Research and Development Agreements - Schedule of Research and Development Revenue from Related Party Relates to Revenue from Research and Development Agreements (Detail)

v3.20.2

Research and Development Agreements - Schedule of Research and Development Revenue from Related Party Relates to Revenue from Research and Development Agreements (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue Recognition [Line Items]
Total research and development revenue, related party	$ 4,298	$ 3,187	$ 12,138	$ 14,811
Millennium Pharmaceuticals Inc
Revenue Recognition [Line Items]
Total research and development revenue, related party	1,566	2,903	4,962	14,527
Millennium Pharmaceuticals Inc | Takeda Individual Project Agreement
Revenue Recognition [Line Items]
Total research and development revenue, related party	0	0	0	54
Millennium Pharmaceuticals Inc | Takeda Development Agreement
Revenue Recognition [Line Items]
Total research and development revenue, related party	86	2,581	307	13,707
Millennium Pharmaceuticals Inc | Takeda Multi Target Agreement
Revenue Recognition [Line Items]
Total research and development revenue, related party	$ 1,480	$ 322	$ 4,655	$ 766