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Janus Henderson Mid Cap Value Portfolio Annual Fund Operating Expenses - Institutional Shares [Member] - Janus Henderson Mid Cap Value Portfolio
Dec. 31, 2025
Prospectus [Line Items]  
Fee Waiver or Reimbursement over Assets, Date of Termination <span style="font-family:Times New Roman;font-size:7.60pt;">The Adviser has contractually agreed to waive its investment advisory fee and/or reimburse Portfolio expenses to the extent that the Portfolio’s total annual fund operating expenses (excluding any performance adjustments to management fees, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses) exceed 0.77% for at least a one-year period commencing on April 30, 2026. This contractual waiver may be terminated or modified only at the discretion of the Portfolio’s Board of Trustees.</span>
Institutional Shares  
Prospectus [Line Items]  
Management Fees (as a percentage of Assets) 0.65% [1]
Other Expenses (as a percentage of Assets): 0.21%
Expenses (as a percentage of Assets) 0.86%
Fee Waiver or Reimbursement (0.03%) [2]
Net Expenses (as a percentage of Assets) 0.83% [2]
[1] This fee may adjust up or down monthly based on the Portfolio’s performance relative to its benchmark index over the performance measurement period. For more information regarding performance-based advisory fees, refer to “Management Expenses” in the Portfolio’s Prospectus.
[2] The Adviser has contractually agreed to waive its investment advisory fee and/or reimburse Portfolio expenses to the extent that the Portfolio’s total annual fund operating expenses (excluding any performance adjustments to management fees, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses) exceed 0.77% for at least a one-year period commencing on April 30, 2026. This contractual waiver may be terminated or modified only at the discretion of the Portfolio’s Board of Trustees.