Related Parties - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Master Separation Agreement [Member]
Related Party Transaction [Line Items]
Agreement date	May 10, 2005
LMDC Holdings [Member]
Related Party Transaction [Line Items]
Amounts recorded relating to the administrative services agreement	$ 879	$ 1,456	$ 7,637
Net referral fees for underwriting, private placement, M&A and restructuring transactions	795	(1,646)	5,947
Obligations pursuant to the tax receivable agreement	19,577	1,249
LMDC Holdings [Member] \| Administrative and Support Services and Other Receivables [Member]
Related Party Transaction [Line Items]
Receivables from related party	1,107	3,112
LMDC Holdings [Member] \| Referral Fees for Underwriting and Private Placement Transactions [Member]
Related Party Transaction [Line Items]
Receivables from related party		4,682
LMDC Holdings [Member] \| Referral Fees [Member]
Related Party Transaction [Line Items]
Payables to related party	1,077	3,051
LAZ-MD Holdings [Member] \| Administrative Services Agreement [Member]
Related Party Transaction [Line Items]
Amounts recorded relating to the administrative services agreement	856	1,000	1,000
MBA Lazard Holdings S.A. [Member]
Related Party Transaction [Line Items]
Percentage of ownership	50.00%	50.00%	50.00%
Referral fees for restructuring, M&A transactions and fee sharing	$ (5,557)	$ (2,221)	$ 1,506

Amounts recorded relating to net referral fees for underwriting, private placement, and restructuring transactions

No definition available.

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- Definition

Payable pursuant to the tax receivable agreement.

+ References

No definition available.

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- Definition

Referral fees for restructuring, M&A transactions and fee sharing.

+ References

No definition available.

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- Definition

Related party transaction agreement date.

+ References

No definition available.

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- Definition

Amount for accounts payable to related parties. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(k)(1))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 850

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 850

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph k

-Subparagraph 1

-Article 4

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19

-Subparagraph a

-Article 5

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(a))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 850

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

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- Definition

Cost associated with reimbursable income. This occurs when a services entity incurs expenses on behalf of the client and passes through the cost of reimbursable expenses to a client.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.2)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

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- Definition

Receivables to be collected from (obligations owed to) related parties, net as of the balance sheet date where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth.

+ References

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