Senior Debt - Senior Debt (Detail) - USD ($)	9 Months Ended
Sep. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Senior Debt, Outstanding Principal	$ 1,700,000,000	$ 1,700,000,000
Senior Debt, Outstanding Unamortized Debt Costs	12,908,000	14,773,000
Senior Debt, Outstanding Carrying Value	1,687,092,000	1,685,227,000
Lazard Group 2025 Senior Notes [Member]
Debt Instrument [Line Items]
Senior Debt, Initial Principal Amount	$ 400,000,000
Senior Debt, Maturity Date	Feb. 13, 2025
Senior Debt, Annual Interest Rate	3.75%
Senior Debt, Outstanding Principal	$ 400,000,000	400,000,000
Senior Debt, Outstanding Unamortized Debt Costs	1,121,000	1,476,000
Senior Debt, Outstanding Carrying Value	398,879,000	398,524,000
Lazard Group 2027 Senior Notes [Member]
Debt Instrument [Line Items]
Senior Debt, Initial Principal Amount	$ 300,000,000
Senior Debt, Maturity Date	Mar. 01, 2027
Senior Debt, Annual Interest Rate	3.625%
Senior Debt, Outstanding Principal	$ 300,000,000	300,000,000
Senior Debt, Outstanding Unamortized Debt Costs	1,723,000	2,015,000
Senior Debt, Outstanding Carrying Value	298,277,000	297,985,000
Lazard Group 2028 Senior Notes [Member]
Debt Instrument [Line Items]
Senior Debt, Initial Principal Amount	$ 500,000,000
Senior Debt, Maturity Date	Sep. 19, 2028
Senior Debt, Annual Interest Rate	4.50%
Senior Debt, Outstanding Principal	$ 500,000,000	500,000,000
Senior Debt, Outstanding Unamortized Debt Costs	5,077,000	5,716,000
Senior Debt, Outstanding Carrying Value	494,923,000	494,284,000
Lazard Group 2029 Senior Notes [Member]
Debt Instrument [Line Items]
Senior Debt, Initial Principal Amount	$ 500,000,000
Senior Debt, Maturity Date	Mar. 11, 2029
Senior Debt, Annual Interest Rate	4.375%
Senior Debt, Outstanding Principal	$ 500,000,000	500,000,000
Senior Debt, Outstanding Unamortized Debt Costs	4,987,000	5,566,000
Senior Debt, Outstanding Carrying Value	$ 495,013,000	$ 494,434,000

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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- Definition

Face (par) amount of debt instrument at time of issuance.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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No definition available.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, excluding unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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