| Form N-CSR Cover | 12 Months Ended |
| Sep. 30, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | Ariel Investment Trust |
| Entity Central Index Key | 0000798365 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Sep. 30, 2024 |
| Shareholder Report | 12 Months Ended |
| Sep. 30, 2024 USD ($) Holding | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | Ariel Investment Trust |
| Entity Central Index Key | 0000798365 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Sep. 30, 2024 |
| Ariel Fund (Investor Class) | |
| Shareholder Report [Line Items] | |
| Fund Name | Ariel Fund |
| Class Name | Investor Class |
| Trading Symbol | ARGFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Ariel Fund (the “Fund”) for the period from 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 arielinvestments.com/fundreports |
| Additional Information Phone Number | 800.292.7435 |
| Additional Information Website | arielinvestments.com/fundreports |
| Expenses [Text Block] | Fund Expenses for the Last 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 Ariel Fund (Investor Class) $ 1.00 % |
| Expenses Paid, Amount | $ 114 |
| Expense Ratio, Percent | 1% |
| Factors Affecting Performance [Text Block] | Management's Discussion of Fund Performance TOP PERFORMANCE CONTRIBUTORS Ariel Fund Investor Class advanced +27.63% over the trailing one-year period, ahead of both the Russell 2500 Value Index’s +26.59% gain and the Russell 2500 Index’s +26.17% return. Several stocks in the portfolio had strong returns. Global cruise vacation company, Royal Caribbean Group (RCL) dditio Additionally, shares of global leader in for-profit education, Adtalem Global Education (ATGE) TOP PERFORMANCE DETRACTORS U.S. direct-to-consumer pool and spa care services company, Leslie’s, Inc. (LESL) Produc Global dental manufacturing company, Envista Holdings Corp. (NVST) form po |
| Performance Past Does Not Indicate Future [Text] | Performance data quoted represents past performance and does not guarantee future results. |
| Line Graph [Table Text Block] | Growth of $10,000 |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1-Year 5-Year 10-Year Ariel Fund (Investor Class) 27.63 % 10.54 % 8.57 % Russell 2500TM Value Index 26.59 % 9.99 % 8.47 % Russell 2500TM Index 26.17 % 10.43 % 9.50 % S&P 500 ® (Broad-based Index) 36.35 % 15.98 % 13.38 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares. |
| Updated Performance Information Location [Text Block] | Pl ea arielinvestments.com/performance orm |
| Net Assets | $ 2,787,556,441 |
| Holdings Count | Holding | 37 |
| Advisory Fees Paid, Amount | $ 15,215,437 |
| Investment Company, Portfolio Turnover | 17% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net assets $ Total number of portfolio holdings 37 Total advisory fees paid $ Portfolio turnover rate as of the end of the reporting period 17 % |
| Holdings [Text Block] | Graphical Representation of Holdings (% of Net Assets) Top Ten Holdings Mohawk Industries, Inc. 4.62 % Madison Square Garden Entertainment Corporation 4.30 % Adtalem Global Education, Inc. 3.70 % Northern Trust Corporation 3.69 % Affiliated Managers Group, Inc. 3.66 % Lazard, Inc. 3.64 % Royal Caribbean Cruises, Ltd. 3.60 % Boyd Gaming Corporation 3.59 % J.M. Smucker Company 3.53 % Jones Lang LaSalle, Inc. 3.48 % Industry Allocation |
| Largest Holdings [Text Block] | Graphical Representation of Holdings (% of Net Assets) Top Ten Holdings Mohawk Industries, Inc. 4.62 % Madison Square Garden Entertainment Corporation 4.30 % Adtalem Global Education, Inc. 3.70 % Northern Trust Corporation 3.69 % Affiliated Managers Group, Inc. 3.66 % Lazard, Inc. 3.64 % Royal Caribbean Cruises, Ltd. 3.60 % Boyd Gaming Corporation 3.59 % J.M. Smucker Company 3.53 % Jones Lang LaSalle, Inc. 3.48 % |
| Ariel Fund (Institutional Class) | |
| Shareholder Report [Line Items] | |
| Fund Name | Ariel Fund |
| Class Name | Institutional Class |
| Trading Symbol | ARAIX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Ariel Fund (the “Fund”) for the period from 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 arielinvestments.com/fundreports |
| Additional Information Phone Number | 800.292.7435 |
| Additional Information Website | arielinvestments.com/fundreports |
| Expenses [Text Block] | Fund Expenses for the Last 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 Ariel Fund (Institutional Class) $ 0.69 % |
| Expenses Paid, Amount | $ 79 |
| Expense Ratio, Percent | 0.69% |
| Factors Affecting Performance [Text Block] | Management's Discussion of Fund Performance TOP PERFORMANCE CONTRIBUTORS Ariel Fund Institutional Class advanced +28.01% over the trailing one-year period, ahead of both the Russell 2500 Value Index’s +26.59% gain and the Russell 2500 Index’s +26.17% return. Several stocks in the portfolio had strong returns Global cruise vacation company, Royal Caribbean Group (RCL) Additionally, shares of global leader in for-profit education, Adtalem Global Education (ATGE) TOP PERFORMANCE DETRACTORS U.S. direct-to-consumer pool and spa care services company, Leslie’s, Inc. (LESL) Global dental manufacturing company, Envista Holdings Corp. (NVST) upside |
| Performance Past Does Not Indicate Future [Text] | Performance data quoted represents past performance and does not guarantee future results. |
| Line Graph [Table Text Block] | Growth of $1,000,000 |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1-Year 5-Year 10-Year Ariel Fund (Institutional Class) 28.01 % 10.89 % 8.91 % Russell 2500 TM 26.59 % 9.99 % 8.47 % Russell 2500 TM 26.17 % 10.43 % 9.50 % S&P 500 ® (Broad-based Index) 36.35 % 15.98 % 13.38 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of ta xes |
| Updated Performance Information Location [Text Block] | Please visit arielinvestments.com/performance |
| Net Assets | $ 2,787,556,441 |
| Holdings Count | Holding | 37 |
| Advisory Fees Paid, Amount | $ 15,215,437 |
| Investment Company, Portfolio Turnover | 17% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net assets $ Total number of portfolio holdings 37 Total advisory fees paid $ Portfolio turnover rate as of the end of the reporting period 17 % |
| Holdings [Text Block] | Graphical Representation of Holdings (% of Net Assets) Top Ten Holdings Mohawk Industries, Inc. 4.62 % Madison Square Garden Entertainment Corporation 4.30 % Adtalem Global Education, Inc. 3.70 % Northern Trust Corporation 3.69 % Affiliated Managers Group, Inc. 3.66 % Lazard, Inc. 3.64 % Royal Caribbean Cruises, Ltd. 3.60 % Boyd Gaming Corporation 3.59 % J.M. Smucker Company 3.53 % Jones Lang LaSalle, Inc. 3.48 % Industry Allocation |
| Largest Holdings [Text Block] | Top Ten Holdings Mohawk Industries, Inc. 4.62 % Madison Square Garden Entertainment Corporation 4.30 % Adtalem Global Education, Inc. 3.70 % Northern Trust Corporation 3.69 % Affiliated Managers Group, Inc. 3.66 % Lazard, Inc. 3.64 % Royal Caribbean Cruises, Ltd. 3.60 % Boyd Gaming Corporation 3.59 % J.M. Smucker Company 3.53 % Jones Lang LaSalle, Inc. 3.48 % |
| Ariel Appreciation Fund (Investor Class) | |
| Shareholder Report [Line Items] | |
| Fund Name | Ariel Appreciation Fund |
| Class Name | Investor Class |
| Trading Symbol | CAAPX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Ariel Appreciation Fund (the “Fund”) for the period from 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 arielinvestments.com/fundreports |
| Additional Information Phone Number | 800.292.7435 |
| Additional Information Website | arielinvestments.com/fundreports |
| Expenses [Text Block] | Fund Expenses for the Last 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 Ariel Appreciation Fund (Investor Class) $ 1.14 % |
| Expenses Paid, Amount | $ 124 |
| Expense Ratio, Percent | 1.14% |
| Factors Affecting Performance [Text Block] | Management's Discussion of Fund Performance TOP PERFORMANCE CONTRIBUTORS Ariel Appreciation Fund Investor Class Several stocks in the portfolio had strong returns. Alternative asset manager, KKR & Co. (KKR) Shares of global investment bank, Goldman Sachs Group, Inc. (GS) ve TOP PERFORMANCE DETRACTORS Retail drugstore operator, Walgreens Boots Alliance, Inc. (WBA) Toy manufacturer, Mattel, Inc. (MAT) ® ® ® wel |
| Performance Past Does Not Indicate Future [Text] | Performance data quoted represents past performance and does not guarantee future results. |
| Line Graph [Table Text Block] | Growth of $10,000 |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1-Year 5-Year 10-Year Ariel Appreciation Fund (Investor Class) 18.31 % 8.66 % 6.95 % Russell Midcap ® 29.01 % 10.33 % 8.93 % Russell Midcap ® 29.33 % 11.30 % 10.19 % S&P 500 ® (Broad-based Index) 36.35 % 15.98 % 13.38 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares. |
| Updated Performance Information Location [Text Block] | Please visit arielinvestments.com/performance o rm |
| Net Assets | $ 1,011,550,147 |
| Holdings Count | Holding | 43 |
| Advisory Fees Paid, Amount | $ 7,304,928 |
| Investment Company, Portfolio Turnover | 17% |
| Additional Fund Statistics [Text Block] | Key Fund Statistic s Net assets $ Total num be 43 Total advis ory f $ Portfolio turnover rate as of the end of the reporting period 17 % |
| Holdings [Text Block] | Graphical Representation of Holdings Asse Top Ten Holdings Northern Trust Corporation 4.14 % Mattel, Inc. 3.76 % Goldman Sachs Group, Inc. 3.61 % Generac Holdings, Inc. 3.26 % Stanley Black & Decker, Inc. 3.13 % Interpublic Group of Companies, Inc. 3.08 % Lazard, Inc. 3.05 % CarMax, Inc. 2.96 % Core Laboratories, Inc. 2.83 % Charles River Laboratories International, Inc. 2.81 % Industry Allocation |
| Largest Holdings [Text Block] | Top Ten Holdings Northern Trust Corporation 4.14 % Mattel, Inc. 3.76 % Goldman Sachs Group, Inc. 3.61 % Generac Holdings, Inc. 3.26 % Stanley Black & Decker, Inc. 3.13 % Interpublic Group of Companies, Inc. 3.08 % Lazard, Inc. 3.05 % CarMax, Inc. 2.96 % Core Laboratories, Inc. 2.83 % Charles River Laboratories International, Inc. 2.81 % |
| Ariel Appreciation Fund - Institutional Class | |
| Shareholder Report [Line Items] | |
| Fund Name | Ariel Appreciation Fund |
| Class Name | Institutional Class |
| Trading Symbol | CAAIX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Ariel Appreciation Fund (the “Fund”) for the period from 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 arielinvestments.com/fundreports ou |
| Additional Information Phone Number | 800.292.7435 |
| Additional Information Website | arielinvestments.com/fundreports |
| Expenses [Text Block] | Fund Expenses for the Last 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 Ariel Appreciation Fund (Institutional Class) $ 0.83 % |
| Expenses Paid, Amount | $ 91 |
| Expense Ratio, Percent | 0.83% |
| Factors Affecting Performance [Text Block] | Management's Discussion of Fund Performance TOP PERFORMANCE CONTRIBUTORS Ariel Appreciation Fund Institutional Class Several stocks in the portfolio had strong returns. Alternative asset manager, KKR & Co. (KKR) Shares of global investment bank, Goldman Sachs Group, Inc. (GS) TOP PERFORMANCE DETRACTORS Retail drugstore operator, Walgreens Boots Alliance, Inc. (WBA) Toy manufacturer, Mattel, Inc. (MAT) ® ® ® an |
| Performance Past Does Not Indicate Future [Text] | Performance data quoted represents past performance and does not guarantee future results. |
| Line Graph [Table Text Block] | Growth of $1,000,000 |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1-Year 5-Year 10-Year Ariel Appreciation Fund (Institutional Class) 18.64 % 8.99 % 7.28 % Russell Midcap ® 29.01 % 10.33 % 8.93 % Russell Midcap ® 29.33 % 11.30 % 10.19 % S&P 500 ® (Broad-based Index) 36.35 % 15.98 % 13.38 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares. |
| Updated Performance Information Location [Text Block] | Please visit arielinvestments.com/performance |
| Net Assets | $ 1,011,550,147 |
| Holdings Count | Holding | 43 |
| Advisory Fees Paid, Amount | $ 7,304,928 |
| Investment Company, Portfolio Turnover | 17% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net assets $ Total number of portfolio holdings 43 Total advisory fees paid $ Portfolio turnover rate as of the end of the reporting period 17 % |
| Holdings [Text Block] | Graphical Representation of Holdings (% of Net Assets) Top Ten Holdings Northern Trust Corporation 4.14 % Mattel, Inc. 3.76 % Goldman Sachs Group, Inc. 3.61 % Generac Holdings, Inc. 3.26 % Stanley Black & Decker, Inc. 3.13 % Interpublic Group of Companies, Inc. 3.08 % Lazard, Inc. 3.05 % CarMax, Inc. 2.96 % Core Laboratories, Inc. 2.83 % Charles River Laboratories International, Inc. 2.81 % Industry Allocation |
| Largest Holdings [Text Block] | Top Ten Holdings Northern Trust Corporation 4.14 % Mattel, Inc. 3.76 % Goldman Sachs Group, Inc. 3.61 % Generac Holdings, Inc. 3.26 % Stanley Black & Decker, Inc. 3.13 % Interpublic Group of Companies, Inc. 3.08 % Lazard, Inc. 3.05 % CarMax, Inc. 2.96 % Core Laboratories, Inc. 2.83 % Charles River Laboratories International, Inc. 2.81 % |
| Ariel Focus Fund (Investor Class) | |
| Shareholder Report [Line Items] | |
| Fund Name | Ariel Focus Fund |
| Class Name | Investor Class |
| Trading Symbol | ARFFX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Ariel Focus Fund (the “Fund”) for the period from 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 arielinvestments.com/fundreports |
| Additional Information Phone Number | 800.292.7435 |
| Additional Information Website | arielinvestments.com/fundreports |
| Expenses [Text Block] | Fund Expenses for the Last 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 Ariel Focus Fund (Investor Class) $ 1.00 % |
| Expenses Paid, Amount | $ 114 |
| Expense Ratio, Percent | 1% |
| Factors Affecting Performance [Text Block] | Management's Discussion of Fund Performance TOP PERFORMANCE CONTRIBUTORS Ariel Focus Fund Investor Class advanced +27.54% over the twelve-month period ended September 30, 2024, trailing 6% Several stocks in the portfolio had strong returns. Manufacturer and distributor of medical devices specializing in spine and dental products, ZimVie, Inc. (ZIMV) believes Manufacturer and distributor of floorcovering products, Mohawk Industries, Inc. (MHK) in TOP PERFORMANCE DETRACTORS Oil and natural gas explorer, APA Corporation (APA) Producer and marketer of crop nutrients, Mosaic Co. (MOS) |
| Performance Past Does Not Indicate Future [Text] | Performance data quoted represents past performance and does not guarantee future results. |
| Line Graph [Table Text Block] | Growth of $10,000 |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1-Year 5-Year 10-Year Ariel Focus Fund (Investor Class) 27.54 % 9.33 % 6.74 % Russell 1000 ® 27.76 % 10.69 % 9.23 % S&P 500 ® (Broad-based Index) 36.35 % 15.98 % 13.38 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares. |
| Updated Performance Information Location [Text Block] | Please visit arielinvestments.com/performance |
| Net Assets | $ 67,610,270 |
| Holdings Count | Holding | 28 |
| Advisory Fees Paid, Amount | $ 325,225 |
| Investment Company, Portfolio Turnover | 19% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net assets $ Total number of portfolio holdings 28 Total advisory fees paid $ Portfolio turnover rate as of the end of the reporting period 19 % |
| Holdings [Text Block] | Top Ten Holdings Mohawk Industries, Inc. 6.66 % Oracle Corporation 6.60 % Snap-on, Inc. 5.94 % Goldman Sachs Group, Inc. 5.88 % BOK Financial Corporation 5.77 % Lockheed Martin Corporation 5.51 % Bank of America Corporation 4.74 % PHINIA, Inc. 4.57 % Resideo Technologies, Inc. 4.51 % J.M. Smucker Company 4.25 % Industry Allocation |
| Largest Holdings [Text Block] | Top Ten Holdings Mohawk Industries, Inc. 6.66 % Oracle Corporation 6.60 % Snap-on, Inc. 5.94 % Goldman Sachs Group, Inc. 5.88 % BOK Financial Corporation 5.77 % Lockheed Martin Corporation 5.51 % Bank of America Corporation 4.74 % PHINIA, Inc. 4.57 % Resideo Technologies, Inc. 4.51 % J.M. Smucker Company 4.25 % |
| Ariel Focus Fund (Institutional Class) | |
| Shareholder Report [Line Items] | |
| Fund Name | Ariel Focus Fund |
| Class Name | Institutional Class |
| Trading Symbol | AFOYX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Ariel Focus Fund (the “Fund”) for the period from 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 arielinvestments.com/fundreports |
| Additional Information Phone Number | 800.292.7435 |
| Additional Information Website | arielinvestments.com/fundreports |
| Expenses [Text Block] | Fund Expenses for the Last 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 Ariel Focus Fund (Institutional Class) $ 0.75 % |
| Expenses Paid, Amount | $ 85 |
| Expense Ratio, Percent | 0.75% |
| Factors Affecting Performance [Text Block] | Management's Discussion of Fund Performance TOP PERFORMANCE CONTRIBUTORS Ariel Focus Fund Institutional Class advanced +27.93% over the twelve-month period ended September 30, 2024, trailing the +27.76% return posted by the Russell 1000 Value Index and the +36.35% gain of the S&P 500 Index. Several stocks in the portfolio had strong returns. Manufacturer and distributor of medical devices specializing in spine and dental products, ZimVie, Inc. (ZIMV) margin Manufacturer and distributor of floorcovering products, Mohawk Industries, Inc. (MHK) TOP PERFORMANCE DETRACTORS Oil and natural gas explorer, APA Corporation (APA) Producer and marketer of crop nutrients, Mosaic Co. (MOS) management’s |
| Performance Past Does Not Indicate Future [Text] | Performance data quoted represents past performance and does not guarantee future results. |
| Line Graph [Table Text Block] | Growth of $1,000,000 |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1-Year 5-Year 10-Year Ariel Focus Fund (Institutional Class) 27.93 % 9.60 % 7.00 % Russell 1000 ® 27.76 % 10.69 % 9.23 % S&P 500 ® (Broad-based Index) 36.35 % 15.98 % 13.38 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares. |
| Updated Performance Information Location [Text Block] | Please arielinvestments.com/performance |
| Net Assets | $ 67,610,270 |
| Holdings Count | Holding | 28 |
| Advisory Fees Paid, Amount | $ 325,225 |
| Investment Company, Portfolio Turnover | 19% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net assets $ Total portfolio 28 Total advisory fees paid $ Portfolio turnover end 19 % |
| Holdings [Text Block] | Graphical Representation of Holdings (% of Net Assets) Top Ten Holdings Mohawk Industries, Inc. 6.66 % Oracle Corporation 6.60 % Snap-on, Inc. 5.94 % Goldman Sachs Group, Inc. 5.88 % BOK Financial Corporation 5.77 % Lockheed Martin Corporation 5.51 % Bank of America Corporation 4.74 % PHINIA, Inc. 4.57 % Resideo Technologies, Inc. 4.51 % J.M. Smucker Company 4.25 % Industry Allocation |
| Largest Holdings [Text Block] | Top Ten Holdings Mohawk Industries, Inc. 6.66 % Oracle Corporation 6.60 % Snap-on, Inc. 5.94 % Goldman Sachs Group, Inc. 5.88 % BOK Financial Corporation 5.77 % Lockheed Martin Corporation 5.51 % Bank of America Corporation 4.74 % PHINIA, Inc. 4.57 % Resideo Technologies, Inc. 4.51 % J.M. Smucker Company 4.25 % |
| Ariel International Fund (Investor Class) | |
| Shareholder Report [Line Items] | |
| Fund Name | Ariel International Fund |
| Class Name | Investor Class |
| Trading Symbol | AINTX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Ariel International Fund (the “Fund”) for the period from 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 arielinvestments.com/fundreports |
| Additional Information Phone Number | 800.292.7435 |
| Additional Information Website | arielinvestments.com/fundreports |
| Expenses [Text Block] | Fund Expenses for the Last 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 Ariel International Fund (Investor Class) $ 1.17 % |
| Expenses Paid, Amount | $ 128 |
| Expense Ratio, Percent | 1.17% |
| Factors Affecting Performance [Text Block] | Management’s Discussion of Fund Performance TOP PERFORMANCE CONTRIBUTORS Ariel International Fund Investor Class Several stocks in the portfolio had strong returns. German mobile telecommunications company, Telefónica Deutschland Holdings AG China-based E-commerce company, JD.com, Inc. TOP PERFORMANCE DETRACTORS Shares of multinational automotive manufacturing company, Stellantis N.V. (STLA) China’s internet search and online community leader, Baidu, Inc. |
| Performance Past Does Not Indicate Future [Text] | Performance data quoted represents past performance and does not guarantee future results. |
| Line Graph [Table Text Block] | Growth of $10,000 |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1-Year 5-Year 10-Year Ariel International Fund (Investor Class) 19.60 % 4.83 % 3.71 % MSCI EAFE Net Index (Broad-based Index) 24.77 % 8.20 % 5.71 % MSCI ACWI ex-US Net Index 25.35 % 7.59 % 5.22 % MSCI EAFE Value Net Index 23.14 % 8.27 % 4.56 % MSCI ACWI ex-US Value Net Index 24.04 % 7.79 % 4.28 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares. |
| Updated Performance Information Location [Text Block] | Please visit arielinvestments.com/performance |
| Net Assets | $ 240,844,787 |
| Holdings Count | Holding | 55 |
| Advisory Fees Paid, Amount | $ 2,348,174 |
| Investment Company, Portfolio Turnover | 69% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net assets $ Total number of portfolio holdings 55 Total advisory fees paid $ Portfolio turnover rate as of the end of the reporting period 69 % |
| Holdings [Text Block] | Graphical Representation of Holdings (% of Net Assets) Top Ten Holdings Michelin (CGDE) 6.48 % Check Point Software Technologies, Ltd. 5.80 % Sanofi 5.51 % Bandai Namco Holdings, Inc. 4.56 % Fresenius Medical Care AG & Company KGaA 4.39 % Siemens AG 4.30 % KBC Group NV 4.16 % AXA SA 4.12 % Endesa SA 3.69 % BNP Paribas SA 3.39 % Sector Allocation Consumer Discretionary 23.79 % Financials 21.74 % Health Care 12.56 % Information Technology 12.10 % Industrials 9.61 % Utilities 9.27 % Consumer Staples 4.89 % Other 4.26 % Geographic Allocation |
| Largest Holdings [Text Block] | Top Ten Holdings Michelin (CGDE) 6.48 % Check Point Software Technologies, Ltd. 5.80 % Sanofi 5.51 % Bandai Namco Holdings, Inc. 4.56 % Fresenius Medical Care AG & Company KGaA 4.39 % Siemens AG 4.30 % KBC Group NV 4.16 % AXA SA 4.12 % Endesa SA 3.69 % BNP Paribas SA 3.39 % |
| Ariel International Fund (Institutional Class) | |
| Shareholder Report [Line Items] | |
| Fund Name | Ariel International Fund |
| Class Name | Institutional Class |
| Trading Symbol | AINIX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find additional information about the Fund at arielinvestments.com/fundreports |
| Additional Information Phone Number | 800.292.7435 |
| Additional Information Website | arielinvestments.com/fundreports |
| Expenses [Text Block] | Fund Expenses for the Last 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 Ariel International Fund (Institutional Class) $ 0.91 % |
| Expenses Paid, Amount | $ 100 |
| Expense Ratio, Percent | 0.91% |
| Factors Affecting Performance [Text Block] | Management’s Discussion of Fund Performance TOP PERFORMANCE CONTRIBUTORS Ariel International Fund Institutional Class advanced +19.86% over the trailing one-year period, trailing both the MSCI EAFE and MSCI ACWI ex-US indices, which returned +24.77% and +25.35%, respectively. Ariel International Fund also lagged both the MSCI EAFE Value Index and the MSCI ACWI ex-US Value Index, which returned +23.14% and +24.04%, respectively. Several stocks in the portfolio had strong returns. German mobile telecommunications company, Telefónica Deutschland Holdings AG China-based E-commerce company, JD.com, Inc. TOP PERFORMANCE DETRACTORS Shares of multinational automotive manufacturing company, Stellantis N.V. (STLA) China’s internet search and online community leader, Baidu, Inc. year optionality |
| Performance Past Does Not Indicate Future [Text] | Performance data quoted represents past performance and does not guarantee future results. |
| Line Graph [Table Text Block] | Growth of $1,000,000 |
| Average Annual Return [Table Text Block] | Average Annual Returns 1-Year 5-Year 10-Year Ariel International Fund (Institutional Class) 19.86 % 5.08 % 3.97 % (Broad-based Index) 24.77 % 8.20 % 5.71 % MSCI ACWI ex-US Net Index 25.35 % 7.59 % 5.22 % MSCI EAFE Value Net Index 23.14 % 8.27 % 4.56 % MSCI ACWI ex-US Value Net Index 24.04 % 7.79 % 4.28 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares. |
| Updated Performance Information Location [Text Block] | Please visit arielinvestments.com/performance |
| Net Assets | $ 240,844,787 |
| Holdings Count | Holding | 55 |
| Advisory Fees Paid, Amount | $ 2,348,174 |
| Investment Company, Portfolio Turnover | 69% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net assets $ Total number of portfolio holdings 55 Total advisory fees paid $ Portfolio turnover rate as of the end of the reporting period 69 % |
| Holdings [Text Block] | Graphical Representation of Holdings (% of Net Assets) Top Ten Holdings Michelin (CGDE) 6.48 % Check Point Software Technologies, Ltd. 5.80 % Sanofi 5.51 % Bandai Namco Holdings, Inc. 4.56 % Fresenius Medical Care AG & Company KGaA 4.39 % Siemens AG 4.30 % KBC Group NV 4.16 % AXA SA 4.12 % Endesa SA 3.69 % BNP Paribas SA 3.39 % Sector Allocation Consumer Discretionary 23.79 % Financials 21.74 % Health Care 12.56 % Information Technology 12.10 % Industrials 9.61 % Utilities 9.27 % Consumer Staples 4.89 % Other 4.26 % Geographic Allocation |
| Largest Holdings [Text Block] | Top Ten Holdings Michelin (CGDE) 6.48 % Check Point Software Technologies, Ltd. 5.80 % Sanofi 5.51 % Bandai Namco Holdings, Inc. 4.56 % Fresenius Medical Care AG & Company KGaA 4.39 % Siemens AG 4.30 % KBC Group NV 4.16 % AXA SA 4.12 % Endesa SA 3.69 % BNP Paribas SA 3.39 % |
| Ariel Global Fund (Investor Class) | |
| Shareholder Report [Line Items] | |
| Fund Name | Ariel Global Fund |
| Class Name | Investor Class |
| Trading Symbol | AGLOX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Ariel Global Fund (the “Fund”) for the period from 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 arielinvestments.com/fundreports |
| Additional Information Phone Number | 800.292.7435 |
| Additional Information Website | arielinvestments.com/fundreports |
| Expenses [Text Block] | Fund Expenses for the Last 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 Ariel Global Fund (Investor Class) $ 1.14 % |
| Expenses Paid, Amount | $ 125 |
| Expense Ratio, Percent | 1.14% |
| Factors Affecting Performance [Text Block] | Management’s Discussion of Fund Performance TOP PERFORMANCE CONTRIBUTORS Ariel Global Fund Investor Class Several stocks in the portfolio had strong returns. China-based E-commerce company, JD.com, Inc. Leading provider of dialysis services, DaVita, Inc. TOP PERFORMANCE DETRACTORS China’s internet search and online community leader, Baidu, Inc. Shares of semiconductor chip manufacturer, Intel Corporation (INTC) |
| Performance Past Does Not Indicate Future [Text] | Performance data quoted represents past performance and does not guarantee future results. |
| Line Graph [Table Text Block] | Growth of $10,000 |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1-Year 5-Year 10-Year Ariel Global Fund (Investor Class) 19.89 % 8.56 % 6.51 % MSCI ACWI Index (Broad-based Index) 31.76 % 12.19 % 9.39 % MSCI ACWI Value Index 26.89 % 9.04 % 6.65 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares. |
| Updated Performance Information Location [Text Block] | Please visit arielinvestments.com/performance |
| Net Assets | $ 57,540,291 |
| Holdings Count | Holding | 56 |
| Advisory Fees Paid, Amount | $ 340,392 |
| Investment Company, Portfolio Turnover | 78% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net assets $ Total number of portfolio holdings 56 Total advisory fees paid $ Portfolio turnover rate as of the end of the reporting period 78 % |
| Holdings [Text Block] | Graphical Representation of Holdings (% of Net Assets) Top Ten Holdings Check Point Software Technologies, Ltd. 5.48 % Microsoft Corporation 5.29 % Michelin (CGDE) 4.76 % JD.com, Inc. 4.58 % Sanofi 3.63 % Verizon Communications, Inc. 3.53 % Fresenius Medical Care AG & Company KGaA 3.16 % Taiwan Semiconductor Manufacturing Company, Ltd. 2.89 % NetApp, Inc. 2.83 % Allstate Corporation 2.82 % Sector Allocation Information Technology 22.84 % Consumer Discretionary 21.07 % Financials 20.61 % Health Care 14.75 % Industrials 6.66 % Communication Services 5.87 % Utilities 3.91 % Other 3.33 % Geographic Allocation |
| Largest Holdings [Text Block] | Top Ten Holdings Check Point Software Technologies, Ltd. 5.48 % Microsoft Corporation 5.29 % Michelin (CGDE) 4.76 % JD.com, Inc. 4.58 % Sanofi 3.63 % Verizon Communications, Inc. 3.53 % Fresenius Medical Care AG & Company KGaA 3.16 % Taiwan Semiconductor Manufacturing Company, Ltd. 2.89 % NetApp, Inc. 2.83 % Allstate Corporation 2.82 % |
| Ariel Global Fund (Institutional Class) | |
| Shareholder Report [Line Items] | |
| Fund Name | Ariel Global Fund |
| Class Name | Institutional Class |
| Trading Symbol | AGLYX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Ariel Global Fund (the “Fund”) for the period from 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 arielinvestments.com/fundreports |
| Additional Information Phone Number | 800.292.7435 |
| Additional Information Website | arielinvestments.com/fundreports |
| Expenses [Text Block] | Fund Expenses for the Last 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 Ariel Global Fund (Institutional Class) $ 0.89 % |
| Expenses Paid, Amount | $ 98 |
| Expense Ratio, Percent | 0.89% |
| Factors Affecting Performance [Text Block] | Several stocks in the portfolio had strong returns. China-based E-commerce company, JD.com, Inc. Leading provider of dialysis services, DaVita, Inc. Shares of semiconductor chip manufacturer, Intel Corporation (INTC) sine ss. |
| Performance Past Does Not Indicate Future [Text] | Performance data quoted represents past performance and does not guarantee future results. |
| Line Graph [Table Text Block] | Growth of $1,000 ,000 |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1-Year 5-Year 10-Year Ariel Global Fund (Institutional Class) 20.14 % 8.83 % 6.77 % MSCI ACWI Index (Broad-based Index) 31.76 % 12.19 % 9.39 % MSCI ACWI Value Index 26.89 % 9.04 % 6.65 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or redemption of Fund shares. |
| Updated Performance Information Location [Text Block] | Please visit arielinvestments.com/performance |
| Net Assets | $ 57,540,291 |
| Holdings Count | Holding | 56 |
| Advisory Fees Paid, Amount | $ 340,392 |
| Investment Company, Portfolio Turnover | 78% |
| Additional Fund Statistics [Text Block] | Net assets $ Total number of portfolio holdings 56 Total advisory fees paid $ Portfolio turnover rate as of the end of the reporting period 78 % |
| Holdings [Text Block] | Graphical Representation of Holdings (% of Net As et s Top Ten Hold ings Check Point Software Technologies, Ltd. 5.48 % Microsoft Corporation 5.29 % Michelin (CGDE) 4.76 % JD.com, Inc. 4.58 % Sanofi 3.63 % Verizon Communications, Inc. 3.53 % Fresenius Medical Care AG & Company KGaA 3.16 % Taiwan Semiconductor Manufacturing Company, Ltd. 2.89 % NetApp, Inc. 2.83 % Allstate Corporation 2.82 % Sector Allocation Information Technology 22.84 % Consumer Discretionary 21.07 % Financials 20.61 % Health Care 14.75 % Industrials 6.66 % Communication Services 5.87 % Utilities 3.91 % Other 3.33 % Geographic Allocation |
| Largest Holdings [Text Block] | Top Ten Hold ings Check Point Software Technologies, Ltd. 5.48 % Microsoft Corporation 5.29 % Michelin (CGDE) 4.76 % JD.com, Inc. 4.58 % Sanofi 3.63 % Verizon Communications, Inc. 3.53 % Fresenius Medical Care AG & Company KGaA 3.16 % Taiwan Semiconductor Manufacturing Company, Ltd. 2.89 % NetApp, Inc. 2.83 % Allstate Corporation 2.82 % |
| Shareholder Report, Line Graph (Details) - USD ($) | 12 Months Ended | ||||||||||
| Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2014 | |
| Ariel Global Fund (Institutional Class) | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Ariel Global Fund (Institutional Class) | ||||||||||
| Account Value | $ 1,926,200 | $ 1,603,300 | $ 1,382,300 | $ 1,532,700 | $ 1,318,300 | $ 1,261,800 | $ 1,303,300 | $ 1,210,900 | $ 1,070,600 | $ 951,200 | $ 1,000,000 |
| Ariel Global Fund (Investor Class) | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Ariel Global Fund (Investor Class) | ||||||||||
| Account Value | $ 18,792 | 15,674 | 13,554 | 15,058 | 12,991 | 12,464 | 12,905 | 12,018 | 10,648 | 9,485 | 10,000 |
| Ariel International Fund (Institutional Class) | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Ariel International Fund (Institutional Class) | ||||||||||
| Account Value | $ 1,475,700 | 1,231,300 | 1,051,000 | 1,305,600 | 1,195,000 | 1,151,900 | 1,177,000 | 1,178,900 | 1,073,700 | 985,200 | 1,000,000 |
| Ariel International Fund (Investor Class) | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Ariel International Fund (Investor Class) | ||||||||||
| Account Value | $ 14,392 | 12,033 | 10,304 | 12,832 | 11,772 | 11,367 | 11,645 | 11,702 | 10,682 | 9,821 | 10,000 |
| Ariel Focus Fund (Institutional Class) | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Ariel Focus Fund (Institutional Class) | ||||||||||
| Account Value | $ 1,967,700 | 1,538,100 | 1,423,400 | 1,669,000 | 1,185,900 | 1,244,300 | 1,331,600 | 1,162,500 | 990,200 | 862,300 | 1,000,000 |
| Ariel Focus Fund (Investor Class) | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Ariel Focus Fund (Investor Class) | ||||||||||
| Account Value | $ 19,197 | 15,053 | 13,959 | 16,406 | 11,685 | 12,290 | 13,195 | 11,542 | 9,857 | 8,602 | 10,000 |
| Ariel Appreciation Fund - Institutional Class | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Ariel Appreciation Fund (Institutional Class) | ||||||||||
| Account Value | $ 2,020,100 | 1,702,700 | 1,476,500 | 1,805,800 | 1,239,100 | 1,313,300 | 1,366,600 | 1,240,000 | 1,099,500 | 964,500 | 1,000,000 |
| Ariel Appreciation Fund (Investor Class) | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Ariel Appreciation Fund (Investor Class) | ||||||||||
| Account Value | $ 19,578 | 16,548 | 14,396 | 17,664 | 12,159 | 12,925 | 13,495 | 12,279 | 10,924 | 9,611 | 10,000 |
| Ariel Fund (Institutional Class) | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Ariel Fund (Institutional Class) | ||||||||||
| Account Value | $ 2,346,800 | 1,833,300 | 1,595,400 | 2,122,100 | 1,277,400 | 1,399,900 | 1,503,000 | 1,303,600 | 1,122,700 | 968,900 | 1,000,000 |
| Ariel Fund (Investor Class) | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Ariel Fund (Investor Class) | ||||||||||
| Account Value | $ 22,762 | 17,835 | 15,569 | 20,773 | 12,544 | 13,789 | 14,855 | 12,921 | 11,162 | 9,660 | 10,000 |
| MSCI ACWI Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | MSCI ACWI Index | ||||||||||
| Account Value | $ 24,526 | 18,614 | 15,409 | 19,422 | 15,240 | 13,799 | 13,612 | 12,400 | 10,451 | 9,334 | 10,000 |
| MSCI EAFE Net Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | MSCI EAFE Net Index | ||||||||||
| Account Value | $ 1,741,900 | 1,396,100 | 1,111,100 | 1,484,100 | 1,180,400 | 1,174,600 | 1,190,500 | 1,158,800 | 972,900 | 913,400 | 1,000,000 |
| Standard & Poor's 500 Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | S&P 500® Index | ||||||||||
| Account Value | $ 35,098 | 25,741 | 21,165 | 25,040 | 19,260 | 16,727 | 16,044 | 13,607 | 11,472 | 9,939 | 10,000 |
| MSCI ACWI Value Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | MSCI ACWI Value Index | ||||||||||
| Account Value | $ 19,046 | 15,010 | 12,832 | 14,915 | 11,363 | 12,354 | 12,353 | 11,789 | 9,977 | 8,921 | 10,000 |
| MSCI ACWI ex-US Net Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | MSCI ACWI ex-US Net Index | ||||||||||
| Account Value | $ 1,663,000 | 1,326,700 | 1,102,000 | 1,472,600 | 1,188,400 | 1,153,700 | 1,168,100 | 1,147,900 | 959,700 | 878,400 | 1,000,000 |
| MSCI EAFE Value Net Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | MSCI EAFE Value Net Index | ||||||||||
| Account Value | $ 1,562,500 | 1,268,900 | 964,900 | 1,208,500 | 925,000 | 1,050,300 | 1,104,600 | 1,108,700 | 904,700 | 874,000 | 1,000,000 |
| MSCI ACWI ex-US Value Net Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | MSCI ACWI ex-US Value Net Index | ||||||||||
| Account Value | $ 1,520,700 | 1,225,900 | 979,400 | 1,224,500 | 932,000 | 1,045,300 | 1,094,600 | 1,090,100 | 896,800 | 838,400 | 1,000,000 |
| Russell 1000 Value Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Russell 1000® Value Index | ||||||||||
| Account Value | $ 24,183 | 18,929 | 16,540 | 18,661 | 13,822 | 14,553 | 13,993 | 12,785 | 11,105 | 9,558 | 10,000 |
| Russell Midcap Value Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Russell Midcap® Value Index | ||||||||||
| Account Value | $ 23,528 | 18,237 | 16,423 | 18,998 | 13,342 | 14,392 | 14,165 | 13,019 | 11,484 | 9,793 | 10,000 |
| Russell Midcap Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Russell Midcap® Index | ||||||||||
| Account Value | $ 26,396 | 20,410 | 17,991 | 22,320 | 16,161 | 15,458 | 14,980 | 13,143 | 11,397 | 9,975 | 10,000 |
| Russell 2500 Value Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Russell 2500TM Value Index | ||||||||||
| Account Value | $ 22,554 | 17,817 | 16,002 | 18,904 | 12,244 | 14,013 | 14,651 | 13,289 | 11,481 | 9,756 | 10,000 |
| Russell 2500 Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Russell 2500TM Index | ||||||||||
| Account Value | $ 24,773 | $ 19,635 | $ 17,644 | $ 22,364 | $ 15,421 | $ 15,086 | $ 15,722 | $ 13,531 | $ 11,487 | $ 10,038 | $ 10,000 |
| Shareholder Report, Average Annual Return (Details) | 12 Months Ended | 60 Months Ended | 120 Months Ended |
| Sep. 30, 2024 | Sep. 30, 2024 | Sep. 30, 2024 | |
| Ariel Global Fund (Institutional Class) | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Ariel Global Fund (Institutional Class) | ||
| Average Annual Return, Percent | 20.14% | 8.83% | 6.77% |
| Ariel Global Fund (Investor Class) | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Ariel Global Fund (Investor Class) | ||
| Average Annual Return, Percent | 19.89% | 8.56% | 6.51% |
| Ariel International Fund (Institutional Class) | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Ariel International Fund (Institutional Class) | ||
| Average Annual Return, Percent | 19.86% | 5.08% | 3.97% |
| Ariel International Fund (Investor Class) | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Ariel International Fund (Investor Class) | ||
| Average Annual Return, Percent | 19.60% | 4.83% | 3.71% |
| Ariel Focus Fund (Institutional Class) | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Ariel Focus Fund (Institutional Class) | ||
| Average Annual Return, Percent | 27.93% | 9.60% | 7% |
| Ariel Focus Fund (Investor Class) | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Ariel Focus Fund (Investor Class) | ||
| Average Annual Return, Percent | 27.54% | 9.33% | 6.74% |
| Ariel Appreciation Fund - Institutional Class | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Ariel Appreciation Fund (Institutional Class) | ||
| Average Annual Return, Percent | 18.64% | 8.99% | 7.28% |
| Ariel Appreciation Fund (Investor Class) | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Ariel Appreciation Fund (Investor Class) | ||
| Average Annual Return, Percent | 18.31% | 8.66% | 6.95% |
| Ariel Fund (Institutional Class) | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Ariel Fund (Institutional Class) | ||
| Average Annual Return, Percent | 28.01% | 10.89% | 8.91% |
| Ariel Fund (Investor Class) | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Ariel Fund (Investor Class) | ||
| Average Annual Return, Percent | 27.63% | 10.54% | 8.57% |
| MSCI ACWI Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | MSCI ACWI Index | ||
| Average Annual Return, Percent | 31.76% | 12.19% | 9.39% |
| MSCI ACWI Index (Broad-based Index) [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | MSCI ACWI Index (Broad-based Index) | ||
| Average Annual Return, Percent | 31.76% | 12.19% | 9.39% |
| MSCI EAFE Net Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | MSCI EAFE Net Index | ||
| Average Annual Return, Percent | 24.77% | 8.20% | 5.71% |
| Standard & Poor's 500 Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | S&P 500® Index | ||
| Average Annual Return, Percent | 36.35% | 15.98% | 13.38% |
| MSCI ACWI Value Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | MSCI ACWI Value Index | ||
| Average Annual Return, Percent | 26.89% | 9.04% | 6.65% |
| MSCI ACWI ex-US Net Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | MSCI ACWI ex-US Net Index | ||
| Average Annual Return, Percent | 25.35% | 7.59% | 5.22% |
| MSCI EAFE Value Net Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | MSCI EAFE Value Net Index | ||
| Average Annual Return, Percent | 23.14% | 8.27% | 4.56% |
| MSCI ACWI ex-US Value Net Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | MSCI ACWI ex-US Value Net Index | ||
| Average Annual Return, Percent | 24.04% | 7.79% | 4.28% |
| Russell 1000 Value Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Russell 1000® Value Index | ||
| Average Annual Return, Percent | 27.76% | 10.69% | 9.23% |
| Russell Midcap Value Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Russell Midcap® Value Index | ||
| Average Annual Return, Percent | 29.01% | 10.33% | 8.93% |
| Russell Midcap Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Russell Midcap® Index | ||
| Average Annual Return, Percent | 29.33% | 11.30% | 10.19% |
| Russell 2500 Value Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Russell 2500TM Value Index | ||
| Average Annual Return, Percent | 26.59% | 9.99% | 8.47% |
| Russell 2500 Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Russell 2500TM Index | ||
| Average Annual Return, Percent | 26.17% | 10.43% | 9.50% |
| Shareholder Report, Holdings (Details) | Sep. 30, 2024 |
| Ariel Fund (Investor Class) | Mohawk Industries, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.62% |
| Ariel Fund (Investor Class) | Madison Square Garden Entertainment Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.30% |
| Ariel Fund (Investor Class) | Adtalem Global Education, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| Ariel Fund (Investor Class) | Northern Trust Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.69% |
| Ariel Fund (Investor Class) | Affiliated Managers Group, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.66% |
| Ariel Fund (Investor Class) | Lazard, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.64% |
| Ariel Fund (Investor Class) | Royal Caribbean Cruises, Ltd. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| Ariel Fund (Investor Class) | Boyd Gaming Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.59% |
| Ariel Fund (Investor Class) | J.M. Smucker Company [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.53% |
| Ariel Fund (Investor Class) | Jones Lang LaSalle, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.48% |
| Ariel Fund (Investor Class) | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 37.14% |
| Ariel Fund (Investor Class) | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.72% |
| Ariel Fund (Investor Class) | Financial Services Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.06% |
| Ariel Fund (Investor Class) | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.22% |
| Ariel Fund (Investor Class) | Consumer Staples Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.53% |
| Ariel Fund (Investor Class) | Real Estate Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.48% |
| Ariel Fund (Investor Class) | Energy Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.33% |
| Ariel Fund (Investor Class) | Short-Term Investment [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.22% |
| Ariel Fund (Institutional Class) | Mohawk Industries, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.62% |
| Ariel Fund (Institutional Class) | Madison Square Garden Entertainment Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.30% |
| Ariel Fund (Institutional Class) | Adtalem Global Education, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.70% |
| Ariel Fund (Institutional Class) | Northern Trust Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.69% |
| Ariel Fund (Institutional Class) | Affiliated Managers Group, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.66% |
| Ariel Fund (Institutional Class) | Lazard, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.64% |
| Ariel Fund (Institutional Class) | Royal Caribbean Cruises, Ltd. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| Ariel Fund (Institutional Class) | Boyd Gaming Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.59% |
| Ariel Fund (Institutional Class) | J.M. Smucker Company [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.53% |
| Ariel Fund (Institutional Class) | Jones Lang LaSalle, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.48% |
| Ariel Fund (Institutional Class) | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 37.14% |
| Ariel Fund (Institutional Class) | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.72% |
| Ariel Fund (Institutional Class) | Financial Services Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.06% |
| Ariel Fund (Institutional Class) | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.22% |
| Ariel Fund (Institutional Class) | Consumer Staples Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.53% |
| Ariel Fund (Institutional Class) | Real Estate Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.48% |
| Ariel Fund (Institutional Class) | Energy Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.33% |
| Ariel Fund (Institutional Class) | Short-Term Investment [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.22% |
| Ariel Appreciation Fund (Investor Class) | Northern Trust Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.14% |
| Ariel Appreciation Fund (Investor Class) | Lazard, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.05% |
| Ariel Appreciation Fund (Investor Class) | Mattel, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.76% |
| Ariel Appreciation Fund (Investor Class) | Goldman Sachs Group, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.61% |
| Ariel Appreciation Fund (Investor Class) | Generac Holdings, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.26% |
| Ariel Appreciation Fund (Investor Class) | Stanley Black & Decker, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.13% |
| Ariel Appreciation Fund (Investor Class) | Interpublic Group of Companies, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.08% |
| Ariel Appreciation Fund (Investor Class) | CarMax, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.96% |
| Ariel Appreciation Fund (Investor Class) | Core Laboratories, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.83% |
| Ariel Appreciation Fund (Investor Class) | Charles River Laboratories International, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.81% |
| Ariel Appreciation Fund (Investor Class) | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 25.90% |
| Ariel Appreciation Fund (Investor Class) | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.39% |
| Ariel Appreciation Fund (Investor Class) | Financial Services Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 24.96% |
| Ariel Appreciation Fund (Investor Class) | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.97% |
| Ariel Appreciation Fund (Investor Class) | Consumer Staples Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.71% |
| Ariel Appreciation Fund (Investor Class) | Real Estate Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.11% |
| Ariel Appreciation Fund (Investor Class) | Energy Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.95% |
| Ariel Appreciation Fund (Investor Class) | Short-Term Investment [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.01% |
| Ariel Appreciation Fund - Institutional Class | Northern Trust Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.14% |
| Ariel Appreciation Fund - Institutional Class | Lazard, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.05% |
| Ariel Appreciation Fund - Institutional Class | Mattel, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.76% |
| Ariel Appreciation Fund - Institutional Class | Goldman Sachs Group, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.61% |
| Ariel Appreciation Fund - Institutional Class | Generac Holdings, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.26% |
| Ariel Appreciation Fund - Institutional Class | Stanley Black & Decker, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.13% |
| Ariel Appreciation Fund - Institutional Class | Interpublic Group of Companies, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.08% |
| Ariel Appreciation Fund - Institutional Class | CarMax, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.96% |
| Ariel Appreciation Fund - Institutional Class | Core Laboratories, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.83% |
| Ariel Appreciation Fund - Institutional Class | Charles River Laboratories International, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.81% |
| Ariel Appreciation Fund - Institutional Class | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 25.90% |
| Ariel Appreciation Fund - Institutional Class | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.39% |
| Ariel Appreciation Fund - Institutional Class | Financial Services Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 24.96% |
| Ariel Appreciation Fund - Institutional Class | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.97% |
| Ariel Appreciation Fund - Institutional Class | Consumer Staples Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.71% |
| Ariel Appreciation Fund - Institutional Class | Real Estate Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.11% |
| Ariel Appreciation Fund - Institutional Class | Energy Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.95% |
| Ariel Appreciation Fund - Institutional Class | Short-Term Investment [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.01% |
| Ariel Focus Fund (Investor Class) | Mohawk Industries, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.66% |
| Ariel Focus Fund (Investor Class) | J.M. Smucker Company [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.25% |
| Ariel Focus Fund (Investor Class) | Goldman Sachs Group, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.88% |
| Ariel Focus Fund (Investor Class) | Oracle Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.60% |
| Ariel Focus Fund (Investor Class) | Snap-on, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.94% |
| Ariel Focus Fund (Investor Class) | BOK Financial Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.77% |
| Ariel Focus Fund (Investor Class) | Lockheed Martin Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.51% |
| Ariel Focus Fund (Investor Class) | Bank of America Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.74% |
| Ariel Focus Fund (Investor Class) | PHINIA, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.57% |
| Ariel Focus Fund (Investor Class) | Resideo Technologies, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.51% |
| Ariel Focus Fund (Investor Class) | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.61% |
| Ariel Focus Fund (Investor Class) | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 23.01% |
| Ariel Focus Fund (Investor Class) | Financial Services Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 24.86% |
| Ariel Focus Fund (Investor Class) | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.96% |
| Ariel Focus Fund (Investor Class) | Consumer Staples Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.25% |
| Ariel Focus Fund (Investor Class) | Energy Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.35% |
| Ariel Focus Fund (Investor Class) | Short-Term Investment [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.09% |
| Ariel Focus Fund (Investor Class) | Technology Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.60% |
| Ariel Focus Fund (Investor Class) | Materials Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.27% |
| Ariel Focus Fund (Institutional Class) | Mohawk Industries, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.66% |
| Ariel Focus Fund (Institutional Class) | J.M. Smucker Company [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.25% |
| Ariel Focus Fund (Institutional Class) | Goldman Sachs Group, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.88% |
| Ariel Focus Fund (Institutional Class) | Oracle Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.60% |
| Ariel Focus Fund (Institutional Class) | Snap-on, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.94% |
| Ariel Focus Fund (Institutional Class) | BOK Financial Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.77% |
| Ariel Focus Fund (Institutional Class) | Lockheed Martin Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.51% |
| Ariel Focus Fund (Institutional Class) | Bank of America Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.74% |
| Ariel Focus Fund (Institutional Class) | PHINIA, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.57% |
| Ariel Focus Fund (Institutional Class) | Resideo Technologies, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.51% |
| Ariel Focus Fund (Institutional Class) | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.61% |
| Ariel Focus Fund (Institutional Class) | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 23.01% |
| Ariel Focus Fund (Institutional Class) | Financial Services Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 24.86% |
| Ariel Focus Fund (Institutional Class) | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.96% |
| Ariel Focus Fund (Institutional Class) | Consumer Staples Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.25% |
| Ariel Focus Fund (Institutional Class) | Energy Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.35% |
| Ariel Focus Fund (Institutional Class) | Short-Term Investment [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.09% |
| Ariel Focus Fund (Institutional Class) | Technology Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.60% |
| Ariel Focus Fund (Institutional Class) | Basic Materials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.27% |
| Ariel International Fund (Investor Class) | Michelin (CGDE) [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.48% |
| Ariel International Fund (Investor Class) | Check Point Software Technologies, Ltd. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| Ariel International Fund (Investor Class) | Sanofi [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.51% |
| Ariel International Fund (Investor Class) | Bandai Namco Holdings, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.56% |
| Ariel International Fund (Investor Class) | Fresenius Medical Care AG & Company KGaA [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.39% |
| Ariel International Fund (Investor Class) | Siemens AG [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.30% |
| Ariel International Fund (Investor Class) | KBC Group NV [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.16% |
| Ariel International Fund (Investor Class) | AXA SA [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.12% |
| Ariel International Fund (Investor Class) | Endesa SA [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.69% |
| Ariel International Fund (Investor Class) | BNP Paribas SA [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.39% |
| Ariel International Fund (Investor Class) | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 23.79% |
| Ariel International Fund (Investor Class) | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.61% |
| Ariel International Fund (Investor Class) | Financial Services Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.74% |
| Ariel International Fund (Investor Class) | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.56% |
| Ariel International Fund (Investor Class) | Consumer Staples Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.89% |
| Ariel International Fund (Investor Class) | Information Technology Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.10% |
| Ariel International Fund (Investor Class) | Utilities Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.27% |
| Ariel International Fund (Investor Class) | Unclassified Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.26% |
| Ariel International Fund (Investor Class) | FRANCE | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.50% |
| Ariel International Fund (Investor Class) | GERMANY | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16.80% |
| Ariel International Fund (Investor Class) | JAPAN | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.10% |
| Ariel International Fund (Investor Class) | ISRAEL | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| Ariel International Fund (Investor Class) | UNITED KINGDOM | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.20% |
| Ariel International Fund (Investor Class) | ITALY | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.90% |
| Ariel International Fund (Investor Class) | SPAIN | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.40% |
| Ariel International Fund (Investor Class) | BELGIUM | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.20% |
| Ariel International Fund (Investor Class) | KOREA, REPUBLIC OF | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.20% |
| Ariel International Fund (Investor Class) | UNITED STATES | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Ariel International Fund (Investor Class) | CHINA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Ariel International Fund (Investor Class) | AUSTRIA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Ariel International Fund (Investor Class) | HONG KONG | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.60% |
| Ariel International Fund (Investor Class) | Other [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.70% |
| Ariel International Fund (Institutional Class) | Michelin (CGDE) [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.48% |
| Ariel International Fund (Institutional Class) | Check Point Software Technologies, Ltd. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| Ariel International Fund (Institutional Class) | Sanofi [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.51% |
| Ariel International Fund (Institutional Class) | Bandai Namco Holdings, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.56% |
| Ariel International Fund (Institutional Class) | Fresenius Medical Care AG & Company KGaA [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.39% |
| Ariel International Fund (Institutional Class) | Siemens AG [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.30% |
| Ariel International Fund (Institutional Class) | KBC Group NV [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.16% |
| Ariel International Fund (Institutional Class) | AXA SA [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.12% |
| Ariel International Fund (Institutional Class) | Endesa SA [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.69% |
| Ariel International Fund (Institutional Class) | BNP Paribas SA [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.39% |
| Ariel International Fund (Institutional Class) | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 23.79% |
| Ariel International Fund (Institutional Class) | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.61% |
| Ariel International Fund (Institutional Class) | Financial Services Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.74% |
| Ariel International Fund (Institutional Class) | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.56% |
| Ariel International Fund (Institutional Class) | Consumer Staples Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.89% |
| Ariel International Fund (Institutional Class) | Information Technology Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.10% |
| Ariel International Fund (Institutional Class) | Utilities Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.27% |
| Ariel International Fund (Institutional Class) | Unclassified Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.26% |
| Ariel International Fund (Institutional Class) | FRANCE | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.50% |
| Ariel International Fund (Institutional Class) | GERMANY | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16.80% |
| Ariel International Fund (Institutional Class) | JAPAN | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.10% |
| Ariel International Fund (Institutional Class) | ISRAEL | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| Ariel International Fund (Institutional Class) | UNITED KINGDOM | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.20% |
| Ariel International Fund (Institutional Class) | ITALY | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.90% |
| Ariel International Fund (Institutional Class) | SPAIN | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.40% |
| Ariel International Fund (Institutional Class) | BELGIUM | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.20% |
| Ariel International Fund (Institutional Class) | KOREA, REPUBLIC OF | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.20% |
| Ariel International Fund (Institutional Class) | UNITED STATES | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| Ariel International Fund (Institutional Class) | CHINA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.80% |
| Ariel International Fund (Institutional Class) | AUSTRIA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Ariel International Fund (Institutional Class) | HONG KONG | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.60% |
| Ariel International Fund (Institutional Class) | Other [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.70% |
| Ariel Global Fund (Investor Class) | Michelin (CGDE) [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.76% |
| Ariel Global Fund (Investor Class) | Check Point Software Technologies, Ltd. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.48% |
| Ariel Global Fund (Investor Class) | Sanofi [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.63% |
| Ariel Global Fund (Investor Class) | Fresenius Medical Care AG & Company KGaA [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.16% |
| Ariel Global Fund (Investor Class) | Microsoft Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.29% |
| Ariel Global Fund (Investor Class) | JD.com, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.58% |
| Ariel Global Fund (Investor Class) | Verizon Communications, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.53% |
| Ariel Global Fund (Investor Class) | Taiwan Semiconductor Manufacturing Company, Ltd. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.89% |
| Ariel Global Fund (Investor Class) | NetApp, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.83% |
| Ariel Global Fund (Investor Class) | Allstate Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.82% |
| Ariel Global Fund (Investor Class) | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.07% |
| Ariel Global Fund (Investor Class) | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.66% |
| Ariel Global Fund (Investor Class) | Financial Services Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.61% |
| Ariel Global Fund (Investor Class) | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.75% |
| Ariel Global Fund (Investor Class) | Information Technology Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.84% |
| Ariel Global Fund (Investor Class) | Utilities Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.91% |
| Ariel Global Fund (Investor Class) | Unclassified Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.33% |
| Ariel Global Fund (Investor Class) | Communications Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.87% |
| Ariel Global Fund (Investor Class) | FRANCE | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.10% |
| Ariel Global Fund (Investor Class) | GERMANY | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.50% |
| Ariel Global Fund (Investor Class) | JAPAN | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.10% |
| Ariel Global Fund (Investor Class) | ISRAEL | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.50% |
| Ariel Global Fund (Investor Class) | UNITED KINGDOM | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Ariel Global Fund (Investor Class) | SPAIN | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.40% |
| Ariel Global Fund (Investor Class) | BELGIUM | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Ariel Global Fund (Investor Class) | KOREA, REPUBLIC OF | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| Ariel Global Fund (Investor Class) | UNITED STATES | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 34.60% |
| Ariel Global Fund (Investor Class) | CHINA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6% |
| Ariel Global Fund (Investor Class) | Other [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.50% |
| Ariel Global Fund (Investor Class) | TAIWAN | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.50% |
| Ariel Global Fund (Institutional Class) | Michelin (CGDE) [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.76% |
| Ariel Global Fund (Institutional Class) | Check Point Software Technologies, Ltd. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.48% |
| Ariel Global Fund (Institutional Class) | Sanofi [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.63% |
| Ariel Global Fund (Institutional Class) | Fresenius Medical Care AG & Company KGaA [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.16% |
| Ariel Global Fund (Institutional Class) | Microsoft Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.29% |
| Ariel Global Fund (Institutional Class) | JD.com, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.58% |
| Ariel Global Fund (Institutional Class) | Verizon Communications, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.53% |
| Ariel Global Fund (Institutional Class) | Taiwan Semiconductor Manufacturing Company, Ltd. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.89% |
| Ariel Global Fund (Institutional Class) | NetApp, Inc. [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.83% |
| Ariel Global Fund (Institutional Class) | Allstate Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.82% |
| Ariel Global Fund (Institutional Class) | Consumer Discretionary Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.07% |
| Ariel Global Fund (Institutional Class) | Industrial Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.66% |
| Ariel Global Fund (Institutional Class) | Financial Services Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.61% |
| Ariel Global Fund (Institutional Class) | Healthcare Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.75% |
| Ariel Global Fund (Institutional Class) | Information Technology Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 22.84% |
| Ariel Global Fund (Institutional Class) | Utilities Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.91% |
| Ariel Global Fund (Institutional Class) | Communications Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.87% |
| Ariel Global Fund (Institutional Class) | Other Sector [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.33% |
| Ariel Global Fund (Institutional Class) | FRANCE | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.10% |
| Ariel Global Fund (Institutional Class) | GERMANY | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.50% |
| Ariel Global Fund (Institutional Class) | JAPAN | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.10% |
| Ariel Global Fund (Institutional Class) | ISRAEL | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.50% |
| Ariel Global Fund (Institutional Class) | UNITED KINGDOM | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Ariel Global Fund (Institutional Class) | SPAIN | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.40% |
| Ariel Global Fund (Institutional Class) | BELGIUM | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Ariel Global Fund (Institutional Class) | KOREA, REPUBLIC OF | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.60% |
| Ariel Global Fund (Institutional Class) | UNITED STATES | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 34.60% |
| Ariel Global Fund (Institutional Class) | CHINA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6% |
| Ariel Global Fund (Institutional Class) | Other [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.50% |
| Ariel Global Fund (Institutional Class) | TAIWAN | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.50% |
