Commitments and Contingencies - Additional Information (Detail)				1 Months Ended	6 Months Ended	12 Months Ended
	Dec. 17, 2017 Defendant	Mar. 04, 2016 USD ($)	Jul. 07, 2014 Defendant	May 31, 2007 Defendant	Jun. 30, 2018 Defendant	Dec. 31, 2020 USD ($) Defendant	Dec. 31, 2019 USD ($)	Dec. 31, 2004 Entity	Jan. 31, 2018 USD ($) Party	Mar. 30, 2017 Party
Loss Contingencies [Line Items]
Accrued legal matters						$ 4,275,000	$ 17,820,000
Provisions for environmental litigation accruals						85,000	5,896,000
Legal litigation settlements						$ 21,300,000	$ 2,707,000
EPA [Member] | Occidental Chemical Corporation [Member]
Loss Contingencies [Line Items]
Number of potentially responsible parties | Party										20
Number of potentially responsible parties that the EPA intends to enter into a final settlement agreement with | Party									15
Remediation cost for identified responsible parties									$ 280,600
8 Mile Stretch of Lower Passaic River [Member]
Loss Contingencies [Line Items]
Cost estimate for remediating Lower Passaic River		$ 1,380,000,000
Minimum [Member] | CERCLA [Member] | Occidental Chemical Corporation [Member]
Loss Contingencies [Line Items]
Number of defendants under complaint | Defendant					120
Minimum [Member] | 17 Mile Stretch of Lower Passaic River [Member] | EPA [Member]
Loss Contingencies [Line Items]
Number of entities to which general notice letters issued | Entity								100
Lower Passaic River [Member] | Minimum [Member] | 17 Mile Stretch of Lower Passaic River [Member]
Loss Contingencies [Line Items]
Parties to perform a remedial investigation and feasibility study | Defendant				70
MTBE [Member] | NJ [Member]
Loss Contingencies [Line Items]
Number of defendants in the MTBE complaint | Defendant						50
MTBE [Member] | NJ [Member] | New Jersey MDL Proceedings
Loss Contingencies [Line Items]
Payment in exchange for satisfaction and release of claims						$ 13,500,000
MTBE [Member] | Minimum [Member] | PA [Member]
Loss Contingencies [Line Items]
Number of defendants in the MTBE complaint | Defendant			50
MTBE [Member] | Minimum [Member] | MARYLAND [Member]
Loss Contingencies [Line Items]
Number of defendants in the MTBE complaint | Defendant	60
Lukoil Americas Corporation [Member] | Settled Litigation [Member]
Loss Contingencies [Line Items]
Legal litigation settlements						$ 20,500,000