Schedule I - Parent Company Only - Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Other Assets [Line Items]
Deferred tax assets	$ 182,781	$ 149,938
Total other non-current assets	407,898	369,867
NEWMARK Group Inc Parent
Other Assets [Line Items]
Deferred tax assets	179,501	150,373
Prepaid expenses	312	1,654
Total other non-current assets	$ 179,813	$ 152,027