Intangible Assets, Net - Summary of Intangible Assets, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Definite-lived intangible assets:
Investment contracts and other	$ 489,570	$ 489,570
Accumulated amortization	(245,293)	(222,695)
Definite-lived intangible assets, net	244,277	266,875
Indefinite-lived intangible assets	43,516	43,516
Total intangible assets, net	$ 287,793	$ 310,391	$ 317,924	$ 338,812