Employee Benefits - Summary of Plan Investment Assets Measured at Fair Value (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Collective Investment Fund Mid-Small Cap Equity Securities [Member] \| Domestic Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets measured at fair value	$ 433	$ 431

Amount of investment within defined benefit plan asset category.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(ii)
-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

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