Schedule I - Condensed Statements of Operations (Parent Company Only) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
REVENUE
Total revenue									$ 2,383,663	$ 2,404,767	$ 2,363,017
OPERATING EXPENSES
Professional services									45,512	49,529	46,543
Other									41,219	99,142	39,983
Total operating expenses	$ 534,709	$ 459,916	$ 421,444	$ 399,841	$ 453,900	$ 2,774	$ 1,410,468	$ 503,086	1,815,910	2,370,228	1,780,982
NET INCOME ATTRIBUTABLE TO LAZARD LTD	$ 127,982	$ 112,536	$ 80,357	$ 66,823	$ 157,786	$ 398,521	$ 374,113	$ 55,953	387,698	986,373	427,277
Parent Company [Member]
REVENUE
Equity in earnings of subsidiaries									326,366	931,036	373,713
Interest and other income									63,019	57,258	55,303
Total revenue									389,385	988,294	429,016
OPERATING EXPENSES
Professional services									1,580	1,779	1,594
Other									107	142	145
Total operating expenses									1,687	1,921	1,739
NET INCOME ATTRIBUTABLE TO LAZARD LTD									$ 387,698	$ 986,373	$ 427,277