Intangible Assets, Net - Summary of Intangible Assets, Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Definite-lived intangible assets:
Investment contracts	$ 158,747	$ 158,747
Accumulated amortization	(155,369)	(155,136)
Definite-lived intangible assets, net	3,378	3,611
Indefinite-lived intangible assets	34,816	34,816
Total intangible assets, net	$ 38,194	$ 38,427	$ 40,236	$ 40,887