Deferred Consideration - Schedule of Deferred Consideration (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Contractual gold payments									$ 16,811	$ 13,226	$ 8,512
Contractual gold payments – gold ounces paid									9,500	9,500
Loss on revaluation of deferred consideration – gold payments	$ (22,385)	$ (8,870)	$ (23,358)	$ (2,208)	$ (5,354)	$ (6,306)	$ (4,037)	$ 4,404	$ (56,821)	$ (11,293)	$ 12,220

Gain/loss from revaluation of deferred consideration.

No definition available.

Name:	wetf_GainLossFromChangeInDeferredConsideration
Namespace Prefix:	wetf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration