v3.26.3
Expense Example - AMERICAN CENTURY MUNICIPAL TRUST
Oct. 01, 2026
USD ($)
HIGH-YIELD MUNICIPAL FUND | HIGH-YIELD MUNICIPAL FUND, INVESTOR CLASS  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year $ 61
Expense Example, with Redemption, 3 Years 193
Expense Example, with Redemption, 5 Years 335
Expense Example, with Redemption, 10 Years 751
HIGH-YIELD MUNICIPAL FUND | HIGH-YIELD MUNICIPAL FUND, I CLASS  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 41
Expense Example, with Redemption, 3 Years 129
Expense Example, with Redemption, 5 Years 225
Expense Example, with Redemption, 10 Years 506
HIGH-YIELD MUNICIPAL FUND | HIGH-YIELD MUNICIPAL FUND, Y CLASS  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 38
Expense Example, with Redemption, 3 Years 119
Expense Example, with Redemption, 5 Years 208
Expense Example, with Redemption, 10 Years 469
HIGH-YIELD MUNICIPAL FUND | HIGH-YIELD MUNICIPAL FUND, A CLASS  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 533
Expense Example, with Redemption, 3 Years 709
Expense Example, with Redemption, 5 Years 901
Expense Example, with Redemption, 10 Years 1,452
HIGH-YIELD MUNICIPAL FUND | HIGH-YIELD MUNICIPAL FUND, C CLASS  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 163
Expense Example, with Redemption, 3 Years 506
Expense Example, with Redemption, 5 Years 872
Expense Example, with Redemption, 10 Years 1,698
INTERMEDIATE-TERM TAX-FREE BOND FUND | INTERMEDIATE-TERM TAX-FREE BOND FUND, INVESTOR CLASS  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 48
Expense Example, with Redemption, 3 Years 151
Expense Example, with Redemption, 5 Years 264
Expense Example, with Redemption, 10 Years 592
INTERMEDIATE-TERM TAX-FREE BOND FUND | INTERMEDIATE-TERM TAX-FREE BOND FUND, I CLASS  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 28
Expense Example, with Redemption, 3 Years 87
Expense Example, with Redemption, 5 Years 152
Expense Example, with Redemption, 10 Years 344
INTERMEDIATE-TERM TAX-FREE BOND FUND | INTERMEDIATE-TERM TAX-FREE BOND FUND, Y CLASS  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 25
Expense Example, with Redemption, 3 Years 77
Expense Example, with Redemption, 5 Years 135
Expense Example, with Redemption, 10 Years 306
INTERMEDIATE-TERM TAX-FREE BOND FUND | INTERMEDIATE-TERM TAX-FREE BOND FUND, A CLASS  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 520
Expense Example, with Redemption, 3 Years 670
Expense Example, with Redemption, 5 Years 833
Expense Example, with Redemption, 10 Years 1,305
INTERMEDIATE-TERM TAX-FREE BOND FUND | INTERMEDIATE-TERM TAX-FREE BOND FUND, C CLASS  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 150
Expense Example, with Redemption, 3 Years 466
Expense Example, with Redemption, 5 Years 803
Expense Example, with Redemption, 10 Years 1,553
TAX-FREE MONEY MARKET FUND | TAX-FREE MONEY MARKET FUND, INVESTOR CLASS  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 50
Expense Example, with Redemption, 3 Years 157
Expense Example, with Redemption, 5 Years 275
Expense Example, with Redemption, 10 Years $ 617