CONDENSED SCHEDULE OF INVESTMENTS (Unaudited) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Investment Holdings [Line Items]
Net unrealized gain/(loss) on open contracts	$ 1,943,202	$ 2,551,354
Percentage of Partners' Capital (in hundredths)	1.02%	1.30%
Unrealized Currency Loss	(1,193,869)	(1,203,865)
Unrealized Currency Loss Percentage of Partners' Capital (in hundredths)	(0.63%)	(0.61%)
Contracts Purchased [Member] \| Futures And Forward Contracts [Member]
Investment Holdings [Line Items]
Net unrealized gain/(loss) on open contracts	2,990,286	2,076,324
Percentage of Partners' Capital (in hundredths)	1.57%	1.05%
Contracts Purchased [Member] \| Futures And Forward Contracts [Member] \| Commodity Contract [Member]
Investment Holdings [Line Items]
Net unrealized gain/(loss) on open contracts	419,645	(257,575)
Percentage of Partners' Capital (in hundredths)	0.22%	(0.13%)
Contracts Purchased [Member] \| Futures And Forward Contracts [Member] \| Equity Contract [Member]
Investment Holdings [Line Items]
Net unrealized gain/(loss) on open contracts	211,017	1,325,665
Percentage of Partners' Capital (in hundredths)	0.11%	0.67%
Contracts Purchased [Member] \| Futures And Forward Contracts [Member] \| Foreign Currency [Member]
Investment Holdings [Line Items]
Net unrealized gain/(loss) on open contracts	242,438	856,313
Percentage of Partners' Capital (in hundredths)	0.13%	0.43%
Contracts Purchased [Member] \| Futures And Forward Contracts [Member] \| Interest Rate Contract [Member]
Investment Holdings [Line Items]
Net unrealized gain/(loss) on open contracts	2,117,186	151,921
Percentage of Partners' Capital (in hundredths)	1.11%	0.08%
Contracts Sold [Member] \| Futures And Forward Contracts [Member]
Investment Holdings [Line Items]
Net unrealized gain/(loss) on open contracts	146,785	1,678,895
Percentage of Partners' Capital (in hundredths)	0.08%	0.86%
Contracts Sold [Member] \| Futures And Forward Contracts [Member] \| Commodity Contract [Member]
Investment Holdings [Line Items]
Net unrealized gain/(loss) on open contracts	681,870	(82,988)
Percentage of Partners' Capital (in hundredths)	0.36%	(0.04%)
Contracts Sold [Member] \| Futures And Forward Contracts [Member] \| Equity Contract [Member]
Investment Holdings [Line Items]
Net unrealized gain/(loss) on open contracts	135,784	(36,283)
Percentage of Partners' Capital (in hundredths)	0.07%	(0.02%)
Contracts Sold [Member] \| Futures And Forward Contracts [Member] \| Foreign Currency [Member]
Investment Holdings [Line Items]
Net unrealized gain/(loss) on open contracts	(534,839)	1,942,804
Percentage of Partners' Capital (in hundredths)	(0.28%)	0.99%
Contracts Sold [Member] \| Futures And Forward Contracts [Member] \| Interest Rate Contract [Member]
Investment Holdings [Line Items]
Net unrealized gain/(loss) on open contracts	$ (136,030)	$ (144,638)
Percentage of Partners' Capital (in hundredths)	(0.07%)	(0.07%)

This element represents the aggregate unrealized foreign currency transaction gain (loss) (pretax) included in determining total unrealized gains or losses for the reporting period. Represents the aggregate of gains (losses) on transactions that are unsettled as of the balance sheet date.

No definition available.

+ Details

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Namespace Prefix:	dwsf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percent of net assets at close of period related to unrealized currency gain (loss).

+ References

No definition available.

+ Details

Name:	dwsf_UnrealizedCurrencyGainPercentageOfPartnersCapital
Namespace Prefix:	dwsf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_InvestmentHoldingsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percent of net assets at close of period. For schedules of investments that are categorized, each category has a percent of net assets for the aggregated value of the Investments in the category.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 12

-Paragraph 3

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 12C

-Paragraph Column D

-Article 12

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 12C

-Paragraph 2

-Article 12

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 946

-SubTopic 320

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-12.3)

-URI http://asc.fasb.org/extlink&oid=6955306&loc=d3e611133-123010

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 946

-SubTopic 320

-Section S99

-Paragraph 4

-Subparagraph (SX 210.12-12C.Column D.2)

-URI http://asc.fasb.org/extlink&oid=6955306&loc=d3e611225-123010

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the net excess or deficiency of the fair value of an investment (security, contract) over or under its cost (face amount, notional amount), respectively, which excess value or deficiency has not been recognized in earnings of the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-INV

-Section Glossary

-IssueDate 2008-05-01

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant