Schedule I - Condensed Statements of Operations (Parent Company) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
REVENUE
Total revenue									$ 1,994,013	$ 1,919,638	$ 2,003,077
OPERATING EXPENSES
Professional services									(43,958)	(48,324)	(43,502)
Other									(38,099)	(39,286)	(40,009)
Total operating expenses	(565,890)	(382,080)	(392,377)	(448,216)	(466,665)	(374,681)	(388,090)	(364,577)	(1,788,563)	(1,594,013)	(1,661,718)
NET INCOME	(4,106)	33,673	34,162	29,056	(8,123)	67,133	71,566	59,983	92,785	190,559	194,423
LAZARD LTD (parent company only) [Member]
REVENUE
Equity in earnings of subsidiaries									20,598	109,294	109,576
Interest and other income									65,319	67,042	66,722
Total revenue									85,917	176,336	176,298
OPERATING EXPENSES
Professional services									1,477	1,276	1,217
Other									131	143	102
Total operating expenses									1,608	1,419	1,319
NET INCOME									$ 84,309	$ 174,917	$ 174,979