Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
NET INCOME	$ 108,725	$ 111,470	$ 418,765	$ 342,801
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX:
Currency translation adjustments	(8,676)	19,748	(34,783)	62,847
Employee benefit plans:
Actuarial gain (loss) (net of tax expense (benefit) of $214 and $(1,197) for the three months ended September 30, 2018 and 2017, respectively, and $618 and $(3,673) for the nine months ended September 30, 2018 and 2017, respectively)	863	(4,715)	4,149	(13,819)
Adjustment for items reclassified to earnings (net of tax expense of $264 and $204 for the three months ended September 30, 2018 and 2017, respectively, and $948 and $676 for the nine months ended September 30, 2018 and 2017, respectively)	949	1,081	2,788	3,523
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	(6,864)	16,114	(27,846)	52,551
COMPREHENSIVE INCOME	101,861	127,584	390,919	395,352
LESS - COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS	1,653	2,262	5,037	5,662
COMPREHENSIVE INCOME ATTRIBUTABLE TO LAZARD LTD	$ 100,208	$ 125,322	$ 385,882	$ 389,690