Schedule I - Condensed Statements of Operations (Parent Company Only) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
REVENUE
Total revenue									$ 2,404,767	$ 2,363,017	$ 2,064,733
OPERATING EXPENSES
Professional services									49,529	46,543	42,663
Other									99,142	39,983	80,258
Total operating expenses	$ 453,900	$ 2,774	$ 1,410,468	$ 503,086	$ 434,347	$ 452,499	$ 467,916	$ 426,220	2,370,228	1,780,982	1,768,545
NET INCOME ATTRIBUTABLE TO LAZARD LTD	$ 157,786	$ 398,521	$ 374,113	$ 55,953	$ 172,384	$ 88,859	$ 85,192	$ 80,842	986,373	427,277	160,212
Parent Company [Member]
REVENUE
Equity in earnings of subsidiaries									931,036	373,713	103,769
Interest and other income									57,258	55,303	58,227
Total revenue									988,294	429,016	161,996
OPERATING EXPENSES
Professional services									1,779	1,594	1,662
Other									142	145	122
Total operating expenses									1,921	1,739	1,784
NET INCOME ATTRIBUTABLE TO LAZARD LTD									$ 986,373	$ 427,277	$ 160,212