Investment Risks - American Century Mutual Funds, Inc - BALANCED FUND	Mar. 01, 2026
Style Risk Member
Prospectus [Line Items]
Risk [Text Block]	Style Risk — If at any time the market is not favoring the investment styles used to manage the fund’s equity portions, that portion’s gains may not be as big as, or its losses may be bigger than, those of other equity funds using different investment styles.
Investment Process Risk Member
Prospectus [Line Items]
Risk [Text Block]	Investment Process Risk — Stocks selected by the portfolio managers using quantitative models may perform differently than expected due to the portfolio managers’ judgments regarding the factors used in the models, the weight placed on each factor, changes from the factors’ historical trends, and technical issues with the construction and implementation of the models (including, for example, data problems and/or software or other implementation issues). There is no guarantee that the use of the quantitative models will result in effective investment decisions for the fund. Additionally, the commonality of portfolio holdings across quantitative investment managers may amplify losses.
Market Risk Member
Prospectus [Line Items]
Risk [Text Block]	Market Risk — The value of the fund’s shares will go up and down based on the performance of the companies whose securities it owns and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
Interest Rate Risk1 Member
Prospectus [Line Items]
Risk [Text Block]	Interest Rate Risk — Investments in debt securities are sensitive to interest rate changes. Generally, the value of debt securities and the funds that hold them decline as interest rates rise. The fund’s fixed-income investments are designed to reduce this risk. Interest rate risk, however, is generally higher for the fixed-income portion of the Balanced Fund than for funds that have shorter-weighted maturities, such as money market funds and short-term bond funds. A period of rising interest rates may negatively affect the fund’s performance.
Credit Risk1 Member
Prospectus [Line Items]
Risk [Text Block]	Credit Risk — Debt securities, even investment-grade debt securities, are subject to credit risk. Credit risk is the risk that the inability or perceived inability of the issuer to make interest and principal payments will cause the value of the securities to decrease. As a result the fund’s share price could also decrease. Changes in the credit rating of a debt security held by the fund could have a similar effect.
Allocation Risk Member
Prospectus [Line Items]
Risk [Text Block]	Allocation Risk — The fund’s ability to achieve its investment objective depends in part on the portfolio managers’ skill in determining the fund’s asset class allocations and in selecting and weighting investments within each class. The portfolio managers’ evaluations and assumptions regarding asset classes and investments may differ from actual market conditions.
High-Yield Risk Member
Prospectus [Line Items]
Risk [Text Block]	High-Yield Risk – Issuers of high-yield securities are more vulnerable to real or perceived economic changes (such as an economic downturn or a prolonged period of rising interest rates), political changes or adverse developments specific to an issuer. These factors may be more likely to cause an issuer of low quality bonds to default on its obligations. High-yield securities are speculative.
ETF Risk Member
Prospectus [Line Items]
Risk [Text Block]	ETF Risk — ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
Prepayment And Extension Risk Member
Prospectus [Line Items]
Risk [Text Block]	Prepayment and Extension Risk — The fund may invest in debt securities backed by mortgages or other assets. If these underlying assets are prepaid, the fund may benefit less from declining interest rates than funds of similar maturity that invest less heavily in mortgage- and asset-backed securities. Conversely, an issuer may exercise its right to pay principal on an obligation held by the fund later than expected (extend the obligation) especially in periods of rising interest rates. These events may lengthen the maturity and potentially reduce the value of these securities.
Foreign Securities Risk Member
Prospectus [Line Items]
Risk [Text Block]	Foreign Securities Risk — Foreign securities have certain unique risks, such as currency risk, social, political and economic risk, and foreign market and trading risk. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Investing in emerging market countries generally is also riskier than investing in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change, and significant volatility in their financial markets. These countries also may lack the legal, business and social framework to support securities markets.
Bank Loan Risk Member
Prospectus [Line Items]
Risk [Text Block]	Bank Loan Risk — The market for bank loans may not be highly liquid and the fund may have difficulty selling them. Bank loans may not be considered securities, thus the fund may not be afforded anti-fraud protections available under the federal securities laws. In connection with purchasing loan participations, the fund generally will have no right to enforce compliance by borrowers with loan terms nor any set off rights, and the fund may not benefit directly from any posted collateral. As a result, the fund may be subject to the credit risk of both the borrower and the lender selling the participation. Bank loan transactions may take more than seven days to settle, meaning that proceeds would be unavailable to make additional investments or meet redemptions.
Collateralized Obligations Risk Member
Prospectus [Line Items]
Risk [Text Block]	Collateralized Obligations Risk — Collateralized obligations, such as collateralized loan obligations (CLOs), are subject to credit, interest rate, valuation, and prepayment and extension risks. These securities also are subject to risk of default on the underlying asset, particularly during periods of economic downturn. The market value of collateralized obligations may be affected by, among other things, changes in the market value of the underlying assets held by the collateralized obligation, changes in the distributions on the underlying assets, defaults and recoveries on the underlying assets, capital gains and losses on the underlying assets, prepayments on underlying assets and the availability, and prices and interest rates of underlying assets. Lower rated tranches of such debt are subject to a higher risk of total loss and deferral or nonpayment of interest than the more senior tranches to which they are subordinated. Some of the collateralized obligations in which the fund invests may be covenant-lite loans. Covenant-lite loans contain fewer or less restrictive constraints on the borrower. The fund may have fewer rights against a borrower and an accompanying greater risk of loss when it invests in covenant-lite loans.
Counterparty Risk Member
Prospectus [Line Items]
Risk [Text Block]	Counterparty Risk – If the fund enters into financial contracts, the fund will be subject to the credit risk presented by the counterparties.
Currency Risk Member
Prospectus [Line Items]
Risk [Text Block]	Currency Risk – Because the fund may invest in securities denominated in foreign currencies, the fund could experience gains or losses based solely on changes in the exchange rate between foreign currencies and the U.S. dollar.
Derivative Risk Member
Prospectus [Line Items]
Risk [Text Block]	Derivative Risk — The use of derivative instruments involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other traditional instruments. Derivatives are subject to a number of risks, including liquidity, interest rate, market, credit and correlation risk. Derivatives used for hedging or risk management may not operate as intended, may expose the fund to other risks, and may be insufficient to protect the fund from the risks they were intended to hedge.
Liquidity Risk Member
Prospectus [Line Items]
Risk [Text Block]	Liquidity Risk — The fund may also be subject to liquidity risk. During periods of market turbulence or unusually low trading activity, in order to meet redemptions it may be necessary for the fund to sell securities at prices that could have an adverse effect on the fund’s share price. Changing regulatory and market conditions, including increases in interest rates and credit spreads may adversely affect the liquidity of the fund’s investments.
Small-Cap Stock Risks Member
Prospectus [Line Items]
Risk [Text Block]	Small-Cap Stock Risks — Stocks of smaller companies can be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs.
Price Volatility Risk Member
Prospectus [Line Items]
Risk [Text Block]	Price Volatility Risk — The value of the fund’s shares may fluctuate significantly in the short term.
Risk Lose Money [Member]
Prospectus [Line Items]
Risk [Text Block]	Principal Loss Risk — At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
Risk Not Insured Depository Institution [Member]
Prospectus [Line Items]
Risk [Text Block]	An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Investment Risks - American Century Mutual Funds, Inc - BALANCED FUND

Mar. 01, 2026

Style Risk — If at any time the market is not favoring the investment styles used to manage the fund’s equity portions, that portion’s gains may not be as big as, or its losses may be bigger than, those of other equity funds using different investment styles.