Schedule I - Condensed Statements of Changes in Stockholders' Equity (Parent Company) (Parenthetical) (Detail) (USD $)	12 Months Ended								12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Class A Common stock [Member]	Dec. 31, 2011 Class A Common stock [Member]	Dec. 31, 2010 Class A Common stock [Member]	Dec. 31, 2012 Class B Common stock [Member]	Dec. 31, 2011 Class B Common stock [Member]	Dec. 31, 2010 Class B Common stock [Member]	Dec. 31, 2012 LAZARD LTD (parent company only) [Member]	Dec. 31, 2011 LAZARD LTD (parent company only) [Member]
Share-based incentive compensation and related tax benefits or expense	$ 972	$ 972							$ 972	$ 972
Common stock, issued			128,216,423	123,009,311	119,697,936	1	1	1