Janus Henderson International Dividend Fund Performance Management - Class A C S I N T Shares [Member] - Janus Henderson International Dividend Fund	Jun. 30, 2026
Prospectus [Line Items]
Bar Chart and Performance Table [Heading]	<span style="color:#FFFFFF;font-family:Times New Roman;font-size:10.45pt;font-weight:bold;margin-left:0.0pt;text-transform:uppercase;">Performance information</span>
Performance Narrative [Text Block]	The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Returns shown for periods prior to June 5, 2017, are those of Henderson Dividend & Income Builder Fund (the “Predecessor Fund”). The Predecessor Fund was advised by Henderson Global Investors (North America) Inc. and subadvised by Henderson Investment Management Limited. Class A Shares, Class C Shares, Class I Shares, and Class R6 Shares of the Predecessor Fund were reorganized into Class A Shares, Class C Shares, Class I Shares, and Class N Shares, respectively, of the Fund on June 2, 2017. Class A Shares, Class C Shares, and Class I Shares of the Predecessor Fund commenced operations with the Predecessor Fund’s inception on August 1, 2012. Class R6 Shares of the Predecessor Fund commenced operations on November 30, 2015. Class S Shares and Class T Shares of the Fund commenced operations on June 5, 2017. •The performance shown for Class A Shares for periods prior to June 5, 2017, reflects the performance of Class A Shares of the Predecessor Fund and is calculated using the fees and expenses of Class A Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers. •The performance shown for Class C Shares for periods prior to June 5, 2017, reflects the performance of Class C Shares of the Predecessor Fund and is calculated using the fees and expenses of Class C Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers. •The performance shown for Class I Shares for periods prior to June 5, 2017, reflects the performance of Class I Shares of the Predecessor Fund and is calculated using the fees and expenses of Class I Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers. •The performance shown for Class N Shares for periods prior to June 5, 2017, reflects the performance of Class R6 Shares of the Predecessor Fund and is calculated using the fees and expenses of Class R6 Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers, except that for periods prior to November 30, 2015, performance shown for Class N Shares reflects the performance of Class I Shares of the Predecessor Fund, calculated using the estimated fees and expenses of Class N Shares, net of any applicable fee and expense limitations or waivers. •The performance shown for Class S Shares for periods prior to June 5, 2017, reflects the performance of Class I Shares of the Predecessor Fund, calculated using the estimated fees and expenses of Class S Shares, net of any applicable fee and expense limitations or waivers. •The performance shown for Class T Shares for periods prior to June 5, 2017, reflects the performance of Class I Shares of the Predecessor Fund, calculated using the estimated fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers. Returns of the Fund will be different from the Predecessor Fund as they have different expenses. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund changed its investment strategy on October 28, 2022, and again changed its investment strategy on June 24, 2025. Performance prior to June 24, 2025, reflects the Fund’s former investment strategies, and its performance may have differed if the Fund’s current investment strategy had been in place. The Fund’s (and the Predecessor Fund’s) past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.Updated performance information is available at janushenderson.com/performance or by calling 1-877-335-2687.
Performance Past Does Not Indicate Future [Text]	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;">The Fund’s (and the Predecessor Fund’s) past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.</span>
Performance Information Illustrates Variability of Returns [Text]	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The bar chart depicts the change in performance from year to year during the periods indicated. </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The bar chart figures do not </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.</span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. All figures assume reinvestment of dividends and distributions.</span>
Performance Additional Market Index [Text]	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. All figures assume reinvestment of dividends and distributions.</span>
Bar Chart Does Not Reflect Sales Loads [Text]	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">The bar chart figures do not </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.</span>
Bar Chart [Heading]	Annual Total Returns for Class I Shares (calendar year-end)
Bar Chart Closing [Text Block]	Best Quarter:4th Quarter 202216.57%Worst Quarter:1st Quarter 2020-17.83%Class I Shares’ year-to-date return as of the calendar quarter endedSeptember 30, 2026was18.03%.
Performance Table Heading	<span style="font-family:Times New Roman;font-size:8.55pt;font-weight:bold;margin-left:0.0pt;">Average Annual Total Returns </span><span style="font-family:Times New Roman;font-size:8.55pt;margin-left:0.0pt;">(periods ended 12/31/25)</span>
Performance Table Narrative	The Fund’s broad-based benchmark index is the MSCI World ex-USA Index. The index is described below.•The MSCI World ex-USA Index is designed to measure the equity market performance of developed market countries in North America, Europe, and the Asia/Pacific Region, excluding the United States.After-tax returns are calculated using distributions for the Predecessor Fund’s Class I Shares for the period prior to June 5, 2017. If Class I Shares of the Fund had been available during periods prior to June 5, 2017, the distributions used to calculate the after-tax returns may have been different. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-advantaged account, such as a 401(k) plan or an IRA.
Performance Table Does Reflect Sales Loads	<span style="font-family:Times New Roman;font-size:7.60pt;">The one year return is calculated to include the contingent deferred sales charge.</span>
Performance Table Uses Highest Federal Rate	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. </span>
Performance Table Not Relevant to Tax Deferred	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">Actual after-tax returns depend on </span><span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;">your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-advantaged account, such as a 401(k) plan or an IRA.</span>
Performance Table Closing [Text Block]	Updated performance information is available at janushenderson.com/performance or by calling 1-877-335-2687.
Performance Availability Website Address [Text]	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;">janushenderson.com/performance</span>
Performance Availability Phone [Text]	<span style="color:#000000;font-family:Times New Roman;font-size:9.50pt;font-style:italic;">1-877-335-2687</span>
Class I
Prospectus [Line Items]
Year to Date Return, Label [Optional Text]	<span style="font-family:Times New Roman;font-size:9.50pt;margin-left:0.0pt;">Class I Shares’ year-to-date return as of the calendar quarter ended</span>
Bar Chart, Year to Date Return	18.03%
Bar Chart, Year to Date Return, Date	Sep. 30, 2026
Highest Quarterly Return, Label [Optional Text]	<span style="font-family:Times New Roman;font-size:8.55pt;font-weight:bold;margin-left:0.0pt;">Best Quarter:</span>
Highest Quarterly Return	16.57%
Highest Quarterly Return, Date	Dec. 31, 2022
Lowest Quarterly Return, Label [Optional Text]	<span style="font-family:Times New Roman;font-size:8.55pt;font-weight:bold;margin-left:0.0pt;">Worst Quarter:</span>
Lowest Quarterly Return	(17.83%)
Lowest Quarterly Return, Date	Mar. 31, 2020

Janus Henderson International Dividend Fund Performance Management - Class A C S I N T Shares [Member] - Janus Henderson International Dividend Fund

Jun. 30, 2026

Bar Chart and Performance Table [Heading]

Performance information

Performance Narrative [Text Block]

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time. Returns shown for periods prior to June 5, 2017, are those of Henderson Dividend & Income Builder Fund (the “Predecessor Fund”). The Predecessor Fund was advised by Henderson Global Investors (North America) Inc. and subadvised by Henderson Investment Management Limited. Class A Shares, Class C Shares, Class I Shares, and Class R6 Shares of the Predecessor Fund were reorganized into Class A Shares, Class C Shares, Class I Shares, and Class N Shares, respectively, of the Fund on June 2, 2017. Class A Shares, Class C Shares, and Class I Shares of the Predecessor Fund commenced operations with the Predecessor Fund’s inception on August 1, 2012. Class R6 Shares of the Predecessor Fund commenced operations on November 30, 2015. Class S Shares and Class T Shares of the Fund commenced operations on June 5, 2017. •The performance shown for Class A Shares for periods prior to June 5, 2017, reflects the performance of Class A Shares of the Predecessor Fund and is calculated using the fees and expenses of Class A Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers. •The performance shown for Class C Shares for periods prior to June 5, 2017, reflects the performance of Class C Shares of the Predecessor Fund and is calculated using the fees and expenses of Class C Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers. •The performance shown for Class I Shares for periods prior to June 5, 2017, reflects the performance of Class I Shares of the Predecessor Fund and is calculated using the fees and expenses of Class I Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers. •The performance shown for Class N Shares for periods prior to June 5, 2017, reflects the performance of Class R6 Shares of the Predecessor Fund and is calculated using the fees and expenses of Class R6 Shares of the Predecessor Fund, in effect during the periods shown, net of any applicable fee and expense limitations or waivers, except that for periods prior to November 30, 2015, performance shown for Class N Shares reflects the performance of Class I Shares of the Predecessor Fund, calculated using the estimated fees and expenses of Class N Shares, net of any applicable fee and expense limitations or waivers. •The performance shown for Class S Shares for periods prior to June 5, 2017, reflects the performance of Class I Shares of the Predecessor Fund, calculated using the estimated fees and expenses of Class S Shares, net of any applicable fee and expense limitations or waivers. •The performance shown for Class T Shares for periods prior to June 5, 2017, reflects the performance of Class I Shares of the Predecessor Fund, calculated using the estimated fees and expenses of Class T Shares, net of any applicable fee and expense limitations or waivers. Returns of the Fund will be different from the Predecessor Fund as they have different expenses. The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. All figures assume reinvestment of dividends and distributions. For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower. The Fund changed its investment strategy on October 28, 2022, and again changed its investment strategy on June 24, 2025. Performance prior to June 24, 2025, reflects the Fund’s former investment strategies, and its performance may have differed if the Fund’s current investment strategy had been in place. The Fund’s (and the Predecessor Fund’s) past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.Updated performance information is available at janushenderson.com/performance or by calling 1-877-335-2687.

Performance Past Does Not Indicate Future [Text]

The Fund’s (and the Predecessor Fund’s) past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.

Performance Information Illustrates Variability of Returns [Text]

The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. All figures assume reinvestment of dividends and distributions.

Performance Additional Market Index [Text]

The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index. All figures assume reinvestment of dividends and distributions.

Bar Chart Does Not Reflect Sales Loads [Text]

The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower.

Bar Chart [Heading]

Annual Total Returns for Class I Shares (calendar year-end)

Bar Chart Closing [Text Block]

Best Quarter:4th Quarter 202216.57%Worst Quarter:1st Quarter 2020-17.83%Class I Shares’ year-to-date return as of the calendar quarter endedSeptember 30, 2026was18.03%.

Performance Table Heading

Average Annual Total Returns (periods ended 12/31/25)

Performance Table Narrative

The Fund’s broad-based benchmark index is the MSCI World ex-USA Index. The index is described below.•The MSCI World ex-USA Index is designed to measure the equity market performance of developed market countries in North America, Europe, and the Asia/Pacific Region, excluding the United States.After-tax returns are calculated using distributions for the Predecessor Fund’s Class I Shares for the period prior to June 5, 2017. If Class I Shares of the Fund had been available during periods prior to June 5, 2017, the distributions used to calculate the after-tax returns may have been different. After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-advantaged account, such as a 401(k) plan or an IRA.

Performance Table Does Reflect Sales Loads

The one year return is calculated to include the contingent deferred sales charge.

Performance Table Uses Highest Federal Rate

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-advantaged account, such as a 401(k) plan or an IRA.

Performance Table Closing [Text Block]

Updated performance information is available at janushenderson.com/performance or by calling 1-877-335-2687.

Performance Availability Website Address [Text]

janushenderson.com/performance

Performance Availability Phone [Text]

1-877-335-2687

Class I

Prospectus [Line Items]

Year to Date Return, Label [Optional Text]

Class I Shares’ year-to-date return as of the calendar quarter ended

Bar Chart, Year to Date Return

18.03%