This annual shareholder report contains important information about DWS Government & Agency Securities Portfolio (the "Fund") for the period May 1, 2025 to April 30, 2026.

Additional Information [Text Block]

You can find additional information about the Fund on the Fund's website at dws.com/mutualreports. You can also request this information by contacting us at (800) 728-3337.

Additional Information Phone Number

(800) 728-3337

Additional Information Website

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Expenses [Text Block]

What were the Fund costs for the last year?

(Based on a hypothetical $10,000 investment)

Table Summary
Fund	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
DWS Government & Agency Money Fund	$17	0.17%

Gross expense ratio as of the latest prospectus: 0.22%. See prospectus for any contractual or voluntary waivers; without a waiver, costs would have been higher.

Expenses Paid, Amount

$ 17

Expense Ratio, Percent

0.17%

AssetsNet

$ 5,592,469,167

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 1,952,349

Additional Fund Statistics [Text Block]

Key Fund Statistics

Table Summary
Net Assets ($)	5,592,469,167
Number of Portfolio Holdings	95
Total Net Advisory Fees Paid ($)	1,952,349
Weighted Average Maturity	30 days
7-Day Current Yield	3.54%

Weighted average maturity, also known as effective maturity, is the weighted average of the maturity date of bonds held by the Fund taking into consideration any available maturity shortening features.

Yields fluctuate and are not guaranteed. The 7-day current yield is the annualized net investment income per share as of April 30, 2026. The 7-Day Current Yield would have been 3.49% had certain expenses not been reduced.

Holdings [Text Block]

What did the Fund invest in?

Asset Allocation

Table Summary
Asset Type	% of Net Assets
Government & Agency Obligations	53%
Repurchase Agreements	46%
Other Assets and Liabilities, Net	1%
Total	100%

Holdings-based data is subject to change.

C000035156

Shareholder Report [Line Items]

Fund Name

DWS Government & Agency Securities Portfolio

Class Name

DWS Government Cash Institutional Shares

Trading Symbol

DBBXX

Annual or Semi-Annual Statement [Text Block]

This annual shareholder report contains important information about DWS Government & Agency Securities Portfolio (the "Fund") for the period May 1, 2025 to April 30, 2026.

Additional Information [Text Block]

You can find additional information about the Fund on the Fund's website at dws.com/mutualreports. You can also request this information by contacting us at (800) 730-1313.

Additional Information Phone Number

(800) 730-1313

Additional Information Website

Expenses [Text Block]

What were the Fund costs for the last year?

(Based on a hypothetical $10,000 investment)

Table Summary
Fund	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
DWS Government Cash Institutional Shares	$15	0.15%

Gross expense ratio as of the latest prospectus: 0.20%. See prospectus for any contractual or voluntary waivers; without a waiver, costs would have been higher.

Expenses Paid, Amount

$ 15

Expense Ratio, Percent

0.15%

AssetsNet

$ 5,592,469,167

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 1,952,349

Additional Fund Statistics [Text Block]

Key Fund Statistics

Table Summary
Net Assets ($)	5,592,469,167
Number of Portfolio Holdings	95
Total Net Advisory Fees Paid ($)	1,952,349
Weighted Average Maturity	30 days
7-Day Current Yield	3.56%

Yields fluctuate and are not guaranteed. The 7-day current yield is the annualized net investment income per share as of April 30, 2026. The 7-Day Current Yield would have been 3.53% had certain expenses not been reduced.

Holdings [Text Block]

What did the Fund invest in?

Asset Allocation

Table Summary
Asset Type	% of Net Assets
Government & Agency Obligations	53%
Repurchase Agreements	46%
Other Assets and Liabilities, Net	1%
Total	100%

Holdings-based data is subject to change.

C000035157

Shareholder Report [Line Items]

Fund Name

DWS Government & Agency Securities Portfolio

Class Name

Government Cash Managed Shares

Trading Symbol

DCMXX

Annual or Semi-Annual Statement [Text Block]

This annual shareholder report contains important information about DWS Government & Agency Securities Portfolio (the "Fund") for the period May 1, 2025 to April 30, 2026.

Additional Information [Text Block]

You can find additional information about the Fund on the Fund's website at dws.com/mutualreports. You can also request this information by contacting us at (800) 730-1313.

Additional Information Phone Number

(800) 730-1313

Additional Information Website

Expenses [Text Block]

What were the Fund costs for the last year?

(Based on a hypothetical $10,000 investment)

Table Summary
Fund	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
Government Cash Managed Shares	$38	0.37%

Gross expense ratio as of the latest prospectus: 0.42%. See prospectus for any contractual or voluntary waivers; without a waiver, costs would have been higher.

Expenses Paid, Amount

$ 38

Expense Ratio, Percent

0.37%

AssetsNet

$ 5,592,469,167

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 1,952,349

Additional Fund Statistics [Text Block]

Key Fund Statistics

Table Summary
Net Assets ($)	5,592,469,167
Number of Portfolio Holdings	95
Total Net Advisory Fees Paid ($)	1,952,349
Weighted Average Maturity	30 days
7-Day Current Yield	3.34%

Yields fluctuate and are not guaranteed. The 7-day current yield is the annualized net investment income per share as of April 30, 2026. The 7-Day Current Yield would have been 3.24% had certain expenses not been reduced.

Holdings [Text Block]

What did the Fund invest in?

Asset Allocation

Table Summary
Asset Type	% of Net Assets
Government & Agency Obligations	53%
Repurchase Agreements	46%
Other Assets and Liabilities, Net	1%
Total	100%

Holdings-based data is subject to change.

C000017334

Shareholder Report [Line Items]

Fund Name

DWS Government & Agency Securities Portfolio

Class Name

Service Shares

Trading Symbol

CAGXX

Annual or Semi-Annual Statement [Text Block]

This annual shareholder report contains important information about DWS Government & Agency Securities Portfolio (the "Fund") for the period May 1, 2025 to April 30, 2026.

Additional Information [Text Block]

You can find additional information about the Fund on the Fund's website at dws.com/mutualreports. You can also request this information by contacting us at (800) 730-1313.

Additional Information Phone Number

(800) 730-1313

Additional Information Website

Expenses [Text Block]

What were the Fund costs for the last year?

(Based on a hypothetical $10,000 investment)

Table Summary
Fund	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
Service Shares	$102	1.00%

Gross expense ratio as of the latest prospectus: 1.05%. See prospectus for any contractual or voluntary waivers; without a waiver, costs would have been higher.

Expenses Paid, Amount

$ 102

Expense Ratio, Percent

1.00%

AssetsNet

$ 5,592,469,167

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 1,952,349

Additional Fund Statistics [Text Block]

Key Fund Statistics

Table Summary
Net Assets ($)	5,592,469,167
Number of Portfolio Holdings	95
Total Net Advisory Fees Paid ($)	1,952,349
Weighted Average Maturity	30 days
7-Day Current Yield	2.71%

Yields fluctuate and are not guaranteed. The 7-day current yield is the annualized net investment income per share as of April 30, 2026. The 7-Day Current Yield would have been 2.63% had certain expenses not been reduced.

Holdings [Text Block]

What did the Fund invest in?

Asset Allocation

Table Summary
Asset Type	% of Net Assets
Government & Agency Obligations	53%
Repurchase Agreements	46%
Other Assets and Liabilities, Net	1%
Total	100%

Holdings-based data is subject to change.

C000017348

Shareholder Report [Line Items]

Fund Name

DWS Tax-Exempt Portfolio

Class Name

DWS Tax-Exempt Cash Premier Shares

Trading Symbol

SCIXX

Annual or Semi-Annual Statement [Text Block]

This annual shareholder report contains important information about DWS Tax-Exempt Portfolio (the "Fund") for the period May 1, 2025 to April 30, 2026.

Additional Information [Text Block]

You can find additional information about the Fund on the Fund's website at dws.com/mutualreports. You can also request this information by contacting us at (800) 730-1313.

Additional Information Phone Number

(800) 730-1313

Additional Information Website

Expenses [Text Block]

What were the Fund costs for the last year?

(Based on a hypothetical $10,000 investment)

Table Summary
Fund	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
DWS Tax-Exempt Cash Premier Shares	$20	0.20%

Gross expense ratio as of the latest prospectus: 0.42%. See prospectus for any contractual or voluntary waivers; without a waiver, costs would have been higher.

Expenses Paid, Amount

$ 20

Expense Ratio, Percent

0.20%

AssetsNet

$ 106,483,500

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 0

Additional Fund Statistics [Text Block]

Key Fund Statistics

Table Summary
Net Assets ($)	106,483,500
Number of Portfolio Holdings	79
Total Net Advisory Fees Paid ($)	0
Weighted Average Maturity	6 days
7-Day Current Yield	3.21%

Yields fluctuate and are not guaranteed. The 7-day current yield is the annualized net investment income per share as of April 30, 2026. The 7-Day Current Yield would have been 2.82% had certain expenses not been reduced.

Holdings [Text Block]

What did the Fund invest in?

Asset Allocation

Table Summary
Asset Type	% of Net Assets
Variable Rate Demand Notes	94%
Tax-Exempt Commercial Paper	5%
Other Assets and Liabilities, Net	1%
Total	100%

Holdings-based data is subject to change.

C000035158

Shareholder Report [Line Items]

Fund Name

DWS Tax-Exempt Portfolio

Class Name

DWS Tax-Exempt Money Fund

Trading Symbol

DTBXX

Annual or Semi-Annual Statement [Text Block]

This annual shareholder report contains important information about DWS Tax-Exempt Portfolio (the "Fund") for the period May 1, 2025 to April 30, 2026.

Additional Information [Text Block]

You can find additional information about the Fund on the Fund's website at dws.com/mutualreports. You can also request this information by contacting us at (800) 728-3337.

Additional Information Phone Number

(800) 728-3337

Additional Information Website

Expenses [Text Block]

What were the Fund costs for the last year?

(Based on a hypothetical $10,000 investment)

Table Summary
Fund	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
DWS Tax-Exempt Money Fund	$24	0.24%

Gross expense ratio as of the latest prospectus: 0.41%. See prospectus for any contractual or voluntary waivers; without a waiver, costs would have been higher.

Expenses Paid, Amount

$ 24

Expense Ratio, Percent

0.24%

AssetsNet

$ 106,483,500

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 0

Additional Fund Statistics [Text Block]

Key Fund Statistics

Table Summary
Net Assets ($)	106,483,500
Number of Portfolio Holdings	79
Total Net Advisory Fees Paid ($)	0
Weighted Average Maturity	6 days
7-Day Current Yield	3.21%

Holdings [Text Block]

What did the Fund invest in?

Asset Allocation

Table Summary
Asset Type	% of Net Assets
Variable Rate Demand Notes	94%
Tax-Exempt Commercial Paper	5%
Other Assets and Liabilities, Net	1%
Total	100%

Holdings-based data is subject to change.

C000035159

Shareholder Report [Line Items]

Fund Name

DWS Tax-Exempt Portfolio

Class Name

DWS Tax-Free Money Fund Class S

Trading Symbol

DTCXX

Annual or Semi-Annual Statement [Text Block]

This annual shareholder report contains important information about DWS Tax-Exempt Portfolio (the "Fund") for the period May 1, 2025 to April 30, 2026.

Additional Information [Text Block]

You can find additional information about the Fund on the Fund's website at dws.com/mutualreports. You can also request this information by contacting us at (800) 728-3337.

Additional Information Phone Number

(800) 728-3337

Additional Information Website

Expenses [Text Block]

What were the Fund costs for the last year?

(Based on a hypothetical $10,000 investment)

Table Summary
Fund	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
DWS Tax-Free Money Fund Class S	$28	0.28%

Gross expense ratio as of the latest prospectus: 0.45%. See prospectus for any contractual or voluntary waivers; without a waiver, costs would have been higher.

Expenses Paid, Amount

$ 28

Expense Ratio, Percent

0.28%

AssetsNet

$ 106,483,500

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 0

Additional Fund Statistics [Text Block]

Key Fund Statistics

Table Summary
Net Assets ($)	106,483,500
Number of Portfolio Holdings	79
Total Net Advisory Fees Paid ($)	0
Weighted Average Maturity	6 days
7-Day Current Yield	3.13%

Yields fluctuate and are not guaranteed. The 7-day current yield is the annualized net investment income per share as of April 30, 2026. The 7-Day Current Yield would have been 2.79% had certain expenses not been reduced.

Holdings [Text Block]

What did the Fund invest in?

Asset Allocation

Table Summary
Asset Type	% of Net Assets
Variable Rate Demand Notes	94%
Tax-Exempt Commercial Paper	5%
Other Assets and Liabilities, Net	1%
Total	100%

Holdings-based data is subject to change.

C000017350

Shareholder Report [Line Items]

Fund Name

DWS Tax-Exempt Portfolio

Class Name

Tax-Exempt Cash Managed Shares

Trading Symbol

TXMXX

Annual or Semi-Annual Statement [Text Block]

This annual shareholder report contains important information about DWS Tax-Exempt Portfolio (the "Fund") for the period May 1, 2025 to April 30, 2026.

Additional Information [Text Block]

You can find additional information about the Fund on the Fund's website at dws.com/mutualreports. You can also request this information by contacting us at (800) 730-1313.

Additional Information Phone Number

(800) 730-1313

Additional Information Website

Expenses [Text Block]

What were the Fund costs for the last year?

(Based on a hypothetical $10,000 investment)

Table Summary
Fund	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
Tax-Exempt Cash Managed Shares	$35	0.35%

Gross expense ratio as of the latest prospectus: 0.53%. See prospectus for any contractual or voluntary waivers; without a waiver, costs would have been higher.

Expenses Paid, Amount

$ 35

Expense Ratio, Percent

0.35%

AssetsNet

$ 106,483,500

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 0

Additional Fund Statistics [Text Block]

Key Fund Statistics

Table Summary
Net Assets ($)	106,483,500
Number of Portfolio Holdings	79
Total Net Advisory Fees Paid ($)	0
Weighted Average Maturity	6 days
7-Day Current Yield	3.06%

Holdings [Text Block]

What did the Fund invest in?

Asset Allocation

Table Summary
Asset Type	% of Net Assets
Variable Rate Demand Notes	94%
Tax-Exempt Commercial Paper	5%
Other Assets and Liabilities, Net	1%
Total	100%

Holdings-based data is subject to change.

C000035160

Shareholder Report [Line Items]

Fund Name

DWS Tax-Exempt Portfolio

Class Name

Tax-Free Investment Class

Trading Symbol

DTDXX

Annual or Semi-Annual Statement [Text Block]

This annual shareholder report contains important information about DWS Tax-Exempt Portfolio (the "Fund") for the period May 1, 2025 to April 30, 2026.

Additional Information [Text Block]

You can find additional information about the Fund on the Fund's website at dws.com/mutualreports. You can also request this information by contacting us at (800) 730-1313.

Additional Information Phone Number

(800) 730-1313

Additional Information Website

Expenses [Text Block]

What were the Fund costs for the last year?

(Based on a hypothetical $10,000 investment)

Table Summary
Fund	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
Tax-Free Investment Class	$61	0.60%

Gross expense ratio as of the latest prospectus: 0.78%. See prospectus for any contractual or voluntary waivers; without a waiver, costs would have been higher.

Expenses Paid, Amount

$ 61

Expense Ratio, Percent

0.60%

AssetsNet

$ 106,483,500

Holdings Count | Holding

Advisory Fees Paid, Amount

$ 0

Additional Fund Statistics [Text Block]

Key Fund Statistics

Table Summary
Net Assets ($)	106,483,500
Number of Portfolio Holdings	79
Total Net Advisory Fees Paid ($)	0
Weighted Average Maturity	6 days
7-Day Current Yield	2.81%

Yields fluctuate and are not guaranteed. The 7-day current yield is the annualized net investment income per share as of April 30, 2026. The 7-Day Current Yield would have been 2.50% had certain expenses not been reduced.

Holdings [Text Block]

What did the Fund invest in?

Asset Allocation

Table Summary
Asset Type	% of Net Assets
Variable Rate Demand Notes	94%
Tax-Exempt Commercial Paper	5%
Other Assets and Liabilities, Net	1%
Total	100%

Holdings-based data is subject to change.