Organizational and Description of Business- Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Operating income (loss)	$ 21,708	$ 15,224	$ 49,460	$ 43,852
WisdomTree Japan [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Operating income (loss)	$ (1,342)	$ (1,085)	$ (3,698)	$ (3,447)
Acquisition of ETFS Business [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Acquisition completion date			Apr. 11, 2018