Purification Solutions Goodwill and Long-Lived Assets Impairment Charges - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2018
Goodwill And Intangible Assets [Line Items]
Goodwill impairment charge			$ 92
Lower of cost or market reserve inventory	$ 13		13
Long-lived assets impairment charge			$ 162
Assets impairment charges income tax benefit		$ 30
Reducing of impairment charges and restructuring costs	$ 1
Purification Solutions [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill impairment charge		92
Lower of cost or market reserve inventory		13
Long-lived assets impairment charge		162
Impairment charges of definite lived Intangible assets		64
Purification Solutions [Member] | Property, Plant and Equipment [Member]
Goodwill And Intangible Assets [Line Items]
Long-lived assets impairment charge		$ 98