Janus Henderson Flexible Bond Portfolio Investment Risks - Service Shares [Member] - Janus Henderson Flexible Bond Portfolio	Dec. 31, 2025
Market Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Market Risk. The value of the Portfolio’s holdings may decrease due to short-term market movements and over more prolonged market downturns. As a result, the Portfolio’s net asset value may fluctuate and it may be more difficult to value or sell the Portfolio’s holdings. Market risk may affect a single issuer, industry, economic sector, or the market as a whole. Market risk may be magnified if certain social, political, economic, and other conditions and events (such as financial institution failures, economic recessions, tariffs, trade disputes, terrorism, war, armed conflicts, including related sanctions, social unrest, natural disasters, and epidemics and pandemics) adversely interrupt the global economy and financial markets. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.
Fixed-Income Securities Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Fixed-Income Securities Risk. Fixed-income securities are generally subject to the following risks: •Interest rate risk, which is the risk that prices of bonds and other fixed-income securities will increase as interest rates fall and decrease as interest rates rise. Changing interest rates have unpredictable effects on the markets and may expose fixed-income and related markets to heightened volatility. •Credit risk, which is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default. •Prepayment risk, which is the risk that, during periods of falling interest rates, certain debt obligations may be paid off quicker than originally anticipated, which may cause the Portfolio to reinvest its assets in securities with lower yields, resulting in a decline in the Portfolio’s income or return potential. •Extension risk, which is the risk that, during periods of rising interest rates, certain debt obligations may be paid off substantially slower than originally anticipated, and as a result, the value of those obligations may fall. •Valuation risk, which is the risk that one or more of the fixed-income securities in which the Portfolio invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Valuation may also be affected by changes in the issuer’s financial strength, the market’s perception of such strength, or in the credit rating of the issuer or the security. •Liquidity risk, which is the risk that fixed-income securities may be difficult or impossible to sell at the time that portfolio management would like or at the price portfolio management believes the security is currently worth. Consequently, the Portfolio may have to accept a lower price to sell a security, sell other securities to raise cash, or give up an investment opportunity, any of which could have a negative effect on the Portfolio’s performance. In unusual market conditions, even normally liquid securities may be affected by a degree of liquidity risk (i.e., if the number and capacity of traditional market participants is reduced).
High-Yield Bond Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	High-Yield Bond Risk. High-yield bonds (also known as “junk” bonds) are considered speculative and may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.
Mortgage- and Asset-Backed Securities Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Mortgage- and Asset-Backed Securities Risk. Mortgage- and asset-backed securities represent interests in “pools” of commercial or residential mortgages or other assets, including consumer loans or receivables. The value of mortgage- and asset-backed securities will be influenced by factors affecting the real estate market and the assets underlying these securities. Investments in mortgage-and asset-backed securities may be subject to credit risk, valuation risk, liquidity risk, extension risk, and prepayment risk. These securities also are subject to risk of default on the underlying mortgage or asset, particularly during periods of economic downturn.
Foreign Exposure Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Foreign Exposure Risk. Foreign markets can be more volatile than the U.S. market. As a result, the Portfolio’s returns and net asset value may be affected by fluctuations in currency exchange rates or political or economic conditions in a particular country. Investments in foreign securities, particularly those of issuers located in emerging market countries, tend to have greater exposure to liquidity risk than domestic securities. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Portfolio to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Portfolio has invested a significant amount of its assets may have a greater effect on the Portfolio’s performance than it would in a more geographically diversified portfolio.
Sovereign Debt Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Sovereign Debt Risk. Investments in U.S. and non-U.S. government debt securities (“sovereign debt”) can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner. A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole. In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Portfolio may collect all or part of the sovereign debt that a governmental entity has not repaid. In addition, to the extent the Portfolio invests in non-U.S. sovereign debt, it may be subject to currency risk.
Credit Risk Transfer Securities Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Credit Risk Transfer Securities Risk. CRTs are unguaranteed and unsecured fixed or floating rate general obligations that are commonly issued by government sponsored enterprises. CRTs are not directly linked to or backed by the underlying mortgage loans, so investors such as the Portfolio have no direct recourse to the underlying mortgage loans in the event of a default. The risks associated with CRTs are different from the risks associated with investments in mortgage-backed securities issued by government sponsored enterprises or private issuers because some or all of the mortgage default or credit risk associated with the underlying mortgage loans is transferred to investors. These risks are in addition to the risks described under “Fixed-Income Securities Risk.”
Floating Rate Obligations Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Floating Rate Obligations Risk. The Portfolio may invest in floating rate obligations with interest rates that reset regularly. The interest rates on floating rate obligations typically reset quarterly, although rates on some obligations may adjust at other intervals. Changes in the interest rates on floating rate obligations could result in lower income to the Portfolio. In addition, the secondary market on which floating rate obligations are traded may be less liquid than the market for investment grade securities or other types of income-producing securities, which may have an adverse impact on their market price. There is also a potential that there is no active market to trade floating rate obligations, that there may be restrictions on their transfer, or that the issuer may default. As a result, the Portfolio may be unable to sell floating rate obligations at the desired time or may be able to sell only at a price less than fair market value.
Portfolio Turnover Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Portfolio’s performance.
TBA Commitments Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	TBA Commitments Risk. Although TBA commitments must meet industry-accepted “good delivery” standards, there can be no assurance that a security purchased on a forward commitment basis will ultimately be issued or delivered by the counterparty. If the counterparty to a transaction fails to deliver the securities, the Portfolio could suffer a loss. Because TBA commitments do not require the delivery of a specific security, the characteristics of a security delivered to the Portfolio may be less favorable than expected. There is a risk that the security that the Portfolio buys will lose value between the purchase and settlement dates. TBA purchase and sales commitments may significantly increase the portfolio turnover rate and are not included in the portfolio turnover rate calculation.
Portfolio Management Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Portfolio Management Risk. The Portfolio is an actively managed investment portfolio and is therefore subject to the risk that the investment strategies and research process employed for the Portfolio may fail to produce the intended results. Accordingly, the Portfolio may underperform benchmark indices or other funds with similar investment objectives.
Derivatives Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Derivatives Risk. Derivatives can be volatile and involve risks in addition to the risks of the underlying referenced securities or asset. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost, and can therefore involve leverage. Leverage may cause the Portfolio to be more volatile than if it had not used leverage. Derivatives entail the risk that the counterparty may default on its payment obligations. If the counterparty to a derivative transaction defaults, the Portfolio may lose the net amount of the payments that it contractually is entitled to receive. The Portfolio’s investments in interest rate futures in particular entail the risk that portfolio management’s prediction of the direction of interest rates is wrong, and the Portfolio could incur a loss. Derivatives used for hedging purposes may reduce or eliminate gains or cause losses if the market moves in a manner different from that anticipated by portfolio management or if the cost of the derivative outweighs the benefit of the hedge.
Short Exposure Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Short Exposure Risk. The Portfolio may enter into a derivatives transaction to obtain short investment exposure to the underlying reference asset. If the value of the underlying reference asset on which the Portfolio has obtained a short investment exposure increases, the Portfolio will incur a loss. This potential loss is theoretically unlimited. A short exposure through a derivative also exposes the Portfolio to credit risk, counterparty risk, and leverage risk.
Rule 144A Securities and Other Exempt Securities Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Rule 144A Securities and Other Exempt Securities Risk. Investments in securities issued under Regulation S and Rule 144A and other securities exempt from certain registration requirements could have the effect of decreasing the Portfolio’s liquidity profile or preventing the Portfolio from disposing of them promptly at advantageous prices. Investments in securities exempt from certain registration requirements may be less liquid than other investments because such securities may not always be readily sold in broad public markets and may have no active trading market. As a result, they may be difficult to value because market quotations may not be readily available.
Securities Lending Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Securities Lending Risk. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Portfolio may experience delays and costs in recovering the security or gaining access to the collateral provided to the Portfolio to collateralize the loan. If the Portfolio is unable to recover a security on loan, the Portfolio may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Portfolio.
ESG Integration Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	ESG Integration Risk. There is a risk that considering ESG Factors as part of the Portfolio’s investment process may fail to produce the intended results or that the Portfolio may perform differently from funds that have a similar investment style but do not formally incorporate such considerations in their strategy. Information related to ESG Factors provided by issuers and third parties, which portfolio management may utilize, continues to develop and may be incomplete or inaccurate, use different or inconsistent methodologies, or be applied differently across issuers and industries.
Risk Lose Money [Member]
Prospectus [Line Items]
Risk [Text Block]	The biggest risk is that the Portfolio’s returns and yields will vary, and you could lose money.
Risk Not Insured Depository Institution [Member]
Prospectus [Line Items]
Risk [Text Block]	An investment in the Portfolio is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.