Janus Henderson Flexible Bond Fund Investment Strategy - Class A C S I N R T Shares [Member] - Janus Henderson Flexible Bond Fund	Jun. 30, 2026
Prospectus [Line Items]
Strategy [Heading]	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;margin-left:0.0pt;text-transform:uppercase;">Principal investment strategies</span>
Strategy Narrative [Text Block]	The Fund pursues its investment objective by investing, under normal circumstances, at least 80% of its net assets (plus any borrowings for investment purposes) in bonds and other debt instruments. Derivative instruments that provide investment exposure to investments in the Fund’s 80% investment policy, or to one or more of the market risk factors associated with such investments, may be counted toward compliance with the Fund’s 80% investment policy. Bonds and other debt instruments are used by issuers to borrow money. The issuer usually pays interest at a fixed, variable, or floating rate, and must repay the amount borrowed, normally at the maturity of the security. Bonds and other debt instruments include, but are not limited to, government notes and bonds, corporate bonds, commercial and residential mortgage-backed securities, asset-backed securities, credit risk transfer securities (“CRTs”), money market instruments, fixed and floating rate obligations with varying durations, and debt instruments that have contractual restrictions that prohibit or limit their public resale, which may include Rule 144A debt securities. The Fund’s average portfolio duration typically ranges between three and seven years. As of June 30, 2026, the Fund’s average portfolio duration was 5.75 years. The Fund will invest at least 65% of its net assets in investment grade debt instruments. The Fund will limit its investment in below investment grade debt instruments (also known as “junk” bonds) to 35% or less of its net assets. The Fund generates total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund may enter into “to be announced” or “TBA” commitments when purchasing mortgage-backed securities or other securities. The Fund may also invest in foreign securities. Due to the nature of the securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. Additionally, the Fund may invest its assets in derivatives. Derivative instruments have a value derived from, or directly linked to, an underlying asset, such as fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use futures, including Treasury bond futures, to manage interest rate risk, yield curve positioning, and country exposure. The Fund may also use index credit default swaps for hedging purposes (to offset risks associated with an investment exposure, or market conditions), to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund relative to its benchmark index, and to earn income, enhance returns, or preserve capital. The Fund’s exposure to derivatives will vary. The Fund may take short positions on derivatives instruments. Portfolio management’s investment process is research-driven, incorporating “top-down” and “bottom-up” factors to identify and manage exposure to risks across sectors, industries, and individual investments. Portfolio management evaluates expected risk-adjusted returns on a portfolio and position level by analyzing fundamentals, valuations, and market technical indicators. This research encompasses both traditional fundamental analysis and data driven quantitative models and signals from such models.As part of its investment process, portfolio management considers environmental, social, and governance (“ESG”) risks and opportunities (“ESG Factors”) that it believes are financially material, alongside other fundamental investment factors. Examples of potential financially material ESG Factors include: corporate governance, company culture, exposure to climate change, and human capital management. To assess ESG Factors, portfolio management uses issuer reports, third-party data, and internally-generated analyses and may engage directly with issuers. ESG Factors are one of many considerations in the investment decision-making process, may not be determinative in deciding to include or exclude an investment from the portfolio, and may not be considered for every investment decision.The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions, in an amount equal to up to one-third of its total assets as determined at the time of the loan origination.

Janus Henderson Flexible Bond Fund Investment Strategy - Class A C S I N R T Shares [Member] - Janus Henderson Flexible Bond Fund

Jun. 30, 2026

<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;margin-left:0.0pt;text-transform:uppercase;">Principal investment strategies</span>

Strategy Narrative [Text Block]

The Fund pursues its investment objective by investing, under normal circumstances, at least 80% of its net assets (plus any borrowings for investment purposes) in bonds and other debt instruments. Derivative instruments that provide investment exposure to investments in the Fund’s 80% investment policy, or to one or more of the market risk factors associated with such investments, may be counted toward compliance with the Fund’s 80% investment policy. Bonds and other debt instruments are used by issuers to borrow money. The issuer usually pays interest at a fixed, variable, or floating rate, and must repay the amount borrowed, normally at the maturity of the security. Bonds and other debt instruments include, but are not limited to, government notes and bonds, corporate bonds, commercial and residential mortgage-backed securities, asset-backed securities, credit risk transfer securities (“CRTs”), money market instruments, fixed and floating rate obligations with varying durations, and debt instruments that have contractual restrictions that prohibit or limit their public resale, which may include Rule 144A debt securities. The Fund’s average portfolio duration typically ranges between three and seven years. As of June 30, 2026, the Fund’s average portfolio duration was 5.75 years. The Fund will invest at least 65% of its net assets in investment grade debt instruments. The Fund will limit its investment in below investment grade debt instruments (also known as “junk” bonds) to 35% or less of its net assets. The Fund generates total return from a combination of current income and capital appreciation, but income is usually the dominant portion. The Fund may enter into “to be announced” or “TBA” commitments when purchasing mortgage-backed securities or other securities. The Fund may also invest in foreign securities. Due to the nature of the securities in which the Fund invests, it may have relatively high portfolio turnover compared to other funds. Additionally, the Fund may invest its assets in derivatives. Derivative instruments have a value derived from, or directly linked to, an underlying asset, such as fixed-income securities, commodities, currencies, interest rates, or market indices. In particular, the Fund may use futures, including Treasury bond futures, to manage interest rate risk, yield curve positioning, and country exposure. The Fund may also use index credit default swaps for hedging purposes (to offset risks associated with an investment exposure, or market conditions), to increase or decrease the Fund’s exposure to a particular market, to manage or adjust the risk profile of the Fund relative to its benchmark index, and to earn income, enhance returns, or preserve capital. The Fund’s exposure to derivatives will vary. The Fund may take short positions on derivatives instruments. Portfolio management’s investment process is research-driven, incorporating “top-down” and “bottom-up” factors to identify and manage exposure to risks across sectors, industries, and individual investments. Portfolio management evaluates expected risk-adjusted returns on a portfolio and position level by analyzing fundamentals, valuations, and market technical indicators. This research encompasses both traditional fundamental analysis and data driven quantitative models and signals from such models.As part of its investment process, portfolio management considers environmental, social, and governance (“ESG”) risks and opportunities (“ESG Factors”) that it believes are financially material, alongside other fundamental investment factors. Examples of potential financially material ESG Factors include: corporate governance, company culture, exposure to climate change, and human capital management. To assess ESG Factors, portfolio management uses issuer reports, third-party data, and internally-generated analyses and may engage directly with issuers. ESG Factors are one of many considerations in the investment decision-making process, may not be determinative in deciding to include or exclude an investment from the portfolio, and may not be considered for every investment decision.The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions, in an amount equal to up to one-third of its total assets as determined at the time of the loan origination.