License Agreement - Additional Information (Details) - USD ($) $ in Thousands			1 Months Ended			3 Months Ended		12 Months Ended
	Aug. 22, 2023	Mar. 23, 2020	Apr. 30, 2024	Mar. 31, 2024	Apr. 30, 2019	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2019	Aug. 31, 2010
License Agreement [Line Items]
Annual minimum royalty obligations									$ 200
Seattle Genetics Agreement
License Agreement [Line Items]
Annual license maintenance fees	$ 300
Transition Agreement
License Agreement [Line Items]
Termination date						The Company terminated the Transition Agreement in the first quarter of 2025.
Astellas Pharma Inc. \| Collaboration and License Agreement
License Agreement [Line Items]
Sublicense fees				$ 600		$ 200
Upfront payment received		$ 80,000
Immuno Gen Inc
License Agreement [Line Items]
Milestone payment			$ 5,000
Clinical Development Milestone Payment			$ 35,000
Immuno Gen Inc \| Collaborative Arrangement
License Agreement [Line Items]
Upfront payment received								$ 7,500
Immuno Gen Inc \| Clinical development milestones \| Maximum [Member]
License Agreement [Line Items]
Milestone payment								35,000
Immuno Gen Inc \| Regulatory approval and commercial milestone \| Maximum [Member]
License Agreement [Line Items]
Milestone payment								$ 320,000
UCSB
License Agreement [Line Items]
Annual license maintenance fees					$ 800
License payment term					2031
Percentage of remaining maintenance fees outstanding					50.00%
Sublicense fees						$ 1,100	$ 1,600

CytomX Therapeutics, Inc. 10-Q