Total anticipated costs associated with remediation, site restoration, postclosure, monitoring commitments, or other exit costs that may occur on the sale, disposal, or abandonment of a particular property resulting from unanticipated contamination of the assets.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.Y.Q4)
-URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751

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

Guarantees and Contingencies (Detail) $ in Millions		1 Months Ended
Guarantees and Contingencies (Detail) $ in Millions	Mar. 04, 2016 USD ($)	Mar. 31, 2014 USD ($)	Mar. 31, 2021 case
MTBE Cases
Loss Contingencies [Line Items]
Total number of remaining active cases filed \| case			3
Lower Passaic River
Loss Contingencies [Line Items]
Estimated remediation cost	$ 1,380
Gowanus Canal Superfund Site
Loss Contingencies [Line Items]
Estimated remediation cost		$ 506