v3.26.1
Variable Interest Entities Reflects adoption of ASU 2015-12 - Balances Relating to Variable Interest Entities in which BlackRock is Not Primary Beneficiary (Detail) - Variable Interest Entity, Not Primary Beneficiary [Member] - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Investments [Member]    
Variable Interest Entity [Line Items]    
Sponsored investment products $ 2,603 $ 2,325
Advisory Fee Receivables [Member]    
Variable Interest Entity [Line Items]    
Sponsored investment products 131 101
Other Net Assets (Liabilities) [Member]    
Variable Interest Entity [Line Items]    
Sponsored investment products (12) (12)
Maximum Risk of Loss [Member]    
Variable Interest Entity [Line Items]    
Sponsored investment products $ 2,751 $ 2,443