v3.25.2
Shareholder Report, Average Annual Return (Details)
 12 Months Ended 60 Months Ended 120 Months Ended
Apr. 30, 2025
Apr. 30, 2025
Apr. 30, 2025
Columbia U.S. Treasury Index Fund - Class A      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Class A    
Average Annual Return, Percent 7.26% (1.97%) 0.74%
Columbia U.S. Treasury Index Fund - Institutional Class      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Institutional Class    
Average Annual Return, Percent 7.53% (1.80%) 0.90%
Columbia U.S. Treasury Index Fund - Institutional 2 Class      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Institutional 2 Class    
Average Annual Return, Percent 7.54% (1.79%) 0.90%
Columbia U.S. Treasury Index Fund - Institutional 3 Class      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Institutional 3 Class    
Average Annual Return, Percent [1] 7.40% (1.81%) 0.88%
Bloomberg U.S. Aggregate Bond Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name Bloomberg U.S. Aggregate Bond Index    
Average Annual Return, Percent [2] 8.02% (0.67%) 1.54%
FTSE USBIG Treasury Index [Member]      
Average Annual Return [Line Items]      
Line Graph and Table Measure Name FTSE USBIG Treasury Index    
Average Annual Return, Percent 7.67% (1.65%) 1.07%
[1] The returns shown for periods prior to March 1, 2017 (including Since Fund Inception returns, if shown) include the returns of Institutional Class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit columbiathreadneedleus.com/investment-products/mutual-funds/appended-performance for more information.
[2] Effective August 1, 2024, the Fund compares its performance to the Bloomberg U.S. Aggregate Bond Index, a broad-based performance index, as required by new regulatory requirements. The Fund’s performance also continues to be compared to its prior benchmarks, which management believes more closely represent the market sectors/and or asset classes in which the Fund primarily invests.