v3.26.3
Janus Henderson Small Cap Value Fund Average Annual Total Returns - Class A C S I N R T Shares [Member]
 12 Months Ended 60 Months Ended 120 Months Ended
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Russell 3000® Index (reflects no deduction for expenses, fees, or taxes)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 17.15% 13.15% 14.29%
Russell 2000® Value Index (reflects no deduction for expenses, fees, or taxes)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 12.59% 8.88% 9.27%
Class A | Return Before Taxes[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent [1] 1.19% 5.91% 6.69%
Class C | Return Before Taxes[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent [2] 5.78% 6.51% 6.67%
Class S | Return Before Taxes[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 7.34% 7.10% 7.27%
Class I | Return Before Taxes[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 7.68% 7.49% 7.66%
Class N | Return Before Taxes[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 7.89% 7.64% 7.81%
Class R | Return Before Taxes[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 7.07% 6.83% 7.00%
Class T | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 6.58% 6.10% 6.34%
Class T | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 5.15% 5.70% 5.90%
Class T | Return Before Taxes[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 7.63% 7.38% 7.55%
[1] Calculated assuming maximum permitted sales loads.
[2] The one year return is calculated to include the contingent deferred sales charge.