Derivative Instruments - Effect of Fair Value and Cash Flow Hedge Accounting on Consolidated Statement of Income (Parenthetical) (Detail) $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($)
Derivative Instrument Detail [Abstract]
Gains (losses) recognized in earnings related discontinuance of cash flow hedges	$ 41

Amount, before tax, of reclassification from accumulated other comprehensive income (AOCI) for gain (loss) from discontinuance of cash flow hedge included in assessment of hedge effectiveness.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959

Name:	us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeReclassificationForDiscontinuanceBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration