Performance Management - Circle Reserve Fund |
Apr. 30, 2026 |
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| Prospectus [Line Items] | |
| Bar Chart and Performance Table [Heading] | Performance Information |
| Performance Narrative [Text Block] | The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. To the extent that dividends and distributions have been paid by the Fund, the performance information for the Fund in the chart and table assumes reinvestment of the dividends and distributions. As with all such investments, past performance is not an indication of future results. The table includes all applicable fees. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. The Fund is a money market fund managed pursuant to the requirements of Rule 2a-7 under the Investment Company Act. Updated information on the Fund’s performance can be obtained by visiting www.blackrock.com/cash or can be obtained by phone at (800) 441-7450.
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| Performance Past Does Not Indicate Future [Text] | As with all such investments, past performance is not an indication of future results. |
| Performance Information Illustrates Variability of Returns [Text] | The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. |
| Bar Chart [Heading] | Institutional Shares ANNUAL TOTAL RETURNS Circle Reserve Fund As of 12/31 |
| Bar Chart Closing [Text Block] | During the periods shown in the bar chart, the highest return for a quarter was 1.34% (quarter ended December 31, 2023) and the lowest return for a quarter was 0.99% (quarter ended December 31, 2025). The year-to-date return as of June 30, 2026 was 1.79%.
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| Performance Table Heading | For the periods ended 12/31/25Average Annual Total Returns |
| Performance Table Narrative | To obtain the Fund’s current 7-day yield, call (800) 441-7450 or visit the Fund’s website at www.blackrock.com/cash.
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| Money Market Seven Day Yield Phone | (800) 441-7450 |
| Performance Availability Website Address [Text] | www.blackrock.com/cash |
| Performance Availability Phone [Text] | (800) 441-7450 |
| Institutional Shares | |
| Prospectus [Line Items] | |
| Year to Date Return, Label [Optional Text] | year-to-datereturn |
| Bar Chart, Year to Date Return | 1.79% |
| Bar Chart, Year to Date Return, Date | Jun. 30, 2026 |
| Highest Quarterly Return, Label [Optional Text] | highest return |
| Highest Quarterly Return | 1.34% |
| Highest Quarterly Return, Date | Dec. 31, 2023 |
| Lowest Quarterly Return, Label [Optional Text] | lowest return |
| Lowest Quarterly Return | 0.99% |
| Lowest Quarterly Return, Date | Dec. 31, 2025 |