v3.26.1
Cover Page - shares
 6 Months Ended
Jun. 30, 2026
Aug. 12, 2026
Document Information [Line Items]    
Document Type 10-Q  
Document Fiscal Period Focus Q2  
Document Fiscal Year Focus 2026  
Amendment Flag false  
Entity Interactive Data Current Yes  
Current Fiscal Year End Date --12-31  
Entity Central Index Key 0002029769  
Document Quarterly Report true  
Document Transition Report false  
Document Period End Date Jun. 30, 2026  
Entity Registrant Name OAKTREE ACQUISITION CORP. III LIFE SCIENCES  
Entity File Number 001-42383  
Entity Tax Identification Number 98-1799512  
Entity Incorporation, State or Country Code E9  
Entity Current Reporting Status Yes  
Entity Filer Category Non-accelerated Filer  
Entity Shell Company true  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Address, Address Line One 333 South Grand Avenue, 28th Floor  
Entity Address, City or Town Los Angeles  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 90071  
City Area Code 213  
Local Phone Number 830-6300  
Entity Ex Transition Period false  
Common Class A [Member]    
Document Information [Line Items]    
Trading Symbol OACCU  
Security Exchange Name NASDAQ  
Title of 12(b) Security Units, each consisting of one Class A ordinary share, $0.0001 par value, and one-fifth of one redeemable warrant  
Entity Common Stock, Shares Outstanding   19,783,010
Class A ordinary shares [Member]    
Document Information [Line Items]    
Trading Symbol OACC  
Security Exchange Name NASDAQ  
Title of 12(b) Security Class A ordinary shares included as part of the units  
Redeemable warrants [Member]    
Document Information [Line Items]    
Trading Symbol OACCW  
Security Exchange Name NASDAQ  
Title of 12(b) Security Redeemable warrants included as part of the units, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50  
Common Class B [Member]    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   4,799,758