Financial Risk Management Activities - Notional Amounts of Outstanding Financial Risk Management Derivative Contracts (Detail) MMBbls in Millions	Mar. 31, 2021 USD ($) MMBbls	Dec. 31, 2020 USD ($) MMBbls
Commodity Derivative Contracts
Derivative [Line Items]
Commodity - crude oil \| MMBbls	41.3	27.4
Foreign Exchange Forwards
Derivative [Line Items]
Outstanding gross notional amount	$ 121,000,000	$ 163,000,000
Interest Rate Swaps
Derivative [Line Items]
Outstanding gross notional amount	$ 100,000,000	$ 100,000,000

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.

No definition available.

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- Definition

Nominal number of units used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959

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Nominal or face amount used to calculate payment on derivative.

+ References

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