Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
Finite Lived Intangible Assets [Line Items]
Impairment loss	$ 2,200		$ 0
Alloy Piping Products [Member]
Finite Lived Intangible Assets [Line Items]
Impairment loss		$ 0