Impairments (Details) - USD ($) $ in Thousands	3 Months Ended					12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Impairments	$ 30,138	$ 0	$ 0	$ 572	$ 17,386	$ 30,710	$ 17,386
GCC—Intangible Asset [Member]
Impairments							9,953
Wisdom Tree Japan [Member]
Impairments						572	326
Advisor Engine - Financial ineterest [Member] | Financial Interests [Member]
Impairments						$ 30,138
AdvisorEngine—Option [Member]
Impairments							3,278
Thesys—Series Y Preferred [Member]
Impairments							$ 3,829