NORTHERN ULTRASHORT FIXED INCOME FUND [Member] Average Annual Total Returns - NORTHERN ULTRASHORT FIXED INCOME FUND |
12 Months Ended | 60 Months Ended | 120 Months Ended |
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
|
| Bloomberg Global Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes) | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 8.18% | (2.14%) | 1.26% |
| ICE BofA 1-Year U.S. Treasury Note Index (reflects no deduction for fees, expenses, or taxes) | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 4.15% | 2.48% | 2.03% |
| ULTRA-SHORT FIXED INCOME FUND | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 5.16% | 3.22% | 2.67% |
| ULTRA-SHORT FIXED INCOME FUND | After Taxes on Distributions | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 3.19% | 1.91% | 1.65% |
| ULTRA-SHORT FIXED INCOME FUND | After Taxes on Distributions and Sales | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 3.03% | 1.90% | 1.61% |