Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended
	Mar. 31, 2025 Segment
Accounting Policies [Abstract]
Number of operating segment	1
Number of reporting segment	1
Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description	Operating segments are identified as components of an enterprise about which discrete financial information is available for evaluation by the chief operating decision-maker (CODM) in making decisions regarding resource allocation and assessing performance. The Company operates and manages its business as one reporting and one operating segment, which is the business of designing and developing ecDTx, for which no revenue has been recorded. All of the Company’s long-lived assets are located in the United States. The Company’s CODM is its Chief Executive Officer. For purposes of assessing the Company’s financial performance and making resource allocation decisions, the CODM reviews total expenses, as well as expenses by nature.
Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration]	srt:ChiefExecutiveOfficerMember

Boundless Bio, Inc. 10-Q