Commitments and Contingencies (Narrative) (Detail) $ in Millions		6 Months Ended
Feb. 10, 2021 USD ($)	Jun. 30, 2021 USD ($) Lawsuits
Commitments And Contingencies [Line Items]
Other material lawsuits pending \| Lawsuits		0
Credit Suisse [Member]
Commitments And Contingencies [Line Items]
Damages Sought Value		$ 604
Damages Paid Value	$ 600
Fuel Line Lenders [Member]
Commitments And Contingencies [Line Items]
PREPA working capital		$ 700

Amount of damages awarded to the plaintiff in the legal matter.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration