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 - Additional Information (Detail) $ in Millions		1 Months Ended	3 Months Ended
	Mar. 04, 2016 USD ($)	Mar. 31, 2014 USD ($)	Mar. 31, 2019 USD ($) 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	$ 1,380.0
Gowanus Canal Superfund Site
Loss Contingencies [Line Items]
Estimated remediation cost		$ 506.0
Ector Drum, Inc. Superfund Site
Loss Contingencies [Line Items]
Estimated remediation cost			$ 3.5