Postretirement Benefit Plans - Amounts Recognized in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
United States [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net actuarial loss	$ 20,755	$ 18,801
United Kingdom [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net actuarial loss	$ 5,989	$ 6,188

Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-14A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (j)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480506/715-20-50-1

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant