v3.26.1
Document and Entity Information - shares
 6 Months Ended
Jun. 30, 2026
Jul. 10, 2026
Document and Entity Information    
Document Type 10-Q  
Document Quarterly Report true  
Document Transition Report false  
Document Period End Date Jun. 30, 2026  
Entity File Number 333-291359  
Entity Registrant Name Beacon Topco, Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 41-2339925  
Entity Address State Or Province MD  
Entity Address, Address Line One 20400 Century Boulevard  
Entity Address, Adress Line Two Suite 210  
Entity Address, City or Town Germantown  
Entity Address, Postal Zip Code 20874  
City Area Code 443  
Local Phone Number 917-0966  
Title of 12(b) Security None  
No Trading Symbol Flag true  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company true  
Entity Common Stock, Shares Outstanding   100
Entity Central Index Key 0002094256  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Amendment Flag false