2.4.0.8090502 - Disclosure - Derivatives and Hedging, Effect of Trading Activities on the Statements of Financial Condition (Details)truefalsefalse1false USDfalsefalse$c20130401to20130630http://www.sec.gov/CIK0001097396duration2013-04-01T00:00:002013-06-30T00:00:00U002Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false USDfalsefalse$c20120401to20120630http://www.sec.gov/CIK0001097396duration2012-04-01T00:00:002012-06-30T00:00:00U002Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3false USDfalsefalse$c20130101to20130630http://www.sec.gov/CIK0001097396duration2013-01-01T00:00:002013-06-30T00:00:00U002Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$4false USDfalsefalse$c20120101to20120630http://www.sec.gov/CIK0001097396duration2012-01-01T00:00:002012-06-30T00:00:00U002Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$5false USDfalsefalse$c20121231http://www.sec.gov/CIK0001097396instant2012-12-31T00:00:000001-01-01T00:00:00U002Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 4dwsx_FuturesAndForwardContractsAbstractdwsx_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Futures and Forward Contracts [Abstract]2false 5dwsx_InvestmentOwnedUnrealizedCurrencyGainLossdwsx_falsedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse-83271-83271USD$falsetruefalse2falsefalsefalse00falsefalsefalse3truefalsefalse-83271-83271USD$falsetruefalse4falsefalsefalse00falsefalsefalse5truefalsefalse18331833USD$falsetruefalsexbrli:monetaryItemTypemonetaryThis element represents the aggregate unrealized foreign currency transaction gain (loss) (pretax) included in determining total unrealized gains or losses for the reporting period. 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This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. true2Total net unrealized gain on open contracts4true 4dwsx_EffectOfTradingActivitiesOnStatementsOfIncomeAbstractdwsx_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Effect of Trading Activities on Statements of Income [Abstract]5false 5us-gaap_ForeignCurrencyTransactionGainLossUnrealizedus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse-13160-13160USD$falsefalsefalse2truefalsefalse-2785-2785USD$falsefalsefalse3truefalsefalse-85103-85103USD$falsefalsefalse4truefalsefalse-3078-3078USD$falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe aggregate unrealized foreign currency transaction gain (loss) (pretax) included in determining net income for the reporting period. Represents the aggregate of gains (losses) on transactions that are unsettled as of the balance sheet date, which is therefore an adjustment to reconcile income (loss) from continuing operations to net cash provided by or used in continuing operations. Excludes foreign currency transactions designated as hedges of net investment in a foreign entity and intercompany foreign currency transactions that are of a long-term nature, when the entities to the transaction are consolidated, combined, or accounted for by the equity method in the reporting entity's financial statements. For certain entities, primarily banks, that are dealers in foreign exchange, foreign currency transaction gains (losses) may be disclosed as dealer gains (losses).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 -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. 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This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Unrealized currency gain (loss)6false 5us-gaap_TradingSecuritiesRealizedGainLossus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse576827576827USD$falsefalsefalse2truefalsefalse-285558-285558USD$falsefalsefalse3truefalsefalse554206554206USD$falsefalsefalse4truefalsefalse-287492-287492USD$falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThis item represents the gain (loss) realized during the period from the sale of trading securities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph c -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c)) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563 false2Net realized7false 5us-gaap_TradingSecuritiesUnrealizedHoldingGainLossus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse-293304-293304USD$falsefalsefalse2truefalsefalse-21261-21261USD$falsefalsefalse3truefalsefalse-152923-152923USD$falsefalsefalse4truefalsefalse5535755357USD$falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe net change in the difference between the fair value and the carrying value, or in the comparative fair values, of trading securities held at each balance sheet date, that was included in earnings for the period. 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Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=16383099&loc=d3e24584-111560 false2Net change in unrealized8false 5us-gaap_NetRealizedOrUnrealizedGainLossOnTradingSecuritiesus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse791025791025USD$falsefalsefalse2truefalsefalse-1474266-1474266USD$falsefalsefalse3truefalsefalse13495871349587USD$falsefalsefalse4truefalsefalse-1773915-1773915USD$falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe sum of the realized and unrealized net gain (loss) on trading securities during the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 12 -Subparagraph a -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. 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