XML 150 R135.htm IDEA: XBRL DOCUMENT
v3.25.4

Net Capital Requirements - Additional Information (Detail) - USD ($) $ in Billions | Dec. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract] |  |
Net capital requirement in certain regulated subsidiaries | $ 2.2 | $ 1.8

X
- Definition Net capital requirements. + References No definition available. + Details
Name: | blk_NetCapitalRequirements
Namespace Prefix: | blk_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | srt_RegulatoryCapitalRequirementsAbstract
Namespace Prefix: | srt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration