Employee Benefit Plans - Components of Net Periodic Benefit Cost (Credit) (Parenthetical) (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Compensation And Retirement Disclosure [Abstract]
Tax expense (benefit) on other changes in plan assets and benefit obligations recognized in AOCI	$ 14,872	$ 45	$ (8,067)

Tax expense (benefit) on other changes in plan assets and benefit obligations recognized in AOCI.

No definition available.

Name:	laz_TaxExpenseBenefitOnOtherChangesInPlanAssetsAndBenefitObligationsRecognizedInAOCI
Namespace Prefix:	laz_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration