CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2021
NEWMARK Group Inc Parent
Reduction for dividends on preferred stock or units	$ 0.0	$ 6.2

The amount of preferred stock dividends that is an adjustment to net income apportioned to common stockholders.

No definition available.

Name:	us-gaap_PreferredStockDividendsIncomeStatementImpact
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration