v3.26.3
Janus Henderson Money Market Fund Investment Risks - Class T Shares [Member] - Janus Henderson Money Market Fund
Jun. 30, 2026
Money Market Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Money Market Risk.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 the sale of your Shares.An investment in the Fund is not a bank account and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.The Adviser is not required to reimburse the Fund for losses, and you should not expect that the Adviser will provide financial support to the Fund at any time, including during periods of market stress.Accordingly, if the value of Fund Shares were to fall below $1.00 per share, there is no guarantee that the Adviser or its affiliates would protect the Fund or redeeming shareholders against any loss of principal.
Liquidity Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Liquidity Risk. The liquidity of the securities which the Fund holds may deteriorate rapidly due to credit events affecting one or more issuers or guarantors or due to general market conditions and a lack of willing buyers. In such cases, the Fund may have to accept a lower price or may be unable to sell a security. An inability to sell one or more securities may negatively affect the Fund’s ability to maintain a $1.00 share price or prevent the Fund from being able to take advantage of other investment opportunities. Additionally, adverse market conditions impacting the trading of the value of money market instruments and/or an unusually high volume of redemption requests could cause the Fund to be unable to pay redemption proceeds within a short period of time. If the Fund is forced to sell securities at an unfavorable time and/or under unfavorable conditions, such sales may adversely affect the Fund’s ability to maintain the value of your investment at $1.00 per share.
Credit Quality Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Credit Quality Risk. The value of the securities which the Fund holds may fall based on an issuer’s actual or perceived creditworthiness, or an issuer’s ability to meet its obligations. The credit quality of the Fund’s holdings can change rapidly in certain market environments and any downgrade or default of a portfolio security could cause the Fund’s yield to fall or cause the value of the Fund’s Shares to fall below $1.00 per share.
Interest Rate Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Interest Rate Risk. Although the Fund seeks to invest only in high-quality, short-term money market instruments, there is a risk that the value of the securities it holds will fall as a result of the changes in interest rates. Rising interest rates could cause the value of the Fund’s investments to decline, and a decline in interest rates is likely to cause the Fund’s yield to decline. During periods of unusually low or negative interest rates, the Fund’s yield may approach or fall below zero. Such low interest rate environments may prevent the Fund from providing a positive yield or could impair the Fund’s ability to maintain the value of your investment at $1.00 per share. Over time, the real value of the Fund’s yield may be eroded by inflation.
Retail Money Market Fund Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Retail Money Market Fund Risk. The Fund is classified as a “retail money market fund,” as such term is defined in or interpreted under the rules governing money market funds. A retail money market fund is a money market fund that has policies and procedures reasonably designed to limit all beneficial owners of the fund to natural persons. The Fund may impose a discretionary liquidity fee of up to 2% on Fund redemptions if the Fund’s Board of Trustees, or its delegate, determines that a liquidity fee is in the best interests of the Fund. The Board of Trustees has delegated liquidity fee determinations to the Adviser, subject to Board guidelines and oversight.
Market Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Market Risk. The Fund’s yield will vary as the short-term securities in its portfolio mature and the proceeds are reinvested in securities with different interest rates. For capital preservation and liquidity, the Fund may have a greater concentration in short-term securities including, but not limited to, investing up to all of its assets in overnight securities, which may result in a reduction of the Fund’s yield.
Collateral Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Collateral Risk. With respect to collateral received in repurchase transactions or other investments, the Fund may have significant exposure to financial services, mortgage markets, and government agencies not secured by the full faith and credit of the United States. Such exposure, depending on market conditions, could have a negative impact on the Fund, including minimizing the value of any collateral.
Counterparty Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Counterparty Risk. Fund transactions involving a counterparty are subject to the risk that the counterparty or a third party will not fulfill its obligation to the Fund (“counterparty risk”). Counterparty risk may arise because of the counterparty’s financial condition (i.e., financial difficulties, bankruptcy, or insolvency), market activities and developments, or other reasons, whether foreseen or not. A counterparty’s inability to fulfill its obligation may result in significant financial loss to the Fund. The Fund may be unable to recover its investment from the counterparty or may obtain a limited recovery, and/or recovery may be delayed. The Fund may be exposed to counterparty risk through its investments in certain securities, including, but not limited to, repurchase agreements and debt securities. The Fund intends to enter into financial transactions with counterparties that the Adviser believes to be creditworthy at the time of the transaction. There is always the risk that the Adviser’s analysis of a counterparty’s creditworthiness is incorrect or may change due to market conditions. To the extent that the Fund focuses its transactions with a limited number of counterparties, it will have greater exposure to the risks associated with one or more counterparties.
Commercial Paper Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Commercial Paper Risk. Commercial paper is a debt obligation usually issued by corporations in order to finance their current operations. Commercial paper is usually repaid at maturity by the issuer from the proceeds of the issuance of new commercial paper. As a result, investments in commercial paper are subject to the risk that the issuer cannot issue enough new commercial paper to satisfy its outstanding commercial paper, also known as rollover risk. In addition, under certain circumstances commercial paper may become illiquid or may suffer from reduced liquidity.
Variable and Floating Rate Demand Notes Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Variable and Floating Rate Demand Notes Risk. Variable and floating rate securities are subject to changes in value based on changes in market interest rates or changes in the issuer’s or guarantor’s creditworthiness. Demand features, which are often issued by third-party financial institutions, may shorten the life of a variable or floating rate security. Accordingly, the credit quality and liquidity of the Fund’s investments may be dependent in part on the credit quality of the third-party financial institutions supporting the Fund’s investments. In addition, the absence of an active market for these securities could make it difficult for the Fund to dispose of them if the issuer defaults and the third party is unable to fulfill its liquidity or guarantee demand feature obligations.
U.S. Government Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] U.S. Government Securities Risk. Certain U.S. Government securities are not guaranteed or backed by the full faith and credit of the United States. For these securities, the Fund must look principally to the agency or instrumentality issuing or guaranteeing the securities for repayment and may not be able to assert a claim against the United States if the agency or instrumentality does not meet its commitment. Such securities may involve increased risk of loss of principal and interest compared to government debt securities that are backed by the full faith and credit of the United States.
Repurchase Agreement Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] Repurchase Agreement Risk. Repurchase agreements involve the risk that the seller will fail to repurchase the security, as agreed. In that case, the Fund will bear the risk of market value fluctuations until the security can be sold and may encounter delays and incur costs in liquidating the security.
Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] You could lose money by investing in the Fund.
Risk Not Insured [Member]  
Prospectus [Line Items]  
Risk [Text Block] An investment in the Fund is not a bank account and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk Money Market Fund May Not Preserve Dollar [Member]  
Prospectus [Line Items]  
Risk [Text Block] Although the Fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so.
Risk Money Market Fund Sponsor May Not Provide Support [Member]  
Prospectus [Line Items]  
Risk [Text Block] The Adviser is not required to reimburse the Fund for losses, and you should not expect that the Adviser will provide financial support to the Fund at any time, including during periods of market stress.