Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	149,811,000	148,716,000
Common stock, shares outstanding	149,811,000	148,716,000
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	2,000,000	2,000,000
Accounts receivable from related parties	$ 27,258	$ 26,884
Securities owned, at fair value	34,771	34,895
Preferred Stock Redemption Value	$ 88,642	$ 72,667
Series A Redeemable Convertible Preferred Stock [Member]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	14,750	14,750
Preferred stock, shares issued	14,750	14,750
Preferred stock, shares outstanding	14,750	14,750
WisdomTree ETF [Member]
Securities owned, at fair value	$ 23,626	$ 23,932