Employee Retirement Benefits - Defined Contribution Plan (Detail) - USD ($)	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure
Matching contributions to 401(k) and Top Hat plans	$ 6,000,000	$ 8,000,000
Qualified Pension Plans
Defined Benefit Plan Disclosure
Pension contributions	$ 0

Amount of cash outflow for pension benefit. Includes, but is not limited to, employer contribution to fund plan asset and payment to retiree. Excludes other postretirement benefit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3536-108585

Name:	us-gaap_PensionContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration