Goodwill and Other Intangible Assets - Summary of Intangible Assets, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Definite-lived intangible assets, net:
Investment contracts and other	$ 489,570	$ 489,570
Accumulated amortization	(252,822)	(222,695)
Definite-lived intangible assets, net	236,748	266,875
Indefinite-lived intangible assets	43,516	43,516
Total intangible assets, net	$ 280,264	$ 310,391	$ 338,812	$ 301,954