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Janus Henderson Small Cap Value Fund Average Annual Total Returns - Class L 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 L | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 6.74% 6.32% 6.56%
Class L | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 5.26% 5.88% 6.09%
Class L | Return Before Taxes[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent 7.85% 7.63% 7.79%