Revenue Recognition - Estimated Revenue Expected to be Recognized in Future Related to Performance Obligations (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction Price Allocated to the Remaining Performance Obligation as of December 31, 2018	$ 5,176
Bristol-Myers Squibb Company ("BMS") and Pfizer Inc. ("Pfizer") | 2016 Agreement
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction Price Allocated to the Remaining Performance Obligation as of December 31, 2018	$ 451
Expected Year By Which Revenue Recognition Will Be Completed	2021
Percentage of Revenue Recognized	96.00%
Daiichi Sankyo, Inc ("Daiichi") | 2016 Agreement
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction Price Allocated to the Remaining Performance Obligation as of December 31, 2018	$ 2,355
Expected Year By Which Revenue Recognition Will Be Completed	2025
Percentage of Revenue Recognized	86.00%
Daiichi Sankyo, Inc ("Daiichi") | 2014 Agreement
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction Price Allocated to the Remaining Performance Obligation as of December 31, 2018	$ 673
Expected Year By Which Revenue Recognition Will Be Completed	2021
Percentage of Revenue Recognized	98.00%
Bayer Pharma AG | 2016 Agreement
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction Price Allocated to the Remaining Performance Obligation as of December 31, 2018	$ 1,697
Expected Year By Which Revenue Recognition Will Be Completed	2025
Percentage of Revenue Recognized	90.00%