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		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue Recognition [Line Items]
Total research and development revenue	$ 6,040	$ 5,211	$ 7,840	$ 11,624
Millennium Pharmaceuticals Inc
Revenue Recognition [Line Items]
Total research and development revenue	3,063	5,211	3,396	11,624
Millennium Pharmaceuticals Inc | Takeda Individual Project Agreement
Revenue Recognition [Line Items]
Total research and development revenue	0	0	0	54
Millennium Pharmaceuticals Inc | Takeda Development Agreement
Revenue Recognition [Line Items]
Total research and development revenue	3,028	5,012	3,176	11,126
Millennium Pharmaceuticals Inc | Takeda Multi Target Agreement
Revenue Recognition [Line Items]
Total research and development revenue	$ 35	$ 199	$ 220	$ 444