Net Income Per Share of Class A Common Stock - Company's Basic and Diluted Net Income Per Share and Weighted Average Shares Outstanding (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Net income attributable to Lazard Ltd	$ 53,217	$ 60,282	$ 31,353	$ 15,360	$ (5,365)	$ 33,301	$ 30,821	$ 25,552	$ 160,212	$ 84,309	$ 174,917
Add (deduct) - adjustment associated with Class A common stock issuable on a non-contingent basis										7	284
Net income attributable to Lazard Ltd - basic									160,212	84,316	175,201
Adjustments to income relating to interest expense and changes in net income attributable to noncontrolling interests resulting from assumed Class A common stock issuances in connection with share-based incentive compensation, convertible debt, convertible preferred stock and exchangeable interests, net of tax									1,065	371	12,512
Net income attributable to Lazard Ltd - diluted									$ 161,277	$ 84,687	$ 187,713
Weighted average number of shares of Class A common stock outstanding									120,096,305	116,163,821	115,005,676
Add - adjustment for shares of Class A common stock issuable on a non-contingent basis									757,962	790,168	3,026,344
Weighted average number of shares of Class A common stock outstanding - basic									120,854,267	116,953,989	118,032,020
Weighted average number of incremental shares of Class A common stock issuable from share-based incentive compensation, convertible debt, convertible preferred stock and exchangeable interests									12,882,812	12,371,633	19,597,505
Weighted average number of shares of Class A common stock outstanding - diluted									133,737,079	129,325,622	137,629,525
Net income attributable to Lazard Ltd per share of Class A common stock:
Basic	$ 0.44	$ 0.49	$ 0.26	$ 0.13	$ (0.05)	$ 0.29	$ 0.26	$ 0.21	$ 1.33	$ 0.72	$ 1.48
Diluted	$ 0.40	$ 0.45	$ 0.24	$ 0.12	$ (0.05)	$ 0.26	$ 0.24	$ 0.20	$ 1.21	$ 0.65	$ 1.36