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Shareholder Report
 12 Months Ended
Sep. 30, 2024
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSR
Amendment Flag false
Registrant Name Janus Investment Fund
Entity Central Index Key 0000277751
Entity Investment Company Type N-1A
Document Period End Date Sep. 30, 2024
C000077650 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Balanced Fund
Class Name Class A Shares
Trading Symbol JDBAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Balanced Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Balanced Fund
(Class A Shares/JDBAX)		 $99 0.88%
Expenses Paid, Amount $ 99
Expense Ratio, Percent 0.88%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Balanced Fund Class A Shares returned 25.96%. Its broad-based benchmarks, the S&P 500® Index, and the Bloomberg U.S. Aggregate Bond Index returned 36.35% and 11.57%, respectively. Its performance benchmark, the Balanced Index, returned 25.05%.
Top Contributors to Performance
The equity allocation performed in line with the S&P 500® Index, with NVIDIA being a top contributor to relative results. The graphics chip company reported strong earnings supported by robust demand for graphics processor units used in generative artificial intelligence (AI). American Express, another contributor, reported strong profits growth that reflected higher customer balances and healthy spending by affluent cardmembers. The fixed income allocation outperformed the Bloomberg U.S. Aggregate Bond Index, largely driven by asset allocation decisions. Overweight allocations to both securitized and corporate credit proved beneficial.
Top Detractors from Performance
Within equities, footwear company Nike detracted relative to the S&P 500 Index as the company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending. Consulting firm Accenture also detracted when business slowed due to a shift in IT spending toward AI and away from legacy software projects. In the fixed income allocation, security selection within agency mortgage-backed securities hindered results relative to the Bloomberg U.S. Aggregate Bond Index.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Balanced Fund (Class A Shares/JDBAX) at NAV 25.96% 9.19% 8.74%
Janus Henderson Balanced Fund (Class A Shares/JDBAX) at Maximum Offering Price - 5.75% 18.70% 7.90% 8.09%
S&P 500® Index 36.35% 15.98% 13.38%
Bloomberg U.S. Aggregate Bond Index 11.57% 0.33% 1.84%
Balanced Index 25.05% 9.06% 8.34%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 26,509,000,000
Holdings Count | Holding 769
Advisory Fees Paid, Amount $ 135,400,000
Investment Company Portfolio Turnover 76.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $26,509M
Number of portfolio holdings 769
Total investment advisory fee paid $135.4M
Portfolio turnover rate 76%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
Asset Allocation (% of net assets)
Common Stocks 61.9
Corporate Bonds 12.7
Asset-Backed/Commercial Mortgage-Backed Securities 10.6
Mortgage-Backed Securities 8.8
United States Treasury Notes/Bonds 4.5
Investment Companies 2.9
Bank Loans and Mezzanine Loans 0.6
Other (2.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
C000077651 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Balanced Fund
Class Name Class C Shares
Trading Symbol JABCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Balanced Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Balanced Fund
(Class C Shares/JABCX)		 $182 1.62%
Expenses Paid, Amount $ 182
Expense Ratio, Percent 1.62%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Balanced Fund Class C Shares returned 25.03%. Its broad-based benchmarks, the S&P 500® Index, and the Bloomberg U.S. Aggregate Bond Index returned 36.35% and 11.57%, respectively. Its performance benchmark, the Balanced Index, returned 25.05%.
Top Contributors to Performance
The equity allocation performed in line with the S&P 500® Index, with NVIDIA being a top contributor to relative results. The graphics chip company reported strong earnings supported by robust demand for graphics processor units used in generative artificial intelligence (AI). American Express, another contributor, reported strong profits growth that reflected higher customer balances and healthy spending by affluent cardmembers. The fixed income allocation outperformed the Bloomberg U.S. Aggregate Bond Index, largely driven by asset allocation decisions. Overweight allocations to both securitized and corporate credit proved beneficial.
Top Detractors from Performance
Within equities, footwear company Nike detracted relative to the S&P 500 Index as the company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending. Consulting firm Accenture also detracted when business slowed due to a shift in IT spending toward AI and away from legacy software projects. In the fixed income allocation, security selection within agency mortgage-backed securities hindered results relative to the Bloomberg U.S. Aggregate Bond Index.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Balanced Fund (Class C Shares/JABCX) at NAV 25.03% 8.41% 7.98%
Janus Henderson Balanced Fund (Class C Shares/JABCX) with Contingent Deferred Sales Charge 24.03%* 8.41% 7.98%
S&P 500® Index 36.35% 15.98% 13.38%
Bloomberg U.S. Aggregate Bond Index 11.57% 0.33% 1.84%
Balanced Index 25.05% 9.06% 8.34%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 26,509,000,000
Holdings Count | Holding 769
Advisory Fees Paid, Amount $ 135,400,000
Investment Company Portfolio Turnover 76.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $26,509M
Number of portfolio holdings 769
Total investment advisory fee paid $135.4M
Portfolio turnover rate 76%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
Asset Allocation (% of net assets)
Common Stocks 61.9
Corporate Bonds 12.7
Asset-Backed/Commercial Mortgage-Backed Securities 10.6
Mortgage-Backed Securities 8.8
United States Treasury Notes/Bonds 4.5
Investment Companies 2.9
Bank Loans and Mezzanine Loans 0.6
Other (2.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
C000083512 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Balanced Fund
Class Name Class D Shares
Trading Symbol JANBX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Balanced Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Balanced Fund
(Class D Shares/JANBX)		 $78 0.69%
Expenses Paid, Amount $ 78
Expense Ratio, Percent 0.69%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Balanced Fund Class D Shares returned 26.17%. Its broad-based benchmarks, the S&P 500® Index, and the Bloomberg U.S. Aggregate Bond Index returned 36.35% and 11.57%, respectively. Its performance benchmark, the Balanced Index, returned 25.05%.
Top Contributors to Performance
The equity allocation performed in line with the S&P 500® Index, with NVIDIA being a top contributor to relative results. The graphics chip company reported strong earnings supported by robust demand for graphics processor units used in generative artificial intelligence (AI). American Express, another contributor, reported strong profits growth that reflected higher customer balances and healthy spending by affluent cardmembers. The fixed income allocation outperformed the Bloomberg U.S. Aggregate Bond Index, largely driven by asset allocation decisions. Overweight allocations to both securitized and corporate credit proved beneficial.
Top Detractors from Performance
Within equities, footwear company Nike detracted relative to the S&P 500 Index as the company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending. Consulting firm Accenture also detracted when business slowed due to a shift in IT spending toward AI and away from legacy software projects. In the fixed income allocation, security selection within agency mortgage-backed securities hindered results relative to the Bloomberg U.S. Aggregate Bond Index.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Balanced Fund (Class D Shares/JANBX) 26.17% 9.39% 8.96%
S&P 500® Index 36.35% 15.98% 13.38%
Bloomberg U.S. Aggregate Bond Index 11.57% 0.33% 1.84%
Balanced Index 25.05% 9.06% 8.34%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 26,509,000,000
Holdings Count | Holding 769
Advisory Fees Paid, Amount $ 135,400,000
Investment Company Portfolio Turnover 76.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $26,509M
Number of portfolio holdings 769
Total investment advisory fee paid $135.4M
Portfolio turnover rate 76%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
Asset Allocation (% of net assets)
Common Stocks 61.9
Corporate Bonds 12.7
Asset-Backed/Commercial Mortgage-Backed Securities 10.6
Mortgage-Backed Securities 8.8
United States Treasury Notes/Bonds 4.5
Investment Companies 2.9
Bank Loans and Mezzanine Loans 0.6
Other (2.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
C000077652 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Balanced Fund
Class Name Class I Shares
Trading Symbol JBALX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Balanced Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Balanced Fund
(Class I Shares/JBALX)		 $75 0.66%
Expenses Paid, Amount $ 75
Expense Ratio, Percent 0.66%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Balanced Fund Class I Shares returned 26.23%. Its broad-based benchmarks, the S&P 500® Index, and the Bloomberg U.S. Aggregate Bond Index returned 36.35% and 11.57%, respectively. Its performance benchmark, the Balanced Index, returned 25.05%.
Top Contributors to Performance
The equity allocation performed in line with the S&P 500® Index, with NVIDIA being a top contributor to relative results. The graphics chip company reported strong earnings supported by robust demand for graphics processor units used in generative artificial intelligence (AI). American Express, another contributor, reported strong profits growth that reflected higher customer balances and healthy spending by affluent cardmembers. The fixed income allocation outperformed the Bloomberg U.S. Aggregate Bond Index, largely driven by asset allocation decisions. Overweight allocations to both securitized and corporate credit proved beneficial.
Top Detractors from Performance
Within equities, footwear company Nike detracted relative to the S&P 500 Index as the company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending. Consulting firm Accenture also detracted when business slowed due to a shift in IT spending toward AI and away from legacy software projects. In the fixed income allocation, security selection within agency mortgage-backed securities hindered results relative to the Bloomberg U.S. Aggregate Bond Index.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Balanced Fund (Class I Shares/JBALX) 26.23% 9.44% 9.02%
S&P 500® Index 36.35% 15.98% 13.38%
Bloomberg U.S. Aggregate Bond Index 11.57% 0.33% 1.84%
Balanced Index 25.05% 9.06% 8.34%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 26,509,000,000
Holdings Count | Holding 769
Advisory Fees Paid, Amount $ 135,400,000
Investment Company Portfolio Turnover 76.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $26,509M
Number of portfolio holdings 769
Total investment advisory fee paid $135.4M
Portfolio turnover rate 76%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
Asset Allocation (% of net assets)
Common Stocks 61.9
Corporate Bonds 12.7
Asset-Backed/Commercial Mortgage-Backed Securities 10.6
Mortgage-Backed Securities 8.8
United States Treasury Notes/Bonds 4.5
Investment Companies 2.9
Bank Loans and Mezzanine Loans 0.6
Other (2.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
C000114869 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Balanced Fund
Class Name Class N Shares
Trading Symbol JABNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Balanced Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Balanced Fund
(Class N Shares/JABNX)		 $65 0.57%
Expenses Paid, Amount $ 65
Expense Ratio, Percent 0.57%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Balanced Fund Class N Shares returned 26.32%. Its broad-based benchmarks, the S&P 500® Index, and the Bloomberg U.S. Aggregate Bond Index returned 36.35% and 11.57%, respectively. Its performance benchmark, the Balanced Index, returned 25.05%.
Top Contributors to Performance
The equity allocation performed in line with the S&P 500® Index, with NVIDIA being a top contributor to relative results. The graphics chip company reported strong earnings supported by robust demand for graphics processor units used in generative artificial intelligence (AI). American Express, another contributor, reported strong profits growth that reflected higher customer balances and healthy spending by affluent cardmembers. The fixed income allocation outperformed the Bloomberg U.S. Aggregate Bond Index, largely driven by asset allocation decisions. Overweight allocations to both securitized and corporate credit proved beneficial.
Top Detractors from Performance
Within equities, footwear company Nike detracted relative to the S&P 500 Index as the company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending. Consulting firm Accenture also detracted when business slowed due to a shift in IT spending toward AI and away from legacy software projects. In the fixed income allocation, security selection within agency mortgage-backed securities hindered results relative to the Bloomberg U.S. Aggregate Bond Index.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Balanced Fund (Class N Shares/JABNX) 26.32% 9.53% 9.11%
S&P 500® Index 36.35% 15.98% 13.38%
Bloomberg U.S. Aggregate Bond Index 11.57% 0.33% 1.84%
Balanced Index 25.05% 9.06% 8.34%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 26,509,000,000
Holdings Count | Holding 769
Advisory Fees Paid, Amount $ 135,400,000
Investment Company Portfolio Turnover 76.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $26,509M
Number of portfolio holdings 769
Total investment advisory fee paid $135.4M
Portfolio turnover rate 76%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
Asset Allocation (% of net assets)
Common Stocks 61.9
Corporate Bonds 12.7
Asset-Backed/Commercial Mortgage-Backed Securities 10.6
Mortgage-Backed Securities 8.8
United States Treasury Notes/Bonds 4.5
Investment Companies 2.9
Bank Loans and Mezzanine Loans 0.6
Other (2.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
C000077653 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Balanced Fund
Class Name Class R Shares
Trading Symbol JDBRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Balanced Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Balanced Fund
(Class R Shares/JDBRX)		 $148 1.31%
Expenses Paid, Amount $ 148
Expense Ratio, Percent 1.31%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Balanced Fund Class R Shares returned 25.43%. Its broad-based benchmarks, the S&P 500® Index, and the Bloomberg U.S. Aggregate Bond Index returned 36.35% and 11.57%, respectively. Its performance benchmark, the Balanced Index, returned 25.05%.
Top Contributors to Performance
The equity allocation performed in line with the S&P 500® Index, with NVIDIA being a top contributor to relative results. The graphics chip company reported strong earnings supported by robust demand for graphics processor units used in generative artificial intelligence (AI). American Express, another contributor, reported strong profits growth that reflected higher customer balances and healthy spending by affluent cardmembers. The fixed income allocation outperformed the Bloomberg U.S. Aggregate Bond Index, largely driven by asset allocation decisions. Overweight allocations to both securitized and corporate credit proved beneficial.
Top Detractors from Performance
Within equities, footwear company Nike detracted relative to the S&P 500 Index as the company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending. Consulting firm Accenture also detracted when business slowed due to a shift in IT spending toward AI and away from legacy software projects. In the fixed income allocation, security selection within agency mortgage-backed securities hindered results relative to the Bloomberg U.S. Aggregate Bond Index.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Balanced Fund (Class R Shares/JDBRX) 25.43% 8.72% 8.30%
S&P 500® Index 36.35% 15.98% 13.38%
Bloomberg U.S. Aggregate Bond Index 11.57% 0.33% 1.84%
Balanced Index 25.05% 9.06% 8.34%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 26,509,000,000
Holdings Count | Holding 769
Advisory Fees Paid, Amount $ 135,400,000
Investment Company Portfolio Turnover 76.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $26,509M
Number of portfolio holdings 769
Total investment advisory fee paid $135.4M
Portfolio turnover rate 76%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
Asset Allocation (% of net assets)
Common Stocks 61.9
Corporate Bonds 12.7
Asset-Backed/Commercial Mortgage-Backed Securities 10.6
Mortgage-Backed Securities 8.8
United States Treasury Notes/Bonds 4.5
Investment Companies 2.9
Bank Loans and Mezzanine Loans 0.6
Other (2.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
C000077654 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Balanced Fund
Class Name Class S Shares
Trading Symbol JABRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Balanced Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Balanced Fund
(Class S Shares/JABRX)		 $120 1.06%
Expenses Paid, Amount $ 120
Expense Ratio, Percent 1.06%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Balanced Fund Class S Shares returned 25.73%. Its broad-based benchmarks, the S&P 500® Index, and the Bloomberg U.S. Aggregate Bond Index returned 36.35% and 11.57%, respectively. Its performance benchmark, the Balanced Index, returned 25.05%.
Top Contributors to Performance
The equity allocation performed in line with the S&P 500® Index, with NVIDIA being a top contributor to relative results. The graphics chip company reported strong earnings supported by robust demand for graphics processor units used in generative artificial intelligence (AI). American Express, another contributor, reported strong profits growth that reflected higher customer balances and healthy spending by affluent cardmembers. The fixed income allocation outperformed the Bloomberg U.S. Aggregate Bond Index, largely driven by asset allocation decisions. Overweight allocations to both securitized and corporate credit proved beneficial.
Top Detractors from Performance
Within equities, footwear company Nike detracted relative to the S&P 500 Index as the company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending. Consulting firm Accenture also detracted when business slowed due to a shift in IT spending toward AI and away from legacy software projects. In the fixed income allocation, security selection within agency mortgage-backed securities hindered results relative to the Bloomberg U.S. Aggregate Bond Index.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Balanced Fund (Class S Shares/JABRX) 25.73% 8.99% 8.57%
S&P 500® Index 36.35% 15.98% 13.38%
Bloomberg U.S. Aggregate Bond Index 11.57% 0.33% 1.84%
Balanced Index 25.05% 9.06% 8.34%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 26,509,000,000
Holdings Count | Holding 769
Advisory Fees Paid, Amount $ 135,400,000
Investment Company Portfolio Turnover 76.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $26,509M
Number of portfolio holdings 769
Total investment advisory fee paid $135.4M
Portfolio turnover rate 76%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
Asset Allocation (% of net assets)
Common Stocks 61.9
Corporate Bonds 12.7
Asset-Backed/Commercial Mortgage-Backed Securities 10.6
Mortgage-Backed Securities 8.8
United States Treasury Notes/Bonds 4.5
Investment Companies 2.9
Bank Loans and Mezzanine Loans 0.6
Other (2.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
C000028918 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Balanced Fund
Class Name Class T Shares
Trading Symbol JABAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Balanced Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Balanced Fund
(Class T Shares/JABAX)		 $90 0.80%
Expenses Paid, Amount $ 90
Expense Ratio, Percent 0.80%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Balanced Fund Class T Shares returned 26.05%. Its broad-based benchmarks, the S&P 500® Index, and the Bloomberg U.S. Aggregate Bond Index returned 36.35% and 11.57%, respectively. Its performance benchmark, the Balanced Index, returned 25.05%.
Top Contributors to Performance
The equity allocation performed in line with the S&P 500® Index, with NVIDIA being a top contributor to relative results. The graphics chip company reported strong earnings supported by robust demand for graphics processor units used in generative artificial intelligence (AI). American Express, another contributor, reported strong profits growth that reflected higher customer balances and healthy spending by affluent cardmembers. The fixed income allocation outperformed the Bloomberg U.S. Aggregate Bond Index, largely driven by asset allocation decisions. Overweight allocations to both securitized and corporate credit proved beneficial.
Top Detractors from Performance
Within equities, footwear company Nike detracted relative to the S&P 500 Index as the company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending. Consulting firm Accenture also detracted when business slowed due to a shift in IT spending toward AI and away from legacy software projects. In the fixed income allocation, security selection within agency mortgage-backed securities hindered results relative to the Bloomberg U.S. Aggregate Bond Index.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Balanced Fund (Class T Shares/JABAX) 26.05% 9.27% 8.84%
S&P 500® Index 36.35% 15.98% 13.38%
Bloomberg U.S. Aggregate Bond Index 11.57% 0.33% 1.84%
Balanced Index 25.05% 9.06% 8.34%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 26,509,000,000
Holdings Count | Holding 769
Advisory Fees Paid, Amount $ 135,400,000
Investment Company Portfolio Turnover 76.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $26,509M
Number of portfolio holdings 769
Total investment advisory fee paid $135.4M
Portfolio turnover rate 76%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
Asset Allocation (% of net assets)
Common Stocks 61.9
Corporate Bonds 12.7
Asset-Backed/Commercial Mortgage-Backed Securities 10.6
Mortgage-Backed Securities 8.8
United States Treasury Notes/Bonds 4.5
Investment Companies 2.9
Bank Loans and Mezzanine Loans 0.6
Other (2.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.8
NVIDIA Corp 4.9
Apple Inc 3.8
Alphabet Inc - Class C 2.7
Amazon.com Inc 2.5
C000077655 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Technology and Innovation Fund
Class Name Class A Shares
Trading Symbol JATAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Technology and Innovation Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Technology and Innovation Fund
(Class A Shares/JATAX)		 $122 0.98%
Expenses Paid, Amount $ 122
Expense Ratio, Percent 0.98%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Technology and Innovation Fund Class A Shares returned 48.83%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%. Its additional benchmark, the MSCI All Country World Information Technology IndexSM, returned 48.35%.
Top Contributors to Performance
Positioning in Apple contributed to returns relative to the additional benchmark; the slower pace of iPhones sales pressured the stock, and our underweight allocation proved beneficial. The Fund’s out-of-benchmark investment in social media company Meta Platforms also contributed. Shares rose on the company’s strong earnings performance and excitement around its artificial intelligence initiatives.
Top Detractors from Performance
Cloud services provider CCC Intelligence Solutions detracted relative to the additional benchmark as shares declined on concerns over stock sales by a large investor. The Fund also held underweight positions in several mega-cap technology stocks, such as graphic chipmaker NVIDIA, that outperformed the market due to excitement around artificial intelligence. This positioning dampened relative performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Technology and Innovation Fund (Class A Shares/JATAX) at NAV 48.83% 19.77% 19.16%
Janus Henderson Global Technology and Innovation Fund (Class A Shares/JATAX) at Maximum Offering Price - 5.75% 40.28% 18.36% 18.46%
S&P 500® Index 36.35% 15.98% 13.38%
MSCI All Country World Information Technology IndexSM 48.35% 22.78% 19.12%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,230,000,000
Holdings Count | Holding 72
Advisory Fees Paid, Amount $ 40,300,000
Investment Company Portfolio Turnover 30.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,230M
Number of portfolio holdings 72
Total investment advisory fee paid $40.3M
Portfolio turnover rate 30%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
Asset Allocation (% of net assets)
Common Stocks 94.3
Investment Companies 4.9
Private Placements 0.8
Investments Purchased with Cash Collateral from Securities Lending 0.1
Warrants 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
C000077656 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Technology and Innovation Fund
Class Name Class C Shares
Trading Symbol JAGCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Technology and Innovation Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Technology and Innovation Fund
(Class C Shares/JAGCX)		 $214 1.73%
Expenses Paid, Amount $ 214
Expense Ratio, Percent 1.73%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Technology and Innovation Fund Class C Shares returned 47.72%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%. Its additional benchmark, the MSCI All Country World Information Technology IndexSM, returned 48.35%.
Top Contributors to Performance
Positioning in Apple contributed to returns relative to the additional benchmark; the slower pace of iPhones sales pressured the stock, and our underweight allocation proved beneficial. The Fund’s out-of-benchmark investment in social media company Meta Platforms also contributed. Shares rose on the company’s strong earnings performance and excitement around its artificial intelligence initiatives.
Top Detractors from Performance
Cloud services provider CCC Intelligence Solutions detracted relative to the additional benchmark as shares declined on concerns over stock sales by a large investor. The Fund also held underweight positions in several mega-cap technology stocks, such as graphic chipmaker NVIDIA, that outperformed the market due to excitement around artificial intelligence. This positioning dampened relative performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Technology and Innovation Fund (Class C Shares/JAGCX) at NAV 47.72% 18.96% 18.35%
Janus Henderson Global Technology and Innovation Fund (Class C Shares/JAGCX) with Contingent Deferred Sales Charge 46.72%* 18.96% 18.35%
S&P 500® Index 36.35% 15.98% 13.38%
MSCI All Country World Information Technology IndexSM 48.35% 22.78% 19.12%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,230,000,000
Holdings Count | Holding 72
Advisory Fees Paid, Amount $ 40,300,000
Investment Company Portfolio Turnover 30.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,230M
Number of portfolio holdings 72
Total investment advisory fee paid $40.3M
Portfolio turnover rate 30%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
Asset Allocation (% of net assets)
Common Stocks 94.3
Investment Companies 4.9
Private Placements 0.8
Investments Purchased with Cash Collateral from Securities Lending 0.1
Warrants 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
C000083513 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Technology and Innovation Fund
Class Name Class D Shares
Trading Symbol JNGTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Technology and Innovation Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Technology and Innovation Fund
(Class D Shares/JNGTX)		 $97 0.78%
Expenses Paid, Amount $ 97
Expense Ratio, Percent 0.78%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Technology and Innovation Fund Class D Shares returned 49.09%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%. Its additional benchmark, the MSCI All Country World Information Technology IndexSM, returned 48.35%.
Top Contributors to Performance
Positioning in Apple contributed to returns relative to the additional benchmark; the slower pace of iPhones sales pressured the stock, and our underweight allocation proved beneficial. The Fund’s out-of-benchmark investment in social media company Meta Platforms also contributed. Shares rose on the company’s strong earnings performance and excitement around its artificial intelligence initiatives.
Top Detractors from Performance
Cloud services provider CCC Intelligence Solutions detracted relative to the additional benchmark as shares declined on concerns over stock sales by a large investor. The Fund also held underweight positions in several mega-cap technology stocks, such as graphic chipmaker NVIDIA, that outperformed the market due to excitement around artificial intelligence. This positioning dampened relative performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Technology and Innovation Fund (Class D Shares/JNGTX) 49.09% 20.00% 19.39%
S&P 500® Index 36.35% 15.98% 13.38%
MSCI All Country World Information Technology IndexSM 48.35% 22.78% 19.12%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 7,230,000,000
Holdings Count | Holding 72
Advisory Fees Paid, Amount $ 40,300,000
Investment Company Portfolio Turnover 30.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,230M
Number of portfolio holdings 72
Total investment advisory fee paid $40.3M
Portfolio turnover rate 30%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
Asset Allocation (% of net assets)
Common Stocks 94.3
Investment Companies 4.9
Private Placements 0.8
Investments Purchased with Cash Collateral from Securities Lending 0.1
Warrants 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
C000077657 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Technology and Innovation Fund
Class Name Class I Shares
Trading Symbol JATIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Technology and Innovation Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Technology and Innovation Fund
(Class I Shares/JATIX)		 $93 0.75%
Expenses Paid, Amount $ 93
Expense Ratio, Percent 0.75%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Technology and Innovation Fund Class I Shares returned 49.15%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%. Its additional benchmark, the MSCI All Country World Information Technology IndexSM, returned 48.35%.
Top Contributors to Performance
Positioning in Apple contributed to returns relative to the additional benchmark; the slower pace of iPhones sales pressured the stock, and our underweight allocation proved beneficial. The Fund’s out-of-benchmark investment in social media company Meta Platforms also contributed. Shares rose on the company’s strong earnings performance and excitement around its artificial intelligence initiatives.
Top Detractors from Performance
Cloud services provider CCC Intelligence Solutions detracted relative to the additional benchmark as shares declined on concerns over stock sales by a large investor. The Fund also held underweight positions in several mega-cap technology stocks, such as graphic chipmaker NVIDIA, that outperformed the market due to excitement around artificial intelligence. This positioning dampened relative performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Technology and Innovation Fund (Class I Shares/JATIX) 49.15% 20.05% 19.46%
S&P 500® Index 36.35% 15.98% 13.38%
MSCI All Country World Information Technology IndexSM 48.35% 22.78% 19.12%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,230,000,000
Holdings Count | Holding 72
Advisory Fees Paid, Amount $ 40,300,000
Investment Company Portfolio Turnover 30.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,230M
Number of portfolio holdings 72
Total investment advisory fee paid $40.3M
Portfolio turnover rate 30%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
Asset Allocation (% of net assets)
Common Stocks 94.3
Investment Companies 4.9
Private Placements 0.8
Investments Purchased with Cash Collateral from Securities Lending 0.1
Warrants 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
C000177052 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Technology and Innovation Fund
Class Name Class N Shares
Trading Symbol JATNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Technology and Innovation Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Technology and Innovation Fund
(Class N Shares/JATNX)		 $82 0.66%
Expenses Paid, Amount $ 82
Expense Ratio, Percent 0.66%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Technology and Innovation Fund Class N Shares returned 49.28%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%. Its additional benchmark, the MSCI All Country World Information Technology IndexSM, returned 48.35%.
Top Contributors to Performance
Positioning in Apple contributed to returns relative to the additional benchmark; the slower pace of iPhones sales pressured the stock, and our underweight allocation proved beneficial. The Fund’s out-of-benchmark investment in social media company Meta Platforms also contributed. Shares rose on the company’s strong earnings performance and excitement around its artificial intelligence initiatives.
Top Detractors from Performance
Cloud services provider CCC Intelligence Solutions detracted relative to the additional benchmark as shares declined on concerns over stock sales by a large investor. The Fund also held underweight positions in several mega-cap technology stocks, such as graphic chipmaker NVIDIA, that outperformed the market due to excitement around artificial intelligence. This positioning dampened relative performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Technology and Innovation Fund (Class N Shares/JATNX) 49.28% 20.15% 19.50%
S&P 500® Index 36.35% 15.98% 13.38%
MSCI All Country World Information Technology IndexSM 48.35% 22.78% 19.12%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,230,000,000
Holdings Count | Holding 72
Advisory Fees Paid, Amount $ 40,300,000
Investment Company Portfolio Turnover 30.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,230M
Number of portfolio holdings 72
Total investment advisory fee paid $40.3M
Portfolio turnover rate 30%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
Asset Allocation (% of net assets)
Common Stocks 94.3
Investment Companies 4.9
Private Placements 0.8
Investments Purchased with Cash Collateral from Securities Lending 0.1
Warrants 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
C000077658 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Technology and Innovation Fund
Class Name Class S Shares
Trading Symbol JATSX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Technology and Innovation Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Technology and Innovation Fund
(Class S Shares/JATSX)		 $145 1.17%
Expenses Paid, Amount $ 145
Expense Ratio, Percent 1.17%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Technology and Innovation Fund Class S Shares returned 48.54%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%. Its additional benchmark, the MSCI All Country World Information Technology IndexSM, returned 48.35%.
Top Contributors to Performance
Positioning in Apple contributed to returns relative to the additional benchmark; the slower pace of iPhones sales pressured the stock, and our underweight allocation proved beneficial. The Fund’s out-of-benchmark investment in social media company Meta Platforms also contributed. Shares rose on the company’s strong earnings performance and excitement around its artificial intelligence initiatives.
Top Detractors from Performance
Cloud services provider CCC Intelligence Solutions detracted relative to the additional benchmark as shares declined on concerns over stock sales by a large investor. The Fund also held underweight positions in several mega-cap technology stocks, such as graphic chipmaker NVIDIA, that outperformed the market due to excitement around artificial intelligence. This positioning dampened relative performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Technology and Innovation Fund (Class S Shares/JATSX) 48.54% 19.55% 18.97%
S&P 500® Index 36.35% 15.98% 13.38%
MSCI All Country World Information Technology IndexSM 48.35% 22.78% 19.12%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,230,000,000
Holdings Count | Holding 72
Advisory Fees Paid, Amount $ 40,300,000
Investment Company Portfolio Turnover 30.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,230M
Number of portfolio holdings 72
Total investment advisory fee paid $40.3M
Portfolio turnover rate 30%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
Asset Allocation (% of net assets)
Common Stocks 94.3
Investment Companies 4.9
Private Placements 0.8
Investments Purchased with Cash Collateral from Securities Lending 0.1
Warrants 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
C000028919 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Technology and Innovation Fund
Class Name Class T Shares
Trading Symbol JAGTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Technology and Innovation Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Technology and Innovation Fund
(Class T Shares/JAGTX)		 $112 0.90%
Expenses Paid, Amount $ 112
Expense Ratio, Percent 0.90%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Technology and Innovation Fund Class T Shares returned 48.94%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%. Its additional benchmark, the MSCI All Country World Information Technology IndexSM, returned 48.35%.
Top Contributors to Performance
Positioning in Apple contributed to returns relative to the additional benchmark; the slower pace of iPhones sales pressured the stock, and our underweight allocation proved beneficial. The Fund’s out-of-benchmark investment in social media company Meta Platforms also contributed. Shares rose on the company’s strong earnings performance and excitement around its artificial intelligence initiatives.
Top Detractors from Performance
Cloud services provider CCC Intelligence Solutions detracted relative to the additional benchmark as shares declined on concerns over stock sales by a large investor. The Fund also held underweight positions in several mega-cap technology stocks, such as graphic chipmaker NVIDIA, that outperformed the market due to excitement around artificial intelligence. This positioning dampened relative performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Technology and Innovation Fund (Class T Shares/JAGTX) 48.94% 19.87% 19.29%
S&P 500® Index 36.35% 15.98% 13.38%
MSCI All Country World Information Technology IndexSM 48.35% 22.78% 19.12%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,230,000,000
Holdings Count | Holding 72
Advisory Fees Paid, Amount $ 40,300,000
Investment Company Portfolio Turnover 30.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,230M
Number of portfolio holdings 72
Total investment advisory fee paid $40.3M
Portfolio turnover rate 30%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
Asset Allocation (% of net assets)
Common Stocks 94.3
Investment Companies 4.9
Private Placements 0.8
Investments Purchased with Cash Collateral from Securities Lending 0.1
Warrants 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 10.0
Taiwan Semiconductor Manufacturing Co Ltd 6.1
Apple Inc 5.5
ASML Holding NV 4.3
C000077659 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Growth and Income Fund
Class Name Class A Shares
Trading Symbol JDNAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Growth and Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Growth and Income Fund
(Class A Shares/JDNAX)		 $112 0.99%
Expenses Paid, Amount $ 112
Expense Ratio, Percent 0.99%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Growth and Income Fund Class A Shares returned 26.90%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
KLA was a top contributor to relative results. The semiconductor equipment company reported strong earnings growth supported by higher memory chip demand, capital spending on artificial intelligence, and demand stabilization in China. Financial services firm American Express, another contributor, reported strong profits growth that reflected higher customer balances and robust spending by affluent cardmembers.
Top Detractors from Performance
Accenture was a notable detractor from relative performance. The consulting company’s business slowed due to a shift in IT spending toward artificial intelligence and away from legacy software projects. Nike was another detractor, as the footwear and apparel company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Growth and Income Fund (Class A Shares/JDNAX) at NAV 26.90% 11.83% 11.61%
Janus Henderson Growth and Income Fund (Class A Shares/JDNAX) at Maximum Offering Price - 5.75% 19.60% 10.52% 10.95%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Material Change Date Jan. 26, 2024
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,576,000,000
Holdings Count | Holding 66
Advisory Fees Paid, Amount $ 42,200,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,576M
Number of portfolio holdings 66
Total investment advisory fee paid $42.2M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Asset Allocation (% of net assets)
Common Stocks 99.9
Investment Companies 0.1
Other (0.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
Material Fund Change Expenses [Text Block]
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
C000077660 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Growth and Income Fund
Class Name Class C Shares
Trading Symbol JGICX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Growth and Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Growth and Income Fund
(Class C Shares/JGICX)		 $184 1.63%
Expenses Paid, Amount $ 184
Expense Ratio, Percent 1.63%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Growth and Income Fund Class C Shares returned 26.08%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
KLA was a top contributor to relative results. The semiconductor equipment company reported strong earnings growth supported by higher memory chip demand, capital spending on artificial intelligence, and demand stabilization in China. Financial services firm American Express, another contributor, reported strong profits growth that reflected higher customer balances and robust spending by affluent cardmembers.
Top Detractors from Performance
Accenture was a notable detractor from relative performance. The consulting company’s business slowed due to a shift in IT spending toward artificial intelligence and away from legacy software projects. Nike was another detractor, as the footwear and apparel company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Growth and Income Fund (Class C Shares/JGICX) at NAV 26.08% 11.13% 10.84%
Janus Henderson Growth and Income Fund (Class C Shares/JGICX) with Contingent Deferred Sales Charge 25.08%* 11.13% 10.84%
S&P 500® Index 36.35% 15.98% 13.38%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Material Change Date Jan. 26, 2024
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,576,000,000
Holdings Count | Holding 66
Advisory Fees Paid, Amount $ 42,200,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,576M
Number of portfolio holdings 66
Total investment advisory fee paid $42.2M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Asset Allocation (% of net assets)
Common Stocks 99.9
Investment Companies 0.1
Other (0.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
Material Fund Change Expenses [Text Block]
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
C000083515 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Growth and Income Fund
Class Name Class D Shares
Trading Symbol JNGIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Growth and Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Growth and Income Fund
(Class D Shares/JNGIX)		 $84 0.74%
Expenses Paid, Amount $ 84
Expense Ratio, Percent 0.74%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Growth and Income Fund Class D Shares returned 27.20%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
KLA was a top contributor to relative results. The semiconductor equipment company reported strong earnings growth supported by higher memory chip demand, capital spending on artificial intelligence, and demand stabilization in China. Financial services firm American Express, another contributor, reported strong profits growth that reflected higher customer balances and robust spending by affluent cardmembers.
Top Detractors from Performance
Accenture was a notable detractor from relative performance. The consulting company’s business slowed due to a shift in IT spending toward artificial intelligence and away from legacy software projects. Nike was another detractor, as the footwear and apparel company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Growth and Income Fund (Class D Shares/JNGIX) 27.20% 12.12% 11.84%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Material Change Date Jan. 26, 2024
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 7,576,000,000
Holdings Count | Holding 66
Advisory Fees Paid, Amount $ 42,200,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,576M
Number of portfolio holdings 66
Total investment advisory fee paid $42.2M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Asset Allocation (% of net assets)
Common Stocks 99.9
Investment Companies 0.1
Other (0.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
Material Fund Change Expenses [Text Block]
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
C000077661 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Growth and Income Fund
Class Name Class I Shares
Trading Symbol JGINX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Growth and Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Growth and Income Fund
(Class I Shares/JGINX)		 $80 0.70%
Expenses Paid, Amount $ 80
Expense Ratio, Percent 0.70%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Growth and Income Fund Class I Shares returned 27.27%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
KLA was a top contributor to relative results. The semiconductor equipment company reported strong earnings growth supported by higher memory chip demand, capital spending on artificial intelligence, and demand stabilization in China. Financial services firm American Express, another contributor, reported strong profits growth that reflected higher customer balances and robust spending by affluent cardmembers.
Top Detractors from Performance
Accenture was a notable detractor from relative performance. The consulting company’s business slowed due to a shift in IT spending toward artificial intelligence and away from legacy software projects. Nike was another detractor, as the footwear and apparel company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Growth and Income Fund (Class I Shares/JGINX) 27.27% 12.17% 11.91%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Material Change Date Jan. 26, 2024
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,576,000,000
Holdings Count | Holding 66
Advisory Fees Paid, Amount $ 42,200,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,576M
Number of portfolio holdings 66
Total investment advisory fee paid $42.2M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Asset Allocation (% of net assets)
Common Stocks 99.9
Investment Companies 0.1
Other (0.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
Material Fund Change Expenses [Text Block]
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
C000114870 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Growth and Income Fund
Class Name Class N Shares
Trading Symbol JDNNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Growth and Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Growth and Income Fund
(Class N Shares/JDNNX)		 $70 0.62%
Expenses Paid, Amount $ 70
Expense Ratio, Percent 0.62%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Growth and Income Fund Class N Shares returned 27.37%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
KLA was a top contributor to relative results. The semiconductor equipment company reported strong earnings growth supported by higher memory chip demand, capital spending on artificial intelligence, and demand stabilization in China. Financial services firm American Express, another contributor, reported strong profits growth that reflected higher customer balances and robust spending by affluent cardmembers.
Top Detractors from Performance
Accenture was a notable detractor from relative performance. The consulting company’s business slowed due to a shift in IT spending toward artificial intelligence and away from legacy software projects. Nike was another detractor, as the footwear and apparel company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Growth and Income Fund (Class N Shares/JDNNX) 27.37% 12.26% 11.92%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Material Change Date Jan. 26, 2024
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,576,000,000
Holdings Count | Holding 66
Advisory Fees Paid, Amount $ 42,200,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,576M
Number of portfolio holdings 66
Total investment advisory fee paid $42.2M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Asset Allocation (% of net assets)
Common Stocks 99.9
Investment Companies 0.1
Other (0.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
Material Fund Change Expenses [Text Block]
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
C000077662 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Growth and Income Fund
Class Name Class R Shares
Trading Symbol JDNRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Growth and Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Growth and Income Fund
(Class R Shares/JDNRX)		 $156 1.38%
Expenses Paid, Amount $ 156
Expense Ratio, Percent 1.38%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Growth and Income Fund Class R Shares returned 26.40%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
KLA was a top contributor to relative results. The semiconductor equipment company reported strong earnings growth supported by higher memory chip demand, capital spending on artificial intelligence, and demand stabilization in China. Financial services firm American Express, another contributor, reported strong profits growth that reflected higher customer balances and robust spending by affluent cardmembers.
Top Detractors from Performance
Accenture was a notable detractor from relative performance. The consulting company’s business slowed due to a shift in IT spending toward artificial intelligence and away from legacy software projects. Nike was another detractor, as the footwear and apparel company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Growth and Income Fund (Class R Shares/JDNRX) 26.40% 11.40% 11.13%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Material Change Date Jan. 26, 2024
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,576,000,000
Holdings Count | Holding 66
Advisory Fees Paid, Amount $ 42,200,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,576M
Number of portfolio holdings 66
Total investment advisory fee paid $42.2M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Asset Allocation (% of net assets)
Common Stocks 99.9
Investment Companies 0.1
Other (0.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
Material Fund Change Expenses [Text Block]
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
C000077663 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Growth and Income Fund
Class Name Class S Shares
Trading Symbol JADGX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Growth and Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Growth and Income Fund
(Class S Shares/JADGX)		 $126 1.11%
Expenses Paid, Amount $ 126
Expense Ratio, Percent 1.11%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Growth and Income Fund Class S Shares returned 26.75%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
KLA was a top contributor to relative results. The semiconductor equipment company reported strong earnings growth supported by higher memory chip demand, capital spending on artificial intelligence, and demand stabilization in China. Financial services firm American Express, another contributor, reported strong profits growth that reflected higher customer balances and robust spending by affluent cardmembers.
Top Detractors from Performance
Accenture was a notable detractor from relative performance. The consulting company’s business slowed due to a shift in IT spending toward artificial intelligence and away from legacy software projects. Nike was another detractor, as the footwear and apparel company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Growth and Income Fund (Class S Shares/JADGX) 26.75% 11.71% 11.44%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Material Change Date Jan. 26, 2024
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,576,000,000
Holdings Count | Holding 66
Advisory Fees Paid, Amount $ 42,200,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,576M
Number of portfolio holdings 66
Total investment advisory fee paid $42.2M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Asset Allocation (% of net assets)
Common Stocks 99.9
Investment Companies 0.1
Other (0.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
Material Fund Change Expenses [Text Block]
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
C000028923 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Growth and Income Fund
Class Name Class T Shares
Trading Symbol JAGIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Growth and Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Growth and Income Fund
(Class T Shares/JAGIX)		 $97 0.85%
Expenses Paid, Amount $ 97
Expense Ratio, Percent 0.85%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Growth and Income Fund Class T Shares returned 27.08%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
KLA was a top contributor to relative results. The semiconductor equipment company reported strong earnings growth supported by higher memory chip demand, capital spending on artificial intelligence, and demand stabilization in China. Financial services firm American Express, another contributor, reported strong profits growth that reflected higher customer balances and robust spending by affluent cardmembers.
Top Detractors from Performance
Accenture was a notable detractor from relative performance. The consulting company’s business slowed due to a shift in IT spending toward artificial intelligence and away from legacy software projects. Nike was another detractor, as the footwear and apparel company’s revenue growth faced headwinds in a challenging environment for consumer discretionary spending.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Growth and Income Fund (Class T Shares/JAGIX) 27.08% 12.00% 11.73%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Material Change Date Jan. 26, 2024
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 7,576,000,000
Holdings Count | Holding 66
Advisory Fees Paid, Amount $ 42,200,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $7,576M
Number of portfolio holdings 66
Total investment advisory fee paid $42.2M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Asset Allocation (% of net assets)
Common Stocks 99.9
Investment Companies 0.1
Other (0.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.6
Apple Inc 6.3
KLA Corp 3.4
JPMorgan Chase & Co 3.1
American Express Co 3.1
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
Material Fund Change Expenses [Text Block]
Effective January 26, 2024, the Fund's contractual limit on total annual operating expense changed from 0.67% to 0.62%. The cap excludes fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, out-of-pocket transfer agency/shareholder servicing costs, including networking/omnibus/shareholder servicing fees payable by any share class, acquired fund fees and expenses, interest, dividends, taxes, brokerage commissions, and extraordinary expenses.
C000077669 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Research Fund
Class Name Class A Shares
Trading Symbol JRAAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Research Fund
(Class A Shares/JRAAX)		 $106 0.86%
Expenses Paid, Amount $ 106
Expense Ratio, Percent 0.86%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Research Fund Class A Shares returned 45.50%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
NVIDIA was a top contributor to returns relative to the performance benchmark. The graphics chip company reported strong earnings growth supported by robust demand for data center graphics processor units used in generative artificial intelligence. Aircraft component manufacturer Howmet Aerospace was another contributor, as it delivered several quarters of strong profits growth that surpassed expectations.
Top Detractors from Performance
Electric vehicle (EV) manufacturer Rivian Automotive detracted from returns relative to the performance benchmark, as slower EV sales and market share declines hurt its financial performance. We exited the position during the period. Real estate analytics company CoStar Group also detracted, as higher interest rates pressured its commercial real estate business through the first half of the 2024.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Research Fund (Class A Shares/JRAAX) at NAV 45.50% 17.47% 14.29%
Janus Henderson Research Fund (Class A Shares/JRAAX) at Maximum Offering Price - 5.75% 37.13% 16.09% 13.62%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 23,814,000,000
Holdings Count | Holding 85
Advisory Fees Paid, Amount $ 111,600,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $23,814M
Number of portfolio holdings 85
Total investment advisory fee paid $111.6M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
Asset Allocation (% of net assets)
Common Stocks 100.0
Investment Companies 0.1
Investments Purchased with Cash Collateral from Securities Lending 0.0
Private Placements 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
C000077670 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Research Fund
Class Name Class C Shares
Trading Symbol JRACX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Research Fund
(Class C Shares/JRACX)		 $171 1.40%
Expenses Paid, Amount $ 171
Expense Ratio, Percent 1.40%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Research Fund Class C Shares returned 44.73%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
NVIDIA was a top contributor to returns relative to the performance benchmark. The graphics chip company reported strong earnings growth supported by robust demand for data center graphics processor units used in generative artificial intelligence. Aircraft component manufacturer Howmet Aerospace was another contributor, as it delivered several quarters of strong profits growth that surpassed expectations.
Top Detractors from Performance
Electric vehicle (EV) manufacturer Rivian Automotive detracted from returns relative to the performance benchmark, as slower EV sales and market share declines hurt its financial performance. We exited the position during the period. Real estate analytics company CoStar Group also detracted, as higher interest rates pressured its commercial real estate business through the first half of the 2024.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Research Fund (Class C Shares/JRACX) at NAV 44.73% 16.65% 13.50%
Janus Henderson Research Fund (Class C Shares/JRACX) with Contingent Deferred Sales Charge 43.73%* 16.65% 13.50%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 23,814,000,000
Holdings Count | Holding 85
Advisory Fees Paid, Amount $ 111,600,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $23,814M
Number of portfolio holdings 85
Total investment advisory fee paid $111.6M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
Asset Allocation (% of net assets)
Common Stocks 100.0
Investment Companies 0.1
Investments Purchased with Cash Collateral from Securities Lending 0.0
Private Placements 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the Russell 1000® Growth Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the Russell 1000® Growth Index.
C000083517 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Research Fund
Class Name Class D Shares
Trading Symbol JNRFX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Research Fund
(Class D Shares/JNRFX)		 $82 0.67%
Expenses Paid, Amount $ 82
Expense Ratio, Percent 0.67%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Research Fund Class D Shares returned 45.78%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
NVIDIA was a top contributor to returns relative to the performance benchmark. The graphics chip company reported strong earnings growth supported by robust demand for data center graphics processor units used in generative artificial intelligence. Aircraft component manufacturer Howmet Aerospace was another contributor, as it delivered several quarters of strong profits growth that surpassed expectations.
Top Detractors from Performance
Electric vehicle (EV) manufacturer Rivian Automotive detracted from returns relative to the performance benchmark, as slower EV sales and market share declines hurt its financial performance. We exited the position during the period. Real estate analytics company CoStar Group also detracted, as higher interest rates pressured its commercial real estate business through the first half of the 2024.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Research Fund (Class D Shares/JNRFX) 45.78% 17.70% 14.52%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 23,814,000,000
Holdings Count | Holding 85
Advisory Fees Paid, Amount $ 111,600,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $23,814M
Number of portfolio holdings 85
Total investment advisory fee paid $111.6M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
Asset Allocation (% of net assets)
Common Stocks 100.0
Investment Companies 0.1
Investments Purchased with Cash Collateral from Securities Lending 0.0
Private Placements 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
C000077671 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Research Fund
Class Name Class I Shares
Trading Symbol JRAIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Research Fund
(Class I Shares/JRAIX)		 $79 0.64%
Expenses Paid, Amount $ 79
Expense Ratio, Percent 0.64%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Research Fund Class I Shares returned 45.83%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
NVIDIA was a top contributor to returns relative to the performance benchmark. The graphics chip company reported strong earnings growth supported by robust demand for data center graphics processor units used in generative artificial intelligence. Aircraft component manufacturer Howmet Aerospace was another contributor, as it delivered several quarters of strong profits growth that surpassed expectations.
Top Detractors from Performance
Electric vehicle (EV) manufacturer Rivian Automotive detracted from returns relative to the performance benchmark, as slower EV sales and market share declines hurt its financial performance. We exited the position during the period. Real estate analytics company CoStar Group also detracted, as higher interest rates pressured its commercial real estate business through the first half of the 2024.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Research Fund (Class I Shares/JRAIX) 45.83% 17.75% 14.59%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 23,814,000,000
Holdings Count | Holding 85
Advisory Fees Paid, Amount $ 111,600,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $23,814M
Number of portfolio holdings 85
Total investment advisory fee paid $111.6M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
Asset Allocation (% of net assets)
Common Stocks 100.0
Investment Companies 0.1
Investments Purchased with Cash Collateral from Securities Lending 0.0
Private Placements 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to an increase in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the Russell 1000® Growth Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to an increase in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the Russell 1000® Growth Index.
C000114872 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Research Fund
Class Name Class N Shares
Trading Symbol JRANX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Research Fund
(Class N Shares/JRANX)		 $68 0.55%
Expenses Paid, Amount $ 68
Expense Ratio, Percent 0.55%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Research Fund Class N Shares returned 45.95%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
NVIDIA was a top contributor to returns relative to the performance benchmark. The graphics chip company reported strong earnings growth supported by robust demand for data center graphics processor units used in generative artificial intelligence. Aircraft component manufacturer Howmet Aerospace was another contributor, as it delivered several quarters of strong profits growth that surpassed expectations.
Top Detractors from Performance
Electric vehicle (EV) manufacturer Rivian Automotive detracted from returns relative to the performance benchmark, as slower EV sales and market share declines hurt its financial performance. We exited the position during the period. Real estate analytics company CoStar Group also detracted, as higher interest rates pressured its commercial real estate business through the first half of the 2024.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Research Fund (Class N Shares/JRANX) 45.95% 17.85% 14.68%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 23,814,000,000
Holdings Count | Holding 85
Advisory Fees Paid, Amount $ 111,600,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $23,814M
Number of portfolio holdings 85
Total investment advisory fee paid $111.6M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
Asset Allocation (% of net assets)
Common Stocks 100.0
Investment Companies 0.1
Investments Purchased with Cash Collateral from Securities Lending 0.0
Private Placements 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to an increase in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the Russell 1000® Growth Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to an increase in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the Russell 1000® Growth Index.
C000177053 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Research Fund
Class Name Class R Shares
Trading Symbol JRARX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Research Fund
(Class R Shares/JRARX)		 $158 1.29%
Expenses Paid, Amount $ 158
Expense Ratio, Percent 1.29%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Research Fund Class R Shares returned 44.87%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
NVIDIA was a top contributor to returns relative to the performance benchmark. The graphics chip company reported strong earnings growth supported by robust demand for data center graphics processor units used in generative artificial intelligence. Aircraft component manufacturer Howmet Aerospace was another contributor, as it delivered several quarters of strong profits growth that surpassed expectations.
Top Detractors from Performance
Electric vehicle (EV) manufacturer Rivian Automotive detracted from returns relative to the performance benchmark, as slower EV sales and market share declines hurt its financial performance. We exited the position during the period. Real estate analytics company CoStar Group also detracted, as higher interest rates pressured its commercial real estate business through the first half of the 2024.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Research Fund (Class R Shares/JRARX) 44.87% 16.94% 13.91%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 23,814,000,000
Holdings Count | Holding 85
Advisory Fees Paid, Amount $ 111,600,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $23,814M
Number of portfolio holdings 85
Total investment advisory fee paid $111.6M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
Asset Allocation (% of net assets)
Common Stocks 100.0
Investment Companies 0.1
Investments Purchased with Cash Collateral from Securities Lending 0.0
Private Placements 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
C000077672 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Research Fund
Class Name Class S Shares
Trading Symbol JRASX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Research Fund
(Class S Shares/JRASX)		 $130 1.06%
Expenses Paid, Amount $ 130
Expense Ratio, Percent 1.06%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Research Fund Class S Shares returned 45.21%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
NVIDIA was a top contributor to returns relative to the performance benchmark. The graphics chip company reported strong earnings growth supported by robust demand for data center graphics processor units used in generative artificial intelligence. Aircraft component manufacturer Howmet Aerospace was another contributor, as it delivered several quarters of strong profits growth that surpassed expectations.
Top Detractors from Performance
Electric vehicle (EV) manufacturer Rivian Automotive detracted from returns relative to the performance benchmark, as slower EV sales and market share declines hurt its financial performance. We exited the position during the period. Real estate analytics company CoStar Group also detracted, as higher interest rates pressured its commercial real estate business through the first half of the 2024.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Research Fund (Class S Shares/JRASX) 45.21% 17.25% 14.10%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 23,814,000,000
Holdings Count | Holding 85
Advisory Fees Paid, Amount $ 111,600,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $23,814M
Number of portfolio holdings 85
Total investment advisory fee paid $111.6M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
Asset Allocation (% of net assets)
Common Stocks 100.0
Investment Companies 0.1
Investments Purchased with Cash Collateral from Securities Lending 0.0
Private Placements 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
C000028926 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Research Fund
Class Name Class T Shares
Trading Symbol JAMRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Research Fund
(Class T Shares/JAMRX)		 $96 0.78%
Expenses Paid, Amount $ 96
Expense Ratio, Percent 0.78%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Research Fund Class T Shares returned 45.64%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
NVIDIA was a top contributor to returns relative to the performance benchmark. The graphics chip company reported strong earnings growth supported by robust demand for data center graphics processor units used in generative artificial intelligence. Aircraft component manufacturer Howmet Aerospace was another contributor, as it delivered several quarters of strong profits growth that surpassed expectations.
Top Detractors from Performance
Electric vehicle (EV) manufacturer Rivian Automotive detracted from returns relative to the performance benchmark, as slower EV sales and market share declines hurt its financial performance. We exited the position during the period. Real estate analytics company CoStar Group also detracted, as higher interest rates pressured its commercial real estate business through the first half of the 2024.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Research Fund (Class T Shares/JAMRX) 45.64% 17.58% 14.41%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 23,814,000,000
Holdings Count | Holding 85
Advisory Fees Paid, Amount $ 111,600,000
Investment Company Portfolio Turnover 27.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $23,814M
Number of portfolio holdings 85
Total investment advisory fee paid $111.6M
Portfolio turnover rate 27%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
Asset Allocation (% of net assets)
Common Stocks 100.0
Investment Companies 0.1
Investments Purchased with Cash Collateral from Securities Lending 0.0
Private Placements 0.0
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 12.3
Microsoft Corp 11.4
Apple Inc 6.9
Meta Platforms Inc - Class A 6.3
Amazon.com Inc 5.7
C000077678 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Select Fund
Class Name Class A Shares
Trading Symbol JORAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Select Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Select Fund
(Class A Shares/JORAX)		 $119 1.02%
Expenses Paid, Amount $ 119
Expense Ratio, Percent 1.02%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Select Fund Class A Shares returned 32.99%. Its broad-based benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed to relative results. The U.S. independent power producer delivered strong profits growth and guidance, supported by increased energy usage to power artificial intelligence (AI). Taiwan Semiconductor Manufacturing Company, another contributor, delivered strong revenue growth, fueled in part by its fabrication of advance components used in AI.
Top Detractors from Performance
Samsonite International detracted on a relative basis. The Hong Kong-listed multinational luggage company reported lower-than-expected revenue growth and reduced guidance that partly reflected weaker travel spending in China. UK-based online sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the US sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Select Fund (Class A Shares/JORAX) at NAV 32.99% 13.37% 9.81%
Janus Henderson Global Select Fund (Class A Shares/JORAX) at Maximum Offering Price - 5.75% 25.37% 12.02% 9.17%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 2,923,000,000
Holdings Count | Holding 57
Advisory Fees Paid, Amount $ 17,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $2,923M
Number of portfolio holdings 57
Total investment advisory fee paid $17.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
Asset Allocation (% of net assets)
Common Stocks 96.9
Investment Companies 2.0
Preferred Stocks 0.8
Private Placements 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
C000077679 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Select Fund
Class Name Class C Shares
Trading Symbol JORCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Select Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Select Fund
(Class C Shares/JORCX)		 $202 1.74%
Expenses Paid, Amount $ 202
Expense Ratio, Percent 1.74%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Select Fund Class C Shares returned 31.98%. Its broad-based benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed to relative results. The U.S. independent power producer delivered strong profits growth and guidance, supported by increased energy usage to power artificial intelligence (AI). Taiwan Semiconductor Manufacturing Company, another contributor, delivered strong revenue growth, fueled in part by its fabrication of advance components used in AI.
Top Detractors from Performance
Samsonite International detracted on a relative basis. The Hong Kong-listed multinational luggage company reported lower-than-expected revenue growth and reduced guidance that partly reflected weaker travel spending in China. UK-based online sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the US sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Select Fund (Class C Shares/JORCX) at NAV 31.98% 12.41% 8.91%
Janus Henderson Global Select Fund (Class C Shares/JORCX) with Contingent Deferred Sales Charge 30.98%* 12.41% 8.91%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 2,923,000,000
Holdings Count | Holding 57
Advisory Fees Paid, Amount $ 17,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $2,923M
Number of portfolio holdings 57
Total investment advisory fee paid $17.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
Asset Allocation (% of net assets)
Common Stocks 96.9
Investment Companies 2.0
Preferred Stocks 0.8
Private Placements 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
C000083520 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Select Fund
Class Name Class D Shares
Trading Symbol JANRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Select Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Select Fund
(Class D Shares/JANRX)		 $96 0.82%
Expenses Paid, Amount $ 96
Expense Ratio, Percent 0.82%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Select Fund Class D Shares returned 33.23%. Its broad-based benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed to relative results. The U.S. independent power producer delivered strong profits growth and guidance, supported by increased energy usage to power artificial intelligence (AI). Taiwan Semiconductor Manufacturing Company, another contributor, delivered strong revenue growth, fueled in part by its fabrication of advance components used in AI.
Top Detractors from Performance
Samsonite International detracted on a relative basis. The Hong Kong-listed multinational luggage company reported lower-than-expected revenue growth and reduced guidance that partly reflected weaker travel spending in China. UK-based online sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the US sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Select Fund (Class D Shares/JANRX) 33.23% 13.60% 10.03%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 2,923,000,000
Holdings Count | Holding 57
Advisory Fees Paid, Amount $ 17,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $2,923M
Number of portfolio holdings 57
Total investment advisory fee paid $17.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
Asset Allocation (% of net assets)
Common Stocks 96.9
Investment Companies 2.0
Preferred Stocks 0.8
Private Placements 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
C000077680 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Select Fund
Class Name Class I Shares
Trading Symbol JORFX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Select Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Select Fund
(Class I Shares/JORFX)		 $93 0.80%
Expenses Paid, Amount $ 93
Expense Ratio, Percent 0.80%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Select Fund Class I Shares returned 33.20%. Its broad-based benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed to relative results. The U.S. independent power producer delivered strong profits growth and guidance, supported by increased energy usage to power artificial intelligence (AI). Taiwan Semiconductor Manufacturing Company, another contributor, delivered strong revenue growth, fueled in part by its fabrication of advance components used in AI.
Top Detractors from Performance
Samsonite International detracted on a relative basis. The Hong Kong-listed multinational luggage company reported lower-than-expected revenue growth and reduced guidance that partly reflected weaker travel spending in China. UK-based online sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the US sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Select Fund (Class I Shares/JORFX) 33.20% 13.63% 10.11%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 2,923,000,000
Holdings Count | Holding 57
Advisory Fees Paid, Amount $ 17,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $2,923M
Number of portfolio holdings 57
Total investment advisory fee paid $17.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
Asset Allocation (% of net assets)
Common Stocks 96.9
Investment Companies 2.0
Preferred Stocks 0.8
Private Placements 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
C000114874 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Select Fund
Class Name Class N Shares
Trading Symbol JSLNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Select Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Select Fund
(Class N Shares/JSLNX)		 $79 0.68%
Expenses Paid, Amount $ 79
Expense Ratio, Percent 0.68%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Select Fund Class N Shares returned 33.39%. Its broad-based benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed to relative results. The U.S. independent power producer delivered strong profits growth and guidance, supported by increased energy usage to power artificial intelligence (AI). Taiwan Semiconductor Manufacturing Company, another contributor, delivered strong revenue growth, fueled in part by its fabrication of advance components used in AI.
Top Detractors from Performance
Samsonite International detracted on a relative basis. The Hong Kong-listed multinational luggage company reported lower-than-expected revenue growth and reduced guidance that partly reflected weaker travel spending in China. UK-based online sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the US sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Select Fund (Class N Shares/JSLNX) 33.39% 13.76% 10.13%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 2,923,000,000
Holdings Count | Holding 57
Advisory Fees Paid, Amount $ 17,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $2,923M
Number of portfolio holdings 57
Total investment advisory fee paid $17.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
Asset Allocation (% of net assets)
Common Stocks 96.9
Investment Companies 2.0
Preferred Stocks 0.8
Private Placements 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
C000077681 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Select Fund
Class Name Class R Shares
Trading Symbol JORRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Select Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Select Fund
(Class R Shares/JORRX)		 $181 1.56%
Expenses Paid, Amount $ 181
Expense Ratio, Percent 1.56%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Select Fund Class R Shares returned 32.22%. Its broad-based benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed to relative results. The U.S. independent power producer delivered strong profits growth and guidance, supported by increased energy usage to power artificial intelligence (AI). Taiwan Semiconductor Manufacturing Company, another contributor, delivered strong revenue growth, fueled in part by its fabrication of advance components used in AI.
Top Detractors from Performance
Samsonite International detracted on a relative basis. The Hong Kong-listed multinational luggage company reported lower-than-expected revenue growth and reduced guidance that partly reflected weaker travel spending in China. UK-based online sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the US sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Select Fund (Class R Shares/JORRX) 32.22% 12.72% 9.25%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 2,923,000,000
Holdings Count | Holding 57
Advisory Fees Paid, Amount $ 17,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $2,923M
Number of portfolio holdings 57
Total investment advisory fee paid $17.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
Asset Allocation (% of net assets)
Common Stocks 96.9
Investment Companies 2.0
Preferred Stocks 0.8
Private Placements 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
C000077682 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Select Fund
Class Name Class S Shares
Trading Symbol JORIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Select Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Select Fund
(Class S Shares/JORIX)		 $150 1.29%
Expenses Paid, Amount $ 150
Expense Ratio, Percent 1.29%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Select Fund Class S Shares returned 32.56%. Its broad-based benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed to relative results. The U.S. independent power producer delivered strong profits growth and guidance, supported by increased energy usage to power artificial intelligence (AI). Taiwan Semiconductor Manufacturing Company, another contributor, delivered strong revenue growth, fueled in part by its fabrication of advance components used in AI.
Top Detractors from Performance
Samsonite International detracted on a relative basis. The Hong Kong-listed multinational luggage company reported lower-than-expected revenue growth and reduced guidance that partly reflected weaker travel spending in China. UK-based online sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the US sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Select Fund (Class S Shares/JORIX) 32.56% 13.01% 9.54%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 2,923,000,000
Holdings Count | Holding 57
Advisory Fees Paid, Amount $ 17,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $2,923M
Number of portfolio holdings 57
Total investment advisory fee paid $17.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
Asset Allocation (% of net assets)
Common Stocks 96.9
Investment Companies 2.0
Preferred Stocks 0.8
Private Placements 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
C000028933 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Select Fund
Class Name Class T Shares
Trading Symbol JORNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Select Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Select Fund
(Class T Shares/JORNX)		 $106 0.91%
Expenses Paid, Amount $ 106
Expense Ratio, Percent 0.91%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Select Fund Class T Shares returned 33.06%. Its broad-based benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed to relative results. The U.S. independent power producer delivered strong profits growth and guidance, supported by increased energy usage to power artificial intelligence (AI). Taiwan Semiconductor Manufacturing Company, another contributor, delivered strong revenue growth, fueled in part by its fabrication of advance components used in AI.
Top Detractors from Performance
Samsonite International detracted on a relative basis. The Hong Kong-listed multinational luggage company reported lower-than-expected revenue growth and reduced guidance that partly reflected weaker travel spending in China. UK-based online sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the US sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Select Fund (Class T Shares/JORNX) 33.06% 13.49% 9.95%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 2,923,000,000
Holdings Count | Holding 57
Advisory Fees Paid, Amount $ 17,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $2,923M
Number of portfolio holdings 57
Total investment advisory fee paid $17.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
Asset Allocation (% of net assets)
Common Stocks 96.9
Investment Companies 2.0
Preferred Stocks 0.8
Private Placements 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.3
Microsoft Corp 5.0
Vistra Corp 4.7
Liberty Media Corp-Liberty Formula One - Series C 3.5
Teck Resources Ltd 3.5
C000077683 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Contrarian Fund
Class Name Class A Shares
Trading Symbol JCNAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Contrarian Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Contrarian Fund
(Class A Shares/JCNAX)		 $104 0.89%
Expenses Paid, Amount $ 104
Expense Ratio, Percent 0.89%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Contrarian Fund Class A Shares returned 33.40%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to relative returns. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. AST SpaceMobile, another contributor, is an early-stage communications services company building a low-orbit satellite network. The stock rose as the company secured contracts and funding from major telecommunications carriers.
Top Detractors from Performance
An underweight in the information technology sector was a notable drag on relative returns. A position in industrial equipment manufacturer Chart Industries also detracted, as delayed deal closings resulted in disappointing earnings. Oil and gas producer Occidental Petroleum, another detractor, reported weaker-than-expected revenue and profits that pressured the stock performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Contrarian Fund (Class A Shares/JCNAX) at NAV 33.40% 13.82% 9.50%
Janus Henderson Contrarian Fund (Class A Shares/JCNAX) at Maximum Offering Price - 5.75% 25.72% 12.48% 8.85%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 4,993,000,000
Holdings Count | Holding 48
Advisory Fees Paid, Amount $ 22,200,000
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $4,993M
Number of portfolio holdings 48
Total investment advisory fee paid $22.2M
Portfolio turnover rate 42%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.1
Corporate Bonds 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (1.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the S&P 500® Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the S&P 500® Index.
C000077684 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Contrarian Fund
Class Name Class C Shares
Trading Symbol JCNCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Contrarian Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Contrarian Fund
(Class C Shares/JCNCX)		 $187 1.61%
Expenses Paid, Amount $ 187
Expense Ratio, Percent 1.61%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Contrarian Fund Class C Shares returned 32.41%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to relative returns. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. AST SpaceMobile, another contributor, is an early-stage communications services company building a low-orbit satellite network. The stock rose as the company secured contracts and funding from major telecommunications carriers.
Top Detractors from Performance
An underweight in the information technology sector was a notable drag on relative returns. A position in industrial equipment manufacturer Chart Industries also detracted, as delayed deal closings resulted in disappointing earnings. Oil and gas producer Occidental Petroleum, another detractor, reported weaker-than-expected revenue and profits that pressured the stock performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Contrarian Fund (Class C Shares/JCNCX) at NAV 32.41% 13.03% 8.73%
Janus Henderson Contrarian Fund (Class C Shares/JCNCX) with Contingent Deferred Sales Charge 31.41%* 13.03% 8.73%
S&P 500® Index 36.35% 15.98% 13.38%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 4,993,000,000
Holdings Count | Holding 48
Advisory Fees Paid, Amount $ 22,200,000
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $4,993M
Number of portfolio holdings 48
Total investment advisory fee paid $22.2M
Portfolio turnover rate 42%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.1
Corporate Bonds 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (1.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
C000083521 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Contrarian Fund
Class Name Class D Shares
Trading Symbol JACNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Contrarian Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Contrarian Fund
(Class D Shares/JACNX)		 $75 0.64%
Expenses Paid, Amount $ 75
Expense Ratio, Percent 0.64%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Contrarian Fund Class D Shares returned 33.71%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to relative returns. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. AST SpaceMobile, another contributor, is an early-stage communications services company building a low-orbit satellite network. The stock rose as the company secured contracts and funding from major telecommunications carriers.
Top Detractors from Performance
An underweight in the information technology sector was a notable drag on relative returns. A position in industrial equipment manufacturer Chart Industries also detracted, as delayed deal closings resulted in disappointing earnings. Oil and gas producer Occidental Petroleum, another detractor, reported weaker-than-expected revenue and profits that pressured the stock performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Contrarian Fund (Class D Shares/JACNX) 33.71% 14.09% 9.74%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 4,993,000,000
Holdings Count | Holding 48
Advisory Fees Paid, Amount $ 22,200,000
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $4,993M
Number of portfolio holdings 48
Total investment advisory fee paid $22.2M
Portfolio turnover rate 42%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.1
Corporate Bonds 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (1.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the S&P 500® Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the S&P 500® Index.
C000077685 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Contrarian Fund
Class Name Class I Shares
Trading Symbol JCONX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Contrarian Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Contrarian Fund
(Class I Shares/JCONX)		 $72 0.62%
Expenses Paid, Amount $ 72
Expense Ratio, Percent 0.62%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Contrarian Fund Class I Shares returned 33.73%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to relative returns. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. AST SpaceMobile, another contributor, is an early-stage communications services company building a low-orbit satellite network. The stock rose as the company secured contracts and funding from major telecommunications carriers.
Top Detractors from Performance
An underweight in the information technology sector was a notable drag on relative returns. A position in industrial equipment manufacturer Chart Industries also detracted, as delayed deal closings resulted in disappointing earnings. Oil and gas producer Occidental Petroleum, another detractor, reported weaker-than-expected revenue and profits that pressured the stock performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Contrarian Fund (Class I Shares/JCONX) 33.73% 14.13% 9.79%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 4,993,000,000
Holdings Count | Holding 48
Advisory Fees Paid, Amount $ 22,200,000
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $4,993M
Number of portfolio holdings 48
Total investment advisory fee paid $22.2M
Portfolio turnover rate 42%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.1
Corporate Bonds 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (1.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the S&P 500® Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the S&P 500® Index.
C000114875 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Contrarian Fund
Class Name Class N Shares
Trading Symbol JCNNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Contrarian Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Contrarian Fund
(Class N Shares/JCNNX)		 $60 0.51%
Expenses Paid, Amount $ 60
Expense Ratio, Percent 0.51%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Contrarian Fund Class N Shares returned 33.91%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to relative returns. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. AST SpaceMobile, another contributor, is an early-stage communications services company building a low-orbit satellite network. The stock rose as the company secured contracts and funding from major telecommunications carriers.
Top Detractors from Performance
An underweight in the information technology sector was a notable drag on relative returns. A position in industrial equipment manufacturer Chart Industries also detracted, as delayed deal closings resulted in disappointing earnings. Oil and gas producer Occidental Petroleum, another detractor, reported weaker-than-expected revenue and profits that pressured the stock performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Contrarian Fund (Class N Shares/JCNNX) 33.91% 14.25% 9.82%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 4,993,000,000
Holdings Count | Holding 48
Advisory Fees Paid, Amount $ 22,200,000
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $4,993M
Number of portfolio holdings 48
Total investment advisory fee paid $22.2M
Portfolio turnover rate 42%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.1
Corporate Bonds 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (1.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the S&P 500® Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the S&P 500® Index.
C000077686 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Contrarian Fund
Class Name Class R Shares
Trading Symbol JCNRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Contrarian Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Contrarian Fund
(Class R Shares/JCNRX)		 $157 1.35%
Expenses Paid, Amount $ 157
Expense Ratio, Percent 1.35%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Contrarian Fund Class R Shares returned 32.78%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to relative returns. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. AST SpaceMobile, another contributor, is an early-stage communications services company building a low-orbit satellite network. The stock rose as the company secured contracts and funding from major telecommunications carriers.
Top Detractors from Performance
An underweight in the information technology sector was a notable drag on relative returns. A position in industrial equipment manufacturer Chart Industries also detracted, as delayed deal closings resulted in disappointing earnings. Oil and gas producer Occidental Petroleum, another detractor, reported weaker-than-expected revenue and profits that pressured the stock performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Contrarian Fund (Class R Shares/JCNRX) 32.78% 13.26% 8.98%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 4,993,000,000
Holdings Count | Holding 48
Advisory Fees Paid, Amount $ 22,200,000
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $4,993M
Number of portfolio holdings 48
Total investment advisory fee paid $22.2M
Portfolio turnover rate 42%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.1
Corporate Bonds 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (1.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
C000077687 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Contrarian Fund
Class Name Class S Shares
Trading Symbol JCNIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Contrarian Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Contrarian Fund
(Class S Shares/JCNIX)		 $127 1.09%
Expenses Paid, Amount $ 127
Expense Ratio, Percent 1.09%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Contrarian Fund Class S Shares returned 33.10%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to relative returns. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. AST SpaceMobile, another contributor, is an early-stage communications services company building a low-orbit satellite network. The stock rose as the company secured contracts and funding from major telecommunications carriers.
Top Detractors from Performance
An underweight in the information technology sector was a notable drag on relative returns. A position in industrial equipment manufacturer Chart Industries also detracted, as delayed deal closings resulted in disappointing earnings. Oil and gas producer Occidental Petroleum, another detractor, reported weaker-than-expected revenue and profits that pressured the stock performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Contrarian Fund (Class S Shares/JCNIX) 33.10% 13.56% 9.28%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 4,993,000,000
Holdings Count | Holding 48
Advisory Fees Paid, Amount $ 22,200,000
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $4,993M
Number of portfolio holdings 48
Total investment advisory fee paid $22.2M
Portfolio turnover rate 42%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.1
Corporate Bonds 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (1.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
C000028934 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Contrarian Fund
Class Name Class T Shares
Trading Symbol JSVAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Contrarian Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Contrarian Fund
(Class T Shares/JSVAX)		 $86 0.74%
Expenses Paid, Amount $ 86
Expense Ratio, Percent 0.74%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Contrarian Fund Class T Shares returned 33.57%. Its broad-based benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to relative returns. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. AST SpaceMobile, another contributor, is an early-stage communications services company building a low-orbit satellite network. The stock rose as the company secured contracts and funding from major telecommunications carriers.
Top Detractors from Performance
An underweight in the information technology sector was a notable drag on relative returns. A position in industrial equipment manufacturer Chart Industries also detracted, as delayed deal closings resulted in disappointing earnings. Oil and gas producer Occidental Petroleum, another detractor, reported weaker-than-expected revenue and profits that pressured the stock performance.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Contrarian Fund (Class T Shares/JSVAX) 33.57% 13.98% 9.64%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 4,993,000,000
Holdings Count | Holding 48
Advisory Fees Paid, Amount $ 22,200,000
Investment Company Portfolio Turnover 42.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $4,993M
Number of portfolio holdings 48
Total investment advisory fee paid $22.2M
Portfolio turnover rate 42%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.1
Corporate Bonds 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (1.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Caesars Entertainment Inc 5.7
Vertiv Holdings Co 5.5
Oracle Corp 5.1
PNC Financial Services Group Inc/The 3.5
Amazon.com Inc 3.5
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the S&P 500® Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to a decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the S&P 500® Index.
C000077688 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Overseas Fund
Class Name Class A Shares
Trading Symbol JDIAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Overseas Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Overseas Fund
(Class A Shares/JDIAX)		 $131 1.18%
Expenses Paid, Amount $ 131
Expense Ratio, Percent 1.18%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Overseas Fund Class A Shares returned 21.36%. Its broad-based benchmark, the MSCI All Country World ex-USA IndexSM, returned 25.35%.
Top Contributors to Performance
Taiwan Semiconductor Manufacturing Company (TSMC) contributed to relative performance. TSMC delivered strong revenue growth, fueled in part by its fabrication of graphics processing units integral to the deployment of generative artificial intelligence. Italy-based international banking group UniCredit, another contributor, was rewarded by investors for its disciplined, shareholder-friendly capital allocation.
Top Detractors from Performance
Samsonite International detracted from relative results. The multinational luggage company reported lower-than-expected revenue growth and reduced guidance, due in part to macroeconomic weakness in China. UK-based online and sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the U.S. sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Overseas Fund (Class A Shares/JDIAX) at NAV 21.36% 10.94% 4.76%
Janus Henderson Overseas Fund (Class A Shares/JDIAX) at Maximum Offering Price - 5.75% 14.38% 9.63% 4.14%
MSCI All Country World ex-USA IndexSM 25.35% 7.59% 5.22%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,543,000,000
Holdings Count | Holding 46
Advisory Fees Paid, Amount $ 23,800,000
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,543M
Number of portfolio holdings 46
Total investment advisory fee paid $23.8M
Portfolio turnover rate 45%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
Asset Allocation (% of net assets)
Common Stocks 95.7
Investment Companies 2.3
Preferred Stocks 1.8
Investments Purchased with Cash Collateral from Securities Lending 0.4
Other (0.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
C000077689 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Overseas Fund
Class Name Class C Shares
Trading Symbol JIGCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Overseas Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Overseas Fund
(Class C Shares/JIGCX)		 $202 1.83%
Expenses Paid, Amount $ 202
Expense Ratio, Percent 1.83%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Overseas Fund Class C Shares returned 20.58%. Its broad-based benchmark, the MSCI All Country World ex-USA IndexSM, returned 25.35%.
Top Contributors to Performance
Taiwan Semiconductor Manufacturing Company (TSMC) contributed to relative performance. TSMC delivered strong revenue growth, fueled in part by its fabrication of graphics processing units integral to the deployment of generative artificial intelligence. Italy-based international banking group UniCredit, another contributor, was rewarded by investors for its disciplined, shareholder-friendly capital allocation.
Top Detractors from Performance
Samsonite International detracted from relative results. The multinational luggage company reported lower-than-expected revenue growth and reduced guidance, due in part to macroeconomic weakness in China. UK-based online and sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the U.S. sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Overseas Fund (Class C Shares/JIGCX) at NAV 20.58% 10.07% 3.96%
Janus Henderson Overseas Fund (Class C Shares/JIGCX) with Contingent Deferred Sales Charge 19.58%* 10.07% 3.96%
MSCI All Country World ex-USA IndexSM 25.35% 7.59% 5.22%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,543,000,000
Holdings Count | Holding 46
Advisory Fees Paid, Amount $ 23,800,000
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,543M
Number of portfolio holdings 46
Total investment advisory fee paid $23.8M
Portfolio turnover rate 45%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
Asset Allocation (% of net assets)
Common Stocks 95.7
Investment Companies 2.3
Preferred Stocks 1.8
Investments Purchased with Cash Collateral from Securities Lending 0.4
Other (0.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
Previously, Janus Henderson Investors US LLC contractually agreed to limit the net annual fund operating expenses of Class C Shares of the Fund to the extent they exceeded 1.95%. The cap excluded performance adjustments to management fees, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses. This limit was in effect for a period of one year and was discontinued on June 16, 2024.
Material Fund Change Expenses [Text Block]
Previously, Janus Henderson Investors US LLC contractually agreed to limit the net annual fund operating expenses of Class C Shares of the Fund to the extent they exceeded 1.95%. The cap excluded performance adjustments to management fees, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses. This limit was in effect for a period of one year and was discontinued on June 16, 2024.
C000083522 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Overseas Fund
Class Name Class D Shares
Trading Symbol JNOSX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Overseas Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Overseas Fund
(Class D Shares/JNOSX)		 $104 0.94%
Expenses Paid, Amount $ 104
Expense Ratio, Percent 0.94%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Overseas Fund Class D Shares returned 21.65%. Its broad-based benchmark, the MSCI All Country World ex-USA IndexSM, returned 25.35%.
Top Contributors to Performance
Taiwan Semiconductor Manufacturing Company (TSMC) contributed to relative performance. TSMC delivered strong revenue growth, fueled in part by its fabrication of graphics processing units integral to the deployment of generative artificial intelligence. Italy-based international banking group UniCredit, another contributor, was rewarded by investors for its disciplined, shareholder-friendly capital allocation.
Top Detractors from Performance
Samsonite International detracted from relative results. The multinational luggage company reported lower-than-expected revenue growth and reduced guidance, due in part to macroeconomic weakness in China. UK-based online and sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the U.S. sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Overseas Fund (Class D Shares/JNOSX) 21.65% 11.24% 5.06%
MSCI All Country World ex-USA IndexSM 25.35% 7.59% 5.22%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 3,543,000,000
Holdings Count | Holding 46
Advisory Fees Paid, Amount $ 23,800,000
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,543M
Number of portfolio holdings 46
Total investment advisory fee paid $23.8M
Portfolio turnover rate 45%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
Asset Allocation (% of net assets)
Common Stocks 95.7
Investment Companies 2.3
Preferred Stocks 1.8
Investments Purchased with Cash Collateral from Securities Lending 0.4
Other (0.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
Previously, Janus Henderson Investors US LLC contractually agreed to limit the net annual fund operating expenses of Class D Shares of the Fund to the extent they exceeded 0.95%. The cap excluded performance adjustments to management fees, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses. This limit was in effect for a period of one year and was discontinued on June 16, 2024.
Material Fund Change Expenses [Text Block]
Previously, Janus Henderson Investors US LLC contractually agreed to limit the net annual fund operating expenses of Class D Shares of the Fund to the extent they exceeded 0.95%. The cap excluded performance adjustments to management fees, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses. This limit was in effect for a period of one year and was discontinued on June 16, 2024.
C000077690 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Overseas Fund
Class Name Class I Shares
Trading Symbol JIGFX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Overseas Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Overseas Fund
(Class I Shares/JIGFX)		 $100 0.90%
Expenses Paid, Amount $ 100
Expense Ratio, Percent 0.90%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Overseas Fund Class I Shares returned 21.71%. Its broad-based benchmark, the MSCI All Country World ex-USA IndexSM, returned 25.35%.
Top Contributors to Performance
Taiwan Semiconductor Manufacturing Company (TSMC) contributed to relative performance. TSMC delivered strong revenue growth, fueled in part by its fabrication of graphics processing units integral to the deployment of generative artificial intelligence. Italy-based international banking group UniCredit, another contributor, was rewarded by investors for its disciplined, shareholder-friendly capital allocation.
Top Detractors from Performance
Samsonite International detracted from relative results. The multinational luggage company reported lower-than-expected revenue growth and reduced guidance, due in part to macroeconomic weakness in China. UK-based online and sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the U.S. sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Overseas Fund (Class I Shares/JIGFX) 21.71% 11.29% 5.10%
MSCI All Country World ex-USA IndexSM 25.35% 7.59% 5.22%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,543,000,000
Holdings Count | Holding 46
Advisory Fees Paid, Amount $ 23,800,000
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,543M
Number of portfolio holdings 46
Total investment advisory fee paid $23.8M
Portfolio turnover rate 45%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
Asset Allocation (% of net assets)
Common Stocks 95.7
Investment Companies 2.3
Preferred Stocks 1.8
Investments Purchased with Cash Collateral from Securities Lending 0.4
Other (0.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
C000114876 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Overseas Fund
Class Name Class N Shares
Trading Symbol JDINX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Overseas Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Overseas Fund
(Class N Shares/JDINX)		 $89 0.80%
Expenses Paid, Amount $ 89
Expense Ratio, Percent 0.80%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Overseas Fund Class N Shares returned 21.83%. Its broad-based benchmark, the MSCI All Country World ex-USA IndexSM, returned 25.35%.
Top Contributors to Performance
Taiwan Semiconductor Manufacturing Company (TSMC) contributed to relative performance. TSMC delivered strong revenue growth, fueled in part by its fabrication of graphics processing units integral to the deployment of generative artificial intelligence. Italy-based international banking group UniCredit, another contributor, was rewarded by investors for its disciplined, shareholder-friendly capital allocation.
Top Detractors from Performance
Samsonite International detracted from relative results. The multinational luggage company reported lower-than-expected revenue growth and reduced guidance, due in part to macroeconomic weakness in China. UK-based online and sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the U.S. sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Overseas Fund (Class N Shares/JDINX) 21.83% 11.40% 5.21%
MSCI All Country World ex-USA IndexSM 25.35% 7.59% 5.22%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,543,000,000
Holdings Count | Holding 46
Advisory Fees Paid, Amount $ 23,800,000
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,543M
Number of portfolio holdings 46
Total investment advisory fee paid $23.8M
Portfolio turnover rate 45%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
Asset Allocation (% of net assets)
Common Stocks 95.7
Investment Companies 2.3
Preferred Stocks 1.8
Investments Purchased with Cash Collateral from Securities Lending 0.4
Other (0.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
C000077691 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Overseas Fund
Class Name Class R Shares
Trading Symbol JDIRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Overseas Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Overseas Fund
(Class R Shares/JDIRX)		 $171 1.55%
Expenses Paid, Amount $ 171
Expense Ratio, Percent 1.55%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Overseas Fund Class R Shares returned 20.93%. Its broad-based benchmark, the MSCI All Country World ex-USA IndexSM, returned 25.35%.
Top Contributors to Performance
Taiwan Semiconductor Manufacturing Company (TSMC) contributed to relative performance. TSMC delivered strong revenue growth, fueled in part by its fabrication of graphics processing units integral to the deployment of generative artificial intelligence. Italy-based international banking group UniCredit, another contributor, was rewarded by investors for its disciplined, shareholder-friendly capital allocation.
Top Detractors from Performance
Samsonite International detracted from relative results. The multinational luggage company reported lower-than-expected revenue growth and reduced guidance, due in part to macroeconomic weakness in China. UK-based online and sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the U.S. sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Overseas Fund (Class R Shares/JDIRX) 20.93% 10.57% 4.44%
MSCI All Country World ex-USA IndexSM 25.35% 7.59% 5.22%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,543,000,000
Holdings Count | Holding 46
Advisory Fees Paid, Amount $ 23,800,000
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,543M
Number of portfolio holdings 46
Total investment advisory fee paid $23.8M
Portfolio turnover rate 45%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
Asset Allocation (% of net assets)
Common Stocks 95.7
Investment Companies 2.3
Preferred Stocks 1.8
Investments Purchased with Cash Collateral from Securities Lending 0.4
Other (0.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
Previously, Janus Henderson Investors US LLC contractually agreed to limit the net annual fund operating expenses of Class R Shares of the Fund to the extent they exceeded 1.54%. The cap excluded performance adjustments to management fees, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses. This limit was in effect for a period of one year and was discontinued on June 16, 2024.
Material Fund Change Expenses [Text Block]
Previously, Janus Henderson Investors US LLC contractually agreed to limit the net annual fund operating expenses of Class R Shares of the Fund to the extent they exceeded 1.54%. The cap excluded performance adjustments to management fees, brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses. This limit was in effect for a period of one year and was discontinued on June 16, 2024.
C000077692 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Overseas Fund
Class Name Class S Shares
Trading Symbol JIGRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Overseas Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Overseas Fund
(Class S Shares/JIGRX)		 $143 1.29%
Expenses Paid, Amount $ 143
Expense Ratio, Percent 1.29%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Overseas Fund Class S Shares returned 21.23%. Its broad-based benchmark, the MSCI All Country World ex-USA IndexSM, returned 25.35%.
Top Contributors to Performance
Taiwan Semiconductor Manufacturing Company (TSMC) contributed to relative performance. TSMC delivered strong revenue growth, fueled in part by its fabrication of graphics processing units integral to the deployment of generative artificial intelligence. Italy-based international banking group UniCredit, another contributor, was rewarded by investors for its disciplined, shareholder-friendly capital allocation.
Top Detractors from Performance
Samsonite International detracted from relative results. The multinational luggage company reported lower-than-expected revenue growth and reduced guidance, due in part to macroeconomic weakness in China. UK-based online and sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the U.S. sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Overseas Fund (Class S Shares/JIGRX) 21.23% 10.85% 4.70%
MSCI All Country World ex-USA IndexSM 25.35% 7.59% 5.22%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,543,000,000
Holdings Count | Holding 46
Advisory Fees Paid, Amount $ 23,800,000
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,543M
Number of portfolio holdings 46
Total investment advisory fee paid $23.8M
Portfolio turnover rate 45%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
Asset Allocation (% of net assets)
Common Stocks 95.7
Investment Companies 2.3
Preferred Stocks 1.8
Investments Purchased with Cash Collateral from Securities Lending 0.4
Other (0.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
C000028935 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Overseas Fund
Class Name Class T Shares
Trading Symbol JAOSX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Overseas Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Overseas Fund
(Class T Shares/JAOSX)		 $114 1.03%
Expenses Paid, Amount $ 114
Expense Ratio, Percent 1.03%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Overseas Fund Class T Shares returned 21.54%. Its broad-based benchmark, the MSCI All Country World ex-USA IndexSM, returned 25.35%.
Top Contributors to Performance
Taiwan Semiconductor Manufacturing Company (TSMC) contributed to relative performance. TSMC delivered strong revenue growth, fueled in part by its fabrication of graphics processing units integral to the deployment of generative artificial intelligence. Italy-based international banking group UniCredit, another contributor, was rewarded by investors for its disciplined, shareholder-friendly capital allocation.
Top Detractors from Performance
Samsonite International detracted from relative results. The multinational luggage company reported lower-than-expected revenue growth and reduced guidance, due in part to macroeconomic weakness in China. UK-based online and sports betting company Entain, another detractor, faced regulatory uncertainty and competitive challenges in the U.S. sports betting market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Overseas Fund (Class T Shares/JAOSX) 21.54% 11.14% 4.97%
MSCI All Country World ex-USA IndexSM 25.35% 7.59% 5.22%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,543,000,000
Holdings Count | Holding 46
Advisory Fees Paid, Amount $ 23,800,000
Investment Company Portfolio Turnover 45.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,543M
Number of portfolio holdings 46
Total investment advisory fee paid $23.8M
Portfolio turnover rate 45%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
Asset Allocation (% of net assets)
Common Stocks 95.7
Investment Companies 2.3
Preferred Stocks 1.8
Investments Purchased with Cash Collateral from Securities Lending 0.4
Other (0.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 6.9
Teck Resources Ltd 4.1
BAE Systems PLC 4.0
Liberty Media Corp-Liberty Formula One - Series C 3.6
BNP Paribas SA 3.6
C000077722 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Triton Fund
Class Name Class A Shares
Trading Symbol JGMAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Triton Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Triton Fund
(Class A Shares/JGMAX)		 $123 1.10%
Expenses Paid, Amount $ 123
Expense Ratio, Percent 1.10%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Triton Fund Class A Shares returned 23.06%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2500™ Growth Index, returned 25.20%. Its additional benchmark, the Russell 2000® Growth Index, returned 27.66%.
Top Contributors to Performance
AST SpaceMobile was a top contributor relative to the performance benchmark. This early-stage communications services company secured major contracts and funding to support its development of a low-orbit satellite network. Healthcare company Vaxcyte, another contributor, reported positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Triton Fund (Class A Shares/JGMAX) at NAV 23.06% 6.95% 9.54%
Janus Henderson Triton Fund (Class A Shares/JGMAX) at Maximum Offering Price - 5.75% 15.99% 5.69% 8.89%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2500™ Growth Index 25.20% 9.75% 9.98%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 6,661,000,000
Holdings Count | Holding 130
Advisory Fees Paid, Amount $ 41,600,000
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $6,661M
Number of portfolio holdings 130
Total investment advisory fee paid $41.6M
Portfolio turnover rate 19%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
Asset Allocation (% of net assets)
Common Stocks 99.2
Investments Purchased with Cash Collateral from Securities Lending 0.9
Investment Companies 0.7
Private Placements 0.4
Warrants 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
C000077723 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Triton Fund
Class Name Class C Shares
Trading Symbol JGMCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Triton Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Triton Fund
(Class C Shares/JGMCX)		 $187 1.68%
Expenses Paid, Amount $ 187
Expense Ratio, Percent 1.68%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Triton Fund Class C Shares returned 22.39%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2500™ Growth Index, returned 25.20%. Its additional benchmark, the Russell 2000® Growth Index, returned 27.66%.
Top Contributors to Performance
AST SpaceMobile was a top contributor relative to the performance benchmark. This early-stage communications services company secured major contracts and funding to support its development of a low-orbit satellite network. Healthcare company Vaxcyte, another contributor, reported positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Triton Fund (Class C Shares/JGMCX) at NAV 22.39% 6.39% 8.92%
Janus Henderson Triton Fund (Class C Shares/JGMCX) with Contingent Deferred Sales Charge 21.39%* 6.39% 8.92%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2500™ Growth Index 25.20% 9.75% 9.98%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 6,661,000,000
Holdings Count | Holding 130
Advisory Fees Paid, Amount $ 41,600,000
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $6,661M
Number of portfolio holdings 130
Total investment advisory fee paid $41.6M
Portfolio turnover rate 19%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
Asset Allocation (% of net assets)
Common Stocks 99.2
Investments Purchased with Cash Collateral from Securities Lending 0.9
Investment Companies 0.7
Private Placements 0.4
Warrants 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
C000083530 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Triton Fund
Class Name Class D Shares
Trading Symbol JANIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Triton Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Triton Fund
(Class D Shares/JANIX)		 $88 0.79%
Expenses Paid, Amount $ 88
Expense Ratio, Percent 0.79%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Triton Fund Class D Shares returned 23.44%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2500™ Growth Index, returned 25.20%. Its additional benchmark, the Russell 2000® Growth Index, returned 27.66%.
Top Contributors to Performance
AST SpaceMobile was a top contributor relative to the performance benchmark. This early-stage communications services company secured major contracts and funding to support its development of a low-orbit satellite network. Healthcare company Vaxcyte, another contributor, reported positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Triton Fund (Class D Shares/JANIX) 23.44% 7.30% 9.89%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2500™ Growth Index 25.20% 9.75% 9.98%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 6,661,000,000
Holdings Count | Holding 130
Advisory Fees Paid, Amount $ 41,600,000
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $6,661M
Number of portfolio holdings 130
Total investment advisory fee paid $41.6M
Portfolio turnover rate 19%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
Asset Allocation (% of net assets)
Common Stocks 99.2
Investments Purchased with Cash Collateral from Securities Lending 0.9
Investment Companies 0.7
Private Placements 0.4
Warrants 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
C000077724 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Triton Fund
Class Name Class I Shares
Trading Symbol JSMGX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Triton Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Triton Fund
(Class I Shares/JSMGX)		 $86 0.77%
Expenses Paid, Amount $ 86
Expense Ratio, Percent 0.77%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Triton Fund Class I Shares returned 23.48%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2500™ Growth Index, returned 25.20%. Its additional benchmark, the Russell 2000® Growth Index, returned 27.66%.
Top Contributors to Performance
AST SpaceMobile was a top contributor relative to the performance benchmark. This early-stage communications services company secured major contracts and funding to support its development of a low-orbit satellite network. Healthcare company Vaxcyte, another contributor, reported positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Triton Fund (Class I Shares/JSMGX) 23.48% 7.33% 9.93%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2500™ Growth Index 25.20% 9.75% 9.98%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 6,661,000,000
Holdings Count | Holding 130
Advisory Fees Paid, Amount $ 41,600,000
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $6,661M
Number of portfolio holdings 130
Total investment advisory fee paid $41.6M
Portfolio turnover rate 19%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
Asset Allocation (% of net assets)
Common Stocks 99.2
Investments Purchased with Cash Collateral from Securities Lending 0.9
Investment Companies 0.7
Private Placements 0.4
Warrants 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
C000114880 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Triton Fund
Class Name Class N Shares
Trading Symbol JGMNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Triton Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Triton Fund
(Class N Shares/JGMNX)		 $74 0.66%
Expenses Paid, Amount $ 74
Expense Ratio, Percent 0.66%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Triton Fund Class N Shares returned 23.59%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2500™ Growth Index, returned 25.20%. Its additional benchmark, the Russell 2000® Growth Index, returned 27.66%.
Top Contributors to Performance
AST SpaceMobile was a top contributor relative to the performance benchmark. This early-stage communications services company secured major contracts and funding to support its development of a low-orbit satellite network. Healthcare company Vaxcyte, another contributor, reported positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Triton Fund (Class N Shares/JGMNX) 23.59% 7.44% 10.04%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2500™ Growth Index 25.20% 9.75% 9.98%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 6,661,000,000
Holdings Count | Holding 130
Advisory Fees Paid, Amount $ 41,600,000
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $6,661M
Number of portfolio holdings 130
Total investment advisory fee paid $41.6M
Portfolio turnover rate 19%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
Asset Allocation (% of net assets)
Common Stocks 99.2
Investments Purchased with Cash Collateral from Securities Lending 0.9
Investment Companies 0.7
Private Placements 0.4
Warrants 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
C000077725 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Triton Fund
Class Name Class R Shares
Trading Symbol JGMRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Triton Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Triton Fund
(Class R Shares/JGMRX)		 $157 1.41%
Expenses Paid, Amount $ 157
Expense Ratio, Percent 1.41%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Triton Fund Class R Shares returned 22.68%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2500™ Growth Index, returned 25.20%. Its additional benchmark, the Russell 2000® Growth Index, returned 27.66%.
Top Contributors to Performance
AST SpaceMobile was a top contributor relative to the performance benchmark. This early-stage communications services company secured major contracts and funding to support its development of a low-orbit satellite network. Healthcare company Vaxcyte, another contributor, reported positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Triton Fund (Class R Shares/JGMRX) 22.68% 6.64% 9.22%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2500™ Growth Index 25.20% 9.75% 9.98%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 6,661,000,000
Holdings Count | Holding 130
Advisory Fees Paid, Amount $ 41,600,000
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $6,661M
Number of portfolio holdings 130
Total investment advisory fee paid $41.6M
Portfolio turnover rate 19%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
Asset Allocation (% of net assets)
Common Stocks 99.2
Investments Purchased with Cash Collateral from Securities Lending 0.9
Investment Companies 0.7
Private Placements 0.4
Warrants 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
C000077726 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Triton Fund
Class Name Class S Shares
Trading Symbol JGMIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Triton Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Triton Fund
(Class S Shares/JGMIX)		 $129 1.16%
Expenses Paid, Amount $ 129
Expense Ratio, Percent 1.16%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Triton Fund Class S Shares returned 22.97%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2500™ Growth Index, returned 25.20%. Its additional benchmark, the Russell 2000® Growth Index, returned 27.66%.
Top Contributors to Performance
AST SpaceMobile was a top contributor relative to the performance benchmark. This early-stage communications services company secured major contracts and funding to support its development of a low-orbit satellite network. Healthcare company Vaxcyte, another contributor, reported positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Triton Fund (Class S Shares/JGMIX) 22.97% 6.90% 9.49%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2500™ Growth Index 25.20% 9.75% 9.98%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 6,661,000,000
Holdings Count | Holding 130
Advisory Fees Paid, Amount $ 41,600,000
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $6,661M
Number of portfolio holdings 130
Total investment advisory fee paid $41.6M
Portfolio turnover rate 19%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
Asset Allocation (% of net assets)
Common Stocks 99.2
Investments Purchased with Cash Collateral from Securities Lending 0.9
Investment Companies 0.7
Private Placements 0.4
Warrants 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
C000028947 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Triton Fund
Class Name Class T Shares
Trading Symbol JATTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Triton Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Triton Fund
(Class T Shares/JATTX)		 $101 0.90%
Expenses Paid, Amount $ 101
Expense Ratio, Percent 0.90%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Triton Fund Class T Shares returned 23.34%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2500™ Growth Index, returned 25.20%. Its additional benchmark, the Russell 2000® Growth Index, returned 27.66%.
Top Contributors to Performance
AST SpaceMobile was a top contributor relative to the performance benchmark. This early-stage communications services company secured major contracts and funding to support its development of a low-orbit satellite network. Healthcare company Vaxcyte, another contributor, reported positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Triton Fund (Class T Shares/JATTX) 23.34% 7.18% 9.78%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2500™ Growth Index 25.20% 9.75% 9.98%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 6,661,000,000
Holdings Count | Holding 130
Advisory Fees Paid, Amount $ 41,600,000
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $6,661M
Number of portfolio holdings 130
Total investment advisory fee paid $41.6M
Portfolio turnover rate 19%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
Asset Allocation (% of net assets)
Common Stocks 99.2
Investments Purchased with Cash Collateral from Securities Lending 0.9
Investment Companies 0.7
Private Placements 0.4
Warrants 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
SS&C Technologies Holdings Inc 2.7
Blackbaud Inc 2.4
Teledyne Technologies Inc 1.9
Crown Holdings Inc 1.9
Cboe Global Markets Inc 1.8
C000100475 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Venture Fund
Class Name Class A Shares
Trading Symbol JVTAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Venture Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Venture Fund
(Class A Shares/JVTAX)		 $115 1.01%
Expenses Paid, Amount $ 115
Expense Ratio, Percent 1.01%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Venture Fund Class A Shares returned 27.42%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2000® Growth Index, returned 27.66%. Its additional benchmark, the Russell 2000® Index, returned 26.76%.
Top Contributors to Performance
Stride was a top contributor to returns relative to the performance benchmark. The education services company reported positive earnings, supported by strong student enrollment and retention metrics for its K-12 remote learning platform. AST SpaceMobile, another contributor, is an early-stage communications services company that has secured major contracts and funding to support its development of a low-orbit satellite network.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Venture Fund (Class A Shares/JVTAX) at NAV 27.42% 8.75% 9.70%
Janus Henderson Venture Fund (Class A Shares/JVTAX) at Maximum Offering Price - 5.75% 20.08% 7.47% 9.06%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
Russell 2000® Index 26.76% 9.39% 8.78%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,242,000,000
Holdings Count | Holding 140
Advisory Fees Paid, Amount $ 19,200,000
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,242M
Number of portfolio holdings 140
Total investment advisory fee paid $19.2M
Portfolio turnover rate 18%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
Asset Allocation (% of net assets)
Common Stocks 98.6
Investment Companies 1.0
Investments Purchased with Cash Collateral from Securities Lending 0.8
Private Placements 0.6
Warrants 0.0
Other (1.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
C000100476 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Venture Fund
Class Name Class C Shares
Trading Symbol JVTCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Venture Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Venture Fund
(Class C Shares/JVTCX)		 $187 1.65%
Expenses Paid, Amount $ 187
Expense Ratio, Percent 1.65%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Venture Fund Class C Shares returned 26.68%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2000® Growth Index, returned 27.66%. Its additional benchmark, the Russell 2000® Index, returned 26.76%.
Top Contributors to Performance
Stride was a top contributor to returns relative to the performance benchmark. The education services company reported positive earnings, supported by strong student enrollment and retention metrics for its K-12 remote learning platform. AST SpaceMobile, another contributor, is an early-stage communications services company that has secured major contracts and funding to support its development of a low-orbit satellite network.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Venture Fund (Class C Shares/JVTCX) at NAV 26.68% 7.94% 8.90%
Janus Henderson Venture Fund (Class C Shares/JVTCX) with Contingent Deferred Sales Charge 25.68%* 7.94% 8.90%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
Russell 2000® Index 26.76% 9.39% 8.78%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,242,000,000
Holdings Count | Holding 140
Advisory Fees Paid, Amount $ 19,200,000
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,242M
Number of portfolio holdings 140
Total investment advisory fee paid $19.2M
Portfolio turnover rate 18%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
Asset Allocation (% of net assets)
Common Stocks 98.6
Investment Companies 1.0
Investments Purchased with Cash Collateral from Securities Lending 0.8
Private Placements 0.6
Warrants 0.0
Other (1.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
C000083533 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Venture Fund
Class Name Class D Shares
Trading Symbol JANVX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Venture Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Venture Fund
(Class D Shares/JANVX)		 $90 0.79%
Expenses Paid, Amount $ 90
Expense Ratio, Percent 0.79%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Venture Fund Class D Shares returned 27.69%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2000® Growth Index, returned 27.66%. Its additional benchmark, the Russell 2000® Index, returned 26.76%.
Top Contributors to Performance
Stride was a top contributor to returns relative to the performance benchmark. The education services company reported positive earnings, supported by strong student enrollment and retention metrics for its K-12 remote learning platform. AST SpaceMobile, another contributor, is an early-stage communications services company that has secured major contracts and funding to support its development of a low-orbit satellite network.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Venture Fund (Class D Shares/JANVX) 27.69% 8.99% 9.94%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
Russell 2000® Index 26.76% 9.39% 8.78%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 3,242,000,000
Holdings Count | Holding 140
Advisory Fees Paid, Amount $ 19,200,000
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,242M
Number of portfolio holdings 140
Total investment advisory fee paid $19.2M
Portfolio turnover rate 18%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
Asset Allocation (% of net assets)
Common Stocks 98.6
Investment Companies 1.0
Investments Purchased with Cash Collateral from Securities Lending 0.8
Private Placements 0.6
Warrants 0.0
Other (1.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
C000100477 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Venture Fund
Class Name Class I Shares
Trading Symbol JVTIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Venture Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Venture Fund
(Class I Shares/JVTIX)		 $87 0.76%
Expenses Paid, Amount $ 87
Expense Ratio, Percent 0.76%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Venture Fund Class I Shares returned 27.73%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2000® Growth Index, returned 27.66%. Its additional benchmark, the Russell 2000® Index, returned 26.76%.
Top Contributors to Performance
Stride was a top contributor to returns relative to the performance benchmark. The education services company reported positive earnings, supported by strong student enrollment and retention metrics for its K-12 remote learning platform. AST SpaceMobile, another contributor, is an early-stage communications services company that has secured major contracts and funding to support its development of a low-orbit satellite network.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Venture Fund (Class I Shares/JVTIX) 27.73% 9.03% 9.99%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
Russell 2000® Index 26.76% 9.39% 8.78%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,242,000,000
Holdings Count | Holding 140
Advisory Fees Paid, Amount $ 19,200,000
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,242M
Number of portfolio holdings 140
Total investment advisory fee paid $19.2M
Portfolio turnover rate 18%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
Asset Allocation (% of net assets)
Common Stocks 98.6
Investment Companies 1.0
Investments Purchased with Cash Collateral from Securities Lending 0.8
Private Placements 0.6
Warrants 0.0
Other (1.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
C000114881 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Venture Fund
Class Name Class N Shares
Trading Symbol JVTNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Venture Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Venture Fund
(Class N Shares/JVTNX)		 $76 0.67%
Expenses Paid, Amount $ 76
Expense Ratio, Percent 0.67%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Venture Fund Class N Shares returned 27.85%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2000® Growth Index, returned 27.66%. Its additional benchmark, the Russell 2000® Index, returned 26.76%.
Top Contributors to Performance
Stride was a top contributor to returns relative to the performance benchmark. The education services company reported positive earnings, supported by strong student enrollment and retention metrics for its K-12 remote learning platform. AST SpaceMobile, another contributor, is an early-stage communications services company that has secured major contracts and funding to support its development of a low-orbit satellite network.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Venture Fund (Class N Shares/JVTNX) 27.85% 9.13% 10.09%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
Russell 2000® Index 26.76% 9.39% 8.78%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,242,000,000
Holdings Count | Holding 140
Advisory Fees Paid, Amount $ 19,200,000
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,242M
Number of portfolio holdings 140
Total investment advisory fee paid $19.2M
Portfolio turnover rate 18%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
Asset Allocation (% of net assets)
Common Stocks 98.6
Investment Companies 1.0
Investments Purchased with Cash Collateral from Securities Lending 0.8
Private Placements 0.6
Warrants 0.0
Other (1.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
C000100478 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Venture Fund
Class Name Class S Shares
Trading Symbol JVTSX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Venture Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Venture Fund
(Class S Shares/JVTSX)		 $133 1.17%
Expenses Paid, Amount $ 133
Expense Ratio, Percent 1.17%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Venture Fund Class S Shares returned 27.21%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2000® Growth Index, returned 27.66%. Its additional benchmark, the Russell 2000® Index, returned 26.76%.
Top Contributors to Performance
Stride was a top contributor to returns relative to the performance benchmark. The education services company reported positive earnings, supported by strong student enrollment and retention metrics for its K-12 remote learning platform. AST SpaceMobile, another contributor, is an early-stage communications services company that has secured major contracts and funding to support its development of a low-orbit satellite network.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Venture Fund (Class S Shares/JVTSX) 27.21% 8.58% 9.54%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
Russell 2000® Index 26.76% 9.39% 8.78%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,242,000,000
Holdings Count | Holding 140
Advisory Fees Paid, Amount $ 19,200,000
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,242M
Number of portfolio holdings 140
Total investment advisory fee paid $19.2M
Portfolio turnover rate 18%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
Asset Allocation (% of net assets)
Common Stocks 98.6
Investment Companies 1.0
Investments Purchased with Cash Collateral from Securities Lending 0.8
Private Placements 0.6
Warrants 0.0
Other (1.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
C000028950 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Venture Fund
Class Name Class T Shares
Trading Symbol JAVTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Venture Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Venture Fund
(Class T Shares/JAVTX)		 $102 0.90%
Expenses Paid, Amount $ 102
Expense Ratio, Percent 0.90%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Venture Fund Class T Shares returned 27.56%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell 2000® Growth Index, returned 27.66%. Its additional benchmark, the Russell 2000® Index, returned 26.76%.
Top Contributors to Performance
Stride was a top contributor to returns relative to the performance benchmark. The education services company reported positive earnings, supported by strong student enrollment and retention metrics for its K-12 remote learning platform. AST SpaceMobile, another contributor, is an early-stage communications services company that has secured major contracts and funding to support its development of a low-orbit satellite network.
Top Detractors from Performance
Rentokil Initial was a notable detractor from returns relative to the performance benchmark. The consumer services company faced revenue and earnings headwinds because of the slower-than-expected integration of its U.S. Terminix pest control business. ON Semiconductor, another detractor, reported weaker business trends due to slowing in the electric vehicle market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Venture Fund (Class T Shares/JAVTX) 27.56% 8.87% 9.83%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell 2000® Growth Index 27.66% 8.82% 8.95%
Russell 2000® Index 26.76% 9.39% 8.78%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,242,000,000
Holdings Count | Holding 140
Advisory Fees Paid, Amount $ 19,200,000
Investment Company Portfolio Turnover 18.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,242M
Number of portfolio holdings 140
Total investment advisory fee paid $19.2M
Portfolio turnover rate 18%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
Asset Allocation (% of net assets)
Common Stocks 98.6
Investment Companies 1.0
Investments Purchased with Cash Collateral from Securities Lending 0.8
Private Placements 0.6
Warrants 0.0
Other (1.0)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Stride Inc 2.4
SS&C Technologies Holdings Inc 2.1
Vaxcyte Inc 2.1
Descartes Systems Group Inc/The 1.9
Blackbaud Inc 1.7
C000077732 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Research Fund
Class Name Class A Shares
Trading Symbol JDWAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Research Fund
(Class A Shares/JDWAX)		 $115 0.97%
Expenses Paid, Amount $ 115
Expense Ratio, Percent 0.97%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Research Fund Class A Shares returned 36.90%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed relative to the broad-based benchmark. The U.S. independent power producer delivered strong profits growth and guidance supported by increased energy usage to power artificial intelligence (AI). NVIDIA, another contributor, reported robust earnings supported by strong demand for its data center graphics processor units used in generative AI.
Top Detractors from Performance
Weaker consumer spending trends in China pressured revenue growth and share price performance for Germany-based multinational automaker Porsche and France-based global spirits company Pernod Ricard. Both stocks were notable detractors from returns compared to the broad-based benchmark.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Research Fund (Class A Shares/JDWAX) at NAV 36.90% 13.79% 10.40%
Janus Henderson Global Research Fund (Class A Shares/JDWAX) at Maximum Offering Price - 5.75% 29.02% 12.45% 9.75%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,870,000,000
Holdings Count | Holding 115
Advisory Fees Paid, Amount $ 20,400,000
Investment Company Portfolio Turnover 28.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,870M
Number of portfolio holdings 115
Total investment advisory fee paid $20.4M
Portfolio turnover rate 28%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
Asset Allocation (% of net assets)
Common Stocks 98.2
Preferred Stocks 1.0
Investment Companies 0.6
Investments Purchased with Cash Collateral from Securities Lending 0.5
Private Placements 0.0
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
C000077733 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Research Fund
Class Name Class C Shares
Trading Symbol JWWCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Research Fund
(Class C Shares/JWWCX)		 $207 1.76%
Expenses Paid, Amount $ 207
Expense Ratio, Percent 1.76%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Research Fund Class C Shares returned 35.79%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed relative to the broad-based benchmark. The U.S. independent power producer delivered strong profits growth and guidance supported by increased energy usage to power artificial intelligence (AI). NVIDIA, another contributor, reported robust earnings supported by strong demand for its data center graphics processor units used in generative AI.
Top Detractors from Performance
Weaker consumer spending trends in China pressured revenue growth and share price performance for Germany-based multinational automaker Porsche and France-based global spirits company Pernod Ricard. Both stocks were notable detractors from returns compared to the broad-based benchmark.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Research Fund (Class C Shares/JWWCX) at NAV 35.79% 12.99% 9.64%
Janus Henderson Global Research Fund (Class C Shares/JWWCX) with Contingent Deferred Sales Charge 34.79%* 12.99% 9.64%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,870,000,000
Holdings Count | Holding 115
Advisory Fees Paid, Amount $ 20,400,000
Investment Company Portfolio Turnover 28.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,870M
Number of portfolio holdings 115
Total investment advisory fee paid $20.4M
Portfolio turnover rate 28%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
Asset Allocation (% of net assets)
Common Stocks 98.2
Preferred Stocks 1.0
Investment Companies 0.6
Investments Purchased with Cash Collateral from Securities Lending 0.5
Private Placements 0.0
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
C000083534 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Research Fund
Class Name Class D Shares
Trading Symbol JANWX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Research Fund
(Class D Shares/JANWX)		 $89 0.75%
Expenses Paid, Amount $ 89
Expense Ratio, Percent 0.75%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Research Fund Class D Shares returned 37.18%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed relative to the broad-based benchmark. The U.S. independent power producer delivered strong profits growth and guidance supported by increased energy usage to power artificial intelligence (AI). NVIDIA, another contributor, reported robust earnings supported by strong demand for its data center graphics processor units used in generative AI.
Top Detractors from Performance
Weaker consumer spending trends in China pressured revenue growth and share price performance for Germany-based multinational automaker Porsche and France-based global spirits company Pernod Ricard. Both stocks were notable detractors from returns compared to the broad-based benchmark.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Research Fund (Class D Shares/JANWX) 37.18% 14.10% 10.70%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 3,870,000,000
Holdings Count | Holding 115
Advisory Fees Paid, Amount $ 20,400,000
Investment Company Portfolio Turnover 28.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,870M
Number of portfolio holdings 115
Total investment advisory fee paid $20.4M
Portfolio turnover rate 28%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
Asset Allocation (% of net assets)
Common Stocks 98.2
Preferred Stocks 1.0
Investment Companies 0.6
Investments Purchased with Cash Collateral from Securities Lending 0.5
Private Placements 0.0
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
C000077734 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Research Fund
Class Name Class I Shares
Trading Symbol JWWFX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Research Fund
(Class I Shares/JWWFX)		 $83 0.70%
Expenses Paid, Amount $ 83
Expense Ratio, Percent 0.70%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Research Fund Class I Shares returned 37.25%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed relative to the broad-based benchmark. The U.S. independent power producer delivered strong profits growth and guidance supported by increased energy usage to power artificial intelligence (AI). NVIDIA, another contributor, reported robust earnings supported by strong demand for its data center graphics processor units used in generative AI.
Top Detractors from Performance
Weaker consumer spending trends in China pressured revenue growth and share price performance for Germany-based multinational automaker Porsche and France-based global spirits company Pernod Ricard. Both stocks were notable detractors from returns compared to the broad-based benchmark.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Research Fund (Class I Shares/JWWFX) 37.25% 14.18% 10.79%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,870,000,000
Holdings Count | Holding 115
Advisory Fees Paid, Amount $ 20,400,000
Investment Company Portfolio Turnover 28.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,870M
Number of portfolio holdings 115
Total investment advisory fee paid $20.4M
Portfolio turnover rate 28%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
Asset Allocation (% of net assets)
Common Stocks 98.2
Preferred Stocks 1.0
Investment Companies 0.6
Investments Purchased with Cash Collateral from Securities Lending 0.5
Private Placements 0.0
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to an increase in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the MSCI World IndexSM.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to an increase in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the MSCI World IndexSM.
C000114882 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Research Fund
Class Name Class N Shares
Trading Symbol JDWNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Research Fund
(Class N Shares/JDWNX)		 $74 0.62%
Expenses Paid, Amount $ 74
Expense Ratio, Percent 0.62%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Research Fund Class N Shares returned 37.36%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed relative to the broad-based benchmark. The U.S. independent power producer delivered strong profits growth and guidance supported by increased energy usage to power artificial intelligence (AI). NVIDIA, another contributor, reported robust earnings supported by strong demand for its data center graphics processor units used in generative AI.
Top Detractors from Performance
Weaker consumer spending trends in China pressured revenue growth and share price performance for Germany-based multinational automaker Porsche and France-based global spirits company Pernod Ricard. Both stocks were notable detractors from returns compared to the broad-based benchmark.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Research Fund (Class N Shares/JDWNX) 37.36% 14.25% 10.78%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,870,000,000
Holdings Count | Holding 115
Advisory Fees Paid, Amount $ 20,400,000
Investment Company Portfolio Turnover 28.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,870M
Number of portfolio holdings 115
Total investment advisory fee paid $20.4M
Portfolio turnover rate 28%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
Asset Allocation (% of net assets)
Common Stocks 98.2
Preferred Stocks 1.0
Investment Companies 0.6
Investments Purchased with Cash Collateral from Securities Lending 0.5
Private Placements 0.0
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to an increase in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the MSCI World IndexSM.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to an increase in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the MSCI World IndexSM.
C000077735 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Research Fund
Class Name Class R Shares
Trading Symbol JDWRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Research Fund
(Class R Shares/JDWRX)		 $165 1.40%
Expenses Paid, Amount $ 165
Expense Ratio, Percent 1.40%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Research Fund Class R Shares returned 36.28%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed relative to the broad-based benchmark. The U.S. independent power producer delivered strong profits growth and guidance supported by increased energy usage to power artificial intelligence (AI). NVIDIA, another contributor, reported robust earnings supported by strong demand for its data center graphics processor units used in generative AI.
Top Detractors from Performance
Weaker consumer spending trends in China pressured revenue growth and share price performance for Germany-based multinational automaker Porsche and France-based global spirits company Pernod Ricard. Both stocks were notable detractors from returns compared to the broad-based benchmark.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Research Fund (Class R Shares/JDWRX) 36.28% 13.37% 10.01%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,870,000,000
Holdings Count | Holding 115
Advisory Fees Paid, Amount $ 20,400,000
Investment Company Portfolio Turnover 28.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,870M
Number of portfolio holdings 115
Total investment advisory fee paid $20.4M
Portfolio turnover rate 28%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
Asset Allocation (% of net assets)
Common Stocks 98.2
Preferred Stocks 1.0
Investment Companies 0.6
Investments Purchased with Cash Collateral from Securities Lending 0.5
Private Placements 0.0
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
C000077736 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Research Fund
Class Name Class S Shares
Trading Symbol JWGRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Research Fund
(Class S Shares/JWGRX)		 $134 1.13%
Expenses Paid, Amount $ 134
Expense Ratio, Percent 1.13%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Research Fund Class S Shares returned 36.65%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed relative to the broad-based benchmark. The U.S. independent power producer delivered strong profits growth and guidance supported by increased energy usage to power artificial intelligence (AI). NVIDIA, another contributor, reported robust earnings supported by strong demand for its data center graphics processor units used in generative AI.
Top Detractors from Performance
Weaker consumer spending trends in China pressured revenue growth and share price performance for Germany-based multinational automaker Porsche and France-based global spirits company Pernod Ricard. Both stocks were notable detractors from returns compared to the broad-based benchmark.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Research Fund (Class S Shares/JWGRX) 36.65% 13.68% 10.31%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,870,000,000
Holdings Count | Holding 115
Advisory Fees Paid, Amount $ 20,400,000
Investment Company Portfolio Turnover 28.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,870M
Number of portfolio holdings 115
Total investment advisory fee paid $20.4M
Portfolio turnover rate 28%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
Asset Allocation (% of net assets)
Common Stocks 98.2
Preferred Stocks 1.0
Investment Companies 0.6
Investments Purchased with Cash Collateral from Securities Lending 0.5
Private Placements 0.0
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
C000028951 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Research Fund
Class Name Class T Shares
Trading Symbol JAWWX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Research Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Research Fund
(Class T Shares/JAWWX)		 $102 0.86%
Expenses Paid, Amount $ 102
Expense Ratio, Percent 0.86%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Research Fund Class T Shares returned 37.04%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the MSCI All Country World IndexSM, returned 31.76%.
Top Contributors to Performance
Vistra Energy contributed relative to the broad-based benchmark. The U.S. independent power producer delivered strong profits growth and guidance supported by increased energy usage to power artificial intelligence (AI). NVIDIA, another contributor, reported robust earnings supported by strong demand for its data center graphics processor units used in generative AI.
Top Detractors from Performance
Weaker consumer spending trends in China pressured revenue growth and share price performance for Germany-based multinational automaker Porsche and France-based global spirits company Pernod Ricard. Both stocks were notable detractors from returns compared to the broad-based benchmark.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Research Fund (Class T Shares/JAWWX) 37.04% 13.99% 10.60%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI All Country World IndexSM 31.76% 12.19% 9.39%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 3,870,000,000
Holdings Count | Holding 115
Advisory Fees Paid, Amount $ 20,400,000
Investment Company Portfolio Turnover 28.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $3,870M
Number of portfolio holdings 115
Total investment advisory fee paid $20.4M
Portfolio turnover rate 28%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
Asset Allocation (% of net assets)
Common Stocks 98.2
Preferred Stocks 1.0
Investment Companies 0.6
Investments Purchased with Cash Collateral from Securities Lending 0.5
Private Placements 0.0
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
NVIDIA Corp 5.4
Microsoft Corp 5.4
Alphabet Inc - Class C 3.8
Apple Inc 3.3
Amazon.com Inc 2.9
C000077737 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Enterprise Fund
Class Name Class A Shares
Trading Symbol JDMAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Enterprise Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Enterprise Fund
(Class A Shares/JDMAX)		 $125 1.11%
Expenses Paid, Amount $ 125
Expense Ratio, Percent 1.11%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Enterprise Fund Class A Shares returned 25.74%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell Midcap® Growth Index, returned 29.33%.
Top Contributors to Performance
GoDaddy contributed to returns relative to the performance benchmark. The website domain registration company has augmented its earnings growth by cross-selling other higher-margin services such as website design and digital payments. Software company Constellation Software, another contributor, benefited from strong competitive positioning and pricing power in niche market segments.
Top Detractors from Performance
Returns as compared to the performance benchmark were hindered by not owning several stocks that were strong contributors for the index but which we believed carried elevated risk. ON Semiconductor was a relative detractor among owned stocks, as demand for the company’s chips slowed along with electric vehicle sales. Rentokil Initial, another relative detractor, faced business headwinds for its U.S. pest control business.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Enterprise Fund (Class A Shares/JDMAX) at NAV 25.74% 10.95% 12.69%
Janus Henderson Enterprise Fund (Class A Shares/JDMAX) at Maximum Offering Price - 5.75% 18.51% 9.65% 12.03%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell Midcap® Growth Index 29.33% 11.48% 11.30%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,784,000,000
Holdings Count | Holding 80
Advisory Fees Paid, Amount $ 128,500,000
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,784M
Number of portfolio holdings 80
Total investment advisory fee paid $128.5M
Portfolio turnover rate 15%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
Asset Allocation (% of net assets)
Common Stocks 95.4
Investment Companies 4.7
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (0.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
C000077738 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Enterprise Fund
Class Name Class C Shares
Trading Symbol JGRCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Enterprise Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Enterprise Fund
(Class C Shares/JGRCX)		 $182 1.62%
Expenses Paid, Amount $ 182
Expense Ratio, Percent 1.62%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Enterprise Fund Class C Shares returned 25.12%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell Midcap® Growth Index, returned 29.33%.
Top Contributors to Performance
GoDaddy contributed to returns relative to the performance benchmark. The website domain registration company has augmented its earnings growth by cross-selling other higher-margin services such as website design and digital payments. Software company Constellation Software, another contributor, benefited from strong competitive positioning and pricing power in niche market segments.
Top Detractors from Performance
Returns as compared to the performance benchmark were hindered by not owning several stocks that were strong contributors for the index but which we believed carried elevated risk. ON Semiconductor was a relative detractor among owned stocks, as demand for the company’s chips slowed along with electric vehicle sales. Rentokil Initial, another relative detractor, faced business headwinds for its U.S. pest control business.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Enterprise Fund (Class C Shares/JGRCX) at NAV 25.12% 10.37% 12.05%
Janus Henderson Enterprise Fund (Class C Shares/JGRCX) with Contingent Deferred Sales Charge 24.12%* 10.37% 12.05%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell Midcap® Growth Index 29.33% 11.48% 11.30%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,784,000,000
Holdings Count | Holding 80
Advisory Fees Paid, Amount $ 128,500,000
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,784M
Number of portfolio holdings 80
Total investment advisory fee paid $128.5M
Portfolio turnover rate 15%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
Asset Allocation (% of net assets)
Common Stocks 95.4
Investment Companies 4.7
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (0.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
C000083535 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Enterprise Fund
Class Name Class D Shares
Trading Symbol JANEX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Enterprise Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Enterprise Fund
(Class D Shares/JANEX)		 $89 0.79%
Expenses Paid, Amount $ 89
Expense Ratio, Percent 0.79%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Enterprise Fund Class D Shares returned 26.15%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell Midcap® Growth Index, returned 29.33%.
Top Contributors to Performance
GoDaddy contributed to returns relative to the performance benchmark. The website domain registration company has augmented its earnings growth by cross-selling other higher-margin services such as website design and digital payments. Software company Constellation Software, another contributor, benefited from strong competitive positioning and pricing power in niche market segments.
Top Detractors from Performance
Returns as compared to the performance benchmark were hindered by not owning several stocks that were strong contributors for the index but which we believed carried elevated risk. ON Semiconductor was a relative detractor among owned stocks, as demand for the company’s chips slowed along with electric vehicle sales. Rentokil Initial, another relative detractor, faced business headwinds for its U.S. pest control business.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Enterprise Fund (Class D Shares/JANEX) 26.15% 11.31% 13.04%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell Midcap® Growth Index 29.33% 11.48% 11.30%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 22,784,000,000
Holdings Count | Holding 80
Advisory Fees Paid, Amount $ 128,500,000
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,784M
Number of portfolio holdings 80
Total investment advisory fee paid $128.5M
Portfolio turnover rate 15%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
Asset Allocation (% of net assets)
Common Stocks 95.4
Investment Companies 4.7
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (0.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
C000077739 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Enterprise Fund
Class Name Class I Shares
Trading Symbol JMGRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Enterprise Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Enterprise Fund
(Class I Shares/JMGRX)		 $86 0.76%
Expenses Paid, Amount $ 86
Expense Ratio, Percent 0.76%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Enterprise Fund Class I Shares returned 26.18%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell Midcap® Growth Index, returned 29.33%.
Top Contributors to Performance
GoDaddy contributed to returns relative to the performance benchmark. The website domain registration company has augmented its earnings growth by cross-selling other higher-margin services such as website design and digital payments. Software company Constellation Software, another contributor, benefited from strong competitive positioning and pricing power in niche market segments.
Top Detractors from Performance
Returns as compared to the performance benchmark were hindered by not owning several stocks that were strong contributors for the index but which we believed carried elevated risk. ON Semiconductor was a relative detractor among owned stocks, as demand for the company’s chips slowed along with electric vehicle sales. Rentokil Initial, another relative detractor, faced business headwinds for its U.S. pest control business.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Enterprise Fund (Class I Shares/JMGRX) 26.18% 11.35% 13.10%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell Midcap® Growth Index 29.33% 11.48% 11.30%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,784,000,000
Holdings Count | Holding 80
Advisory Fees Paid, Amount $ 128,500,000
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,784M
Number of portfolio holdings 80
Total investment advisory fee paid $128.5M
Portfolio turnover rate 15%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
Asset Allocation (% of net assets)
Common Stocks 95.4
Investment Companies 4.7
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (0.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
C000114883 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Enterprise Fund
Class Name Class N Shares
Trading Symbol JDMNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Enterprise Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Enterprise Fund
(Class N Shares/JDMNX)		 $75 0.66%
Expenses Paid, Amount $ 75
Expense Ratio, Percent 0.66%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Enterprise Fund Class N Shares returned 26.32%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell Midcap® Growth Index, returned 29.33%.
Top Contributors to Performance
GoDaddy contributed to returns relative to the performance benchmark. The website domain registration company has augmented its earnings growth by cross-selling other higher-margin services such as website design and digital payments. Software company Constellation Software, another contributor, benefited from strong competitive positioning and pricing power in niche market segments.
Top Detractors from Performance
Returns as compared to the performance benchmark were hindered by not owning several stocks that were strong contributors for the index but which we believed carried elevated risk. ON Semiconductor was a relative detractor among owned stocks, as demand for the company’s chips slowed along with electric vehicle sales. Rentokil Initial, another relative detractor, faced business headwinds for its U.S. pest control business.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Enterprise Fund (Class N Shares/JDMNX) 26.32% 11.46% 13.21%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell Midcap® Growth Index 29.33% 11.48% 11.30%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,784,000,000
Holdings Count | Holding 80
Advisory Fees Paid, Amount $ 128,500,000
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,784M
Number of portfolio holdings 80
Total investment advisory fee paid $128.5M
Portfolio turnover rate 15%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
Asset Allocation (% of net assets)
Common Stocks 95.4
Investment Companies 4.7
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (0.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
C000077740 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Enterprise Fund
Class Name Class R Shares
Trading Symbol JDMRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Enterprise Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Enterprise Fund
(Class R Shares/JDMRX)		 $158 1.40%
Expenses Paid, Amount $ 158
Expense Ratio, Percent 1.40%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Enterprise Fund Class R Shares returned 25.38%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell Midcap® Growth Index, returned 29.33%.
Top Contributors to Performance
GoDaddy contributed to returns relative to the performance benchmark. The website domain registration company has augmented its earnings growth by cross-selling other higher-margin services such as website design and digital payments. Software company Constellation Software, another contributor, benefited from strong competitive positioning and pricing power in niche market segments.
Top Detractors from Performance
Returns as compared to the performance benchmark were hindered by not owning several stocks that were strong contributors for the index but which we believed carried elevated risk. ON Semiconductor was a relative detractor among owned stocks, as demand for the company’s chips slowed along with electric vehicle sales. Rentokil Initial, another relative detractor, faced business headwinds for its U.S. pest control business.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Enterprise Fund (Class R Shares/JDMRX) 25.38% 10.63% 12.37%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell Midcap® Growth Index 29.33% 11.48% 11.30%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,784,000,000
Holdings Count | Holding 80
Advisory Fees Paid, Amount $ 128,500,000
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,784M
Number of portfolio holdings 80
Total investment advisory fee paid $128.5M
Portfolio turnover rate 15%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
Asset Allocation (% of net assets)
Common Stocks 95.4
Investment Companies 4.7
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (0.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
C000077741 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Enterprise Fund
Class Name Class S Shares
Trading Symbol JGRTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Enterprise Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Enterprise Fund
(Class S Shares/JGRTX)		 $131 1.16%
Expenses Paid, Amount $ 131
Expense Ratio, Percent 1.16%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Enterprise Fund Class S Shares returned 25.69%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell Midcap® Growth Index, returned 29.33%.
Top Contributors to Performance
GoDaddy contributed to returns relative to the performance benchmark. The website domain registration company has augmented its earnings growth by cross-selling other higher-margin services such as website design and digital payments. Software company Constellation Software, another contributor, benefited from strong competitive positioning and pricing power in niche market segments.
Top Detractors from Performance
Returns as compared to the performance benchmark were hindered by not owning several stocks that were strong contributors for the index but which we believed carried elevated risk. ON Semiconductor was a relative detractor among owned stocks, as demand for the company’s chips slowed along with electric vehicle sales. Rentokil Initial, another relative detractor, faced business headwinds for its U.S. pest control business.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Enterprise Fund (Class S Shares/JGRTX) 25.69% 10.91% 12.65%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell Midcap® Growth Index 29.33% 11.48% 11.30%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,784,000,000
Holdings Count | Holding 80
Advisory Fees Paid, Amount $ 128,500,000
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,784M
Number of portfolio holdings 80
Total investment advisory fee paid $128.5M
Portfolio turnover rate 15%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
Asset Allocation (% of net assets)
Common Stocks 95.4
Investment Companies 4.7
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (0.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
C000028952 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Enterprise Fund
Class Name Class T Shares
Trading Symbol JAENX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Enterprise Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Enterprise Fund
(Class T Shares/JAENX)		 $102 0.90%
Expenses Paid, Amount $ 102
Expense Ratio, Percent 0.90%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Enterprise Fund Class T Shares returned 26.02%. Its broad-based benchmark, the Russell 3000® Index, returned 35.19%. Its performance benchmark, the Russell Midcap® Growth Index, returned 29.33%.
Top Contributors to Performance
GoDaddy contributed to returns relative to the performance benchmark. The website domain registration company has augmented its earnings growth by cross-selling other higher-margin services such as website design and digital payments. Software company Constellation Software, another contributor, benefited from strong competitive positioning and pricing power in niche market segments.
Top Detractors from Performance
Returns as compared to the performance benchmark were hindered by not owning several stocks that were strong contributors for the index but which we believed carried elevated risk. ON Semiconductor was a relative detractor among owned stocks, as demand for the company’s chips slowed along with electric vehicle sales. Rentokil Initial, another relative detractor, faced business headwinds for its U.S. pest control business.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Enterprise Fund (Class T Shares/JAENX) 26.02% 11.19% 12.93%
Russell 3000® Index 35.19% 15.26% 12.83%
Russell Midcap® Growth Index 29.33% 11.48% 11.30%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,784,000,000
Holdings Count | Holding 80
Advisory Fees Paid, Amount $ 128,500,000
Investment Company Portfolio Turnover 15.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,784M
Number of portfolio holdings 80
Total investment advisory fee paid $128.5M
Portfolio turnover rate 15%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
Asset Allocation (% of net assets)
Common Stocks 95.4
Investment Companies 4.7
Investments Purchased with Cash Collateral from Securities Lending 0.3
Other (0.4)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Constellation Software Inc/Canada 4.6
GoDaddy Inc 3.6
SS&C Technologies Holdings Inc 3.1
Teleflex Inc 3.1
Boston Scientific Corp 2.9
C000077752 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Life Sciences Fund
Class Name Class A Shares
Trading Symbol JFNAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Life Sciences Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Life Sciences Fund
(Class A Shares/JFNAX)		 $111 0.98%
Expenses Paid, Amount $ 111
Expense Ratio, Percent 0.98%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Life Sciences Fund Class A Shares returned 26.28%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the MSCI World Health Care IndexSM, returned 20.84%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Vaxcyte was a key contributor relative to the performance benchmark, aided by positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease. ImmunoGen, another relative contributor, has sought to develop antibody-drug conjugates to improve cancer treatment. The company was acquired for a premium by pharmaceutical company AbbVie, benefiting the share price performance.
Top Detractors from Performance
89bio and Akero Therapeutics detracted relative to the performance benchmark. Both companies are seeking to develop treatments for liver disease, and both faced uncertainty around clinical trials that pressured their share performance. We felt these concerns were unwarranted and held onto the stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Life Sciences Fund (Class A Shares/JFNAX) at NAV 26.28% 14.02% 10.80%
Janus Henderson Global Life Sciences Fund (Class A Shares/JFNAX) at Maximum Offering Price - 5.75% 19.02% 12.68% 10.14%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI World Health Care IndexSM 20.84% 11.61% 8.96%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,732,000,000
Holdings Count | Holding 113
Advisory Fees Paid, Amount $ 32,800,000
Investment Company Portfolio Turnover 35.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,732M
Number of portfolio holdings 113
Total investment advisory fee paid $32.8M
Portfolio turnover rate 35%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
Asset Allocation (% of net assets)
Common Stocks 98.4
Private Placements 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.2
Private Investment in Public Equity (PIPES) 0.2
Investment Companies 0.0
Convertible Corporate Bonds 0.0
Warrants 0.0
Rights 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
C000077753 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Life Sciences Fund
Class Name Class C Shares
Trading Symbol JFNCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Life Sciences Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Life Sciences Fund
(Class C Shares/JFNCX)		 $196 1.74%
Expenses Paid, Amount $ 196
Expense Ratio, Percent 1.74%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Life Sciences Fund Class C Shares returned 25.34%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the MSCI World Health Care IndexSM, returned 20.84%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Vaxcyte was a key contributor relative to the performance benchmark, aided by positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease. ImmunoGen, another relative contributor, has sought to develop antibody-drug conjugates to improve cancer treatment. The company was acquired for a premium by pharmaceutical company AbbVie, benefiting the share price performance.
Top Detractors from Performance
89bio and Akero Therapeutics detracted relative to the performance benchmark. Both companies are seeking to develop treatments for liver disease, and both faced uncertainty around clinical trials that pressured their share performance. We felt these concerns were unwarranted and held onto the stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Life Sciences Fund (Class C Shares/JFNCX) at NAV 25.34% 13.21% 9.99%
Janus Henderson Global Life Sciences Fund (Class C Shares/JFNCX) with Contingent Deferred Sales Charge 24.34%* 13.21% 9.99%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI World Health Care IndexSM 20.84% 11.61% 8.96%
S&P 500® Index 36.35% 15.98% 13.38%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,732,000,000
Holdings Count | Holding 113
Advisory Fees Paid, Amount $ 32,800,000
Investment Company Portfolio Turnover 35.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,732M
Number of portfolio holdings 113
Total investment advisory fee paid $32.8M
Portfolio turnover rate 35%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
Asset Allocation (% of net assets)
Common Stocks 98.4
Private Placements 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.2
Private Investment in Public Equity (PIPES) 0.2
Investment Companies 0.0
Convertible Corporate Bonds 0.0
Warrants 0.0
Rights 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
C000083538 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Life Sciences Fund
Class Name Class D Shares
Trading Symbol JNGLX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Life Sciences Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Life Sciences Fund
(Class D Shares/JNGLX)		 $91 0.80%
Expenses Paid, Amount $ 91
Expense Ratio, Percent 0.80%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Life Sciences Fund Class D Shares returned 26.52%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the MSCI World Health Care IndexSM, returned 20.84%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Vaxcyte was a key contributor relative to the performance benchmark, aided by positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease. ImmunoGen, another relative contributor, has sought to develop antibody-drug conjugates to improve cancer treatment. The company was acquired for a premium by pharmaceutical company AbbVie, benefiting the share price performance.
Top Detractors from Performance
89bio and Akero Therapeutics detracted relative to the performance benchmark. Both companies are seeking to develop treatments for liver disease, and both faced uncertainty around clinical trials that pressured their share performance. We felt these concerns were unwarranted and held onto the stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Life Sciences Fund (Class D Shares/JNGLX) 26.52% 14.22% 11.00%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI World Health Care IndexSM 20.84% 11.61% 8.96%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 5,732,000,000
Holdings Count | Holding 113
Advisory Fees Paid, Amount $ 32,800,000
Investment Company Portfolio Turnover 35.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,732M
Number of portfolio holdings 113
Total investment advisory fee paid $32.8M
Portfolio turnover rate 35%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
Asset Allocation (% of net assets)
Common Stocks 98.4
Private Placements 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.2
Private Investment in Public Equity (PIPES) 0.2
Investment Companies 0.0
Convertible Corporate Bonds 0.0
Warrants 0.0
Rights 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
C000077754 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Life Sciences Fund
Class Name Class I Shares
Trading Symbol JFNIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Life Sciences Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Life Sciences Fund
(Class I Shares/JFNIX)		 $87 0.77%
Expenses Paid, Amount $ 87
Expense Ratio, Percent 0.77%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Life Sciences Fund Class I Shares returned 26.56%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the MSCI World Health Care IndexSM, returned 20.84%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Vaxcyte was a key contributor relative to the performance benchmark, aided by positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease. ImmunoGen, another relative contributor, has sought to develop antibody-drug conjugates to improve cancer treatment. The company was acquired for a premium by pharmaceutical company AbbVie, benefiting the share price performance.
Top Detractors from Performance
89bio and Akero Therapeutics detracted relative to the performance benchmark. Both companies are seeking to develop treatments for liver disease, and both faced uncertainty around clinical trials that pressured their share performance. We felt these concerns were unwarranted and held onto the stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Life Sciences Fund (Class I Shares/JFNIX) 26.56% 14.27% 11.05%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI World Health Care IndexSM 20.84% 11.61% 8.96%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,732,000,000
Holdings Count | Holding 113
Advisory Fees Paid, Amount $ 32,800,000
Investment Company Portfolio Turnover 35.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,732M
Number of portfolio holdings 113
Total investment advisory fee paid $32.8M
Portfolio turnover rate 35%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
Asset Allocation (% of net assets)
Common Stocks 98.4
Private Placements 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.2
Private Investment in Public Equity (PIPES) 0.2
Investment Companies 0.0
Convertible Corporate Bonds 0.0
Warrants 0.0
Rights 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
C000198286 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Life Sciences Fund
Class Name Class N Shares
Trading Symbol JFNNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Life Sciences Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Life Sciences Fund
(Class N Shares/JFNNX)		 $77 0.68%
Expenses Paid, Amount $ 77
Expense Ratio, Percent 0.68%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Life Sciences Fund Class N Shares returned 26.69%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the MSCI World Health Care IndexSM, returned 20.84%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Vaxcyte was a key contributor relative to the performance benchmark, aided by positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease. ImmunoGen, another relative contributor, has sought to develop antibody-drug conjugates to improve cancer treatment. The company was acquired for a premium by pharmaceutical company AbbVie, benefiting the share price performance.
Top Detractors from Performance
89bio and Akero Therapeutics detracted relative to the performance benchmark. Both companies are seeking to develop treatments for liver disease, and both faced uncertainty around clinical trials that pressured their share performance. We felt these concerns were unwarranted and held onto the stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Life Sciences Fund (Class N Shares/JFNNX) 26.69% 14.37% 11.06%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI World Health Care IndexSM 20.84% 11.61% 8.96%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,732,000,000
Holdings Count | Holding 113
Advisory Fees Paid, Amount $ 32,800,000
Investment Company Portfolio Turnover 35.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,732M
Number of portfolio holdings 113
Total investment advisory fee paid $32.8M
Portfolio turnover rate 35%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
Asset Allocation (% of net assets)
Common Stocks 98.4
Private Placements 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.2
Private Investment in Public Equity (PIPES) 0.2
Investment Companies 0.0
Convertible Corporate Bonds 0.0
Warrants 0.0
Rights 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
C000077755 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Life Sciences Fund
Class Name Class S Shares
Trading Symbol JFNSX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Life Sciences Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Life Sciences Fund
(Class S Shares/JFNSX)		 $133 1.18%
Expenses Paid, Amount $ 133
Expense Ratio, Percent 1.18%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Life Sciences Fund Class S Shares returned 26.04%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the MSCI World Health Care IndexSM, returned 20.84%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Vaxcyte was a key contributor relative to the performance benchmark, aided by positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease. ImmunoGen, another relative contributor, has sought to develop antibody-drug conjugates to improve cancer treatment. The company was acquired for a premium by pharmaceutical company AbbVie, benefiting the share price performance.
Top Detractors from Performance
89bio and Akero Therapeutics detracted relative to the performance benchmark. Both companies are seeking to develop treatments for liver disease, and both faced uncertainty around clinical trials that pressured their share performance. We felt these concerns were unwarranted and held onto the stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Life Sciences Fund (Class S Shares/JFNSX) 26.04% 13.80% 10.60%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI World Health Care IndexSM 20.84% 11.61% 8.96%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,732,000,000
Holdings Count | Holding 113
Advisory Fees Paid, Amount $ 32,800,000
Investment Company Portfolio Turnover 35.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,732M
Number of portfolio holdings 113
Total investment advisory fee paid $32.8M
Portfolio turnover rate 35%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
Asset Allocation (% of net assets)
Common Stocks 98.4
Private Placements 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.2
Private Investment in Public Equity (PIPES) 0.2
Investment Companies 0.0
Convertible Corporate Bonds 0.0
Warrants 0.0
Rights 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
C000028956 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Life Sciences Fund
Class Name Class T Shares
Trading Symbol JAGLX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Life Sciences Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Life Sciences Fund
(Class T Shares/JAGLX)		 $103 0.91%
Expenses Paid, Amount $ 103
Expense Ratio, Percent 0.91%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Life Sciences Fund Class T Shares returned 26.38%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the MSCI World Health Care IndexSM, returned 20.84%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Vaxcyte was a key contributor relative to the performance benchmark, aided by positive clinical trial results for its vaccine that targets 31 strains of invasive pneumococcal disease. ImmunoGen, another relative contributor, has sought to develop antibody-drug conjugates to improve cancer treatment. The company was acquired for a premium by pharmaceutical company AbbVie, benefiting the share price performance.
Top Detractors from Performance
89bio and Akero Therapeutics detracted relative to the performance benchmark. Both companies are seeking to develop treatments for liver disease, and both faced uncertainty around clinical trials that pressured their share performance. We felt these concerns were unwarranted and held onto the stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Life Sciences Fund (Class T Shares/JAGLX) 26.38% 14.10% 10.89%
MSCI World IndexSM 32.43% 13.04% 10.07%
MSCI World Health Care IndexSM 20.84% 11.61% 8.96%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,732,000,000
Holdings Count | Holding 113
Advisory Fees Paid, Amount $ 32,800,000
Investment Company Portfolio Turnover 35.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,732M
Number of portfolio holdings 113
Total investment advisory fee paid $32.8M
Portfolio turnover rate 35%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
Asset Allocation (% of net assets)
Common Stocks 98.4
Private Placements 0.9
Investments Purchased with Cash Collateral from Securities Lending 0.2
Private Investment in Public Equity (PIPES) 0.2
Investment Companies 0.0
Convertible Corporate Bonds 0.0
Warrants 0.0
Rights 0.0
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Eli Lilly & Co 8.4
UnitedHealth Group Inc 6.8
Novo Nordisk A/S - Class B 4.6
AstraZeneca PLC 3.6
AbbVie Inc 3.6
C000077597 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Real Estate Fund
Class Name Class A Shares
Trading Symbol JERAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Real Estate Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Real Estate Fund
(Class A Shares/JERAX)		 $112 0.99%
Expenses Paid, Amount $ 112
Expense Ratio, Percent 0.99%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Real Estate Fund Class A Shares returned 25.87%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the FTSE EPRA Nareit Global Index, returned 29.06%. Its additional benchmark, the FTSE EPRA Nareit Global Net Index, returned 27.80%.
Top Contributors to Performance
Australian logistics-focused company Goodman was the leading contributor relative to the performance benchmark. CBRE was another key contributor, due to posting strong results over the period and an improved outlook for office leasing and real estate transactions. A position in U.S. net lease owner Spirit Realty Capital also contributed relative to the performance benchmark after the company’s share price rose following the merger between Spirt and larger peer Realty Income early in the review period.
Top Detractors from Performance
China Resources was the leading detractor from returns relative to the performance benchmark. Cold storage owner/operator Americold Realty Trust also detracted after it was affected by negative sentiment around the potential demand implications from new weight-loss drugs. Mexican industrial property company Vesta contributed negatively. Its share price fell following the surprise results of the Mexican election in June, when the Morena party won a supermajority in both houses, heightening fears of undemocratic constitutional changes.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Real Estate Fund (Class A Shares/JERAX) at NAV 25.87% 2.84% 5.63%
Janus Henderson Global Real Estate Fund (Class A Shares/JERAX) at Maximum Offering Price - 5.75% 18.60% 1.63% 5.00%
MSCI World IndexSM 32.43% 13.04% 10.07%
FTSE EPRA Nareit Global Index 29.06% 1.76% 4.67%
FTSE EPRA Nareit Global Net Index 27.80% 0.84% 3.76%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 425,000,000
Holdings Count | Holding 64
Advisory Fees Paid, Amount $ 2,200,000
Investment Company Portfolio Turnover 87.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $425M
Number of portfolio holdings 64
Total investment advisory fee paid $2.2M
Portfolio turnover rate 87%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Asset Allocation (% of net assets)
Common Stocks 99.5
Investments Purchased with Cash Collateral from Securities Lending 1.3
Investment Companies 0.4
Rights 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
C000077598 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Real Estate Fund
Class Name Class C Shares
Trading Symbol JERCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Real Estate Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Real Estate Fund
(Class C Shares/JERCX)		 $201 1.79%
Expenses Paid, Amount $ 201
Expense Ratio, Percent 1.79%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Real Estate Fund Class C Shares returned 24.87%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the FTSE EPRA Nareit Global Index, returned 29.06%. Its additional benchmark, the FTSE EPRA Nareit Global Net Index, returned 27.80%.
Top Contributors to Performance
Australian logistics-focused company Goodman was the leading contributor relative to the performance benchmark. CBRE was another key contributor, due to posting strong results over the period and an improved outlook for office leasing and real estate transactions. A position in U.S. net lease owner Spirit Realty Capital also contributed relative to the performance benchmark after the company’s share price rose following the merger between Spirt and larger peer Realty Income early in the review period.
Top Detractors from Performance
China Resources was the leading detractor from returns relative to the performance benchmark. Cold storage owner/operator Americold Realty Trust also detracted after it was affected by negative sentiment around the potential demand implications from new weight-loss drugs. Mexican industrial property company Vesta contributed negatively. Its share price fell following the surprise results of the Mexican election in June, when the Morena party won a supermajority in both houses, heightening fears of undemocratic constitutional changes.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Real Estate Fund (Class C Shares/JERCX) at NAV 24.87% 2.02% 4.81%
Janus Henderson Global Real Estate Fund (Class C Shares/JERCX) with Contingent Deferred Sales Charge 23.87%* 2.02% 4.81%
MSCI World IndexSM 32.43% 13.04% 10.07%
FTSE EPRA Nareit Global Index 29.06% 1.76% 4.67%
FTSE EPRA Nareit Global Net Index 27.80% 0.84% 3.76%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 425,000,000
Holdings Count | Holding 64
Advisory Fees Paid, Amount $ 2,200,000
Investment Company Portfolio Turnover 87.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $425M
Number of portfolio holdings 64
Total investment advisory fee paid $2.2M
Portfolio turnover rate 87%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Asset Allocation (% of net assets)
Common Stocks 99.5
Investments Purchased with Cash Collateral from Securities Lending 1.3
Investment Companies 0.4
Rights 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
C000083540 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Real Estate Fund
Class Name Class D Shares
Trading Symbol JNGSX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Real Estate Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Real Estate Fund
(Class D Shares/JNGSX)		 $90 0.80%
Expenses Paid, Amount $ 90
Expense Ratio, Percent 0.80%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Real Estate Fund Class D Shares returned 26.15%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the FTSE EPRA Nareit Global Index, returned 29.06%. Its additional benchmark, the FTSE EPRA Nareit Global Net Index, returned 27.80%.
Top Contributors to Performance
Australian logistics-focused company Goodman was the leading contributor relative to the performance benchmark. CBRE was another key contributor, due to posting strong results over the period and an improved outlook for office leasing and real estate transactions. A position in U.S. net lease owner Spirit Realty Capital also contributed relative to the performance benchmark after the company’s share price rose following the merger between Spirt and larger peer Realty Income early in the review period.
Top Detractors from Performance
China Resources was the leading detractor from returns relative to the performance benchmark. Cold storage owner/operator Americold Realty Trust also detracted after it was affected by negative sentiment around the potential demand implications from new weight-loss drugs. Mexican industrial property company Vesta contributed negatively. Its share price fell following the surprise results of the Mexican election in June, when the Morena party won a supermajority in both houses, heightening fears of undemocratic constitutional changes.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Real Estate Fund (Class D Shares/JNGSX) 26.15% 3.03% 5.81%
MSCI World IndexSM 32.43% 13.04% 10.07%
FTSE EPRA Nareit Global Index 29.06% 1.76% 4.67%
FTSE EPRA Nareit Global Net Index 27.80% 0.84% 3.76%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 425,000,000
Holdings Count | Holding 64
Advisory Fees Paid, Amount $ 2,200,000
Investment Company Portfolio Turnover 87.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $425M
Number of portfolio holdings 64
Total investment advisory fee paid $2.2M
Portfolio turnover rate 87%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Asset Allocation (% of net assets)
Common Stocks 99.5
Investments Purchased with Cash Collateral from Securities Lending 1.3
Investment Companies 0.4
Rights 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
C000077599 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Real Estate Fund
Class Name Class I Shares
Trading Symbol JERIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Real Estate Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Real Estate Fund
(Class I Shares/JERIX)		 $83 0.73%
Expenses Paid, Amount $ 83
Expense Ratio, Percent 0.73%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Real Estate Fund Class I Shares returned 26.17%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the FTSE EPRA Nareit Global Index, returned 29.06%. Its additional benchmark, the FTSE EPRA Nareit Global Net Index, returned 27.80%.
Top Contributors to Performance
Australian logistics-focused company Goodman was the leading contributor relative to the performance benchmark. CBRE was another key contributor, due to posting strong results over the period and an improved outlook for office leasing and real estate transactions. A position in U.S. net lease owner Spirit Realty Capital also contributed relative to the performance benchmark after the company’s share price rose following the merger between Spirt and larger peer Realty Income early in the review period.
Top Detractors from Performance
China Resources was the leading detractor from returns relative to the performance benchmark. Cold storage owner/operator Americold Realty Trust also detracted after it was affected by negative sentiment around the potential demand implications from new weight-loss drugs. Mexican industrial property company Vesta contributed negatively. Its share price fell following the surprise results of the Mexican election in June, when the Morena party won a supermajority in both houses, heightening fears of undemocratic constitutional changes.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Real Estate Fund (Class I Shares/JERIX) 26.17% 3.08% 5.89%
MSCI World IndexSM 32.43% 13.04% 10.07%
FTSE EPRA Nareit Global Index 29.06% 1.76% 4.67%
FTSE EPRA Nareit Global Net Index 27.80% 0.84% 3.76%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 425,000,000
Holdings Count | Holding 64
Advisory Fees Paid, Amount $ 2,200,000
Investment Company Portfolio Turnover 87.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $425M
Number of portfolio holdings 64
Total investment advisory fee paid $2.2M
Portfolio turnover rate 87%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Asset Allocation (% of net assets)
Common Stocks 99.5
Investments Purchased with Cash Collateral from Securities Lending 1.3
Investment Companies 0.4
Rights 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
C000198287 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Real Estate Fund
Class Name Class N Shares
Trading Symbol JERNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Real Estate Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Real Estate Fund
(Class N Shares/JERNX)		 $70 0.62%
Expenses Paid, Amount $ 70
Expense Ratio, Percent 0.62%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Real Estate Fund Class N Shares returned 26.30%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the FTSE EPRA Nareit Global Index, returned 29.06%. Its additional benchmark, the FTSE EPRA Nareit Global Net Index, returned 27.80%.
Top Contributors to Performance
Australian logistics-focused company Goodman was the leading contributor relative to the performance benchmark. CBRE was another key contributor, due to posting strong results over the period and an improved outlook for office leasing and real estate transactions. A position in U.S. net lease owner Spirit Realty Capital also contributed relative to the performance benchmark after the company’s share price rose following the merger between Spirt and larger peer Realty Income early in the review period.
Top Detractors from Performance
China Resources was the leading detractor from returns relative to the performance benchmark. Cold storage owner/operator Americold Realty Trust also detracted after it was affected by negative sentiment around the potential demand implications from new weight-loss drugs. Mexican industrial property company Vesta contributed negatively. Its share price fell following the surprise results of the Mexican election in June, when the Morena party won a supermajority in both houses, heightening fears of undemocratic constitutional changes.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Real Estate Fund (Class N Shares/JERNX) 26.30% 3.18% 5.96%
MSCI World IndexSM 32.43% 13.04% 10.07%
FTSE EPRA Nareit Global Index 29.06% 1.76% 4.67%
FTSE EPRA Nareit Global Net Index 27.80% 0.84% 3.76%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 425,000,000
Holdings Count | Holding 64
Advisory Fees Paid, Amount $ 2,200,000
Investment Company Portfolio Turnover 87.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $425M
Number of portfolio holdings 64
Total investment advisory fee paid $2.2M
Portfolio turnover rate 87%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Asset Allocation (% of net assets)
Common Stocks 99.5
Investments Purchased with Cash Collateral from Securities Lending 1.3
Investment Companies 0.4
Rights 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
C000077600 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Real Estate Fund
Class Name Class S Shares
Trading Symbol JERSX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Real Estate Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Real Estate Fund
(Class S Shares/JERSX)		 $131 1.16%
Expenses Paid, Amount $ 131
Expense Ratio, Percent 1.16%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Real Estate Fund Class S Shares returned 25.67%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the FTSE EPRA Nareit Global Index, returned 29.06%. Its additional benchmark, the FTSE EPRA Nareit Global Net Index, returned 27.80%.
Top Contributors to Performance
Australian logistics-focused company Goodman was the leading contributor relative to the performance benchmark. CBRE was another key contributor, due to posting strong results over the period and an improved outlook for office leasing and real estate transactions. A position in U.S. net lease owner Spirit Realty Capital also contributed relative to the performance benchmark after the company’s share price rose following the merger between Spirt and larger peer Realty Income early in the review period.
Top Detractors from Performance
China Resources was the leading detractor from returns relative to the performance benchmark. Cold storage owner/operator Americold Realty Trust also detracted after it was affected by negative sentiment around the potential demand implications from new weight-loss drugs. Mexican industrial property company Vesta contributed negatively. Its share price fell following the surprise results of the Mexican election in June, when the Morena party won a supermajority in both houses, heightening fears of undemocratic constitutional changes.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Real Estate Fund (Class S Shares/JERSX) 25.67% 2.66% 5.44%
MSCI World IndexSM 32.43% 13.04% 10.07%
FTSE EPRA Nareit Global Index 29.06% 1.76% 4.67%
FTSE EPRA Nareit Global Net Index 27.80% 0.84% 3.76%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 425,000,000
Holdings Count | Holding 64
Advisory Fees Paid, Amount $ 2,200,000
Investment Company Portfolio Turnover 87.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $425M
Number of portfolio holdings 64
Total investment advisory fee paid $2.2M
Portfolio turnover rate 87%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Asset Allocation (% of net assets)
Common Stocks 99.5
Investments Purchased with Cash Collateral from Securities Lending 1.3
Investment Companies 0.4
Rights 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
C000077601 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Real Estate Fund
Class Name Class T Shares
Trading Symbol JERTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Real Estate Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Material Fund Change Notice [Text Block]
This report describes changes to the Fund that occurred during the reporting period.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Real Estate Fund
(Class T Shares/JERTX)		 $98 0.87%
Expenses Paid, Amount $ 98
Expense Ratio, Percent 0.87%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Real Estate Fund Class T Shares returned 26.12%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its performance benchmark, the FTSE EPRA Nareit Global Index, returned 29.06%. Its additional benchmark, the FTSE EPRA Nareit Global Net Index, returned 27.80%.
Top Contributors to Performance
Australian logistics-focused company Goodman was the leading contributor relative to the performance benchmark. CBRE was another key contributor, due to posting strong results over the period and an improved outlook for office leasing and real estate transactions. A position in U.S. net lease owner Spirit Realty Capital also contributed relative to the performance benchmark after the company’s share price rose following the merger between Spirt and larger peer Realty Income early in the review period.
Top Detractors from Performance
China Resources was the leading detractor from returns relative to the performance benchmark. Cold storage owner/operator Americold Realty Trust also detracted after it was affected by negative sentiment around the potential demand implications from new weight-loss drugs. Mexican industrial property company Vesta contributed negatively. Its share price fell following the surprise results of the Mexican election in June, when the Morena party won a supermajority in both houses, heightening fears of undemocratic constitutional changes.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Real Estate Fund (Class T Shares/JERTX) 26.12% 2.95% 5.74%
MSCI World IndexSM 32.43% 13.04% 10.07%
FTSE EPRA Nareit Global Index 29.06% 1.76% 4.67%
FTSE EPRA Nareit Global Net Index 27.80% 0.84% 3.76%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 425,000,000
Holdings Count | Holding 64
Advisory Fees Paid, Amount $ 2,200,000
Investment Company Portfolio Turnover 87.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $425M
Number of portfolio holdings 64
Total investment advisory fee paid $2.2M
Portfolio turnover rate 87%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Asset Allocation (% of net assets)
Common Stocks 99.5
Investments Purchased with Cash Collateral from Securities Lending 1.3
Investment Companies 0.4
Rights 0.0
Other (1.2)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Equinix Inc 6.2
Realty Income Corp 5.1
Public Storage 5.0
Welltower Inc 4.7
Prologis Inc 4.2
Material Fund Change [Text Block]
What material changes have occurred since the beginning of the fiscal year?
This is a summary of certain changes of the Fund since September 30, 2023.
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
Material Fund Change Expenses [Text Block]
The Fund’s net expense ratio materially changed from the prior fiscal year due to an decrease in the Fund’s advisory fee rate, which adjusts up or down based on the Fund’s performance relative to the FTSE EPRA/NAREIT Global Index.
C000077618 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Forty Fund
Class Name Class A Shares
Trading Symbol JDCAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Forty Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Forty Fund
(Class A Shares/JDCAX)		 $102 0.84%
Expenses Paid, Amount $ 102
Expense Ratio, Percent 0.84%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Forty Fund Class A Shares returned 42.41%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to returns relative to the performance benchmark. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. Enterprise software company Oracle also contributed, supported by growing demand for artificial intelligence and its strong market positioning in cloud infrastructure.
Top Detractors from Performance
Real estate analytics company CoStar Group was a notable detractor from returns relative to the performance benchmark. Higher interest rates pressured CoStar’s core commercial real estate business through the first half of the 2024. Agricultural equipment maker Deere & Company, another detractor, faced uncertainties around farm fundamentals and elevated interest rates in key markets such as Brazil.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Forty Fund (Class A Shares/JDCAX) at NAV 42.41% 16.36% 15.66%
Janus Henderson Forty Fund (Class A Shares/JDCAX) at Maximum Offering Price - 5.75% 34.22% 14.99% 14.98%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,096,000,000
Holdings Count | Holding 40
Advisory Fees Paid, Amount $ 98,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,096M
Number of portfolio holdings 40
Total investment advisory fee paid $98.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.2
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
C000077619 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Forty Fund
Class Name Class C Shares
Trading Symbol JACCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Forty Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Forty Fund
(Class C Shares/JACCX)		 $183 1.52%
Expenses Paid, Amount $ 183
Expense Ratio, Percent 1.52%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Forty Fund Class C Shares returned 41.44%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to returns relative to the performance benchmark. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. Enterprise software company Oracle also contributed, supported by growing demand for artificial intelligence and its strong market positioning in cloud infrastructure.
Top Detractors from Performance
Real estate analytics company CoStar Group was a notable detractor from returns relative to the performance benchmark. Higher interest rates pressured CoStar’s core commercial real estate business through the first half of the 2024. Agricultural equipment maker Deere & Company, another detractor, faced uncertainties around farm fundamentals and elevated interest rates in key markets such as Brazil.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Forty Fund (Class C Shares/JACCX) at NAV 41.44% 15.58% 14.94%
Janus Henderson Forty Fund (Class C Shares/JACCX) with Contingent Deferred Sales Charge 40.44%* 15.58% 14.94%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,096,000,000
Holdings Count | Holding 40
Advisory Fees Paid, Amount $ 98,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,096M
Number of portfolio holdings 40
Total investment advisory fee paid $98.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.2
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
C000177054 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Forty Fund
Class Name Class D Shares
Trading Symbol JFRDX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Forty Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Forty Fund
(Class D Shares/JFRDX)		 $76 0.63%
Expenses Paid, Amount $ 76
Expense Ratio, Percent 0.63%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Forty Fund Class D Shares returned 42.68%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to returns relative to the performance benchmark. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. Enterprise software company Oracle also contributed, supported by growing demand for artificial intelligence and its strong market positioning in cloud infrastructure.
Top Detractors from Performance
Real estate analytics company CoStar Group was a notable detractor from returns relative to the performance benchmark. Higher interest rates pressured CoStar’s core commercial real estate business through the first half of the 2024. Agricultural equipment maker Deere & Company, another detractor, faced uncertainties around farm fundamentals and elevated interest rates in key markets such as Brazil.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Forty Fund (Class D Shares/JFRDX) 42.68% 16.60% 15.84%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 22,096,000,000
Holdings Count | Holding 40
Advisory Fees Paid, Amount $ 98,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,096M
Number of portfolio holdings 40
Total investment advisory fee paid $98.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.2
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
C000077620 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Forty Fund
Class Name Class I Shares
Trading Symbol JCAPX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Forty Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Forty Fund
(Class I Shares/JCAPX)		 $72 0.59%
Expenses Paid, Amount $ 72
Expense Ratio, Percent 0.59%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Forty Fund Class I Shares returned 42.76%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to returns relative to the performance benchmark. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. Enterprise software company Oracle also contributed, supported by growing demand for artificial intelligence and its strong market positioning in cloud infrastructure.
Top Detractors from Performance
Real estate analytics company CoStar Group was a notable detractor from returns relative to the performance benchmark. Higher interest rates pressured CoStar’s core commercial real estate business through the first half of the 2024. Agricultural equipment maker Deere & Company, another detractor, faced uncertainties around farm fundamentals and elevated interest rates in key markets such as Brazil.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Forty Fund (Class I Shares/JCAPX) 42.76% 16.66% 15.99%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,096,000,000
Holdings Count | Holding 40
Advisory Fees Paid, Amount $ 98,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,096M
Number of portfolio holdings 40
Total investment advisory fee paid $98.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.2
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
C000114888 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Forty Fund
Class Name Class N Shares
Trading Symbol JFRNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Forty Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Forty Fund
(Class N Shares/JFRNX)		 $63 0.52%
Expenses Paid, Amount $ 63
Expense Ratio, Percent 0.52%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Forty Fund Class N Shares returned 42.86%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to returns relative to the performance benchmark. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. Enterprise software company Oracle also contributed, supported by growing demand for artificial intelligence and its strong market positioning in cloud infrastructure.
Top Detractors from Performance
Real estate analytics company CoStar Group was a notable detractor from returns relative to the performance benchmark. Higher interest rates pressured CoStar’s core commercial real estate business through the first half of the 2024. Agricultural equipment maker Deere & Company, another detractor, faced uncertainties around farm fundamentals and elevated interest rates in key markets such as Brazil.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Forty Fund (Class N Shares/JFRNX) 42.86% 16.74% 16.08%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,096,000,000
Holdings Count | Holding 40
Advisory Fees Paid, Amount $ 98,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,096M
Number of portfolio holdings 40
Total investment advisory fee paid $98.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.2
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
C000077621 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Forty Fund
Class Name Class R Shares
Trading Symbol JDCRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Forty Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Forty Fund
(Class R Shares/JDCRX)		 $152 1.26%
Expenses Paid, Amount $ 152
Expense Ratio, Percent 1.26%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Forty Fund Class R Shares returned 41.79%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to returns relative to the performance benchmark. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. Enterprise software company Oracle also contributed, supported by growing demand for artificial intelligence and its strong market positioning in cloud infrastructure.
Top Detractors from Performance
Real estate analytics company CoStar Group was a notable detractor from returns relative to the performance benchmark. Higher interest rates pressured CoStar’s core commercial real estate business through the first half of the 2024. Agricultural equipment maker Deere & Company, another detractor, faced uncertainties around farm fundamentals and elevated interest rates in key markets such as Brazil.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Forty Fund (Class R Shares/JDCRX) 41.79% 15.88% 15.22%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,096,000,000
Holdings Count | Holding 40
Advisory Fees Paid, Amount $ 98,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,096M
Number of portfolio holdings 40
Total investment advisory fee paid $98.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.2
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
C000077622 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Forty Fund
Class Name Class S Shares
Trading Symbol JARTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Forty Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Forty Fund
(Class S Shares/JARTX)		 $121 1.00%
Expenses Paid, Amount $ 121
Expense Ratio, Percent 1.00%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Forty Fund Class S Shares returned 42.18%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to returns relative to the performance benchmark. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. Enterprise software company Oracle also contributed, supported by growing demand for artificial intelligence and its strong market positioning in cloud infrastructure.
Top Detractors from Performance
Real estate analytics company CoStar Group was a notable detractor from returns relative to the performance benchmark. Higher interest rates pressured CoStar’s core commercial real estate business through the first half of the 2024. Agricultural equipment maker Deere & Company, another detractor, faced uncertainties around farm fundamentals and elevated interest rates in key markets such as Brazil.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Forty Fund (Class S Shares/JARTX) 42.18% 16.18% 15.52%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,096,000,000
Holdings Count | Holding 40
Advisory Fees Paid, Amount $ 98,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,096M
Number of portfolio holdings 40
Total investment advisory fee paid $98.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.2
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
C000077623 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Forty Fund
Class Name Class T Shares
Trading Symbol JACTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Forty Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Forty Fund
(Class T Shares/JACTX)		 $90 0.74%
Expenses Paid, Amount $ 90
Expense Ratio, Percent 0.74%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Forty Fund Class T Shares returned 42.52%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Growth Index, returned 42.19%. Its additional benchmark, the S&P 500® Index, returned 36.35%.
Top Contributors to Performance
Howmet Aerospace was a top contributor to returns relative to the performance benchmark. This manufacturer of precision aircraft components delivered several quarters of strong profits growth that surpassed expectations. Enterprise software company Oracle also contributed, supported by growing demand for artificial intelligence and its strong market positioning in cloud infrastructure.
Top Detractors from Performance
Real estate analytics company CoStar Group was a notable detractor from returns relative to the performance benchmark. Higher interest rates pressured CoStar’s core commercial real estate business through the first half of the 2024. Agricultural equipment maker Deere & Company, another detractor, faced uncertainties around farm fundamentals and elevated interest rates in key markets such as Brazil.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Forty Fund (Class T Shares/JACTX) 42.52% 16.47% 15.81%
Russell 1000® Index 35.68% 15.64% 13.10%
Russell 1000® Growth Index 42.19% 19.74% 16.52%
S&P 500® Index 36.35% 15.98% 13.38%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,096,000,000
Holdings Count | Holding 40
Advisory Fees Paid, Amount $ 98,000,000.0
Investment Company Portfolio Turnover 36.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22,096M
Number of portfolio holdings 40
Total investment advisory fee paid $98.0M
Portfolio turnover rate 36%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 1.2
Other (0.3)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 9.7
NVIDIA Corp 8.0
Amazon.com Inc 6.6
Apple Inc 6.4
Meta Platforms Inc - Class A 5.4
C000183873 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Emerging Markets Fund
Class Name Class A Shares
Trading Symbol HEMAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Emerging Markets Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Emerging Markets Fund
(Class A Shares/HEMAX)		 $151 1.39%
Expenses Paid, Amount $ 151
Expense Ratio, Percent 1.39%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Emerging Markets Fund Class A Shares returned 17.00%. Its broad-based benchmark, the MSCI Emerging Markets IndexSM, returned 26.05%.
Top Contributors to Performance
Several Fund holdings in India contributed to returns relative to the benchmark. Online travel agent MakeMyTrip, a top relative contributor, gained market share and strengthened profit margins as it capitalized on accelerating travel spending by higher-income Indian consumers. Bharti Airtel, another contributor, benefited from its strong competitive positioning as one of two major carriers in India’s telecommunications market.
Top Detractors from Performance
Samsung Electronics detracted from returns relative to the benchmark. The South Korea-based global electronics and semiconductor manufacturer faced competitive challenges and uncertainty around the near-term outlook for semiconductor sales. ZJLD Group was another detractor. Worries over the pace of consumer spending in China pressured the beverage company’s shares despite its brand strength in the baijiu liquor market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Emerging Markets Fund (Class A Shares/HEMAX) at NAV 17.00% 3.43% 1.90%
Janus Henderson Emerging Markets Fund (Class A Shares/HEMAX) at Maximum Offering Price - 5.75% 10.30% 2.22% 1.30%
MSCI Emerging Markets IndexSM 26.05% 5.75% 4.02%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 32,000,000
Holdings Count | Holding 59
Advisory Fees Paid, Amount $ 100,000
Investment Company Portfolio Turnover 64.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $32M
Number of portfolio holdings 59
Total investment advisory fee paid $0.1M
Portfolio turnover rate 64%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
Asset Allocation (% of net assets)
Common Stocks 98.5
Preferred Stocks 1.9
Private Placements 0.2
Other (0.6)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
C000183875 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Emerging Markets Fund
Class Name Class C Shares
Trading Symbol HEMCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Emerging Markets Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Emerging Markets Fund
(Class C Shares/HEMCX)		 $229 2.12%
Expenses Paid, Amount $ 229
Expense Ratio, Percent 2.12%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Emerging Markets Fund Class C Shares returned 16.17%. Its broad-based benchmark, the MSCI Emerging Markets IndexSM, returned 26.05%.
Top Contributors to Performance
Several Fund holdings in India contributed to returns relative to the benchmark. Online travel agent MakeMyTrip, a top relative contributor, gained market share and strengthened profit margins as it capitalized on accelerating travel spending by higher-income Indian consumers. Bharti Airtel, another contributor, benefited from its strong competitive positioning as one of two major carriers in India’s telecommunications market.
Top Detractors from Performance
Samsung Electronics detracted from returns relative to the benchmark. The South Korea-based global electronics and semiconductor manufacturer faced competitive challenges and uncertainty around the near-term outlook for semiconductor sales. ZJLD Group was another detractor. Worries over the pace of consumer spending in China pressured the beverage company’s shares despite its brand strength in the baijiu liquor market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Emerging Markets Fund (Class C Shares/HEMCX) at NAV 16.17% 2.67% 1.14%
Janus Henderson Emerging Markets Fund (Class C Shares/HEMCX) with Contingent Deferred Sales Charge 15.17%* 2.67% 1.14%
MSCI Emerging Markets IndexSM 26.05% 5.75% 4.02%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 32,000,000
Holdings Count | Holding 59
Advisory Fees Paid, Amount $ 100,000
Investment Company Portfolio Turnover 64.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $32M
Number of portfolio holdings 59
Total investment advisory fee paid $0.1M
Portfolio turnover rate 64%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
Asset Allocation (% of net assets)
Common Stocks 98.5
Preferred Stocks 1.9
Private Placements 0.2
Other (0.6)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
C000183876 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Emerging Markets Fund
Class Name Class D Shares
Trading Symbol HEMDX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Emerging Markets Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Emerging Markets Fund
(Class D Shares/HEMDX)		 $129 1.19%
Expenses Paid, Amount $ 129
Expense Ratio, Percent 1.19%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Emerging Markets Fund Class D Shares returned 17.27%. Its broad-based benchmark, the MSCI Emerging Markets IndexSM, returned 26.05%.
Top Contributors to Performance
Several Fund holdings in India contributed to returns relative to the benchmark. Online travel agent MakeMyTrip, a top relative contributor, gained market share and strengthened profit margins as it capitalized on accelerating travel spending by higher-income Indian consumers. Bharti Airtel, another contributor, benefited from its strong competitive positioning as one of two major carriers in India’s telecommunications market.
Top Detractors from Performance
Samsung Electronics detracted from returns relative to the benchmark. The South Korea-based global electronics and semiconductor manufacturer faced competitive challenges and uncertainty around the near-term outlook for semiconductor sales. ZJLD Group was another detractor. Worries over the pace of consumer spending in China pressured the beverage company’s shares despite its brand strength in the baijiu liquor market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Emerging Markets Fund (Class D Shares/HEMDX) 17.27% 3.65% 2.03%
MSCI Emerging Markets IndexSM 26.05% 5.75% 4.02%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 32,000,000
Holdings Count | Holding 59
Advisory Fees Paid, Amount $ 100,000
Investment Company Portfolio Turnover 64.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $32M
Number of portfolio holdings 59
Total investment advisory fee paid $0.1M
Portfolio turnover rate 64%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
Asset Allocation (% of net assets)
Common Stocks 98.5
Preferred Stocks 1.9
Private Placements 0.2
Other (0.6)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
C000183877 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Emerging Markets Fund
Class Name Class I Shares
Trading Symbol HEMIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Emerging Markets Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Emerging Markets Fund
(Class I Shares/HEMIX)		 $122 1.12%
Expenses Paid, Amount $ 122
Expense Ratio, Percent 1.12%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Emerging Markets Fund Class I Shares returned 17.34%. Its broad-based benchmark, the MSCI Emerging Markets IndexSM, returned 26.05%.
Top Contributors to Performance
Several Fund holdings in India contributed to returns relative to the benchmark. Online travel agent MakeMyTrip, a top relative contributor, gained market share and strengthened profit margins as it capitalized on accelerating travel spending by higher-income Indian consumers. Bharti Airtel, another contributor, benefited from its strong competitive positioning as one of two major carriers in India’s telecommunications market.
Top Detractors from Performance
Samsung Electronics detracted from returns relative to the benchmark. The South Korea-based global electronics and semiconductor manufacturer faced competitive challenges and uncertainty around the near-term outlook for semiconductor sales. ZJLD Group was another detractor. Worries over the pace of consumer spending in China pressured the beverage company’s shares despite its brand strength in the baijiu liquor market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Emerging Markets Fund (Class I Shares/HEMIX) 17.34% 3.70% 2.17%
MSCI Emerging Markets IndexSM 26.05% 5.75% 4.02%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 32,000,000
Holdings Count | Holding 59
Advisory Fees Paid, Amount $ 100,000
Investment Company Portfolio Turnover 64.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $32M
Number of portfolio holdings 59
Total investment advisory fee paid $0.1M
Portfolio turnover rate 64%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
Asset Allocation (% of net assets)
Common Stocks 98.5
Preferred Stocks 1.9
Private Placements 0.2
Other (0.6)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
C000183878 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Emerging Markets Fund
Class Name Class N Shares
Trading Symbol HEMRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Emerging Markets Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Emerging Markets Fund
(Class N Shares/HEMRX)		 $113 1.04%
Expenses Paid, Amount $ 113
Expense Ratio, Percent 1.04%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Emerging Markets Fund Class N Shares returned 17.33%. Its broad-based benchmark, the MSCI Emerging Markets IndexSM, returned 26.05%.
Top Contributors to Performance
Several Fund holdings in India contributed to returns relative to the benchmark. Online travel agent MakeMyTrip, a top relative contributor, gained market share and strengthened profit margins as it capitalized on accelerating travel spending by higher-income Indian consumers. Bharti Airtel, another contributor, benefited from its strong competitive positioning as one of two major carriers in India’s telecommunications market.
Top Detractors from Performance
Samsung Electronics detracted from returns relative to the benchmark. The South Korea-based global electronics and semiconductor manufacturer faced competitive challenges and uncertainty around the near-term outlook for semiconductor sales. ZJLD Group was another detractor. Worries over the pace of consumer spending in China pressured the beverage company’s shares despite its brand strength in the baijiu liquor market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Emerging Markets Fund (Class N Shares/HEMRX) 17.33% 3.76% 2.18%
MSCI Emerging Markets IndexSM 26.05% 5.75% 4.02%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 32,000,000
Holdings Count | Holding 59
Advisory Fees Paid, Amount $ 100,000
Investment Company Portfolio Turnover 64.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $32M
Number of portfolio holdings 59
Total investment advisory fee paid $0.1M
Portfolio turnover rate 64%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
Asset Allocation (% of net assets)
Common Stocks 98.5
Preferred Stocks 1.9
Private Placements 0.2
Other (0.6)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
C000183880 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Emerging Markets Fund
Class Name Class S Shares
Trading Symbol HEMSX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Emerging Markets Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Emerging Markets Fund
(Class S Shares/HEMSX)		 $168 1.55%
Expenses Paid, Amount $ 168
Expense Ratio, Percent 1.55%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Emerging Markets Fund Class S Shares returned 16.80%. Its broad-based benchmark, the MSCI Emerging Markets IndexSM, returned 26.05%.
Top Contributors to Performance
Several Fund holdings in India contributed to returns relative to the benchmark. Online travel agent MakeMyTrip, a top relative contributor, gained market share and strengthened profit margins as it capitalized on accelerating travel spending by higher-income Indian consumers. Bharti Airtel, another contributor, benefited from its strong competitive positioning as one of two major carriers in India’s telecommunications market.
Top Detractors from Performance
Samsung Electronics detracted from returns relative to the benchmark. The South Korea-based global electronics and semiconductor manufacturer faced competitive challenges and uncertainty around the near-term outlook for semiconductor sales. ZJLD Group was another detractor. Worries over the pace of consumer spending in China pressured the beverage company’s shares despite its brand strength in the baijiu liquor market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Emerging Markets Fund (Class S Shares/HEMSX) 16.80% 3.28% 1.76%
MSCI Emerging Markets IndexSM 26.05% 5.75% 4.02%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 32,000,000
Holdings Count | Holding 59
Advisory Fees Paid, Amount $ 100,000
Investment Company Portfolio Turnover 64.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $32M
Number of portfolio holdings 59
Total investment advisory fee paid $0.1M
Portfolio turnover rate 64%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
Asset Allocation (% of net assets)
Common Stocks 98.5
Preferred Stocks 1.9
Private Placements 0.2
Other (0.6)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
C000183881 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Emerging Markets Fund
Class Name Class T Shares
Trading Symbol HEMTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Emerging Markets Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Emerging Markets Fund
(Class T Shares/HEMTX)		 $139 1.28%
Expenses Paid, Amount $ 139
Expense Ratio, Percent 1.28%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Emerging Markets Fund Class T Shares returned 17.05%. Its broad-based benchmark, the MSCI Emerging Markets IndexSM, returned 26.05%.
Top Contributors to Performance
Several Fund holdings in India contributed to returns relative to the benchmark. Online travel agent MakeMyTrip, a top relative contributor, gained market share and strengthened profit margins as it capitalized on accelerating travel spending by higher-income Indian consumers. Bharti Airtel, another contributor, benefited from its strong competitive positioning as one of two major carriers in India’s telecommunications market.
Top Detractors from Performance
Samsung Electronics detracted from returns relative to the benchmark. The South Korea-based global electronics and semiconductor manufacturer faced competitive challenges and uncertainty around the near-term outlook for semiconductor sales. ZJLD Group was another detractor. Worries over the pace of consumer spending in China pressured the beverage company’s shares despite its brand strength in the baijiu liquor market.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Emerging Markets Fund (Class T Shares/HEMTX) 17.05% 3.52% 1.94%
MSCI Emerging Markets IndexSM 26.05% 5.75% 4.02%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 32,000,000
Holdings Count | Holding 59
Advisory Fees Paid, Amount $ 100,000
Investment Company Portfolio Turnover 64.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $32M
Number of portfolio holdings 59
Total investment advisory fee paid $0.1M
Portfolio turnover rate 64%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
Asset Allocation (% of net assets)
Common Stocks 98.5
Preferred Stocks 1.9
Private Placements 0.2
Other (0.6)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Taiwan Semiconductor Manufacturing Co Ltd 9.9
Samsung Electronics Co Ltd 6.7
Tencent Holdings Ltd 3.7
Bharti Airtel Ltd 3.5
AIA Group Ltd 3.2
C000183893 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Equity Income Fund
Class Name Class A Shares
Trading Symbol HFQAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Equity Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Equity Income Fund
(Class A Shares/HFQAX)		 $127 1.15%
Expenses Paid, Amount $ 127
Expense Ratio, Percent 1.15%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Equity Income Fund Class A Shares returned 21.09%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the 85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index, returned 24.84%.
Top Contributors to Performance
U.S. semiconductor manufacturer Qualcomm and electronics companies Taiwan Semiconductor and Hon Hai were key contributors relative to the broad-based benchmark, as enthusiasm for artificial intelligence-related stocks continued until near period end. UK bank NatWest and UK food retailer Tesco also contributed to results. NatWest benefited from the higher interest rate environment and its exposure to a strengthening UK economy, while Tesco saw stronger sales as inflation fell, making grocery spend a smaller part of household expenses.
Top Detractors from Performance
Energy companies BP and Equinor detracted, as volatility around oil prices caused by escalating tensions in the Middle East and a weakening demand outlook hurt their share price. Korean technology company Samsung Electronics also hindered results as lower-than-expected demand for memory chips weighed on the share price. Daimler Trucks was another relative detractor as it experienced a slowing of orders within Europe and difficult performance in China due to the macroeconomic weakness of the region.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Equity Income Fund (Class A Shares/HFQAX) at NAV 21.09% 7.42% 5.10%
Janus Henderson Global Equity Income Fund (Class A Shares/HFQAX) at Maximum Offering Price - 5.75% 14.10% 6.16% 4.48%
MSCI World IndexSM 32.43% 13.04% 10.07%
85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index 24.84% 8.10% 5.41%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,869,000,000
Holdings Count | Holding 71
Advisory Fees Paid, Amount $ 37,400,000
Investment Company Portfolio Turnover 155.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,869M
Number of portfolio holdings 71
Total investment advisory fee paid $37.4M
Portfolio turnover rate 155%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
Asset Allocation (% of net assets)
Common Stocks 93.5
Investment Companies 3.7
Preferred Stocks 1.7
Other 1.1
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
C000183894 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Equity Income Fund
Class Name Class C Shares
Trading Symbol HFQCX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Equity Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Equity Income Fund
(Class C Shares/HFQCX)		 $191 1.73%
Expenses Paid, Amount $ 191
Expense Ratio, Percent 1.73%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Equity Income Fund Class C Shares returned 20.29%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the 85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index, returned 24.84%.
Top Contributors to Performance
U.S. semiconductor manufacturer Qualcomm and electronics companies Taiwan Semiconductor and Hon Hai were key contributors relative to the broad-based benchmark, as enthusiasm for artificial intelligence-related stocks continued until near period end. UK bank NatWest and UK food retailer Tesco also contributed to results. NatWest benefited from the higher interest rate environment and its exposure to a strengthening UK economy, while Tesco saw stronger sales as inflation fell, making grocery spend a smaller part of household expenses.
Top Detractors from Performance
Energy companies BP and Equinor detracted, as volatility around oil prices caused by escalating tensions in the Middle East and a weakening demand outlook hurt their share price. Korean technology company Samsung Electronics also hindered results as lower-than-expected demand for memory chips weighed on the share price. Daimler Trucks was another relative detractor as it experienced a slowing of orders within Europe and difficult performance in China due to the macroeconomic weakness of the region.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Equity Income Fund (Class C Shares/HFQCX) at NAV 20.29% 6.69% 4.38%
Janus Henderson Global Equity Income Fund (Class C Shares/HFQCX) with Contingent Deferred Sales Charge 19.29%* 6.69% 4.38%
MSCI World IndexSM 32.43% 13.04% 10.07%
85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index 24.84% 8.10% 5.41%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,869,000,000
Holdings Count | Holding 71
Advisory Fees Paid, Amount $ 37,400,000
Investment Company Portfolio Turnover 155.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,869M
Number of portfolio holdings 71
Total investment advisory fee paid $37.4M
Portfolio turnover rate 155%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
Asset Allocation (% of net assets)
Common Stocks 93.5
Investment Companies 3.7
Preferred Stocks 1.7
Other 1.1
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
C000183895 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Equity Income Fund
Class Name Class D Shares
Trading Symbol HFQDX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Equity Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Equity Income Fund
(Class D Shares/HFQDX)		 $96 0.87%
Expenses Paid, Amount $ 96
Expense Ratio, Percent 0.87%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Equity Income Fund Class D Shares returned 21.48%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the 85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index, returned 24.84%.
Top Contributors to Performance
U.S. semiconductor manufacturer Qualcomm and electronics companies Taiwan Semiconductor and Hon Hai were key contributors relative to the broad-based benchmark, as enthusiasm for artificial intelligence-related stocks continued until near period end. UK bank NatWest and UK food retailer Tesco also contributed to results. NatWest benefited from the higher interest rate environment and its exposure to a strengthening UK economy, while Tesco saw stronger sales as inflation fell, making grocery spend a smaller part of household expenses.
Top Detractors from Performance
Energy companies BP and Equinor detracted, as volatility around oil prices caused by escalating tensions in the Middle East and a weakening demand outlook hurt their share price. Korean technology company Samsung Electronics also hindered results as lower-than-expected demand for memory chips weighed on the share price. Daimler Trucks was another relative detractor as it experienced a slowing of orders within Europe and difficult performance in China due to the macroeconomic weakness of the region.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Equity Income Fund (Class D Shares/HFQDX) 21.48% 7.66% 5.27%
MSCI World IndexSM 32.43% 13.04% 10.07%
85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index 24.84% 8.10% 5.41%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 5,869,000,000
Holdings Count | Holding 71
Advisory Fees Paid, Amount $ 37,400,000
Investment Company Portfolio Turnover 155.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,869M
Number of portfolio holdings 71
Total investment advisory fee paid $37.4M
Portfolio turnover rate 155%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
Asset Allocation (% of net assets)
Common Stocks 93.5
Investment Companies 3.7
Preferred Stocks 1.7
Other 1.1
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
C000183896 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Equity Income Fund
Class Name Class I Shares
Trading Symbol HFQIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Equity Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Equity Income Fund
(Class I Shares/HFQIX)		 $87 0.79%
Expenses Paid, Amount $ 87
Expense Ratio, Percent 0.79%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Equity Income Fund Class I Shares returned 21.39%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the 85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index, returned 24.84%.
Top Contributors to Performance
U.S. semiconductor manufacturer Qualcomm and electronics companies Taiwan Semiconductor and Hon Hai were key contributors relative to the broad-based benchmark, as enthusiasm for artificial intelligence-related stocks continued until near period end. UK bank NatWest and UK food retailer Tesco also contributed to results. NatWest benefited from the higher interest rate environment and its exposure to a strengthening UK economy, while Tesco saw stronger sales as inflation fell, making grocery spend a smaller part of household expenses.
Top Detractors from Performance
Energy companies BP and Equinor detracted, as volatility around oil prices caused by escalating tensions in the Middle East and a weakening demand outlook hurt their share price. Korean technology company Samsung Electronics also hindered results as lower-than-expected demand for memory chips weighed on the share price. Daimler Trucks was another relative detractor as it experienced a slowing of orders within Europe and difficult performance in China due to the macroeconomic weakness of the region.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Equity Income Fund (Class I Shares/HFQIX) 21.39% 7.74% 5.42%
MSCI World IndexSM 32.43% 13.04% 10.07%
85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index 24.84% 8.10% 5.41%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,869,000,000
Holdings Count | Holding 71
Advisory Fees Paid, Amount $ 37,400,000
Investment Company Portfolio Turnover 155.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,869M
Number of portfolio holdings 71
Total investment advisory fee paid $37.4M
Portfolio turnover rate 155%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
Asset Allocation (% of net assets)
Common Stocks 93.5
Investment Companies 3.7
Preferred Stocks 1.7
Other 1.1
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
C000183897 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Equity Income Fund
Class Name Class N Shares
Trading Symbol HFQRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Equity Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Equity Income Fund
(Class N Shares/HFQRX)		 $78 0.70%
Expenses Paid, Amount $ 78
Expense Ratio, Percent 0.70%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Equity Income Fund Class N Shares returned 21.50%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the 85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index, returned 24.84%.
Top Contributors to Performance
U.S. semiconductor manufacturer Qualcomm and electronics companies Taiwan Semiconductor and Hon Hai were key contributors relative to the broad-based benchmark, as enthusiasm for artificial intelligence-related stocks continued until near period end. UK bank NatWest and UK food retailer Tesco also contributed to results. NatWest benefited from the higher interest rate environment and its exposure to a strengthening UK economy, while Tesco saw stronger sales as inflation fell, making grocery spend a smaller part of household expenses.
Top Detractors from Performance
Energy companies BP and Equinor detracted, as volatility around oil prices caused by escalating tensions in the Middle East and a weakening demand outlook hurt their share price. Korean technology company Samsung Electronics also hindered results as lower-than-expected demand for memory chips weighed on the share price. Daimler Trucks was another relative detractor as it experienced a slowing of orders within Europe and difficult performance in China due to the macroeconomic weakness of the region.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Equity Income Fund (Class N Shares/HFQRX) 21.50% 7.82% 5.46%
MSCI World IndexSM 32.43% 13.04% 10.07%
85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index 24.84% 8.10% 5.41%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,869,000,000
Holdings Count | Holding 71
Advisory Fees Paid, Amount $ 37,400,000
Investment Company Portfolio Turnover 155.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,869M
Number of portfolio holdings 71
Total investment advisory fee paid $37.4M
Portfolio turnover rate 155%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
Asset Allocation (% of net assets)
Common Stocks 93.5
Investment Companies 3.7
Preferred Stocks 1.7
Other 1.1
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
C000183899 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Equity Income Fund
Class Name Class S Shares
Trading Symbol HFQSX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Equity Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Equity Income Fund
(Class S Shares/HFQSX)		 $133 1.20%
Expenses Paid, Amount $ 133
Expense Ratio, Percent 1.20%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Equity Income Fund Class S Shares returned 20.89%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the 85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index, returned 24.84%.
Top Contributors to Performance
U.S. semiconductor manufacturer Qualcomm and electronics companies Taiwan Semiconductor and Hon Hai were key contributors relative to the broad-based benchmark, as enthusiasm for artificial intelligence-related stocks continued until near period end. UK bank NatWest and UK food retailer Tesco also contributed to results. NatWest benefited from the higher interest rate environment and its exposure to a strengthening UK economy, while Tesco saw stronger sales as inflation fell, making grocery spend a smaller part of household expenses.
Top Detractors from Performance
Energy companies BP and Equinor detracted, as volatility around oil prices caused by escalating tensions in the Middle East and a weakening demand outlook hurt their share price. Korean technology company Samsung Electronics also hindered results as lower-than-expected demand for memory chips weighed on the share price. Daimler Trucks was another relative detractor as it experienced a slowing of orders within Europe and difficult performance in China due to the macroeconomic weakness of the region.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Equity Income Fund (Class S Shares/HFQSX) 20.89% 7.25% 4.96%
MSCI World IndexSM 32.43% 13.04% 10.07%
85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index 24.84% 8.10% 5.41%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,869,000,000
Holdings Count | Holding 71
Advisory Fees Paid, Amount $ 37,400,000
Investment Company Portfolio Turnover 155.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,869M
Number of portfolio holdings 71
Total investment advisory fee paid $37.4M
Portfolio turnover rate 155%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
Asset Allocation (% of net assets)
Common Stocks 93.5
Investment Companies 3.7
Preferred Stocks 1.7
Other 1.1
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
C000183900 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Equity Income Fund
Class Name Class T Shares
Trading Symbol HFQTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Equity Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Equity Income Fund
(Class T Shares/HFQTX)		 $103 0.93%
Expenses Paid, Amount $ 103
Expense Ratio, Percent 0.93%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Equity Income Fund Class T Shares returned 21.21%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%. Its additional benchmark, the 85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index, returned 24.84%.
Top Contributors to Performance
U.S. semiconductor manufacturer Qualcomm and electronics companies Taiwan Semiconductor and Hon Hai were key contributors relative to the broad-based benchmark, as enthusiasm for artificial intelligence-related stocks continued until near period end. UK bank NatWest and UK food retailer Tesco also contributed to results. NatWest benefited from the higher interest rate environment and its exposure to a strengthening UK economy, while Tesco saw stronger sales as inflation fell, making grocery spend a smaller part of household expenses.
Top Detractors from Performance
Energy companies BP and Equinor detracted, as volatility around oil prices caused by escalating tensions in the Middle East and a weakening demand outlook hurt their share price. Korean technology company Samsung Electronics also hindered results as lower-than-expected demand for memory chips weighed on the share price. Daimler Trucks was another relative detractor as it experienced a slowing of orders within Europe and difficult performance in China due to the macroeconomic weakness of the region.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson Global Equity Income Fund (Class T Shares/HFQTX) 21.21% 7.58% 5.22%
MSCI World IndexSM 32.43% 13.04% 10.07%
85% MSCI ACWI ex-US High Div Yld / 15% MSCI USA High Div Yld Index 24.84% 8.10% 5.41%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 5,869,000,000
Holdings Count | Holding 71
Advisory Fees Paid, Amount $ 37,400,000
Investment Company Portfolio Turnover 155.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $5,869M
Number of portfolio holdings 71
Total investment advisory fee paid $37.4M
Portfolio turnover rate 155%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
Asset Allocation (% of net assets)
Common Stocks 93.5
Investment Companies 3.7
Preferred Stocks 1.7
Other 1.1
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
British American Tobacco PLC 3.9
Verizon Communications Inc 3.2
Unilever PLC 3.1
Pernod Ricard SA 3.0
Rio Tinto PLC 2.7
C000183903 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson European Focus Fund
Class Name Class A Shares
Trading Symbol HFEAX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson European Focus Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson European Focus Fund
(Class A Shares/HFEAX)		 $147 1.29%
Expenses Paid, Amount $ 147
Expense Ratio, Percent 1.29%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson European Focus Fund Class A Shares returned 27.55%. Its broad-based benchmark, the MSCI Europe IndexSM, returned 25.23%.
Top Contributors to Performance
Our holdings in BE Semiconductor, ASML, and ASM International (all semiconductor stocks) benefited returns relative to the benchmark. On the back of a troughing semiconductor cycle in early 2023 and further boosted by the artificial intelligence investment wave, semiconductor stocks performed strongly over the first nine months of the period. This strong performance triggered profit-taking in the last three months. However, we believe the prospects of our semiconductor holdings have not changed.
Top Detractors from Performance
Our underweight position in Sanofi (a French pharmaceutical company) detracted from relative performance. The company announced a lower profit outlook and a spinout of its consumer care unit in October 2023. However, it recovered strongly over the rest of the period. Universal Music Group, the Dutch music company, detracted due to unexpectedly slowing subscription growth in July. Anglo American, the mining company, also detracted as Chinese macroeconomic negativity led to weakness in mining stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson European Focus Fund (Class A Shares/HFEAX) at NAV 27.55% 14.17% 5.52%
Janus Henderson European Focus Fund (Class A Shares/HFEAX) at Maximum Offering Price - 5.75% 20.22% 12.83% 4.89%
MSCI Europe IndexSM 25.23% 8.90% 5.59%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 504,000,000
Holdings Count | Holding 43
Advisory Fees Paid, Amount $ 4,100,000
Investment Company Portfolio Turnover 168.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $504M
Number of portfolio holdings 43
Total investment advisory fee paid $4.1M
Portfolio turnover rate 168%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 0.6
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
C000183904 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson European Focus Fund
Class Name Class C Shares
Trading Symbol HFECX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson European Focus Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson European Focus Fund
(Class C Shares/HFECX)		 $229 2.02%
Expenses Paid, Amount $ 229
Expense Ratio, Percent 2.02%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson European Focus Fund Class C Shares returned 26.61%. Its broad-based benchmark, the MSCI Europe IndexSM, returned 25.23%.
Top Contributors to Performance
Our holdings in BE Semiconductor, ASML, and ASM International (all semiconductor stocks) benefited returns relative to the benchmark. On the back of a troughing semiconductor cycle in early 2023 and further boosted by the artificial intelligence investment wave, semiconductor stocks performed strongly over the first nine months of the period. This strong performance triggered profit-taking in the last three months. However, we believe the prospects of our semiconductor holdings have not changed.
Top Detractors from Performance
Our underweight position in Sanofi (a French pharmaceutical company) detracted from relative performance. The company announced a lower profit outlook and a spinout of its consumer care unit in October 2023. However, it recovered strongly over the rest of the period. Universal Music Group, the Dutch music company, detracted due to unexpectedly slowing subscription growth in July. Anglo American, the mining company, also detracted as Chinese macroeconomic negativity led to weakness in mining stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson European Focus Fund (Class C Shares/HFECX) at NAV 26.61% 13.31% 4.71%
Janus Henderson European Focus Fund (Class C Shares/HFECX) with Contingent Deferred Sales Charge 25.61%* 13.31% 4.71%
MSCI Europe IndexSM 25.23% 8.90% 5.59%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 504,000,000
Holdings Count | Holding 43
Advisory Fees Paid, Amount $ 4,100,000
Investment Company Portfolio Turnover 168.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $504M
Number of portfolio holdings 43
Total investment advisory fee paid $4.1M
Portfolio turnover rate 168%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 0.6
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
C000183905 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson European Focus Fund
Class Name Class D Shares
Trading Symbol HFEDX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson European Focus Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson European Focus Fund
(Class D Shares/HFEDX)		 $125 1.10%
Expenses Paid, Amount $ 125
Expense Ratio, Percent 1.10%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson European Focus Fund Class D Shares returned 27.82%. Its broad-based benchmark, the MSCI Europe IndexSM, returned 25.23%.
Top Contributors to Performance
Our holdings in BE Semiconductor, ASML, and ASM International (all semiconductor stocks) benefited returns relative to the benchmark. On the back of a troughing semiconductor cycle in early 2023 and further boosted by the artificial intelligence investment wave, semiconductor stocks performed strongly over the first nine months of the period. This strong performance triggered profit-taking in the last three months. However, we believe the prospects of our semiconductor holdings have not changed.
Top Detractors from Performance
Our underweight position in Sanofi (a French pharmaceutical company) detracted from relative performance. The company announced a lower profit outlook and a spinout of its consumer care unit in October 2023. However, it recovered strongly over the rest of the period. Universal Music Group, the Dutch music company, detracted due to unexpectedly slowing subscription growth in July. Anglo American, the mining company, also detracted as Chinese macroeconomic negativity led to weakness in mining stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson European Focus Fund (Class D Shares/HFEDX) 27.82% 14.39% 5.66%
MSCI Europe IndexSM 25.23% 8.90% 5.59%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 504,000,000
Holdings Count | Holding 43
Advisory Fees Paid, Amount $ 4,100,000
Investment Company Portfolio Turnover 168.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $504M
Number of portfolio holdings 43
Total investment advisory fee paid $4.1M
Portfolio turnover rate 168%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 0.6
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
C000183906 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson European Focus Fund
Class Name Class I Shares
Trading Symbol HFEIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson European Focus Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson European Focus Fund
(Class I Shares/HFEIX)		 $120 1.05%
Expenses Paid, Amount $ 120
Expense Ratio, Percent 1.05%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson European Focus Fund Class I Shares returned 27.85%. Its broad-based benchmark, the MSCI Europe IndexSM, returned 25.23%.
Top Contributors to Performance
Our holdings in BE Semiconductor, ASML, and ASM International (all semiconductor stocks) benefited returns relative to the benchmark. On the back of a troughing semiconductor cycle in early 2023 and further boosted by the artificial intelligence investment wave, semiconductor stocks performed strongly over the first nine months of the period. This strong performance triggered profit-taking in the last three months. However, we believe the prospects of our semiconductor holdings have not changed.
Top Detractors from Performance
Our underweight position in Sanofi (a French pharmaceutical company) detracted from relative performance. The company announced a lower profit outlook and a spinout of its consumer care unit in October 2023. However, it recovered strongly over the rest of the period. Universal Music Group, the Dutch music company, detracted due to unexpectedly slowing subscription growth in July. Anglo American, the mining company, also detracted as Chinese macroeconomic negativity led to weakness in mining stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson European Focus Fund (Class I Shares/HFEIX) 27.85% 14.46% 5.79%
MSCI Europe IndexSM 25.23% 8.90% 5.59%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 504,000,000
Holdings Count | Holding 43
Advisory Fees Paid, Amount $ 4,100,000
Investment Company Portfolio Turnover 168.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $504M
Number of portfolio holdings 43
Total investment advisory fee paid $4.1M
Portfolio turnover rate 168%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 0.6
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
C000183907 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson European Focus Fund
Class Name Class N Shares
Trading Symbol HFERX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson European Focus Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson European Focus Fund
(Class N Shares/HFERX)		 $109 0.96%
Expenses Paid, Amount $ 109
Expense Ratio, Percent 0.96%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson European Focus Fund Class N Shares returned 27.93%. Its broad-based benchmark, the MSCI Europe IndexSM, returned 25.23%.
Top Contributors to Performance
Our holdings in BE Semiconductor, ASML, and ASM International (all semiconductor stocks) benefited returns relative to the benchmark. On the back of a troughing semiconductor cycle in early 2023 and further boosted by the artificial intelligence investment wave, semiconductor stocks performed strongly over the first nine months of the period. This strong performance triggered profit-taking in the last three months. However, we believe the prospects of our semiconductor holdings have not changed.
Top Detractors from Performance
Our underweight position in Sanofi (a French pharmaceutical company) detracted from relative performance. The company announced a lower profit outlook and a spinout of its consumer care unit in October 2023. However, it recovered strongly over the rest of the period. Universal Music Group, the Dutch music company, detracted due to unexpectedly slowing subscription growth in July. Anglo American, the mining company, also detracted as Chinese macroeconomic negativity led to weakness in mining stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson European Focus Fund (Class N Shares/HFERX) 27.93% 14.54% 5.80%
MSCI Europe IndexSM 25.23% 8.90% 5.59%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 504,000,000
Holdings Count | Holding 43
Advisory Fees Paid, Amount $ 4,100,000
Investment Company Portfolio Turnover 168.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $504M
Number of portfolio holdings 43
Total investment advisory fee paid $4.1M
Portfolio turnover rate 168%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 0.6
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
C000183909 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson European Focus Fund
Class Name Class S Shares
Trading Symbol HFESX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson European Focus Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson European Focus Fund
(Class S Shares/HFESX)		 $159 1.40%
Expenses Paid, Amount $ 159
Expense Ratio, Percent 1.40%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson European Focus Fund Class S Shares returned 27.42%. Its broad-based benchmark, the MSCI Europe IndexSM, returned 25.23%.
Top Contributors to Performance
Our holdings in BE Semiconductor, ASML, and ASM International (all semiconductor stocks) benefited returns relative to the benchmark. On the back of a troughing semiconductor cycle in early 2023 and further boosted by the artificial intelligence investment wave, semiconductor stocks performed strongly over the first nine months of the period. This strong performance triggered profit-taking in the last three months. However, we believe the prospects of our semiconductor holdings have not changed.
Top Detractors from Performance
Our underweight position in Sanofi (a French pharmaceutical company) detracted from relative performance. The company announced a lower profit outlook and a spinout of its consumer care unit in October 2023. However, it recovered strongly over the rest of the period. Universal Music Group, the Dutch music company, detracted due to unexpectedly slowing subscription growth in July. Anglo American, the mining company, also detracted as Chinese macroeconomic negativity led to weakness in mining stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson European Focus Fund (Class S Shares/HFESX) 27.42% 14.23% 5.51%
MSCI Europe IndexSM 25.23% 8.90% 5.59%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 504,000,000
Holdings Count | Holding 43
Advisory Fees Paid, Amount $ 4,100,000
Investment Company Portfolio Turnover 168.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $504M
Number of portfolio holdings 43
Total investment advisory fee paid $4.1M
Portfolio turnover rate 168%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 0.6
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
C000183910 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson European Focus Fund
Class Name Class T Shares
Trading Symbol HFETX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson European Focus Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson European Focus Fund
(Class T Shares/HFETX)		 $138 1.21%
Expenses Paid, Amount $ 138
Expense Ratio, Percent 1.21%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson European Focus Fund Class T Shares returned 27.66%. Its broad-based benchmark, the MSCI Europe IndexSM, returned 25.23%.
Top Contributors to Performance
Our holdings in BE Semiconductor, ASML, and ASM International (all semiconductor stocks) benefited returns relative to the benchmark. On the back of a troughing semiconductor cycle in early 2023 and further boosted by the artificial intelligence investment wave, semiconductor stocks performed strongly over the first nine months of the period. This strong performance triggered profit-taking in the last three months. However, we believe the prospects of our semiconductor holdings have not changed.
Top Detractors from Performance
Our underweight position in Sanofi (a French pharmaceutical company) detracted from relative performance. The company announced a lower profit outlook and a spinout of its consumer care unit in October 2023. However, it recovered strongly over the rest of the period. Universal Music Group, the Dutch music company, detracted due to unexpectedly slowing subscription growth in July. Anglo American, the mining company, also detracted as Chinese macroeconomic negativity led to weakness in mining stocks.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
September 30, 2014, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year 5 Year 10 Year
Janus Henderson European Focus Fund (Class T Shares/HFETX) 27.66% 14.27% 5.59%
MSCI Europe IndexSM 25.23% 8.90% 5.59%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 504,000,000
Holdings Count | Holding 43
Advisory Fees Paid, Amount $ 4,100,000
Investment Company Portfolio Turnover 168.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $504M
Number of portfolio holdings 43
Total investment advisory fee paid $4.1M
Portfolio turnover rate 168%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
Asset Allocation (% of net assets)
Common Stocks 99.1
Investment Companies 0.6
Other 0.3
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
ASML Holding NV 4.3
Novartis AG 4.1
LVMH Moet Hennessy Louis Vuitton SE 3.9
Novo Nordisk A/S - Class B 3.8
TotalEnergies SE 3.6
C000219909 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Sustainable Equity Fund
Class Name Class A Shares
Trading Symbol JEASX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Sustainable Equity Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Sustainable Equity Fund
(Class A Shares/JEASX)		 $143 1.23%
Expenses Paid, Amount $ 143
Expense Ratio, Percent 1.23%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Sustainable Equity Fund Class A Shares returned 33.14%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%.
Top Contributors to Performance
Sector allocation contributed to relative performance. A structural underweight in the energy sector and an overweight in the information technology sector were especially positive. Individual stock contributors included semiconductor firm NVIDIA and rail equipment and systems provider Wabtec. NVIDIA posted strong results, and we see the company as well placed to benefit from earnings upgrades. Wabtec also enjoyed strong results and raised its full-year guidance.
Top Detractors from Performance
Stock selection within the healthcare sector detracted relative to the benchmark, due in part to a position in Humana. The healthcare insurer reported increasing hospital utilization trends, which led to concerns about lower margins in the future. Additionally, there was speculation Humana would face a downgrade in its star ratings, which are assigned and published by the Centers for Medicare and Medicaid Services.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
June 25, 2020, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year Since Inception
Janus Henderson Global Sustainable Equity Fund (Class A Shares/JEASX) at NAV 33.14% 12.46%
Janus Henderson Global Sustainable Equity Fund (Class A Shares/JEASX) at Maximum Offering Price - 5.75% 25.53% 10.90%
MSCI World IndexSM 32.43% 14.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 36,000,000
Holdings Count | Holding 55
Advisory Fees Paid, Amount $ 0.0
Investment Company Portfolio Turnover 25.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $36M
Number of portfolio holdings 55
Total investment advisory fee paid $0.0M
Portfolio turnover rate 25%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
Asset Allocation (% of net assets)
Common Stocks 99.0
Investment Companies 1.5
Other (0.5)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
C000219911 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Sustainable Equity Fund
Class Name Class C Shares
Trading Symbol JECTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Sustainable Equity Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Sustainable Equity Fund
(Class C Shares/JECTX)		 $153 1.31%
Expenses Paid, Amount $ 153
Expense Ratio, Percent 1.31%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Sustainable Equity Fund Class C Shares returned 33.03%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%.
Top Contributors to Performance
Sector allocation contributed to relative performance. A structural underweight in the energy sector and an overweight in the information technology sector were especially positive. Individual stock contributors included semiconductor firm NVIDIA and rail equipment and systems provider Wabtec. NVIDIA posted strong results, and we see the company as well placed to benefit from earnings upgrades. Wabtec also enjoyed strong results and raised its full-year guidance.
Top Detractors from Performance
Stock selection within the healthcare sector detracted relative to the benchmark, due in part to a position in Humana. The healthcare insurer reported increasing hospital utilization trends, which led to concerns about lower margins in the future. Additionally, there was speculation Humana would face a downgrade in its star ratings, which are assigned and published by the Centers for Medicare and Medicaid Services.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
June 25, 2020, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year Since Inception
Janus Henderson Global Sustainable Equity Fund (Class C Shares/JECTX) at NAV 33.03% 12.46%
Janus Henderson Global Sustainable Equity Fund (Class C Shares/JECTX) with Contingent Deferred Sales Charge 32.03%* 12.46%
MSCI World IndexSM 32.43% 14.95%
*
Returns include a 1% contingent deferred sales charge on Shares redeemed within 12 months of purchase.
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 36,000,000
Holdings Count | Holding 55
Advisory Fees Paid, Amount $ 0.0
Investment Company Portfolio Turnover 25.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $36M
Number of portfolio holdings 55
Total investment advisory fee paid $0.0M
Portfolio turnover rate 25%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
Asset Allocation (% of net assets)
Common Stocks 99.0
Investment Companies 1.5
Other (0.5)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
C000219910 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Sustainable Equity Fund
Class Name Class D Shares
Trading Symbol JEDTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Sustainable Equity Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Sustainable Equity Fund
(Class D Shares/JEDTX)		 $117 1.00%
Expenses Paid, Amount $ 117
Expense Ratio, Percent 1.00%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Sustainable Equity Fund Class D Shares returned 33.39%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%.
Top Contributors to Performance
Sector allocation contributed to relative performance. A structural underweight in the energy sector and an overweight in the information technology sector were especially positive. Individual stock contributors included semiconductor firm NVIDIA and rail equipment and systems provider Wabtec. NVIDIA posted strong results, and we see the company as well placed to benefit from earnings upgrades. Wabtec also enjoyed strong results and raised its full-year guidance.
Top Detractors from Performance
Stock selection within the healthcare sector detracted relative to the benchmark, due in part to a position in Humana. The healthcare insurer reported increasing hospital utilization trends, which led to concerns about lower margins in the future. Additionally, there was speculation Humana would face a downgrade in its star ratings, which are assigned and published by the Centers for Medicare and Medicaid Services.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
June 25, 2020, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year Since Inception
Janus Henderson Global Sustainable Equity Fund (Class D Shares/JEDTX) 33.39% 12.58%
MSCI World IndexSM 32.43% 14.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 36,000,000
Holdings Count | Holding 55
Advisory Fees Paid, Amount $ 0.0
Investment Company Portfolio Turnover 25.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $36M
Number of portfolio holdings 55
Total investment advisory fee paid $0.0M
Portfolio turnover rate 25%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
Asset Allocation (% of net assets)
Common Stocks 99.0
Investment Companies 1.5
Other (0.5)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
C000219912 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Sustainable Equity Fund
Class Name Class I Shares
Trading Symbol JEUIX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Sustainable Equity Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Sustainable Equity Fund
(Class I Shares/JEUIX)		 $118 1.01%
Expenses Paid, Amount $ 118
Expense Ratio, Percent 1.01%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Sustainable Equity Fund Class I Shares returned 33.42%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%.
Top Contributors to Performance
Sector allocation contributed to relative performance. A structural underweight in the energy sector and an overweight in the information technology sector were especially positive. Individual stock contributors included semiconductor firm NVIDIA and rail equipment and systems provider Wabtec. NVIDIA posted strong results, and we see the company as well placed to benefit from earnings upgrades. Wabtec also enjoyed strong results and raised its full-year guidance.
Top Detractors from Performance
Stock selection within the healthcare sector detracted relative to the benchmark, due in part to a position in Humana. The healthcare insurer reported increasing hospital utilization trends, which led to concerns about lower margins in the future. Additionally, there was speculation Humana would face a downgrade in its star ratings, which are assigned and published by the Centers for Medicare and Medicaid Services.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
June 25, 2020, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year Since Inception
Janus Henderson Global Sustainable Equity Fund (Class I Shares/JEUIX) 33.42% 12.63%
MSCI World IndexSM 32.43% 14.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 36,000,000
Holdings Count | Holding 55
Advisory Fees Paid, Amount $ 0.0
Investment Company Portfolio Turnover 25.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $36M
Number of portfolio holdings 55
Total investment advisory fee paid $0.0M
Portfolio turnover rate 25%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
Asset Allocation (% of net assets)
Common Stocks 99.0
Investment Companies 1.5
Other (0.5)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
C000219908 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Sustainable Equity Fund
Class Name Class N Shares
Trading Symbol JETNX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Sustainable Equity Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Sustainable Equity Fund
(Class N Shares/JETNX)		 $102 0.87%
Expenses Paid, Amount $ 102
Expense Ratio, Percent 0.87%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Sustainable Equity Fund Class N Shares returned 33.62%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%.
Top Contributors to Performance
Sector allocation contributed to relative performance. A structural underweight in the energy sector and an overweight in the information technology sector were especially positive. Individual stock contributors included semiconductor firm NVIDIA and rail equipment and systems provider Wabtec. NVIDIA posted strong results, and we see the company as well placed to benefit from earnings upgrades. Wabtec also enjoyed strong results and raised its full-year guidance.
Top Detractors from Performance
Stock selection within the healthcare sector detracted relative to the benchmark, due in part to a position in Humana. The healthcare insurer reported increasing hospital utilization trends, which led to concerns about lower margins in the future. Additionally, there was speculation Humana would face a downgrade in its star ratings, which are assigned and published by the Centers for Medicare and Medicaid Services.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
June 25, 2020, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year Since Inception
Janus Henderson Global Sustainable Equity Fund (Class N Shares/JETNX) 33.62% 12.75%
MSCI World IndexSM 32.43% 14.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 36,000,000
Holdings Count | Holding 55
Advisory Fees Paid, Amount $ 0.0
Investment Company Portfolio Turnover 25.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $36M
Number of portfolio holdings 55
Total investment advisory fee paid $0.0M
Portfolio turnover rate 25%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
Asset Allocation (% of net assets)
Common Stocks 99.0
Investment Companies 1.5
Other (0.5)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
C000225293 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Sustainable Equity Fund
Class Name Class R Shares
Trading Symbol JEGRX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Sustainable Equity Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Sustainable Equity Fund
(Class R Shares/JEGRX)		 $126 1.08%
Expenses Paid, Amount $ 126
Expense Ratio, Percent 1.08%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Sustainable Equity Fund Class R Shares returned 33.31%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%.
Top Contributors to Performance
Sector allocation contributed to relative performance. A structural underweight in the energy sector and an overweight in the information technology sector were especially positive. Individual stock contributors included semiconductor firm NVIDIA and rail equipment and systems provider Wabtec. NVIDIA posted strong results, and we see the company as well placed to benefit from earnings upgrades. Wabtec also enjoyed strong results and raised its full-year guidance.
Top Detractors from Performance
Stock selection within the healthcare sector detracted relative to the benchmark, due in part to a position in Humana. The healthcare insurer reported increasing hospital utilization trends, which led to concerns about lower margins in the future. Additionally, there was speculation Humana would face a downgrade in its star ratings, which are assigned and published by the Centers for Medicare and Medicaid Services.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
June 25, 2020, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year Since Inception
Janus Henderson Global Sustainable Equity Fund (Class R Shares/JEGRX) 33.31% 12.50%
MSCI World IndexSM 32.43% 14.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 36,000,000
Holdings Count | Holding 55
Advisory Fees Paid, Amount $ 0.0
Investment Company Portfolio Turnover 25.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $36M
Number of portfolio holdings 55
Total investment advisory fee paid $0.0M
Portfolio turnover rate 25%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
Asset Allocation (% of net assets)
Common Stocks 99.0
Investment Companies 1.5
Other (0.5)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
C000219906 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Sustainable Equity Fund
Class Name Class S Shares
Trading Symbol JESSX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Sustainable Equity Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Sustainable Equity Fund
(Class S Shares/JESSX)		 $117 1.00%
Expenses Paid, Amount $ 117
Expense Ratio, Percent 1.00%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Sustainable Equity Fund Class S Shares returned 33.49%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%.
Top Contributors to Performance
Sector allocation contributed to relative performance. A structural underweight in the energy sector and an overweight in the information technology sector were especially positive. Individual stock contributors included semiconductor firm NVIDIA and rail equipment and systems provider Wabtec. NVIDIA posted strong results, and we see the company as well placed to benefit from earnings upgrades. Wabtec also enjoyed strong results and raised its full-year guidance.
Top Detractors from Performance
Stock selection within the healthcare sector detracted relative to the benchmark, due in part to a position in Humana. The healthcare insurer reported increasing hospital utilization trends, which led to concerns about lower margins in the future. Additionally, there was speculation Humana would face a downgrade in its star ratings, which are assigned and published by the Centers for Medicare and Medicaid Services.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
June 25, 2020, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year Since Inception
Janus Henderson Global Sustainable Equity Fund (Class S Shares/JESSX) 33.49% 12.57%
MSCI World IndexSM 32.43% 14.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 36,000,000
Holdings Count | Holding 55
Advisory Fees Paid, Amount $ 0.0
Investment Company Portfolio Turnover 25.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $36M
Number of portfolio holdings 55
Total investment advisory fee paid $0.0M
Portfolio turnover rate 25%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
Asset Allocation (% of net assets)
Common Stocks 99.0
Investment Companies 1.5
Other (0.5)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
C000219907 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson Global Sustainable Equity Fund
Class Name Class T Shares
Trading Symbol JETTX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson Global Sustainable Equity Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson Global Sustainable Equity Fund
(Class T Shares/JETTX)		 $129 1.11%
Expenses Paid, Amount $ 129
Expense Ratio, Percent 1.11%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson Global Sustainable Equity Fund Class T Shares returned 33.30%. Its broad-based benchmark, the MSCI World IndexSM, returned 32.43%.
Top Contributors to Performance
Sector allocation contributed to relative performance. A structural underweight in the energy sector and an overweight in the information technology sector were especially positive. Individual stock contributors included semiconductor firm NVIDIA and rail equipment and systems provider Wabtec. NVIDIA posted strong results, and we see the company as well placed to benefit from earnings upgrades. Wabtec also enjoyed strong results and raised its full-year guidance.
Top Detractors from Performance
Stock selection within the healthcare sector detracted relative to the benchmark, due in part to a position in Humana. The healthcare insurer reported increasing hospital utilization trends, which led to concerns about lower margins in the future. Additionally, there was speculation Humana would face a downgrade in its star ratings, which are assigned and published by the Centers for Medicare and Medicaid Services.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
June 25, 2020, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year Since Inception
Janus Henderson Global Sustainable Equity Fund (Class T Shares/JETTX) 33.30% 12.48%
MSCI World IndexSM 32.43% 14.95%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 36,000,000
Holdings Count | Holding 55
Advisory Fees Paid, Amount $ 0.0
Investment Company Portfolio Turnover 25.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $36M
Number of portfolio holdings 55
Total investment advisory fee paid $0.0M
Portfolio turnover rate 25%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
Asset Allocation (% of net assets)
Common Stocks 99.0
Investment Companies 1.5
Other (0.5)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
Microsoft Corp 5.7
NVIDIA Corp 4.3
Schneider Electric SE 3.4
Wabtec Corp 3.3
Progressive Corp/The 3.2
C000240132 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson U.S. Dividend Income Fund
Class Name Class D Shares
Trading Symbol JDDVX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson U.S. Dividend Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/reports. You can also request this information by contacting us at 1-800-525-3713.
Additional Information Phone Number 1-800-525-3713
Additional Information Website janushenderson.com/reports
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson U.S. Dividend Income Fund
(Class D Shares/JDDVX)		 $100 0.89%
Expenses Paid, Amount $ 100
Expense Ratio, Percent 0.89%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson U.S. Dividend Income Fund Class D Shares returned 23.89%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Value Index, returned 27.76%.
Top Contributors to Performance
Broadcom was a top contributor to returns relative to the performance benchmark. The semiconductor and infrastructure software solutions provider benefited from increased technology spending to support the rollout of artificial intelligence. Financial services firm American Express, another contributor, saw a significant profit increase driven by higher customer balances and spending by affluent cardmembers.
Top Detractors from Performance
Our emphasis on high-quality, dividend-growth stocks hindered returns relative to the performance benchmark, as we did not own several non- or lower-dividend-paying mega-cap technology stocks that were strong drivers of index returns. Starbucks was a relative detractor among stocks we owned, as the coffee purveyor faced slower consumer discretionary spending and higher costs. Oil and gas company ConocoPhillips also underperformed after reporting disappointing earnings.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
December 20, 2022, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year Since Inception
Janus Henderson U.S. Dividend Income Fund (Class D Shares/JDDVX) 23.89% 12.64%
Russell 1000® Index 35.68% 27.56%
Russell 1000® Value Index 27.76% 16.82%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/reports for the most recent performance information.
Net Assets $ 22,000,000
Holdings Count | Holding 52
Advisory Fees Paid, Amount $ 0.0
Investment Company Portfolio Turnover 81.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22M
Number of portfolio holdings 52
Total investment advisory fee paid $0.0M
Portfolio turnover rate 81%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
International Business Machines Corp 4.7
JPMorgan Chase & Co 4.4
CME Group Inc 3.4
UnitedHealth Group Inc 3.2
AbbVie Inc 3.1
Asset Allocation (% of net assets)
Common Stocks 99.9
Investment Companies 0.2
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
International Business Machines Corp 4.7
JPMorgan Chase & Co 4.4
CME Group Inc 3.4
UnitedHealth Group Inc 3.2
AbbVie Inc 3.1
C000240130 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson U.S. Dividend Income Fund
Class Name Class I Shares
Trading Symbol JIDVX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson U.S. Dividend Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson U.S. Dividend Income Fund
(Class I Shares/JIDVX)		 $88 0.79%
Expenses Paid, Amount $ 88
Expense Ratio, Percent 0.79%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson U.S. Dividend Income Fund Class I Shares returned 23.94%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Value Index, returned 27.76%.
Top Contributors to Performance
Broadcom was a top contributor to returns relative to the performance benchmark. The semiconductor and infrastructure software solutions provider benefited from increased technology spending to support the rollout of artificial intelligence. Financial services firm American Express, another contributor, saw a significant profit increase driven by higher customer balances and spending by affluent cardmembers.
Top Detractors from Performance
Our emphasis on high-quality, dividend-growth stocks hindered returns relative to the performance benchmark, as we did not own several non- or lower-dividend-paying mega-cap technology stocks that were strong drivers of index returns. Starbucks was a relative detractor among stocks we owned, as the coffee purveyor faced slower consumer discretionary spending and higher costs. Oil and gas company ConocoPhillips also underperformed after reporting disappointing earnings.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
December 20, 2022, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year Since Inception
Janus Henderson U.S. Dividend Income Fund (Class I Shares/JIDVX) 23.94% 12.71%
Russell 1000® Index 35.68% 27.56%
Russell 1000® Value Index 27.76% 16.82%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,000,000
Holdings Count | Holding 52
Advisory Fees Paid, Amount $ 0.0
Investment Company Portfolio Turnover 81.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22M
Number of portfolio holdings 52
Total investment advisory fee paid $0.0M
Portfolio turnover rate 81%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
International Business Machines Corp 4.7
JPMorgan Chase & Co 4.4
CME Group Inc 3.4
UnitedHealth Group Inc 3.2
AbbVie Inc 3.1
Asset Allocation (% of net assets)
Common Stocks 99.9
Investment Companies 0.2
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
International Business Machines Corp 4.7
JPMorgan Chase & Co 4.4
CME Group Inc 3.4
UnitedHealth Group Inc 3.2
AbbVie Inc 3.1
C000240131 [Member]  
Shareholder Report [Line Items]  
Fund Name Janus Henderson U.S. Dividend Income Fund
Class Name Class N Shares
Trading Symbol JNDVX
Annual or Semi-Annual Statement [Text Block] This annual shareholder report contains important information about the Janus Henderson U.S. Dividend Income Fund (the "Fund”) for the period of October 1, 2023 to September 30, 2024.
Shareholder Report Annual or Semi-Annual annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at janushenderson.com/info. You can also request this information by contacting us at 1-877-335-2687.
Additional Information Phone Number 1-877-335-2687
Additional Information Website janushenderson.com/info
Expenses [Text Block]
What were the costs for the year?
(Based on a hypothetical $10,000 investment)
Fund (Class) Cost of a
$10,000 investment		 Cost paid as a percentage
of a $10,000 investment
Janus Henderson U.S. Dividend Income Fund
(Class N Shares/JNDVX)		 $85 0.76%
Expenses Paid, Amount $ 85
Expense Ratio, Percent 0.76%
Factors Affecting Performance [Text Block]
What impacted Fund performance over the reporting period?
For the 12-month period ended September 30, 2024, the Janus Henderson U.S. Dividend Income Fund Class N Shares returned 23.95%. Its broad-based benchmark, the Russell 1000® Index, returned 35.68%. Its performance benchmark, the Russell 1000® Value Index, returned 27.76%.
Top Contributors to Performance
Broadcom was a top contributor to returns relative to the performance benchmark. The semiconductor and infrastructure software solutions provider benefited from increased technology spending to support the rollout of artificial intelligence. Financial services firm American Express, another contributor, saw a significant profit increase driven by higher customer balances and spending by affluent cardmembers.
Top Detractors from Performance
Our emphasis on high-quality, dividend-growth stocks hindered returns relative to the performance benchmark, as we did not own several non- or lower-dividend-paying mega-cap technology stocks that were strong drivers of index returns. Starbucks was a relative detractor among stocks we owned, as the coffee purveyor faced slower consumer discretionary spending and higher costs. Oil and gas company ConocoPhillips also underperformed after reporting disappointing earnings.
Performance Past Does Not Indicate Future [Text] Keep in mind that the Fund’s past performance is not a good predictor of how the Fund will perform in the future.
Line Graph [Table Text Block]
Total return based on a $10,000 investment
December 20, 2022, through September 30, 2024
Fund Performance - Growth of 10K
Average Annual Return [Table Text Block]
AVERAGE ANNUAL TOTAL RETURN 1 Year Since Inception
Janus Henderson U.S. Dividend Income Fund (Class N Shares/JNDVX) 23.95% 12.72%
Russell 1000® Index 35.68% 27.56%
Russell 1000® Value Index 27.76% 16.82%
No Deduction of Taxes [Text Block] The graph and table include reinvestment of all dividends and distributions and do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemptions of Fund shares.
Updated Performance Information Location [Text Block] Visit janushenderson.com/info for the most recent performance information.
Net Assets $ 22,000,000
Holdings Count | Holding 52
Advisory Fees Paid, Amount $ 0.0
Investment Company Portfolio Turnover 81.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics
Net assets $22M
Number of portfolio holdings 52
Total investment advisory fee paid $0.0M
Portfolio turnover rate 81%
Holdings [Text Block]
What did the Fund invest in?
5 Largest Equity Holdings (% of net assets)
International Business Machines Corp 4.7
JPMorgan Chase & Co 4.4
CME Group Inc 3.4
UnitedHealth Group Inc 3.2
AbbVie Inc 3.1
Asset Allocation (% of net assets)
Common Stocks 99.9
Investment Companies 0.2
Other (0.1)
Top Country Allocations (% of investments)
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
5 Largest Equity Holdings (% of net assets)
International Business Machines Corp 4.7
JPMorgan Chase & Co 4.4
CME Group Inc 3.4
UnitedHealth Group Inc 3.2
AbbVie Inc 3.1