Schedule I - Condensed Statements of Financial Condition (Parent Company) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
ASSETS
Cash and cash equivalents	$ 850,190	$ 1,003,791	$ 1,209,695	$ 917,329
Investments in subsidiaries, equity method	7,012	11,053
Total Assets	2,986,893	3,081,936	3,422,532
Liabilities:
Other liabilities	499,651	440,131
Total Liabilities	2,335,353	2,215,080
Commitments and contingencies
Common stock:
Additional paid-in-capital	846,050	659,013
Retained earnings	182,647	258,646
Accumulated other comprehensive loss, net of tax	(110,541)	(88,364)
Total Stockholders' Equity	651,540	866,856	796,117	523,097
Total liabilities and stockholders' equity	2,986,893	3,081,936
Class A Common stock [Member]
Common stock:
Common stock	1,282	1,230
Common stock held by subsidiary	(349,782)	(104,382)
LAZARD LTD (parent company only) [Member]
ASSETS
Cash and cash equivalents	298	218	210	1,686
Investments in subsidiaries, equity method	(1,852,072)	(1,633,687)
Due from subsidiaries	2,421,780	2,359,798
Total Assets	570,006	726,329
Liabilities:
Due to subsidiaries	254
Other liabilities	96	186
Total Liabilities	350	186
Commitments and contingencies
Common stock:
Additional paid-in-capital	846,050	659,013
Retained earnings	182,647	258,646
Accumulated other comprehensive loss, net of tax	(110,541)	(88,364)
Stockholders' equity subtotal before common stock held by subsidiary and Noncontrolling Interests, total	919,438	830,525
Common stock held by subsidiary	(349,782)	(104,382)
Total Stockholders' Equity	569,656	726,143
Total liabilities and stockholders' equity	570,006	726,329
LAZARD LTD (parent company only) [Member] | Class A Common stock [Member]
Common stock:
Common stock	$ 1,282	$ 1,230