Schedule of Intangible Assets, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Acquired and in-licensed rights	$ 90,000	$ 50,000
Less: accumulated amortization	(11,852)	(9,539)
Total intangible asset, net	$ 78,148	$ 40,461