XML 37 R21.htm IDEA: XBRL DOCUMENT v3.21.1

Financial Instruments Measured at Fair Value and Concentrations of Credit Risk - Summary of Fair Value Measurements and Financial Statement Presentation (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]
Fair Values of Assets	$ 3,311	$ 12,165
Short Term Investments [Member]
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]
Fair Values of Assets	3,045	11,698
Commodity Derivative Contracts [Member]
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]
Fair Values of Assets	266	467
Level 1 [Member]
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]
Fair Values of Assets	3,311	12,165
Level 1 [Member] | Short Term Investments [Member]
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]
Fair Values of Assets	3,045	11,698
Level 1 [Member] | Commodity Derivative Contracts [Member]
Fair Value Concentration Of Risk Financial Statement Captions [Line Items]
Fair Values of Assets	$ 266	$ 467

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Fair value portion of other assets.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherAssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: