v3.25.4
Shareholder Fees - American Century Mutual Funds, Inc
Mar. 01, 2026
USD ($)
BALANCED FUND | BALANCED FUND, INVESTOR CLASS  
Prospectus [Line Items]  
Maximum Account Fee $ 25
BALANCED FUND | BALANCED FUND, I CLASS  
Prospectus [Line Items]  
Maximum Account Fee 0
BALANCED FUND | BALANCED FUND, R5 CLASS  
Prospectus [Line Items]  
Maximum Account Fee $ 0
GROWTH FUND | GROWTH FUND, INVESTOR CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 25
GROWTH FUND | GROWTH FUND, I CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
GROWTH FUND | GROWTH FUND, Y CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
GROWTH FUND | GROWTH FUND, A CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00% [1]
Maximum Account Fee $ 0
GROWTH FUND | GROWTH FUND, C CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 1.00%
Maximum Account Fee $ 0
GROWTH FUND | GROWTH FUND, R CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
GROWTH FUND | GROWTH FUND, R5 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
GROWTH FUND | GROWTH FUND, R6 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
GROWTH FUND | GROWTH FUND, G CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
HERITAGE FUND | HERITAGE FUND, INVESTOR CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 25
HERITAGE FUND | HERITAGE FUND, I CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
HERITAGE FUND | HERITAGE FUND, Y CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
HERITAGE FUND | HERITAGE FUND, A CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00% [2]
Maximum Account Fee $ 0
HERITAGE FUND | HERITAGE FUND, C CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 1.00%
Maximum Account Fee $ 0
HERITAGE FUND | HERITAGE FUND, R CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
HERITAGE FUND | HERITAGE FUND, R5 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
HERITAGE FUND | HERITAGE FUND, R6 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
HERITAGE FUND | HERITAGE FUND, G CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
LARGE CAP EQUITY FUND | LARGE CAP EQUITY FUND, INVESTOR CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 25
LARGE CAP EQUITY FUND | LARGE CAP EQUITY FUND, I CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
LARGE CAP EQUITY FUND | LARGE CAP EQUITY FUND, Y CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
LARGE CAP EQUITY FUND | LARGE CAP EQUITY FUND, A CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00% [3]
Maximum Account Fee $ 0
LARGE CAP EQUITY FUND | LARGE CAP EQUITY FUND, C CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 1.00%
Maximum Account Fee $ 0
LARGE CAP EQUITY FUND | LARGE CAP EQUITY FUND, R CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
LARGE CAP EQUITY FUND | LARGE CAP EQUITY FUND, R5 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
LARGE CAP EQUITY FUND | LARGE CAP EQUITY FUND, R6 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
LARGE CAP EQUITY FUND | LARGE CAP EQUITY FUND, G CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SELECT FUND | SELECT FUND, INVESTOR CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 25
SELECT FUND | SELECT FUND, I CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SELECT FUND | SELECT FUND, Y CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SELECT FUND | SELECT FUND, A CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00% [4]
Maximum Account Fee $ 0
SELECT FUND | SELECT FUND, C CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 1.00%
Maximum Account Fee $ 0
SELECT FUND | SELECT FUND, R CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SELECT FUND | SELECT FUND, R5 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SELECT FUND | SELECT FUND, R6 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SELECT FUND | SELECT FUND, G CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SMALL CAP GROWTH FUND | SMALL CAP GROWTH FUND, INVESTOR CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 25
SMALL CAP GROWTH FUND | SMALL CAP GROWTH FUND, I CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SMALL CAP GROWTH FUND | SMALL CAP GROWTH FUND, Y CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SMALL CAP GROWTH FUND | SMALL CAP GROWTH FUND, A CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00% [5]
Maximum Account Fee $ 0
SMALL CAP GROWTH FUND | SMALL CAP GROWTH FUND, C CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 1.00%
Maximum Account Fee $ 0
SMALL CAP GROWTH FUND | SMALL CAP GROWTH FUND, R CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SMALL CAP GROWTH FUND | SMALL CAP GROWTH FUND, R5 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SMALL CAP GROWTH FUND | SMALL CAP GROWTH FUND, R6 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
SMALL CAP GROWTH FUND | SMALL CAP GROWTH FUND, G CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
ULTRA FUND | ULTRA FUND, INVESTOR CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 25
ULTRA FUND | ULTRA FUND, I CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
ULTRA FUND | ULTRA FUND, Y CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
ULTRA FUND | ULTRA FUND, A CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00% [6]
Maximum Account Fee $ 0
ULTRA FUND | ULTRA FUND, C CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 1.00%
Maximum Account Fee $ 0
ULTRA FUND | ULTRA FUND, R CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
ULTRA FUND | ULTRA FUND, R5 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
ULTRA FUND | ULTRA FUND, R6 CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
ULTRA FUND | ULTRA FUND, G CLASS  
Prospectus [Line Items]  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) 0.00%
Maximum Account Fee $ 0
[1] Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.
[2] Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.
[3] Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.
[4] Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.
[5] Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.
[6] Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.