Incentive Plans - Schedule of Activity Relating to RSUs and DSUs (Parenthetical) (Detail) - shares	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Dividend participation rights	693,714	375,954	454,059

Issuance of restricted stock units in connection with dividend participation rights.

No definition available.

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Namespace Prefix:	laz_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration