S000035596 [Member] Average Annual Total Returns |
12 Months Ended | 60 Months Ended | 120 Months Ended | ||
|---|---|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
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| Bloomberg Global Aggregate Bond Index | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | [1] | 8.17% | (2.15%) | 1.26% | |
| Bloomberg 1-3 Month U.S. Treasury Bill Index | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | [1] | 4.29% | 3.24% | 2.18% | |
| FlexShares Ultra-Short Income Fund | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 4.95% | 3.22% | 2.59% | ||
| FlexShares Ultra-Short Income Fund | After Taxes on Distributions | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 3.00% | 1.80% | 1.53% | ||
| FlexShares Ultra-Short Income Fund | After Taxes on Distributions and Sales | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 2.90% | 1.85% | 1.53% | ||
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