions goodwill impairment test and the resulting impairment charge recorded in the second fiscal quarter of 2018. Based on the Company’s most recent annual goodwill impairment test performed as of May 31, 2018, the fair values of the Reinforcement Materials, Fumed Metal Oxides, and Specialty Compounds reporting units were substantially in excess of their carrying values.