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(B) If the Fund is a Money Market Fund that is a government Money Market Fund, as defined in \u00a7 270.2a\u20137(a)(16), or a retail Money Market Fund, as defined in \u00a7 270.2a\u20137(a)(25), and that is subject to the requirements of \u00a7\u00a7 270.2a\u20137(c)(2)(i) and/or (ii) of this chapter (or is not subject to the requirements of \u00a7\u00a7 270.2a\u20137(c)(2)(i) and/or (ii) of this chapter pursuant to \u00a7 270.2a\u20137(c)(2)(iii) of this chapter, but has chosen to rely on the ability to impose liquidity fees and suspend redemptions consistent with the requirements of \u00a7\u00a7 270.2a\u20137(c)(2)(i) and/or (ii)), include the following statement: You could lose money by investing in the Fund. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The Fund may impose a fee upon sale of your shares or may temporarily suspend your ability to sell shares if the Fund's liquidity falls below required minimums because of market conditions or other factors. An investment in the Fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The Fund's sponsor has no legal obligation to provide financial support to the Fund, and you should not expect that the sponsor will provide financial support to the Fund at any time.  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If an affiliated person, promoter, or principal underwriter of the Fund, or an affiliated person of such a person, has contractually committed to provide financial support to the Fund, and the term of the agreement will extend for at least one year following the effective date of the Fund's registration statement, the statement specified in Item 4(b)(1)(ii)(A), Item 4(b)(1)(ii)(B), or Item 4(b)(1)(ii)(C) may omit the last sentence (\"The Fund's sponsor has no legal obligation to provide financial support to the Fund, and you should not expect that the sponsor will provide financial support to the Fund at any time.\"). 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      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsTREASURYTRUSTFUNDCapital",
      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsTREASURYTRUSTFUNDCashManagement",
      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsTREASURYTRUSTFUNDCashReserve",
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      "en-us": {
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        "label": "Risk Money Market Fund May Impose Fees or Suspend Sales [Text]"
       }
      }
     },
     "localname": "RiskMoneyMarketFundMayImposeFeesOrSuspendSales",
     "nsuri": "http://xbrl.sec.gov/rr/2021",
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      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKLIQUIDFEDERALTRUSTFUNDCapital",
      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsBLACKROCKLIQUIDFEDERALTRUSTFUNDCashManagement",
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      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsTEMPFUNDDollar",
      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsTEMPFUNDInstitutional",
      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsTEMPFUNDPrivateClient",
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      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsTFUNDDollar",
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      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsTFUNDPremier",
      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsTFUNDSelect",
      "http://www.blackrock.com/role/DisclosureRiskReturnDetailDataElementsTREASURYTRUSTFUNDAdministration",
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      }
     },
     "localname": "RiskMoneyMarketFundMayNotPreserveDollar",
     "nsuri": "http://xbrl.sec.gov/rr/2021",
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