v3.26.1
Shareholder Report
 6 Months Ended
Apr. 30, 2026
USD ($)
holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name AMERICAN CENTURY MUTUAL FUNDS, INC.
Entity Central Index Key 0000100334
Entity Investment Company Type N-1A
Document Period End Date Apr. 30, 2026
Shareholder Report Annual or Semi-Annual Semi-Annual Shareholder Report
C000017045 [Member]  
Shareholder Report [Line Items]  
Fund Name Balanced Fund
Class Name Investor Class
Trading Symbol TWBIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Balanced Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Investor Class$440.88%
Expenses Paid, Amount $ 44
Expense Ratio, Percent 0.88%
Net Assets $ 906,333,994
Holdings Count | holding 539
Advisory Fees Paid, Amount $ 3,846,311
Investment Company, Portfolio Turnover 33.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Common Stocks61.1%
U.S. Treasury Securities9.8%
U.S. Government Agency Mortgage-Backed Securities8.6%
Corporate Bonds8.2%
Collateralized Mortgage Obligations4.3%
Asset-Backed Securities3.2%
Convertible Preferred Securities1.2%
Sovereign Governments and Agencies1.0%
Commercial Mortgage-Backed Securities0.5%
Preferred Securities0.4%
Municipal Securities0.3%
Exchange-Traded Funds0.3%
Collateralized Loan Obligations0.2%
U.S. Government Agency Securities0.1%
Short-Term Investments0.9%
Other Assets and Liabilities(0.1)%
C000017047 [Member]  
Shareholder Report [Line Items]  
Fund Name Balanced Fund
Class Name I Class
Trading Symbol ABINX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Balanced Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
I Class$340.68%
Expenses Paid, Amount $ 34
Expense Ratio, Percent 0.68%
Net Assets $ 906,333,994
Holdings Count | holding 539
Advisory Fees Paid, Amount $ 3,846,311
Investment Company, Portfolio Turnover 33.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Common Stocks61.1%
U.S. Treasury Securities9.8%
U.S. Government Agency Mortgage-Backed Securities8.6%
Corporate Bonds8.2%
Collateralized Mortgage Obligations4.3%
Asset-Backed Securities3.2%
Convertible Preferred Securities1.2%
Sovereign Governments and Agencies1.0%
Commercial Mortgage-Backed Securities0.5%
Preferred Securities0.4%
Municipal Securities0.3%
Exchange-Traded Funds0.3%
Collateralized Loan Obligations0.2%
U.S. Government Agency Securities0.1%
Short-Term Investments0.9%
Other Assets and Liabilities(0.1)%
C000189734 [Member]  
Shareholder Report [Line Items]  
Fund Name Balanced Fund
Class Name R5 Class
Trading Symbol ABGNX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Balanced Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R5 Class$340.68%
Expenses Paid, Amount $ 34
Expense Ratio, Percent 0.68%
Net Assets $ 906,333,994
Holdings Count | holding 539
Advisory Fees Paid, Amount $ 3,846,311
Investment Company, Portfolio Turnover 33.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Common Stocks61.1%
U.S. Treasury Securities9.8%
U.S. Government Agency Mortgage-Backed Securities8.6%
Corporate Bonds8.2%
Collateralized Mortgage Obligations4.3%
Asset-Backed Securities3.2%
Convertible Preferred Securities1.2%
Sovereign Governments and Agencies1.0%
Commercial Mortgage-Backed Securities0.5%
Preferred Securities0.4%
Municipal Securities0.3%
Exchange-Traded Funds0.3%
Collateralized Loan Obligations0.2%
U.S. Government Agency Securities0.1%
Short-Term Investments0.9%
Other Assets and Liabilities(0.1)%
C000017101 [Member]  
Shareholder Report [Line Items]  
Fund Name Growth Fund
Class Name Investor Class
Trading Symbol TWCGX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Investor Class$410.83%
Expenses Paid, Amount $ 41
Expense Ratio, Percent 0.83%
Net Assets $ 14,702,172,276
Holdings Count | holding 75
Advisory Fees Paid, Amount $ 54,298,936
Investment Company, Portfolio Turnover 13.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.5%Semiconductors and Semiconductor Equipment24%
Exchange-Traded Funds0.4%Software15%
Short-Term Investments0.3%Interactive Media and Services12%
Other Assets and Liabilities(0.2)%Technology Hardware, Storage and Peripherals9%
 Broadline Retail5%
C000017103 [Member]  
Shareholder Report [Line Items]  
Fund Name Growth Fund
Class Name I Class
Trading Symbol TWGIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
I Class$310.63%
Expenses Paid, Amount $ 31
Expense Ratio, Percent 0.63%
Net Assets $ 14,702,172,276
Holdings Count | holding 75
Advisory Fees Paid, Amount $ 54,298,936
Investment Company, Portfolio Turnover 13.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.5%Semiconductors and Semiconductor Equipment24%
Exchange-Traded Funds0.4%Software15%
Short-Term Investments0.3%Interactive Media and Services12%
Other Assets and Liabilities(0.2)%Technology Hardware, Storage and Peripherals9%
 Broadline Retail5%
C000189744 [Member]  
Shareholder Report [Line Items]  
Fund Name Growth Fund
Class Name Y Class
Trading Symbol AGYWX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Y Class$240.48%
Expenses Paid, Amount $ 24
Expense Ratio, Percent 0.48%
Net Assets $ 14,702,172,276
Holdings Count | holding 75
Advisory Fees Paid, Amount $ 54,298,936
Investment Company, Portfolio Turnover 13.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.5%Semiconductors and Semiconductor Equipment24%
Exchange-Traded Funds0.4%Software15%
Short-Term Investments0.3%Interactive Media and Services12%
Other Assets and Liabilities(0.2)%Technology Hardware, Storage and Peripherals9%
 Broadline Retail5%
C000017102 [Member]  
Shareholder Report [Line Items]  
Fund Name Growth Fund
Class Name A Class
Trading Symbol TCRAX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
A Class$531.08%
Expenses Paid, Amount $ 53
Expense Ratio, Percent 1.08%
Net Assets $ 14,702,172,276
Holdings Count | holding 75
Advisory Fees Paid, Amount $ 54,298,936
Investment Company, Portfolio Turnover 13.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.5%Semiconductors and Semiconductor Equipment24%
Exchange-Traded Funds0.4%Software15%
Short-Term Investments0.3%Interactive Media and Services12%
Other Assets and Liabilities(0.2)%Technology Hardware, Storage and Peripherals9%
 Broadline Retail5%
C000088050 [Member]  
Shareholder Report [Line Items]  
Fund Name Growth Fund
Class Name C Class
Trading Symbol TWRCX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
C Class$891.83%
Expenses Paid, Amount $ 89
Expense Ratio, Percent 1.83%
Net Assets $ 14,702,172,276
Holdings Count | holding 75
Advisory Fees Paid, Amount $ 54,298,936
Investment Company, Portfolio Turnover 13.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.5%Semiconductors and Semiconductor Equipment24%
Exchange-Traded Funds0.4%Software15%
Short-Term Investments0.3%Interactive Media and Services12%
Other Assets and Liabilities(0.2)%Technology Hardware, Storage and Peripherals9%
 Broadline Retail5%
C000017105 [Member]  
Shareholder Report [Line Items]  
Fund Name Growth Fund
Class Name R Class
Trading Symbol AGWRX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R Class$651.33%
Expenses Paid, Amount $ 65
Expense Ratio, Percent 1.33%
Net Assets $ 14,702,172,276
Holdings Count | holding 75
Advisory Fees Paid, Amount $ 54,298,936
Investment Company, Portfolio Turnover 13.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.5%Semiconductors and Semiconductor Equipment24%
Exchange-Traded Funds0.4%Software15%
Short-Term Investments0.3%Interactive Media and Services12%
Other Assets and Liabilities(0.2)%Technology Hardware, Storage and Peripherals9%
 Broadline Retail5%
C000189743 [Member]  
Shareholder Report [Line Items]  
Fund Name Growth Fund
Class Name R5 Class
Trading Symbol AGWUX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R5 Class$310.63%
Expenses Paid, Amount $ 31
Expense Ratio, Percent 0.63%
Net Assets $ 14,702,172,276
Holdings Count | holding 75
Advisory Fees Paid, Amount $ 54,298,936
Investment Company, Portfolio Turnover 13.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.5%Semiconductors and Semiconductor Equipment24%
Exchange-Traded Funds0.4%Software15%
Short-Term Investments0.3%Interactive Media and Services12%
Other Assets and Liabilities(0.2)%Technology Hardware, Storage and Peripherals9%
 Broadline Retail5%
C000131599 [Member]  
Shareholder Report [Line Items]  
Fund Name Growth Fund
Class Name R6 Class
Trading Symbol AGRDX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R6 Class$240.48%
Expenses Paid, Amount $ 24
Expense Ratio, Percent 0.48%
Net Assets $ 14,702,172,276
Holdings Count | holding 75
Advisory Fees Paid, Amount $ 54,298,936
Investment Company, Portfolio Turnover 13.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.5%Semiconductors and Semiconductor Equipment24%
Exchange-Traded Funds0.4%Software15%
Short-Term Investments0.3%Interactive Media and Services12%
Other Assets and Liabilities(0.2)%Technology Hardware, Storage and Peripherals9%
 Broadline Retail5%
C000236113 [Member]  
Shareholder Report [Line Items]  
Fund Name Growth Fund
Class Name G Class
Trading Symbol ACIHX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
G Class$00.00%
Expenses Paid, Amount $ 0
Expense Ratio, Percent 0.00%
Net Assets $ 14,702,172,276
Holdings Count | holding 75
Advisory Fees Paid, Amount $ 54,298,936
Investment Company, Portfolio Turnover 13.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.5%Semiconductors and Semiconductor Equipment24%
Exchange-Traded Funds0.4%Software15%
Short-Term Investments0.3%Interactive Media and Services12%
Other Assets and Liabilities(0.2)%Technology Hardware, Storage and Peripherals9%
 Broadline Retail5%
C000017106 [Member]  
Shareholder Report [Line Items]  
Fund Name Heritage Fund
Class Name Investor Class
Trading Symbol TWHIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Heritage Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Investor Class$491.00%
Expenses Paid, Amount $ 49
Expense Ratio, Percent 1.00%
Net Assets $ 5,363,837,373
Holdings Count | holding 82
Advisory Fees Paid, Amount $ 23,619,798
Investment Company, Portfolio Turnover 31.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks98.2%Hotels, Restaurants and Leisure10%
Short-Term Investments1.9%Aerospace and Defense8%
Other Assets and Liabilities(0.1)%Biotechnology7%
 Software6%
 Semiconductors and Semiconductor Equipment6%
C000017108 [Member]  
Shareholder Report [Line Items]  
Fund Name Heritage Fund
Class Name I Class
Trading Symbol ATHIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Heritage Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
I Class$390.80%
Expenses Paid, Amount $ 39
Expense Ratio, Percent 0.80%
Net Assets $ 5,363,837,373
Holdings Count | holding 82
Advisory Fees Paid, Amount $ 23,619,798
Investment Company, Portfolio Turnover 31.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks98.2%Hotels, Restaurants and Leisure10%
Short-Term Investments1.9%Aerospace and Defense8%
Other Assets and Liabilities(0.1)%Biotechnology7%
 Software6%
 Semiconductors and Semiconductor Equipment6%
C000189746 [Member]  
Shareholder Report [Line Items]  
Fund Name Heritage Fund
Class Name Y Class
Trading Symbol ATHYX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Heritage Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Y Class$320.65%
Expenses Paid, Amount $ 32
Expense Ratio, Percent 0.65%
Net Assets $ 5,363,837,373
Holdings Count | holding 82
Advisory Fees Paid, Amount $ 23,619,798
Investment Company, Portfolio Turnover 31.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks98.2%Hotels, Restaurants and Leisure10%
Short-Term Investments1.9%Aerospace and Defense8%
Other Assets and Liabilities(0.1)%Biotechnology7%
 Software6%
 Semiconductors and Semiconductor Equipment6%
C000017107 [Member]  
Shareholder Report [Line Items]  
Fund Name Heritage Fund
Class Name A Class
Trading Symbol ATHAX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Heritage Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
A Class$611.25%
Expenses Paid, Amount $ 61
Expense Ratio, Percent 1.25%
Net Assets $ 5,363,837,373
Holdings Count | holding 82
Advisory Fees Paid, Amount $ 23,619,798
Investment Company, Portfolio Turnover 31.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks98.2%Hotels, Restaurants and Leisure10%
Short-Term Investments1.9%Aerospace and Defense8%
Other Assets and Liabilities(0.1)%Biotechnology7%
 Software6%
 Semiconductors and Semiconductor Equipment6%
C000017109 [Member]  
Shareholder Report [Line Items]  
Fund Name Heritage Fund
Class Name C Class
Trading Symbol AHGCX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Heritage Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
C Class$972.00%
Expenses Paid, Amount $ 97
Expense Ratio, Percent 2.00%
Net Assets $ 5,363,837,373
Holdings Count | holding 82
Advisory Fees Paid, Amount $ 23,619,798
Investment Company, Portfolio Turnover 31.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks98.2%Hotels, Restaurants and Leisure10%
Short-Term Investments1.9%Aerospace and Defense8%
Other Assets and Liabilities(0.1)%Biotechnology7%
 Software6%
 Semiconductors and Semiconductor Equipment6%
C000055524 [Member]  
Shareholder Report [Line Items]  
Fund Name Heritage Fund
Class Name R Class
Trading Symbol ATHWX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Heritage Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R Class$731.50%
Expenses Paid, Amount $ 73
Expense Ratio, Percent 1.50%
Net Assets $ 5,363,837,373
Holdings Count | holding 82
Advisory Fees Paid, Amount $ 23,619,798
Investment Company, Portfolio Turnover 31.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks98.2%Hotels, Restaurants and Leisure10%
Short-Term Investments1.9%Aerospace and Defense8%
Other Assets and Liabilities(0.1)%Biotechnology7%
 Software6%
 Semiconductors and Semiconductor Equipment6%
C000189745 [Member]  
Shareholder Report [Line Items]  
Fund Name Heritage Fund
Class Name R5 Class
Trading Symbol ATHGX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Heritage Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R5 Class$390.80%
Expenses Paid, Amount $ 39
Expense Ratio, Percent 0.80%
Net Assets $ 5,363,837,373
Holdings Count | holding 82
Advisory Fees Paid, Amount $ 23,619,798
Investment Company, Portfolio Turnover 31.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks98.2%Hotels, Restaurants and Leisure10%
Short-Term Investments1.9%Aerospace and Defense8%
Other Assets and Liabilities(0.1)%Biotechnology7%
 Software6%
 Semiconductors and Semiconductor Equipment6%
C000129042 [Member]  
Shareholder Report [Line Items]  
Fund Name Heritage Fund
Class Name R6 Class
Trading Symbol ATHDX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Heritage Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R6 Class$320.65%
Expenses Paid, Amount $ 32
Expense Ratio, Percent 0.65%
Net Assets $ 5,363,837,373
Holdings Count | holding 82
Advisory Fees Paid, Amount $ 23,619,798
Investment Company, Portfolio Turnover 31.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks98.2%Hotels, Restaurants and Leisure10%
Short-Term Investments1.9%Aerospace and Defense8%
Other Assets and Liabilities(0.1)%Biotechnology7%
 Software6%
 Semiconductors and Semiconductor Equipment6%
C000236114 [Member]  
Shareholder Report [Line Items]  
Fund Name Heritage Fund
Class Name G Class
Trading Symbol ACILX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Heritage Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
G Class$00.00%
Expenses Paid, Amount $ 0
Expense Ratio, Percent 0.00%
Net Assets $ 5,363,837,373
Holdings Count | holding 82
Advisory Fees Paid, Amount $ 23,619,798
Investment Company, Portfolio Turnover 31.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks98.2%Hotels, Restaurants and Leisure10%
Short-Term Investments1.9%Aerospace and Defense8%
Other Assets and Liabilities(0.1)%Biotechnology7%
 Software6%
 Semiconductors and Semiconductor Equipment6%
C000017094 [Member]  
Shareholder Report [Line Items]  
Fund Name Large Cap Equity Fund
Class Name Investor Class
Trading Symbol AFDIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Large Cap Equity Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Investor Class$400.79%
Expenses Paid, Amount $ 40
Expense Ratio, Percent 0.79%
Net Assets $ 3,117,912,034
Holdings Count | holding 100
Advisory Fees Paid, Amount $ 5,424,094
Investment Company, Portfolio Turnover 11.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.8%Semiconductors and Semiconductor Equipment17%
Exchange-Traded Funds0.2%Software9%
Other Assets and Liabilities0.0%Interactive Media and Services9%
 Technology Hardware, Storage and Peripherals5%
 Capital Markets4%
C000017095 [Member]  
Shareholder Report [Line Items]  
Fund Name Large Cap Equity Fund
Class Name I Class
Trading Symbol AFEIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Large Cap Equity Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
I Class$300.59%
Expenses Paid, Amount $ 30
Expense Ratio, Percent 0.59%
Net Assets $ 3,117,912,034
Holdings Count | holding 100
Advisory Fees Paid, Amount $ 5,424,094
Investment Company, Portfolio Turnover 11.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.8%Semiconductors and Semiconductor Equipment17%
Exchange-Traded Funds0.2%Software9%
Other Assets and Liabilities0.0%Interactive Media and Services9%
 Technology Hardware, Storage and Peripherals5%
 Capital Markets4%
C000189742 [Member]  
Shareholder Report [Line Items]  
Fund Name Large Cap Equity Fund
Class Name Y Class
Trading Symbol AFYDX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Large Cap Equity Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Y Class$220.44%
Expenses Paid, Amount $ 22
Expense Ratio, Percent 0.44%
Net Assets $ 3,117,912,034
Holdings Count | holding 100
Advisory Fees Paid, Amount $ 5,424,094
Investment Company, Portfolio Turnover 11.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.8%Semiconductors and Semiconductor Equipment17%
Exchange-Traded Funds0.2%Software9%
Other Assets and Liabilities0.0%Interactive Media and Services9%
 Technology Hardware, Storage and Peripherals5%
 Capital Markets4%
C000017096 [Member]  
Shareholder Report [Line Items]  
Fund Name Large Cap Equity Fund
Class Name A Class
Trading Symbol AFDAX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Large Cap Equity Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
A Class$531.04%
Expenses Paid, Amount $ 53
Expense Ratio, Percent 1.04%
Net Assets $ 3,117,912,034
Holdings Count | holding 100
Advisory Fees Paid, Amount $ 5,424,094
Investment Company, Portfolio Turnover 11.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.8%Semiconductors and Semiconductor Equipment17%
Exchange-Traded Funds0.2%Software9%
Other Assets and Liabilities0.0%Interactive Media and Services9%
 Technology Hardware, Storage and Peripherals5%
 Capital Markets4%
C000017098 [Member]  
Shareholder Report [Line Items]  
Fund Name Large Cap Equity Fund
Class Name C Class
Trading Symbol AFDCX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Large Cap Equity Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
C Class$901.79%
Expenses Paid, Amount $ 90
Expense Ratio, Percent 1.79%
Net Assets $ 3,117,912,034
Holdings Count | holding 100
Advisory Fees Paid, Amount $ 5,424,094
Investment Company, Portfolio Turnover 11.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.8%Semiconductors and Semiconductor Equipment17%
Exchange-Traded Funds0.2%Software9%
Other Assets and Liabilities0.0%Interactive Media and Services9%
 Technology Hardware, Storage and Peripherals5%
 Capital Markets4%
C000017099 [Member]  
Shareholder Report [Line Items]  
Fund Name Large Cap Equity Fund
Class Name R Class
Trading Symbol AFDRX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Large Cap Equity Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R Class$651.29%
Expenses Paid, Amount $ 65
Expense Ratio, Percent 1.29%
Net Assets $ 3,117,912,034
Holdings Count | holding 100
Advisory Fees Paid, Amount $ 5,424,094
Investment Company, Portfolio Turnover 11.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.8%Semiconductors and Semiconductor Equipment17%
Exchange-Traded Funds0.2%Software9%
Other Assets and Liabilities0.0%Interactive Media and Services9%
 Technology Hardware, Storage and Peripherals5%
 Capital Markets4%
C000189741 [Member]  
Shareholder Report [Line Items]  
Fund Name Large Cap Equity Fund
Class Name R5 Class
Trading Symbol AFDGX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Large Cap Equity Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R5 Class$300.59%
Expenses Paid, Amount $ 30
Expense Ratio, Percent 0.59%
Net Assets $ 3,117,912,034
Holdings Count | holding 100
Advisory Fees Paid, Amount $ 5,424,094
Investment Company, Portfolio Turnover 11.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.8%Semiconductors and Semiconductor Equipment17%
Exchange-Traded Funds0.2%Software9%
Other Assets and Liabilities0.0%Interactive Media and Services9%
 Technology Hardware, Storage and Peripherals5%
 Capital Markets4%
C000212514 [Member]  
Shareholder Report [Line Items]  
Fund Name Large Cap Equity Fund
Class Name R6 Class
Trading Symbol AFEDX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Large Cap Equity Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R6 Class$220.44%
Expenses Paid, Amount $ 22
Expense Ratio, Percent 0.44%
Net Assets $ 3,117,912,034
Holdings Count | holding 100
Advisory Fees Paid, Amount $ 5,424,094
Investment Company, Portfolio Turnover 11.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.8%Semiconductors and Semiconductor Equipment17%
Exchange-Traded Funds0.2%Software9%
Other Assets and Liabilities0.0%Interactive Media and Services9%
 Technology Hardware, Storage and Peripherals5%
 Capital Markets4%
C000212513 [Member]  
Shareholder Report [Line Items]  
Fund Name Large Cap Equity Fund
Class Name G Class
Trading Symbol AFEGX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Large Cap Equity Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
G Class$00.00%
Expenses Paid, Amount $ 0
Expense Ratio, Percent 0.00%
Net Assets $ 3,117,912,034
Holdings Count | holding 100
Advisory Fees Paid, Amount $ 5,424,094
Investment Company, Portfolio Turnover 11.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.8%Semiconductors and Semiconductor Equipment17%
Exchange-Traded Funds0.2%Software9%
Other Assets and Liabilities0.0%Interactive Media and Services9%
 Technology Hardware, Storage and Peripherals5%
 Capital Markets4%
C000017053 [Member]  
Shareholder Report [Line Items]  
Fund Name Select Fund
Class Name Investor Class
Trading Symbol TWCIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Select Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Investor Class$450.90%
Expenses Paid, Amount $ 45
Expense Ratio, Percent 0.90%
Net Assets $ 6,389,134,432
Holdings Count | holding 57
Advisory Fees Paid, Amount $ 25,677,910
Investment Company, Portfolio Turnover 7.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.9%Semiconductors and Semiconductor Equipment26%
Short-Term Investments0.4%Interactive Media and Services17%
Other Assets and Liabilities(0.3)%Software11%
 Technology Hardware, Storage and Peripherals9%
 Broadline Retail8%
C000017055 [Member]  
Shareholder Report [Line Items]  
Fund Name Select Fund
Class Name I Class
Trading Symbol TWSIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Select Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
I Class$350.70%
Expenses Paid, Amount $ 35
Expense Ratio, Percent 0.70%
Net Assets $ 6,389,134,432
Holdings Count | holding 57
Advisory Fees Paid, Amount $ 25,677,910
Investment Company, Portfolio Turnover 7.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.9%Semiconductors and Semiconductor Equipment26%
Short-Term Investments0.4%Interactive Media and Services17%
Other Assets and Liabilities(0.3)%Software11%
 Technology Hardware, Storage and Peripherals9%
 Broadline Retail8%
C000189738 [Member]  
Shareholder Report [Line Items]  
Fund Name Select Fund
Class Name Y Class
Trading Symbol ASLWX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Select Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Y Class$270.55%
Expenses Paid, Amount $ 27
Expense Ratio, Percent 0.55%
Net Assets $ 6,389,134,432
Holdings Count | holding 57
Advisory Fees Paid, Amount $ 25,677,910
Investment Company, Portfolio Turnover 7.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.9%Semiconductors and Semiconductor Equipment26%
Short-Term Investments0.4%Interactive Media and Services17%
Other Assets and Liabilities(0.3)%Software11%
 Technology Hardware, Storage and Peripherals9%
 Broadline Retail8%
C000017054 [Member]  
Shareholder Report [Line Items]  
Fund Name Select Fund
Class Name A Class
Trading Symbol TWCAX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Select Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
A Class$571.15%
Expenses Paid, Amount $ 57
Expense Ratio, Percent 1.15%
Net Assets $ 6,389,134,432
Holdings Count | holding 57
Advisory Fees Paid, Amount $ 25,677,910
Investment Company, Portfolio Turnover 7.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.9%Semiconductors and Semiconductor Equipment26%
Short-Term Investments0.4%Interactive Media and Services17%
Other Assets and Liabilities(0.3)%Software11%
 Technology Hardware, Storage and Peripherals9%
 Broadline Retail8%
C000017058 [Member]  
Shareholder Report [Line Items]  
Fund Name Select Fund
Class Name C Class
Trading Symbol ACSLX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Select Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
C Class$941.90%
Expenses Paid, Amount $ 94
Expense Ratio, Percent 1.90%
Net Assets $ 6,389,134,432
Holdings Count | holding 57
Advisory Fees Paid, Amount $ 25,677,910
Investment Company, Portfolio Turnover 7.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.9%Semiconductors and Semiconductor Equipment26%
Short-Term Investments0.4%Interactive Media and Services17%
Other Assets and Liabilities(0.3)%Software11%
 Technology Hardware, Storage and Peripherals9%
 Broadline Retail8%
C000017059 [Member]  
Shareholder Report [Line Items]  
Fund Name Select Fund
Class Name R Class
Trading Symbol ASERX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Select Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R Class$701.40%
Expenses Paid, Amount $ 70
Expense Ratio, Percent 1.40%
Net Assets $ 6,389,134,432
Holdings Count | holding 57
Advisory Fees Paid, Amount $ 25,677,910
Investment Company, Portfolio Turnover 7.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.9%Semiconductors and Semiconductor Equipment26%
Short-Term Investments0.4%Interactive Media and Services17%
Other Assets and Liabilities(0.3)%Software11%
 Technology Hardware, Storage and Peripherals9%
 Broadline Retail8%
C000189737 [Member]  
Shareholder Report [Line Items]  
Fund Name Select Fund
Class Name R5 Class
Trading Symbol ASLGX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Select Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R5 Class$350.70%
Expenses Paid, Amount $ 35
Expense Ratio, Percent 0.70%
Net Assets $ 6,389,134,432
Holdings Count | holding 57
Advisory Fees Paid, Amount $ 25,677,910
Investment Company, Portfolio Turnover 7.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.9%Semiconductors and Semiconductor Equipment26%
Short-Term Investments0.4%Interactive Media and Services17%
Other Assets and Liabilities(0.3)%Software11%
 Technology Hardware, Storage and Peripherals9%
 Broadline Retail8%
C000131597 [Member]  
Shareholder Report [Line Items]  
Fund Name Select Fund
Class Name R6 Class
Trading Symbol ASDEX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Select Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R6 Class$270.55%
Expenses Paid, Amount $ 27
Expense Ratio, Percent 0.55%
Net Assets $ 6,389,134,432
Holdings Count | holding 57
Advisory Fees Paid, Amount $ 25,677,910
Investment Company, Portfolio Turnover 7.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.9%Semiconductors and Semiconductor Equipment26%
Short-Term Investments0.4%Interactive Media and Services17%
Other Assets and Liabilities(0.3)%Software11%
 Technology Hardware, Storage and Peripherals9%
 Broadline Retail8%
C000247666 [Member]  
Shareholder Report [Line Items]  
Fund Name Select Fund
Class Name G Class
Trading Symbol ASLDX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Select Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
G Class$00.00%
Expenses Paid, Amount $ 0
Expense Ratio, Percent 0.00%
Net Assets $ 6,389,134,432
Holdings Count | holding 57
Advisory Fees Paid, Amount $ 25,677,910
Investment Company, Portfolio Turnover 7.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.9%Semiconductors and Semiconductor Equipment26%
Short-Term Investments0.4%Interactive Media and Services17%
Other Assets and Liabilities(0.3)%Software11%
 Technology Hardware, Storage and Peripherals9%
 Broadline Retail8%
C000017049 [Member]  
Shareholder Report [Line Items]  
Fund Name Small Cap Growth Fund
Class Name Investor Class
Trading Symbol ANOIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Small Cap Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Investor Class$581.13%
Expenses Paid, Amount $ 58
Expense Ratio, Percent 1.13%
Net Assets $ 5,059,847,228
Holdings Count | holding 137
Advisory Fees Paid, Amount $ 21,349,645
Investment Company, Portfolio Turnover 32.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.2%Biotechnology13%
Rights0.0%Semiconductors and Semiconductor Equipment9%
Short-Term Investments1.7%Electronic Equipment, Instruments and Components8%
Other Assets and Liabilities(0.9)%Health Care Providers and Services7%
 Aerospace and Defense6%
C000017048 [Member]  
Shareholder Report [Line Items]  
Fund Name Small Cap Growth Fund
Class Name I Class
Trading Symbol ANONX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Small Cap Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
I Class$470.93%
Expenses Paid, Amount $ 47
Expense Ratio, Percent 0.93%
Net Assets $ 5,059,847,228
Holdings Count | holding 137
Advisory Fees Paid, Amount $ 21,349,645
Investment Company, Portfolio Turnover 32.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.2%Biotechnology13%
Rights0.0%Semiconductors and Semiconductor Equipment9%
Short-Term Investments1.7%Electronic Equipment, Instruments and Components8%
Other Assets and Liabilities(0.9)%Health Care Providers and Services7%
 Aerospace and Defense6%
C000189736 [Member]  
Shareholder Report [Line Items]  
Fund Name Small Cap Growth Fund
Class Name Y Class
Trading Symbol ANOYX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Small Cap Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Y Class$400.78%
Expenses Paid, Amount $ 40
Expense Ratio, Percent 0.78%
Net Assets $ 5,059,847,228
Holdings Count | holding 137
Advisory Fees Paid, Amount $ 21,349,645
Investment Company, Portfolio Turnover 32.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.2%Biotechnology13%
Rights0.0%Semiconductors and Semiconductor Equipment9%
Short-Term Investments1.7%Electronic Equipment, Instruments and Components8%
Other Assets and Liabilities(0.9)%Health Care Providers and Services7%
 Aerospace and Defense6%
C000017050 [Member]  
Shareholder Report [Line Items]  
Fund Name Small Cap Growth Fund
Class Name A Class
Trading Symbol ANOAX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Small Cap Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
A Class$701.38%
Expenses Paid, Amount $ 70
Expense Ratio, Percent 1.38%
Net Assets $ 5,059,847,228
Holdings Count | holding 137
Advisory Fees Paid, Amount $ 21,349,645
Investment Company, Portfolio Turnover 32.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.2%Biotechnology13%
Rights0.0%Semiconductors and Semiconductor Equipment9%
Short-Term Investments1.7%Electronic Equipment, Instruments and Components8%
Other Assets and Liabilities(0.9)%Health Care Providers and Services7%
 Aerospace and Defense6%
C000017052 [Member]  
Shareholder Report [Line Items]  
Fund Name Small Cap Growth Fund
Class Name C Class
Trading Symbol ANOCX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Small Cap Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
C Class$1082.13%
Expenses Paid, Amount $ 108
Expense Ratio, Percent 2.13%
Net Assets $ 5,059,847,228
Holdings Count | holding 137
Advisory Fees Paid, Amount $ 21,349,645
Investment Company, Portfolio Turnover 32.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.2%Biotechnology13%
Rights0.0%Semiconductors and Semiconductor Equipment9%
Short-Term Investments1.7%Electronic Equipment, Instruments and Components8%
Other Assets and Liabilities(0.9)%Health Care Providers and Services7%
 Aerospace and Defense6%
C000055516 [Member]  
Shareholder Report [Line Items]  
Fund Name Small Cap Growth Fund
Class Name R Class
Trading Symbol ANORX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Small Cap Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R Class$831.63%
Expenses Paid, Amount $ 83
Expense Ratio, Percent 1.63%
Net Assets $ 5,059,847,228
Holdings Count | holding 137
Advisory Fees Paid, Amount $ 21,349,645
Investment Company, Portfolio Turnover 32.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.2%Biotechnology13%
Rights0.0%Semiconductors and Semiconductor Equipment9%
Short-Term Investments1.7%Electronic Equipment, Instruments and Components8%
Other Assets and Liabilities(0.9)%Health Care Providers and Services7%
 Aerospace and Defense6%
C000189735 [Member]  
Shareholder Report [Line Items]  
Fund Name Small Cap Growth Fund
Class Name R5 Class
Trading Symbol ANOGX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Small Cap Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R5 Class$470.93%
Expenses Paid, Amount $ 47
Expense Ratio, Percent 0.93%
Net Assets $ 5,059,847,228
Holdings Count | holding 137
Advisory Fees Paid, Amount $ 21,349,645
Investment Company, Portfolio Turnover 32.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.2%Biotechnology13%
Rights0.0%Semiconductors and Semiconductor Equipment9%
Short-Term Investments1.7%Electronic Equipment, Instruments and Components8%
Other Assets and Liabilities(0.9)%Health Care Providers and Services7%
 Aerospace and Defense6%
C000131596 [Member]  
Shareholder Report [Line Items]  
Fund Name Small Cap Growth Fund
Class Name R6 Class
Trading Symbol ANODX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Small Cap Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R6 Class$400.78%
Expenses Paid, Amount $ 40
Expense Ratio, Percent 0.78%
Net Assets $ 5,059,847,228
Holdings Count | holding 137
Advisory Fees Paid, Amount $ 21,349,645
Investment Company, Portfolio Turnover 32.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.2%Biotechnology13%
Rights0.0%Semiconductors and Semiconductor Equipment9%
Short-Term Investments1.7%Electronic Equipment, Instruments and Components8%
Other Assets and Liabilities(0.9)%Health Care Providers and Services7%
 Aerospace and Defense6%
C000212512 [Member]  
Shareholder Report [Line Items]  
Fund Name Small Cap Growth Fund
Class Name G Class
Trading Symbol ANOHX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Small Cap Growth Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
G Class$00.00%
Expenses Paid, Amount $ 0
Expense Ratio, Percent 0.00%
Net Assets $ 5,059,847,228
Holdings Count | holding 137
Advisory Fees Paid, Amount $ 21,349,645
Investment Company, Portfolio Turnover 32.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks99.2%Biotechnology13%
Rights0.0%Semiconductors and Semiconductor Equipment9%
Short-Term Investments1.7%Electronic Equipment, Instruments and Components8%
Other Assets and Liabilities(0.9)%Health Care Providers and Services7%
 Aerospace and Defense6%
C000017060 [Member]  
Shareholder Report [Line Items]  
Fund Name Ultra Fund
Class Name Investor Class
Trading Symbol TWCUX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Ultra Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Investor Class$430.87%
Expenses Paid, Amount $ 43
Expense Ratio, Percent 0.87%
Net Assets $ 26,579,895,502
Holdings Count | holding 66
Advisory Fees Paid, Amount $ 106,716,701
Investment Company, Portfolio Turnover 6.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks100.0%Semiconductors and Semiconductor Equipment24%
Rights0.0%Interactive Media and Services15%
Short-Term Investments0.1%Software11%
Other Assets and Liabilities(0.1)%Technology Hardware, Storage and Peripherals8%
 Broadline Retail8%
C000017062 [Member]  
Shareholder Report [Line Items]  
Fund Name Ultra Fund
Class Name I Class
Trading Symbol TWUIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Ultra Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
I Class$330.67%
Expenses Paid, Amount $ 33
Expense Ratio, Percent 0.67%
Net Assets $ 26,579,895,502
Holdings Count | holding 66
Advisory Fees Paid, Amount $ 106,716,701
Investment Company, Portfolio Turnover 6.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks100.0%Semiconductors and Semiconductor Equipment24%
Rights0.0%Interactive Media and Services15%
Short-Term Investments0.1%Software11%
Other Assets and Liabilities(0.1)%Technology Hardware, Storage and Peripherals8%
 Broadline Retail8%
C000189740 [Member]  
Shareholder Report [Line Items]  
Fund Name Ultra Fund
Class Name Y Class
Trading Symbol AULYX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Ultra Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Y Class$260.52%
Expenses Paid, Amount $ 26
Expense Ratio, Percent 0.52%
Net Assets $ 26,579,895,502
Holdings Count | holding 66
Advisory Fees Paid, Amount $ 106,716,701
Investment Company, Portfolio Turnover 6.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks100.0%Semiconductors and Semiconductor Equipment24%
Rights0.0%Interactive Media and Services15%
Short-Term Investments0.1%Software11%
Other Assets and Liabilities(0.1)%Technology Hardware, Storage and Peripherals8%
 Broadline Retail8%
C000017061 [Member]  
Shareholder Report [Line Items]  
Fund Name Ultra Fund
Class Name A Class
Trading Symbol TWUAX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Ultra Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
A Class$551.12%
Expenses Paid, Amount $ 55
Expense Ratio, Percent 1.12%
Net Assets $ 26,579,895,502
Holdings Count | holding 66
Advisory Fees Paid, Amount $ 106,716,701
Investment Company, Portfolio Turnover 6.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks100.0%Semiconductors and Semiconductor Equipment24%
Rights0.0%Interactive Media and Services15%
Short-Term Investments0.1%Software11%
Other Assets and Liabilities(0.1)%Technology Hardware, Storage and Peripherals8%
 Broadline Retail8%
C000017063 [Member]  
Shareholder Report [Line Items]  
Fund Name Ultra Fund
Class Name C Class
Trading Symbol TWCCX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Ultra Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
C Class$921.87%
Expenses Paid, Amount $ 92
Expense Ratio, Percent 1.87%
Net Assets $ 26,579,895,502
Holdings Count | holding 66
Advisory Fees Paid, Amount $ 106,716,701
Investment Company, Portfolio Turnover 6.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks100.0%Semiconductors and Semiconductor Equipment24%
Rights0.0%Interactive Media and Services15%
Short-Term Investments0.1%Software11%
Other Assets and Liabilities(0.1)%Technology Hardware, Storage and Peripherals8%
 Broadline Retail8%
C000017064 [Member]  
Shareholder Report [Line Items]  
Fund Name Ultra Fund
Class Name R Class
Trading Symbol AULRX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Ultra Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R Class$681.37%
Expenses Paid, Amount $ 68
Expense Ratio, Percent 1.37%
Net Assets $ 26,579,895,502
Holdings Count | holding 66
Advisory Fees Paid, Amount $ 106,716,701
Investment Company, Portfolio Turnover 6.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks100.0%Semiconductors and Semiconductor Equipment24%
Rights0.0%Interactive Media and Services15%
Short-Term Investments0.1%Software11%
Other Assets and Liabilities(0.1)%Technology Hardware, Storage and Peripherals8%
 Broadline Retail8%
C000189739 [Member]  
Shareholder Report [Line Items]  
Fund Name Ultra Fund
Class Name R5 Class
Trading Symbol AULGX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Ultra Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R5 Class$330.67%
Expenses Paid, Amount $ 33
Expense Ratio, Percent 0.67%
Net Assets $ 26,579,895,502
Holdings Count | holding 66
Advisory Fees Paid, Amount $ 106,716,701
Investment Company, Portfolio Turnover 6.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks100.0%Semiconductors and Semiconductor Equipment24%
Rights0.0%Interactive Media and Services15%
Short-Term Investments0.1%Software11%
Other Assets and Liabilities(0.1)%Technology Hardware, Storage and Peripherals8%
 Broadline Retail8%
C000131598 [Member]  
Shareholder Report [Line Items]  
Fund Name Ultra Fund
Class Name R6 Class
Trading Symbol AULDX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Ultra Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
R6 Class$260.52%
Expenses Paid, Amount $ 26
Expense Ratio, Percent 0.52%
Net Assets $ 26,579,895,502
Holdings Count | holding 66
Advisory Fees Paid, Amount $ 106,716,701
Investment Company, Portfolio Turnover 6.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks100.0%Semiconductors and Semiconductor Equipment24%
Rights0.0%Interactive Media and Services15%
Short-Term Investments0.1%Software11%
Other Assets and Liabilities(0.1)%Technology Hardware, Storage and Peripherals8%
 Broadline Retail8%
C000214991 [Member]  
Shareholder Report [Line Items]  
Fund Name Ultra Fund
Class Name G Class
Trading Symbol AULNX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Ultra Fund for the period of November 1, 2025 to April 30, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at americancentury.com/docs. You can also request this information by contacting us at 1-800-345-2021.
Additional Information Phone Number 1-800-345-2021
Additional Information Website americancentury.com/docs
Expenses [Text Block]
What were the fund costs for the last six months? (based on a hypothetical $10,000 investment)
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
G Class$00.00%
Expenses Paid, Amount $ 0
Expense Ratio, Percent 0.00%
Net Assets $ 26,579,895,502
Holdings Count | holding 66
Advisory Fees Paid, Amount $ 106,716,701
Investment Company, Portfolio Turnover 6.00%
Holdings [Text Block]
Fund Holdings
Types of Investments in Portfolio (as a % of net assets)
Top Five Industries (as a % of net assets)
Common Stocks100.0%Semiconductors and Semiconductor Equipment24%
Rights0.0%Interactive Media and Services15%
Short-Term Investments0.1%Software11%
Other Assets and Liabilities(0.1)%Technology Hardware, Storage and Peripherals8%
 Broadline Retail8%