Blackrock Funds N-CSR3 Oct 24Certified annual shareholder report (management investment company)Financial data

Company Profile

Form N-CSR Cover

Form N-CSR Cover	12 Months Ended
Form N-CSR Cover	Jul. 31, 2024
Shareholder Report [Line Items]
Document Type	N-CSR
Amendment Flag	false
Registrant Name	BlackRock Funds
Entity Central Index Key	0000844779
Entity Investment Company Type	N-1A
Document Period End Date	Jul. 31, 2024

Shareholder Report

Shareholder Report	12 Months Ended
Shareholder Report	Jul. 31, 2024 USD ($) Holding
Shareholder Report [Line Items]
Document Type	N-CSR
Amendment Flag	false
Registrant Name	BlackRock Funds
Entity Central Index Key	0000844779
Entity Investment Company Type	N-1A
Document Period End Date	Jul. 31, 2024
C000129315
Shareholder Report [Line Items]
Fund Name	BlackRock Short Obligations Fund
Class Name	Institutional Shares
Trading Symbol	BISOX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about BlackRock Short Obligations Fund (the “Fund”) for the period of August 1, 2023 to July 31, 2024.
Shareholder Report Annual or Semi-Annual	Annual Shareholder Report
Additional Information [Text Block]	You can find additional information about the Fund at blackrock.com/fundreports
Material Fund Change Notice [Text Block]
Additional Information Phone Number	(800) 441-7762
Additional Information Website	<span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;">blackrock.com/fundreports</span></span>" id="sjs-B20"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; font-weight: 400; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;">blackrock.com/fundreports</span></span>
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Class name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Institutional Shares $28 0.27%
Expenses Paid, Amount	$ 28
Expense Ratio, Percent	0.27%
Factors Affecting Performance [Text Block]	How did the Fund perform last year? Although inflation came down over the course of the annual period, it remained above the U.S. Federal Reserve’s (the “Fed”) stated 2% target. The Fed responded by keeping short-term interest rates in a range of 5.25% to 5.50%. The central bank’s decision to keep rates elevated translated to attractive yields on short-term debt. What contributed to performance? During the reporting period, the Fund’s duration and yield curve positioning contributed positively. The Fund’s sector allocations were also a source of positive contribution. What detracted from performance? At a time of positive returns for the broader asset class, no aspect of the Fund's positioning was a significant detractor.
Performance Past Does Not Indicate Future [Text]	Past performance is not an indication of future results. </span>Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles." id="sjs-B25"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;">Past performance is not an indication of future results. </span>Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles.
Line Graph [Table Text Block]	Fund performance Cumulative performance: August 1, 2014 through July 31, 2024 Initial investment of $10,000 Institutional Shares Bloomberg U.S. Aggregate Bond Index ICE BofA 6-Month U.S. Treasury Bill Index Aug 14 10,004 10,110 10,002 Sep 14 10,008 10,042 10,003 Oct 14 10,012 10,140 10,003 Nov 14 10,016 10,212 10,003 Dec 14 10,011 10,222 10,005 Jan 15 10,025 10,436 10,008 Feb 15 10,020 10,338 10,009 Mar 15 10,024 10,386 10,009 Apr 15 10,029 10,349 10,013 May 15 10,035 10,324 10,014 Jun 15 10,040 10,211 10,016 Jul 15 10,045 10,282 10,015 Aug 15 10,050 10,268 10,016 Sep 15 10,055 10,337 10,026 Oct 15 10,059 10,339 10,023 Nov 15 10,065 10,311 10,022 Dec 15 10,061 10,278 10,027 Jan 16 10,067 10,420 10,035 Feb 16 10,074 10,494 10,039 Mar 16 10,103 10,590 10,048 Apr 16 10,110 10,630 10,055 May 16 10,118 10,633 10,056 Jun 16 10,125 10,824 10,068 Jul 16 10,143 10,893 10,071 Aug 16 10,152 10,880 10,072 Sep 16 10,160 10,874 10,081 Oct 16 10,169 10,791 10,087 Nov 16 10,178 10,535 10,089 Dec 16 10,192 10,550 10,094 Jan 17 10,201 10,571 10,102 Feb 17 10,221 10,642 10,107 Mar 17 10,221 10,636 10,107 Apr 17 10,232 10,719 10,115 May 17 10,253 10,801 10,121 Jun 17 10,264 10,790 10,131 Jul 17 10,275 10,837 10,141 Aug 17 10,286 10,934 10,155 Sep 17 10,297 10,882 10,162 Oct 17 10,299 10,888 10,172 Nov 17 10,311 10,874 10,180 Dec 17 10,316 10,924 10,191 Jan 18 10,319 10,798 10,202 Feb 18 10,333 10,696 10,208 Mar 18 10,338 10,764 10,223 Apr 18 10,354 10,684 10,238 May 18 10,383 10,761 10,255 Jun 18 10,392 10,747 10,272 Jul 18 10,412 10,750 10,289 Aug 18 10,443 10,819 10,309 Sep 18 10,463 10,749 10,323 Oct 18 10,475 10,664 10,342 Nov 18 10,497 10,728 10,363 Dec 18 10,513 10,925 10,386 Jan 19 10,559 11,041 10,410 Feb 19 10,581 11,035 10,429 Mar 19 10,617 11,247 10,454 Apr 19 10,630 11,250 10,476 May 19 10,664 11,449 10,501 Jun 19 10,698 11,593 10,530 Jul 19 10,720 11,619 10,550 Aug 19 10,753 11,920 10,578 Sep 19 10,773 11,856 10,596 Oct 19 10,793 11,892 10,623 Nov 19 10,811 11,886 10,635 Dec 19 10,829 11,878 10,653 Jan 20 10,858 12,106 10,669 Feb 20 10,874 12,324 10,697 Mar 20 10,782 12,251 10,752 Apr 20 10,882 12,469 10,753 May 20 10,926 12,527 10,750 Jun 20 10,946 12,606 10,752 Jul 20 10,965 12,795 10,756 Aug 20 10,971 12,691 10,757 Sep 20 10,966 12,684 10,759 Oct 20 10,971 12,628 10,761 Nov 20 10,975 12,752 10,763 Dec 20 10,979 12,769 10,764 Jan 21 10,982 12,678 10,765 Feb 21 10,985 12,495 10,767 Mar 21 10,977 12,338 10,769 Apr 21 10,979 12,436 10,770 May 21 10,993 12,477 10,771 Jun 21 10,985 12,564 10,770 Jul 21 10,987 12,705 10,771 Aug 21 10,989 12,681 10,772 Sep 21 10,992 12,571 10,773 Oct 21 10,983 12,567 10,773 Nov 21 10,974 12,604 10,773 Dec 21 10,977 12,572 10,774 Jan 22 10,958 12,301 10,768 Feb 22 10,949 12,164 10,767 Mar 22 10,909 11,826 10,764 Apr 22 10,902 11,377 10,767 May 22 10,920 11,451 10,780 Jun 22 10,896 11,271 10,772 Jul 22 10,931 11,547 10,782 Aug 22 10,947 11,220 10,797 Sep 22 10,933 10,735 10,814 Oct 22 10,956 10,596 10,832 Nov 22 11,004 10,986 10,871 Dec 22 11,046 10,937 10,918 Jan 23 11,113 11,273 10,955 Feb 23 11,135 10,982 10,986 Mar 23 11,171 11,260 11,045 Apr 23 11,230 11,329 11,083 May 23 11,270 11,205 11,110 Jun 23 11,298 11,165 11,163 Jul 23 11,363 11,158 11,209 Aug 23 11,419 11,086 11,260 Sep 23 11,452 10,805 11,310 Oct 23 11,511 10,634 11,361 Nov 23 11,581 11,116 11,420 Dec 23 11,654 11,541 11,479 Jan 24 11,704 11,510 11,529 Feb 24 11,739 11,347 11,570 Mar 24 11,789 11,452 11,621 Apr 24 11,838 11,162 11,668 May 24 11,888 11,352 11,723 Jun 24 11,949 11,459 11,772 Jul 24 12,023 11,727 11,832 See “Average annual total returns” for additional information on fund .
Average Annual Return [Table Text Block]	Average annual total returns Average Annual Total Returns 1 Year 5 Years 10 Years Institutional Shares ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.80 % 2.32 % 1.86 % Bloomberg U.S. Aggregate Bond Index ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.10 0.19 1.61 ICE BofA 6-Month U.S. Treasury Bill Index ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.58 2.32 1.70
No Deduction of Taxes [Text Block]	Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Performance Table Market Index Changed [Text Block]
Material Change Description [Text Block]
Updated Performance Information Location [Text Block]
AssetsNet	$ 1,133,264,082
Holdings Count \| Holding	239
Advisory Fees Paid, Amount	$ 1,584,361
InvestmentCompanyPortfolioTurnover	34%
Additional Fund Statistics [Text Block]	Key Fund statistics Net Assets ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ $1,133,264,082 Number of Portfolio Holdings ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 239 Net Investment Advisory Fees ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ $1,584,361 Portfolio Turnover Rate ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 34%
Holdings [Text Block]	Portfolio composition Maturity allocation Investment Type Percent of Net Assets Corporate Bonds ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 37.0 % Asset-Backed Securities ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.5 U.S. Treasury Obligations ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 1.6 Municipal Bonds ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 0.3 Foreign Agency Obligations ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 0.2 Short-Term Securities ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 56.0 Liabilities in Excess of Other Assets ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (0.6 ) Percent of Net Assets 1-7 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 7.5 % 8-14 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 6.1 15-30 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 3.9 31-60 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 8.5 61-90 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 10.6 91-120 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 10.2 121-150 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 1.5 >150 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 51.7
C000198747
Shareholder Report [Line Items]
Fund Name	BlackRock Short Obligations Fund
Class Name	Investor A Shares
Trading Symbol	BASOX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about BlackRock Short Obligations Fund (the “Fund”) for the period of August 1, 2023 to July 31, 2024.
Shareholder Report Annual or Semi-Annual	Annual Shareholder Report
Additional Information [Text Block]	You can find additional information about the Fund at blackrock.com/fundreports
Material Fund Change Notice [Text Block]
Additional Information Phone Number	(800) 441-7762
Additional Information Website	<span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;">blackrock.com/fundreports</span></span>" id="sjs-B48"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; font-weight: 400; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;">blackrock.com/fundreports</span></span>
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Class name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Investor A Shares $52 0.50%
Expenses Paid, Amount	$ 52
Expense Ratio, Percent	0.50%
Factors Affecting Performance [Text Block]	How did the Fund perform last year? Although inflation came down over the course of the annual period, it remained above the U.S. Federal Reserve’s (the “Fed”) stated 2% target. The Fed responded by keeping short-term interest rates in a range of 5.25% to 5.50%. The central bank’s decision to keep rates elevated translated to attractive yields on short-term debt. What contributed to performance? During the reporting period, the Fund’s duration and yield curve positioning contributed positively. The Fund’s sector allocations were also a source of positive contribution. What detracted from performance? At a time of positive returns for the broader asset class, no aspect of the Fund's positioning was a significant detractor.
Performance Past Does Not Indicate Future [Text]	Past performance is not an indication of future results. </span>Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles." id="sjs-B53"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;">Past performance is not an indication of future results. </span>Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles.
Line Graph [Table Text Block]	Fund performance Cumulative performance: August 1, 2014 through July 31, 2024 Initial investment of $10,000 Investor A Shares Bloomberg U.S. Aggregate Bond Index ICE BofA 6-Month U.S. Treasury Bill Index Aug 14 10,001 10,110 10,002 Sep 14 9,993 10,042 10,003 Oct 14 9,994 10,140 10,003 Nov 14 9,996 10,212 10,003 Dec 14 9,997 10,222 10,005 Jan 15 9,999 10,436 10,008 Feb 15 10,001 10,338 10,009 Mar 15 10,003 10,386 10,009 Apr 15 10,005 10,349 10,013 May 15 10,007 10,324 10,014 Jun 15 10,010 10,211 10,016 Jul 15 10,012 10,282 10,015 Aug 15 10,004 10,268 10,016 Sep 15 10,016 10,337 10,026 Oct 15 10,018 10,339 10,023 Nov 15 10,021 10,311 10,022 Dec 15 10,014 10,278 10,027 Jan 16 10,018 10,420 10,035 Feb 16 10,022 10,494 10,039 Mar 16 10,047 10,590 10,048 Apr 16 10,052 10,630 10,055 May 16 10,057 10,633 10,056 Jun 16 10,072 10,824 10,068 Jul 16 10,077 10,893 10,071 Aug 16 10,083 10,880 10,072 Sep 16 10,089 10,874 10,081 Oct 16 10,105 10,791 10,087 Nov 16 10,112 10,535 10,089 Dec 16 10,112 10,550 10,094 Jan 17 10,119 10,571 10,102 Feb 17 10,136 10,642 10,107 Mar 17 10,144 10,636 10,107 Apr 17 10,152 10,719 10,115 May 17 10,161 10,801 10,121 Jun 17 10,169 10,790 10,131 Jul 17 10,178 10,837 10,141 Aug 17 10,187 10,934 10,155 Sep 17 10,196 10,882 10,162 Oct 17 10,205 10,888 10,172 Nov 17 10,215 10,874 10,180 Dec 17 10,218 10,924 10,191 Jan 18 10,219 10,798 10,202 Feb 18 10,220 10,696 10,208 Mar 18 10,233 10,764 10,223 Apr 18 10,248 10,684 10,238 May 18 10,264 10,761 10,255 Jun 18 10,281 10,747 10,272 Jul 18 10,298 10,750 10,289 Aug 18 10,317 10,819 10,309 Sep 18 10,335 10,749 10,323 Oct 18 10,354 10,664 10,342 Nov 18 10,363 10,728 10,363 Dec 18 10,388 10,925 10,386 Jan 19 10,421 11,041 10,410 Feb 19 10,442 11,035 10,429 Mar 19 10,475 11,247 10,454 Apr 19 10,496 11,250 10,476 May 19 10,529 11,449 10,501 Jun 19 10,560 11,593 10,530 Jul 19 10,570 11,619 10,550 Aug 19 10,600 11,920 10,578 Sep 19 10,618 11,856 10,596 Oct 19 10,647 11,892 10,623 Nov 19 10,652 11,886 10,635 Dec 19 10,669 11,878 10,653 Jan 20 10,695 12,106 10,669 Feb 20 10,720 12,324 10,697 Mar 20 10,628 12,251 10,752 Apr 20 10,725 12,469 10,753 May 20 10,766 12,527 10,750 Jun 20 10,784 12,606 10,752 Jul 20 10,790 12,795 10,756 Aug 20 10,794 12,691 10,757 Sep 20 10,797 12,684 10,759 Oct 20 10,800 12,628 10,761 Nov 20 10,791 12,752 10,763 Dec 20 10,792 12,769 10,764 Jan 21 10,794 12,678 10,765 Feb 21 10,794 12,495 10,767 Mar 21 10,795 12,338 10,769 Apr 21 10,796 12,436 10,770 May 21 10,796 12,477 10,771 Jun 21 10,796 12,564 10,770 Jul 21 10,797 12,705 10,771 Aug 21 10,797 12,681 10,772 Sep 21 10,786 12,571 10,773 Oct 21 10,776 12,567 10,773 Nov 21 10,776 12,604 10,773 Dec 21 10,765 12,572 10,774 Jan 22 10,755 12,301 10,768 Feb 22 10,734 12,164 10,767 Mar 22 10,703 11,826 10,764 Apr 22 10,694 11,377 10,767 May 22 10,710 11,451 10,780 Jun 22 10,684 11,271 10,772 Jul 22 10,705 11,547 10,782 Aug 22 10,719 11,220 10,797 Sep 22 10,714 10,735 10,814 Oct 22 10,724 10,596 10,832 Nov 22 10,769 10,986 10,871 Dec 22 10,819 10,937 10,918 Jan 23 10,872 11,273 10,955 Feb 23 10,891 10,982 10,986 Mar 23 10,935 11,260 11,045 Apr 23 10,980 11,329 11,083 May 23 11,017 11,205 11,110 Jun 23 11,054 11,165 11,163 Jul 23 11,104 11,158 11,209 Aug 23 11,156 11,086 11,260 Sep 23 11,197 10,805 11,310 Oct 23 11,241 10,634 11,361 Nov 23 11,308 11,116 11,420 Dec 23 11,377 11,541 11,479 Jan 24 11,435 11,510 11,529 Feb 24 11,467 11,347 11,570 Mar 24 11,514 11,452 11,621 Apr 24 11,548 11,162 11,668 May 24 11,606 11,352 11,723 Jun 24 11,652 11,459 11,772 Jul 24 11,722 11,727 11,832 See “Average annual total returns” for additional information on fund .
Average Annual Return [Table Text Block]	Average annual total returns Average Annual Total Returns 1 Year 5 Years 10 Years Investor A Shares ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.56 % 2.09 % 1.60 % Bloomberg U.S. Aggregate Bond Index ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.10 0.19 1.61 ICE BofA 6-Month U.S. Treasury Bill Index ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.58 2.32 1.70
No Deduction of Taxes [Text Block]	Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Performance Table Market Index Changed [Text Block]
Material Change Description [Text Block]
Updated Performance Information Location [Text Block]
AssetsNet	$ 1,133,264,082
Holdings Count \| Holding	239
Advisory Fees Paid, Amount	$ 1,584,361
InvestmentCompanyPortfolioTurnover	34%
Additional Fund Statistics [Text Block]	Key Fund statistics Net Assets ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ $1,133,264,082 Number of Portfolio Holdings ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 239 Net Investment Advisory Fees ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ $1,584,361 Portfolio Turnover Rate ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 34%
Holdings [Text Block]	Portfolio composition Maturity allocation Investment Type Percent of Net Assets Corporate Bonds ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 37.0 % Asset-Backed Securities ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.5 U.S. Treasury Obligations ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 1.6 Municipal Bonds ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 0.3 Foreign Agency Obligations ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 0.2 Short-Term Securities ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 56.0 Liabilities in Excess of Other Assets ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (0.6 ) Percent of Net Assets 1-7 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 7.5 % 8-14 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 6.1 15-30 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 3.9 31-60 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 8.5 61-90 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 10.6 91-120 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 10.2 121-150 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 1.5 >150 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 51.7
C000119004
Shareholder Report [Line Items]
Fund Name	BlackRock Short Obligations Fund
Class Name	Class K Shares
Trading Symbol	BBSOX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about BlackRock Short Obligations Fund (the “Fund”) for the period of August 1, 2023 to July 31, 2024.
Shareholder Report Annual or Semi-Annual	Annual Shareholder Report
Additional Information [Text Block]	You can find additional information about the Fund at blackrock.com/fundreports
Material Fund Change Notice [Text Block]
Additional Information Phone Number	(800) 441-7762
Additional Information Website	<span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;">blackrock.com/fundreports</span></span>" id="sjs-B76"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; font-weight: 400; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;">blackrock.com/fundreports</span></span>
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Class name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class K Shares $21 0.20%
Expenses Paid, Amount	$ 21
Expense Ratio, Percent	0.20%
Factors Affecting Performance [Text Block]	How did the Fund perform last year? Although inflation came down over the course of the annual period, it remained above the U.S. Federal Reserve’s (the “Fed”) stated 2% target. The Fed responded by keeping short-term interest rates in a range of 5.25% to 5.50%. The central bank’s decision to keep rates elevated translated to attractive yields on short-term debt. What contributed to performance? During the reporting period, the Fund’s duration and yield curve positioning contributed positively. The Fund’s sector allocations were also a source of positive contribution. What detracted from performance? At a time of positive returns for the broader asset class, no aspect of the Fund's positioning was a significant detractor.
Performance Past Does Not Indicate Future [Text]	Past performance is not an indication of future results. </span>Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles." id="sjs-B81"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 10.6667px; grid-area: auto; line-height: 16px; margin: 0px; overflow: visible; text-align: justify;">Past performance is not an indication of future results. </span>Performance results may include adjustments made for financial reporting purposes in accordance with U.S. generally accepted accounting principles.
Line Graph [Table Text Block]	Fund performance Cumulative performance: August 1, 2014 through July 31, 2024 Initial investment of $10,000 Class K Shares Bloomberg U.S. Aggregate Bond Index ICE BofA 6-Month U.S. Treasury Bill Index Aug 14 10,004 10,110 10,002 Sep 14 9,998 10,042 10,003 Oct 14 10,003 10,140 10,003 Nov 14 10,007 10,212 10,003 Dec 14 10,012 10,222 10,005 Jan 15 10,017 10,436 10,008 Feb 15 10,021 10,338 10,009 Mar 15 10,026 10,386 10,009 Apr 15 10,031 10,349 10,013 May 15 10,036 10,324 10,014 Jun 15 10,042 10,211 10,016 Jul 15 10,047 10,282 10,015 Aug 15 10,042 10,268 10,016 Sep 15 10,057 10,337 10,026 Oct 15 10,062 10,339 10,023 Nov 15 10,068 10,311 10,022 Dec 15 10,064 10,278 10,027 Jan 16 10,071 10,420 10,035 Feb 16 10,078 10,494 10,039 Mar 16 10,106 10,590 10,048 Apr 16 10,114 10,630 10,055 May 16 10,122 10,633 10,056 Jun 16 10,140 10,824 10,068 Jul 16 10,148 10,893 10,071 Aug 16 10,157 10,880 10,072 Sep 16 10,166 10,874 10,081 Oct 16 10,185 10,791 10,087 Nov 16 10,195 10,535 10,089 Dec 16 10,198 10,550 10,094 Jan 17 10,208 10,571 10,102 Feb 17 10,228 10,642 10,107 Mar 17 10,240 10,636 10,107 Apr 17 10,250 10,719 10,115 May 17 10,262 10,801 10,121 Jun 17 10,273 10,790 10,131 Jul 17 10,285 10,837 10,141 Aug 17 10,297 10,934 10,155 Sep 17 10,309 10,882 10,162 Oct 17 10,322 10,888 10,172 Nov 17 10,335 10,874 10,180 Dec 17 10,341 10,924 10,191 Jan 18 10,346 10,798 10,202 Feb 18 10,349 10,696 10,208 Mar 18 10,366 10,764 10,223 Apr 18 10,383 10,684 10,238 May 18 10,412 10,761 10,255 Jun 18 10,421 10,747 10,272 Jul 18 10,442 10,750 10,289 Aug 18 10,473 10,819 10,309 Sep 18 10,494 10,749 10,323 Oct 18 10,506 10,664 10,342 Nov 18 10,528 10,728 10,363 Dec 18 10,545 10,925 10,386 Jan 19 10,591 11,041 10,410 Feb 19 10,615 11,035 10,429 Mar 19 10,640 11,247 10,454 Apr 19 10,665 11,250 10,476 May 19 10,700 11,449 10,501 Jun 19 10,734 11,593 10,530 Jul 19 10,757 11,619 10,550 Aug 19 10,780 11,920 10,578 Sep 19 10,801 11,856 10,596 Oct 19 10,832 11,892 10,623 Nov 19 10,841 11,886 10,635 Dec 19 10,860 11,878 10,653 Jan 20 10,890 12,106 10,669 Feb 20 10,918 12,324 10,697 Mar 20 10,826 12,251 10,752 Apr 20 10,928 12,469 10,753 May 20 10,973 12,527 10,750 Jun 20 10,993 12,606 10,752 Jul 20 11,002 12,795 10,756 Aug 20 11,009 12,691 10,757 Sep 20 11,015 12,684 10,759 Oct 20 11,020 12,628 10,761 Nov 20 11,025 12,752 10,763 Dec 20 11,029 12,769 10,764 Jan 21 11,033 12,678 10,765 Feb 21 11,025 12,495 10,767 Mar 21 11,029 12,338 10,769 Apr 21 11,032 12,436 10,770 May 21 11,036 12,477 10,771 Jun 21 11,039 12,564 10,770 Jul 21 11,042 12,705 10,771 Aug 21 11,045 12,681 10,772 Sep 21 11,036 12,571 10,773 Oct 21 11,039 12,567 10,773 Nov 21 11,031 12,604 10,773 Dec 21 11,024 12,572 10,774 Jan 22 11,016 12,301 10,768 Feb 22 10,997 12,164 10,767 Mar 22 10,968 11,826 10,764 Apr 22 10,962 11,377 10,767 May 22 10,980 11,451 10,780 Jun 22 10,957 11,271 10,772 Jul 22 10,981 11,547 10,782 Aug 22 10,998 11,220 10,797 Sep 22 10,996 10,735 10,814 Oct 22 11,008 10,596 10,832 Nov 22 11,057 10,986 10,871 Dec 22 11,112 10,937 10,918 Jan 23 11,169 11,273 10,955 Feb 23 11,191 10,982 10,986 Mar 23 11,239 11,260 11,045 Apr 23 11,288 11,329 11,083 May 23 11,329 11,205 11,110 Jun 23 11,369 11,165 11,163 Jul 23 11,424 11,158 11,209 Aug 23 11,480 11,086 11,260 Sep 23 11,526 10,805 11,310 Oct 23 11,574 10,634 11,361 Nov 23 11,645 11,116 11,420 Dec 23 11,719 11,541 11,479 Jan 24 11,770 11,510 11,529 Feb 24 11,807 11,347 11,570 Mar 24 11,858 11,452 11,621 Apr 24 11,907 11,162 11,668 May 24 11,970 11,352 11,723 Jun 24 12,020 11,459 11,772 Jul 24 12,096 11,727 11,832 See “Average annual total returns” for additional information on fund .
Average Annual Return [Table Text Block]	Average annual total returns Average Annual Total Returns 1 Year 5 Years 10 Years Class K Shares ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.88 % 2.37 % 1.92 % Bloomberg U.S. Aggregate Bond Index ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.10 0.19 1.61 ICE BofA 6-Month U.S. Treasury Bill Index ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.58 2.32 1.70
No Deduction of Taxes [Text Block]	Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.
Performance Table Market Index Changed [Text Block]
Material Change Description [Text Block]
Updated Performance Information Location [Text Block]
AssetsNet	$ 1,133,264,082
Holdings Count \| Holding	239
Advisory Fees Paid, Amount	$ 1,584,361
InvestmentCompanyPortfolioTurnover	34%
Additional Fund Statistics [Text Block]	Key Fund statistics Net Assets ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ $1,133,264,082 Number of Portfolio Holdings ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 239 Net Investment Advisory Fees ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ $1,584,361 Portfolio Turnover Rate ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 34%
Holdings [Text Block]	Portfolio composition Maturity allocation Investment Type Percent of Net Assets Corporate Bonds ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 37.0 % Asset-Backed Securities ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 5.5 U.S. Treasury Obligations ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 1.6 Municipal Bonds ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 0.3 Foreign Agency Obligations ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 0.2 Short-Term Securities ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 56.0 Liabilities in Excess of Other Assets ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ (0.6 ) Percent of Net Assets 1-7 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 7.5 % 8-14 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 6.1 15-30 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 3.9 31-60 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 8.5 61-90 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 10.6 91-120 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 10.2 121-150 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 1.5 >150 days ........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 51.7

Shareholder Report, Line Graph

Shareholder Report, Line Graph (Details) - USD ($)	1 Months Ended
Shareholder Report, Line Graph (Details) - USD ($)	Aug. 31, 2014	Jul. 31, 2024	Jun. 30, 2024	May 31, 2024	Apr. 30, 2024	Mar. 31, 2024	Feb. 29, 2024	Jan. 31, 2024	Dec. 31, 2023	Nov. 30, 2023	Oct. 31, 2023	Sep. 30, 2023	Aug. 31, 2023	Jul. 31, 2023	Jun. 30, 2023	May 31, 2023	Apr. 30, 2023	Mar. 31, 2023	Feb. 28, 2023	Jan. 31, 2023	Dec. 31, 2022	Nov. 30, 2022	Oct. 31, 2022	Sep. 30, 2022	Aug. 31, 2022	Jul. 31, 2022	Jun. 30, 2022	May 31, 2022	Apr. 30, 2022	Mar. 31, 2022	Feb. 28, 2022	Jan. 31, 2022	Dec. 31, 2021	Nov. 30, 2021	Oct. 31, 2021	Sep. 30, 2021	Aug. 31, 2021	Jul. 31, 2021	Jun. 30, 2021	May 31, 2021	Apr. 30, 2021	Mar. 31, 2021	Feb. 28, 2021	Jan. 31, 2021	Dec. 31, 2020	Nov. 30, 2020	Oct. 31, 2020	Sep. 30, 2020	Aug. 31, 2020	Jul. 31, 2020	Jun. 30, 2020	May 31, 2020	Apr. 30, 2020	Mar. 31, 2020	Feb. 29, 2020	Jan. 31, 2020	Dec. 31, 2019	Nov. 30, 2019	Oct. 31, 2019	Sep. 30, 2019	Aug. 31, 2019	Jul. 31, 2019	Jun. 30, 2019	May 31, 2019	Apr. 30, 2019	Mar. 31, 2019	Feb. 28, 2019	Jan. 31, 2019	Dec. 31, 2018	Nov. 30, 2018	Oct. 31, 2018	Sep. 30, 2018	Aug. 31, 2018	Jul. 31, 2018	Jun. 30, 2018	May 31, 2018	Apr. 30, 2018	Mar. 31, 2018	Feb. 28, 2018	Jan. 31, 2018	Dec. 31, 2017	Nov. 30, 2017	Oct. 31, 2017	Sep. 30, 2017	Aug. 31, 2017	Jul. 31, 2017	Jun. 30, 2017	May 31, 2017	Apr. 30, 2017	Mar. 31, 2017	Feb. 28, 2017	Jan. 31, 2017	Dec. 31, 2016	Nov. 30, 2016	Oct. 31, 2016	Sep. 30, 2016	Aug. 31, 2016	Jul. 31, 2016	Jun. 30, 2016	May 31, 2016	Apr. 30, 2016	Mar. 31, 2016	Feb. 29, 2016	Jan. 31, 2016	Dec. 31, 2015	Nov. 30, 2015	Oct. 31, 2015	Sep. 30, 2015	Aug. 31, 2015	Jul. 31, 2015	Jun. 30, 2015	May 31, 2015	Apr. 30, 2015	Mar. 31, 2015	Feb. 28, 2015	Jan. 31, 2015	Dec. 31, 2014	Nov. 30, 2014	Oct. 31, 2014	Sep. 30, 2014
C000129315
Account Value [Line Items]
Account Value	$ 10,004	$ 12,023	$ 11,949	$ 11,888	$ 11,838	$ 11,789	$ 11,739	$ 11,704	$ 11,654	$ 11,581	$ 11,511	$ 11,452	$ 11,419	$ 11,363	$ 11,298	$ 11,270	$ 11,230	$ 11,171	$ 11,135	$ 11,113	$ 11,046	$ 11,004	$ 10,956	$ 10,933	$ 10,947	$ 10,931	$ 10,896	$ 10,920	$ 10,902	$ 10,909	$ 10,949	$ 10,958	$ 10,977	$ 10,974	$ 10,983	$ 10,992	$ 10,989	$ 10,987	$ 10,985	$ 10,993	$ 10,979	$ 10,977	$ 10,985	$ 10,982	$ 10,979	$ 10,975	$ 10,971	$ 10,966	$ 10,971	$ 10,965	$ 10,946	$ 10,926	$ 10,882	$ 10,782	$ 10,874	$ 10,858	$ 10,829	$ 10,811	$ 10,793	$ 10,773	$ 10,753	$ 10,720	$ 10,698	$ 10,664	$ 10,630	$ 10,617	$ 10,581	$ 10,559	$ 10,513	$ 10,497	$ 10,475	$ 10,463	$ 10,443	$ 10,412	$ 10,392	$ 10,383	$ 10,354	$ 10,338	$ 10,333	$ 10,319	$ 10,316	$ 10,311	$ 10,299	$ 10,297	$ 10,286	$ 10,275	$ 10,264	$ 10,253	$ 10,232	$ 10,221	$ 10,221	$ 10,201	$ 10,192	$ 10,178	$ 10,169	$ 10,160	$ 10,152	$ 10,143	$ 10,125	$ 10,118	$ 10,110	$ 10,103	$ 10,074	$ 10,067	$ 10,061	$ 10,065	$ 10,059	$ 10,055	$ 10,050	$ 10,045	$ 10,040	$ 10,035	$ 10,029	$ 10,024	$ 10,020	$ 10,025	$ 10,011	$ 10,016	$ 10,012	$ 10,008
C000198747
Account Value [Line Items]
Account Value	10,001	11,722	11,652	11,606	11,548	11,514	11,467	11,435	11,377	11,308	11,241	11,197	11,156	11,104	11,054	11,017	10,980	10,935	10,891	10,872	10,819	10,769	10,724	10,714	10,719	10,705	10,684	10,710	10,694	10,703	10,734	10,755	10,765	10,776	10,776	10,786	10,797	10,797	10,796	10,796	10,796	10,795	10,794	10,794	10,792	10,791	10,800	10,797	10,794	10,790	10,784	10,766	10,725	10,628	10,720	10,695	10,669	10,652	10,647	10,618	10,600	10,570	10,560	10,529	10,496	10,475	10,442	10,421	10,388	10,363	10,354	10,335	10,317	10,298	10,281	10,264	10,248	10,233	10,220	10,219	10,218	10,215	10,205	10,196	10,187	10,178	10,169	10,161	10,152	10,144	10,136	10,119	10,112	10,112	10,105	10,089	10,083	10,077	10,072	10,057	10,052	10,047	10,022	10,018	10,014	10,021	10,018	10,016	10,004	10,012	10,010	10,007	10,005	10,003	10,001	9,999	9,997	9,996	9,994	9,993
C000119004
Account Value [Line Items]
Account Value	10,004	12,096	12,020	11,970	11,907	11,858	11,807	11,770	11,719	11,645	11,574	11,526	11,480	11,424	11,369	11,329	11,288	11,239	11,191	11,169	11,112	11,057	11,008	10,996	10,998	10,981	10,957	10,980	10,962	10,968	10,997	11,016	11,024	11,031	11,039	11,036	11,045	11,042	11,039	11,036	11,032	11,029	11,025	11,033	11,029	11,025	11,020	11,015	11,009	11,002	10,993	10,973	10,928	10,826	10,918	10,890	10,860	10,841	10,832	10,801	10,780	10,757	10,734	10,700	10,665	10,640	10,615	10,591	10,545	10,528	10,506	10,494	10,473	10,442	10,421	10,412	10,383	10,366	10,349	10,346	10,341	10,335	10,322	10,309	10,297	10,285	10,273	10,262	10,250	10,240	10,228	10,208	10,198	10,195	10,185	10,166	10,157	10,148	10,140	10,122	10,114	10,106	10,078	10,071	10,064	10,068	10,062	10,057	10,042	10,047	10,042	10,036	10,031	10,026	10,021	10,017	10,012	10,007	10,003	9,998
FR TSR Growth 10k - Benchmark 1
Account Value [Line Items]
Account Value	10,110	11,727	11,459	11,352	11,162	11,452	11,347	11,510	11,541	11,116	10,634	10,805	11,086	11,158	11,165	11,205	11,329	11,260	10,982	11,273	10,937	10,986	10,596	10,735	11,220	11,547	11,271	11,451	11,377	11,826	12,164	12,301	12,572	12,604	12,567	12,571	12,681	12,705	12,564	12,477	12,436	12,338	12,495	12,678	12,769	12,752	12,628	12,684	12,691	12,795	12,606	12,527	12,469	12,251	12,324	12,106	11,878	11,886	11,892	11,856	11,920	11,619	11,593	11,449	11,250	11,247	11,035	11,041	10,925	10,728	10,664	10,749	10,819	10,750	10,747	10,761	10,684	10,764	10,696	10,798	10,924	10,874	10,888	10,882	10,934	10,837	10,790	10,801	10,719	10,636	10,642	10,571	10,550	10,535	10,791	10,874	10,880	10,893	10,824	10,633	10,630	10,590	10,494	10,420	10,278	10,311	10,339	10,337	10,268	10,282	10,211	10,324	10,349	10,386	10,338	10,436	10,222	10,212	10,140	10,042
FR TSR Growth 10k - Benchmark 1
Account Value [Line Items]
Account Value	10,110	11,727	11,459	11,352	11,162	11,452	11,347	11,510	11,541	11,116	10,634	10,805	11,086	11,158	11,165	11,205	11,329	11,260	10,982	11,273	10,937	10,986	10,596	10,735	11,220	11,547	11,271	11,451	11,377	11,826	12,164	12,301	12,572	12,604	12,567	12,571	12,681	12,705	12,564	12,477	12,436	12,338	12,495	12,678	12,769	12,752	12,628	12,684	12,691	12,795	12,606	12,527	12,469	12,251	12,324	12,106	11,878	11,886	11,892	11,856	11,920	11,619	11,593	11,449	11,250	11,247	11,035	11,041	10,925	10,728	10,664	10,749	10,819	10,750	10,747	10,761	10,684	10,764	10,696	10,798	10,924	10,874	10,888	10,882	10,934	10,837	10,790	10,801	10,719	10,636	10,642	10,571	10,550	10,535	10,791	10,874	10,880	10,893	10,824	10,633	10,630	10,590	10,494	10,420	10,278	10,311	10,339	10,337	10,268	10,282	10,211	10,324	10,349	10,386	10,338	10,436	10,222	10,212	10,140	10,042
FR TSR Growth 10k - Benchmark 1
Account Value [Line Items]
Account Value	$ 10,110	$ 11,727	$ 11,459	$ 11,352	$ 11,162	$ 11,452	$ 11,347	$ 11,510	$ 11,541	$ 11,116	$ 10,634	$ 10,805	$ 11,086	$ 11,158	$ 11,165	$ 11,205	$ 11,329	$ 11,260	$ 10,982	$ 11,273	$ 10,937	$ 10,986	$ 10,596	$ 10,735	$ 11,220	$ 11,547	$ 11,271	$ 11,451	$ 11,377	$ 11,826	$ 12,164	$ 12,301	$ 12,572	$ 12,604	$ 12,567	$ 12,571	$ 12,681	$ 12,705	$ 12,564	$ 12,477	$ 12,436	$ 12,338	$ 12,495	$ 12,678	$ 12,769	$ 12,752	$ 12,628	$ 12,684	$ 12,691	$ 12,795	$ 12,606	$ 12,527	$ 12,469	$ 12,251	$ 12,324	$ 12,106	$ 11,878	$ 11,886	$ 11,892	$ 11,856	$ 11,920	$ 11,619	$ 11,593	$ 11,449	$ 11,250	$ 11,247	$ 11,035	$ 11,041	$ 10,925	$ 10,728	$ 10,664	$ 10,749	$ 10,819	$ 10,750	$ 10,747	$ 10,761	$ 10,684	$ 10,764	$ 10,696	$ 10,798	$ 10,924	$ 10,874	$ 10,888	$ 10,882	$ 10,934	$ 10,837	$ 10,790	$ 10,801	$ 10,719	$ 10,636	$ 10,642	$ 10,571	$ 10,550	$ 10,535	$ 10,791	$ 10,874	$ 10,880	$ 10,893	$ 10,824	$ 10,633	$ 10,630	$ 10,590	$ 10,494	$ 10,420	$ 10,278	$ 10,311	$ 10,339	$ 10,337	$ 10,268	$ 10,282	$ 10,211	$ 10,324	$ 10,349	$ 10,386	$ 10,338	$ 10,436	$ 10,222	$ 10,212	$ 10,140	$ 10,042
BlackRock Short Obligations Fund
Account Value [Line Items]
Line Graph and Table Measure Name	Bloomberg U.S. Aggregate Bond Index
BlackRock Short Obligations Fund
Account Value [Line Items]
Line Graph and Table Measure Name	Bloomberg U.S. Aggregate Bond Index
BlackRock Short Obligations Fund
Account Value [Line Items]
Line Graph and Table Measure Name	Bloomberg U.S. Aggregate Bond Index

Shareholder Report, Average Ann

Shareholder Report, Average Annual Return (Details)	1 Months Ended	12 Months Ended	60 Months Ended	120 Months Ended
Shareholder Report, Average Annual Return (Details)	Aug. 31, 2014	Jul. 31, 2024	Jul. 31, 2024	Jul. 31, 2024
Without Sales Load [Member] \| C000129315
Average Annual Return [Line Items]
Average Annual Return, Percent		5.80%	2.32%	1.86%
Without Sales Load [Member] \| C000198747
Average Annual Return [Line Items]
Average Annual Return, Percent		5.56%	2.09%	1.60%
Without Sales Load [Member] \| C000119004
Average Annual Return [Line Items]
Average Annual Return, Percent		5.88%	2.37%	1.92%
FR Notes - Benchmark total return 1 year w/o sales charge
Average Annual Return [Line Items]
Average Annual Return, Percent		5.10%
FR Notes - Benchmark total return 5 year
Average Annual Return [Line Items]
Average Annual Return, Percent			0.19%
FR Notes - Benchmark total return 10 year
Average Annual Return [Line Items]
Average Annual Return, Percent				1.61%
FR Notes - Benchmark total return 1 year w/o sales charge
Average Annual Return [Line Items]
Average Annual Return, Percent		5.10%
FR Notes - Benchmark total return 5 year
Average Annual Return [Line Items]
Average Annual Return, Percent			0.19%
FR Notes - Benchmark total return 10 year
Average Annual Return [Line Items]
Average Annual Return, Percent				1.61%
FR Notes - Benchmark total return 1 year w/o sales charge
Average Annual Return [Line Items]
Average Annual Return, Percent		5.10%
FR Notes - Benchmark total return 5 year
Average Annual Return [Line Items]
Average Annual Return, Percent			0.19%
FR Notes - Benchmark total return 10 year
Average Annual Return [Line Items]
Average Annual Return, Percent				1.61%
BlackRock Short Obligations Fund
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Bloomberg U.S. Aggregate Bond Index
FR Notes - Benchmark total return 1 year w/o sales charge - 2
Average Annual Return [Line Items]
Average Annual Return, Percent		5.58%
FR Notes - Benchmark total return 5 year - 2
Average Annual Return [Line Items]
Average Annual Return, Percent			2.32%
FR Notes - Benchmark total return 10 year - 2
Average Annual Return [Line Items]
Average Annual Return, Percent				1.70%
BlackRock Short Obligations Fund
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Bloomberg U.S. Aggregate Bond Index
FR Notes - Benchmark total return 1 year w/o sales charge - 2
Average Annual Return [Line Items]
Average Annual Return, Percent		5.58%
FR Notes - Benchmark total return 5 year - 2
Average Annual Return [Line Items]
Average Annual Return, Percent			2.32%
FR Notes - Benchmark total return 10 year - 2
Average Annual Return [Line Items]
Average Annual Return, Percent				1.70%
BlackRock Short Obligations Fund
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Bloomberg U.S. Aggregate Bond Index
FR Notes - Benchmark total return 1 year w/o sales charge - 2
Average Annual Return [Line Items]
Average Annual Return, Percent		5.58%
FR Notes - Benchmark total return 5 year - 2
Average Annual Return [Line Items]
Average Annual Return, Percent			2.32%
FR Notes - Benchmark total return 10 year - 2
Average Annual Return [Line Items]
Average Annual Return, Percent				1.70%

Shareholder Report, Holdings (D

Shareholder Report, Holdings (Details)	Jul. 31, 2024
C000129315 \| 1-7 days
Holdings [Line Items]
Percent of Net Asset Value	7.50%
C000129315 \| 8-14 days
Holdings [Line Items]
Percent of Net Asset Value	6.10%
C000129315 \| 15-30 days
Holdings [Line Items]
Percent of Net Asset Value	3.90%
C000129315 \| 31-60 days
Holdings [Line Items]
Percent of Net Asset Value	8.50%
C000129315 \| 61-90 days
Holdings [Line Items]
Percent of Net Asset Value	10.60%
C000129315 \| 91-120 days
Holdings [Line Items]
Percent of Net Asset Value	10.20%
C000129315 \| 121-150 days
Holdings [Line Items]
Percent of Net Asset Value	1.50%
C000129315 \| >150 days
Holdings [Line Items]
Percent of Net Asset Value	51.70%
C000129315 \| Corporate Bonds
Holdings [Line Items]
Percent of Net Asset Value	37%
C000129315 \| Asset-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	5.50%
C000129315 \| U.S. Treasury Obligations
Holdings [Line Items]
Percent of Net Asset Value	1.60%
C000129315 \| Municipal Bonds
Holdings [Line Items]
Percent of Net Asset Value	0.30%
C000129315 \| Foreign Agency Obligations
Holdings [Line Items]
Percent of Net Asset Value	0.20%
C000129315 \| Short-Term Securities
Holdings [Line Items]
Percent of Net Asset Value	56%
C000129315 \| Liabilities in Excess of Other Assets
Holdings [Line Items]
Percent of Net Asset Value	(0.60%)
C000198747 \| 1-7 days
Holdings [Line Items]
Percent of Net Asset Value	7.50%
C000198747 \| 8-14 days
Holdings [Line Items]
Percent of Net Asset Value	6.10%
C000198747 \| 15-30 days
Holdings [Line Items]
Percent of Net Asset Value	3.90%
C000198747 \| 31-60 days
Holdings [Line Items]
Percent of Net Asset Value	8.50%
C000198747 \| 61-90 days
Holdings [Line Items]
Percent of Net Asset Value	10.60%
C000198747 \| 91-120 days
Holdings [Line Items]
Percent of Net Asset Value	10.20%
C000198747 \| 121-150 days
Holdings [Line Items]
Percent of Net Asset Value	1.50%
C000198747 \| >150 days
Holdings [Line Items]
Percent of Net Asset Value	51.70%
C000198747 \| Corporate Bonds
Holdings [Line Items]
Percent of Net Asset Value	37%
C000198747 \| Asset-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	5.50%
C000198747 \| U.S. Treasury Obligations
Holdings [Line Items]
Percent of Net Asset Value	1.60%
C000198747 \| Municipal Bonds
Holdings [Line Items]
Percent of Net Asset Value	0.30%
C000198747 \| Foreign Agency Obligations
Holdings [Line Items]
Percent of Net Asset Value	0.20%
C000198747 \| Short-Term Securities
Holdings [Line Items]
Percent of Net Asset Value	56%
C000198747 \| Liabilities in Excess of Other Assets
Holdings [Line Items]
Percent of Net Asset Value	(0.60%)
C000119004 \| 1-7 days
Holdings [Line Items]
Percent of Net Asset Value	7.50%
C000119004 \| 8-14 days
Holdings [Line Items]
Percent of Net Asset Value	6.10%
C000119004 \| 15-30 days
Holdings [Line Items]
Percent of Net Asset Value	3.90%
C000119004 \| 31-60 days
Holdings [Line Items]
Percent of Net Asset Value	8.50%
C000119004 \| 61-90 days
Holdings [Line Items]
Percent of Net Asset Value	10.60%
C000119004 \| 91-120 days
Holdings [Line Items]
Percent of Net Asset Value	10.20%
C000119004 \| 121-150 days
Holdings [Line Items]
Percent of Net Asset Value	1.50%
C000119004 \| >150 days
Holdings [Line Items]
Percent of Net Asset Value	51.70%
C000119004 \| Corporate Bonds
Holdings [Line Items]
Percent of Net Asset Value	37%
C000119004 \| Asset-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	5.50%
C000119004 \| U.S. Treasury Obligations
Holdings [Line Items]
Percent of Net Asset Value	1.60%
C000119004 \| Municipal Bonds
Holdings [Line Items]
Percent of Net Asset Value	0.30%
C000119004 \| Foreign Agency Obligations
Holdings [Line Items]
Percent of Net Asset Value	0.20%
C000119004 \| Short-Term Securities
Holdings [Line Items]
Percent of Net Asset Value	56%
C000119004 \| Liabilities in Excess of Other Assets
Holdings [Line Items]
Percent of Net Asset Value	(0.60%)