DWS Tax-Exempt Portfolio Average Annual Total Returns - DWS Tax Expt Cash Prmr Shrs [Member] - DWS Tax-Exempt Cash Premier Shares - Return Before Taxes[Member] |
12 Months Ended | 60 Months Ended | 120 Months Ended | |
|---|---|---|---|---|
Jul. 28, 2026 |
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
|
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 2.54% | 1.97% | 1.39% | |
| Performance Inception Date | Nov. 17, 1999 |