v3.26.1
S000012098 [Member] Annual Fund Operating Expenses - Columbia U.S. Treasury Index Fund
Apr. 30, 2026
Prospectus [Line Items]  
Fee Waiver or Reimbursement over Assets, Date of Termination August 31, 2027
Columbia U.S. Treasury Index Fund Class A  
Prospectus [Line Items]  
Management Fees (as a percentage of Assets) 0.40%
Distribution and Service (12b-1) Fees 0.15%
Other Expenses (as a percentage of Assets): 0.00%
Expenses (as a percentage of Assets) 0.55% [1]
Fee Waiver or Reimbursement (0.23%) [2]
Net Expenses (as a percentage of Assets) 0.32%
Columbia U.S. Treasury Index Fund Institutional Class  
Prospectus [Line Items]  
Management Fees (as a percentage of Assets) 0.40%
Distribution and Service (12b-1) Fees 0.00%
Other Expenses (as a percentage of Assets): 0.00%
Expenses (as a percentage of Assets) 0.40% [1]
Fee Waiver or Reimbursement (0.23%) [2]
Net Expenses (as a percentage of Assets) 0.17%
Columbia U.S. Treasury Index Fund Institutional 2 Class  
Prospectus [Line Items]  
Management Fees (as a percentage of Assets) 0.40%
Distribution and Service (12b-1) Fees 0.00%
Other Expenses (as a percentage of Assets): 0.00%
Expenses (as a percentage of Assets) 0.40% [1]
Fee Waiver or Reimbursement (0.23%) [2]
Net Expenses (as a percentage of Assets) 0.17%
Columbia U.S. Treasury Index Fund Institutional 3 Class  
Prospectus [Line Items]  
Management Fees (as a percentage of Assets) 0.40%
Distribution and Service (12b-1) Fees 0.00%
Other Expenses (as a percentage of Assets): 0.00%
Expenses (as a percentage of Assets) 0.40% [1]
Fee Waiver or Reimbursement (0.23%) [2]
Net Expenses (as a percentage of Assets) 0.17%
[1] “Total annual Fund operating expenses” include acquired fund fees and expenses (expenses the Fund incurs indirectly through its investments in other investment companies) and may be higher than the ratio of expenses to average net assets shown in the Financial Highlights section of this prospectus because the ratio of expenses to average net assets does not include acquired fund fees and expenses.
[2] Columbia Management Investment Advisers, LLC and certain of its affiliates have contractually agreed to waive fees and/or to reimburse expenses (excluding transaction costs and certain other investment related expenses, interest, taxes, acquired fund fees and expenses, and infrequent and/or unusual expenses) through August 31, 2027, unless sooner terminated at the sole discretion of the Fund’s Board of Trustees. Under this agreement, the Fund’s net operating expenses, subject to applicable exclusions, will not exceed the annual rates of 0.32% for Class A, 0.17% for Class Inst, 0.17% for Class Inst2 and 0.17% for Class Inst3. Any differences in these annual rates relative to the annual rates noted in the last row of the above table (e.g., net expense ratios) are due to applicable exclusions under the agreement.