v3.25.1
Cover Page - shares
6 Months Ended
Mar. 31, 2025
Apr. 29, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2025  
Document Transition Report false  
Entity File Number 1-39093  
Entity Registrant Name BellRing Brands, Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 87-3296749  
Entity Address, Address Line One 2503 S. Hanley Road  
Entity Address, City or Town St. Louis  
Entity Address, State or Province MO  
Entity Address, Postal Zip Code 63144  
City Area Code 314  
Local Phone Number 644-7600  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Title of 12(b) Security Common Stock, $0.01 par value per share  
Trading Symbol BRBR  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding (in shares)   126,996,712
Entity Central Index Key 0001772016  
Current Fiscal Year End Date --09-30  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Amendment Flag false