Janus Henderson Forty Portfolio Average Annual Total Returns - Institutional Shares [Member]	12 Months Ended	60 Months Ended	120 Months Ended
	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2025
Russell 1000® Index (reflects no deduction for fees, expenses, or taxes)[Member]
Prospectus [Line Items]
Average Annual Return, Percent	17.37%	13.59%	14.59%
Russell 1000® Growth Index (reflects no deduction for fees, expenses, or taxes)[Member]
Prospectus [Line Items]
Average Annual Return, Percent	18.56%	15.32%	18.13%
S&P 500® Index (reflects no deduction for fees, expenses, or taxes)[Member]
Prospectus [Line Items]
Average Annual Return, Percent	17.88%	14.42%	14.82%
Institutional Shares
Prospectus [Line Items]
Average Annual Return, Percent	18.14%	11.65%	16.24%