Exit Activities - Schedule of Operating Losses (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Operating losses		$ 428	$ 1,207
WTAMC [Member]
Operating losses		$ 428	777
WisdomTree Japan Inc. ("WTJ") [Member]
Operating losses	[1]		$ 430

[1] WTJ also recognized an impairment expense of $572 in connection with the termination of its office lease on March 31, 2019