Average Annual Total Returns |
12 Months Ended | 60 Months Ended | 120 Months Ended | 451 Months Ended | |||||
|---|---|---|---|---|---|---|---|---|---|
Mar. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2024 |
Dec. 31, 2024 |
Dec. 31, 2024 |
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| Prospectus [Line Items] | |||||||||
| Average Annual Return, Percent | |||||||||
| Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes) | |||||||||
| Prospectus [Line Items] | |||||||||
| Average Annual Return, Percent | [1] | 1.25% | (0.33%) | 1.35% | |||||
| Bloomberg Intermediate Government Bond Index (reflects no deduction for fees, expenses or taxes) | |||||||||
| Prospectus [Line Items] | |||||||||
| Average Annual Return, Percent | [2] | 2.44% | 0.49% | 1.24% | |||||
| Sit U.S. Government Securities Fund - Class S | |||||||||
| Prospectus [Line Items] | |||||||||
| Average Annual Return, Percent | 2.40% | 0.72% | 1.21% | ||||||
| Performance Inception Date | Jun. 02, 1987 | ||||||||
| Sit U.S. Government Securities Fund - Class S | After Taxes on Distributions | |||||||||
| Prospectus [Line Items] | |||||||||
| Average Annual Return, Percent | 0.85% | (0.22%) | 0.34% | ||||||
| Performance Inception Date | Jun. 02, 1987 | ||||||||
| Sit U.S. Government Securities Fund - Class S | After Taxes on Distributions and Sales | |||||||||
| Prospectus [Line Items] | |||||||||
| Average Annual Return, Percent | 1.41% | 0.15% | 0.55% | ||||||
| Performance Inception Date | Jun. 02, 1987 | ||||||||
| Sit U.S. Government Securities Fund - Class Y | |||||||||
| Prospectus [Line Items] | |||||||||
| Average Annual Return, Percent | 2.77% | 0.97% | |||||||
| Performance Inception Date | Jan. 01, 2020 | ||||||||
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