Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
NET INCOME	$ 259,847	$ 393,692	$ 992,932
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX:
Currency translation adjustments	71,669	(57,920)	(51,182)
Employee benefit plans:
Actuarial gain (loss) (net of tax expense (benefit) of $(3,507), $(5,205) and $5,644 for the years ended December 31, 2017, 2016 and 2015, respectively)	2,085	(24,473)	11,283
Adjustment for items reclassified to earnings (net of tax expense of $2,220, $1,757 and $1,507 for the years ended December 31, 2017, 2016 and 2015, respectively)	7,951	2,526	6,309
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX	81,705	(79,867)	(33,590)
COMPREHENSIVE INCOME	341,552	313,825	959,342
LESS - COMPREHENSIVE INCOME ATTRIBUTABLE TO NONCONTROLLING INTERESTS	6,265	5,993	6,559
COMPREHENSIVE INCOME ATTRIBUTABLE TO LAZARD LTD	$ 335,287	$ 307,832	$ 952,783