2.4.0.81097 - Disclosure - Asset-Backed Securities Issued - Additional Information (Detail)truefalsefalse1false falsefalseeol_PE798-----1310-Q0007_STD_181_20130630_0http://www.sec.gov/CIK0000930236duration2013-01-01T00:00:002013-06-30T00:00:002false USDtruefalse$eol_PE798-----1310-Q0007_STD_182_20120630_0_711461x711371http://www.sec.gov/CIK0000930236duration2012-01-01T00:00:002012-06-30T00:00:00falsefalseAsset-backed Securitiesus-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_AssetBackedSecuritiesMemberus-gaap_DebtInstrumentAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3false USDtruefalse$eol_PE798-----1310-Q0007_STD_0_20130630_0_711461x711371http://www.sec.gov/CIK0000930236instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseAsset-backed Securitiesus-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_AssetBackedSecuritiesMemberus-gaap_DebtInstrumentAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$4false USDtruefalse$eol_PE798-----1310-Q0007_STD_0_20121231_0_711461x711371http://www.sec.gov/CIK0000930236instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseAsset-backed Securitiesus-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_AssetBackedSecuritiesMemberus-gaap_DebtInstrumentAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$5false USDtruefalse$eol_PE798-----1310-Q0007_STD_181_20130630_0_711461x711371_711502x716112http://www.sec.gov/CIK0000930236duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseAsset-backed Securitiesus-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_AssetBackedSecuritiesMemberus-gaap_DebtInstrumentAxisexplicitMemberfalsefalseMaximumus-gaap_RangeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_MaximumMemberus-gaap_RangeAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$6false USDtruefalse$eol_PE798-----1310-Q0007_STD_0_20130630_0_711461x711371_711801x735107http://www.sec.gov/CIK0000930236instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseAsset-backed Securitiesus-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_AssetBackedSecuritiesMemberus-gaap_DebtInstrumentAxisexplicitMemberfalsefalseContractual maturities of over five yearsus-gaap_InvestmentSecondaryCategorizationAxisxbrldihttp://xbrl.org/2006/xbrldirwt_MaturityOverFiveYearsMemberus-gaap_InvestmentSecondaryCategorizationAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$7false USDtruefalse$eol_PE798-----1310-Q0007_STD_0_20130630_0_711461x711371_711801x826334http://www.sec.gov/CIK0000930236instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseAsset-backed Securitiesus-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_AssetBackedSecuritiesMemberus-gaap_DebtInstrumentAxisexplicitMemberfalsefalseContractual maturities of one to five yearsus-gaap_InvestmentSecondaryCategorizationAxisxbrldihttp://xbrl.org/2006/xbrldirwt_MaturityOneToFiveYearsMemberus-gaap_InvestmentSecondaryCategorizationAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$8false USDtruefalse$eol_PE798-----1310-Q0007_STD_0_20130630_0_710256x740247_711461x711371http://www.sec.gov/CIK0000930236instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseAsset-backed Securitiesus-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_AssetBackedSecuritiesMemberus-gaap_DebtInstrumentAxisexplicitMemberfalsefalseCertificates With Principal Valueus-gaap_InvestmentTypeAxisxbrldihttp://xbrl.org/2006/xbrldirwt_CertificatesWithPrincipalValueMemberus-gaap_InvestmentTypeAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$9false USDtruefalse$eol_PE798-----1310-Q0007_STD_0_20121231_0_710256x740247_711461x711371http://www.sec.gov/CIK0000930236instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseAsset-backed Securitiesus-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_AssetBackedSecuritiesMemberus-gaap_DebtInstrumentAxisexplicitMemberfalsefalseCertificates With Principal Valueus-gaap_InvestmentTypeAxisxbrldihttp://xbrl.org/2006/xbrldirwt_CertificatesWithPrincipalValueMemberus-gaap_InvestmentTypeAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$10false USDtruefalse$eol_PE798-----1310-Q0007_STD_0_20130630_0_710256x740247_711461x711371_711801x735107http://www.sec.gov/CIK0000930236instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseAsset-backed Securitiesus-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_AssetBackedSecuritiesMemberus-gaap_DebtInstrumentAxisexplicitMemberfalsefalseCertificates With Principal Valueus-gaap_InvestmentTypeAxisxbrldihttp://xbrl.org/2006/xbrldirwt_CertificatesWithPrincipalValueMemberus-gaap_InvestmentTypeAxisexplicitMemberfalsefalseContractual maturities of over five yearsus-gaap_InvestmentSecondaryCategorizationAxisxbrldihttp://xbrl.org/2006/xbrldirwt_MaturityOverFiveYearsMemberus-gaap_InvestmentSecondaryCategorizationAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$11false USDtruefalse$eol_PE798-----1310-Q0007_STD_0_20130630_0_710256x740247_711461x711371_711801x826334http://www.sec.gov/CIK0000930236instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseAsset-backed Securitiesus-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_AssetBackedSecuritiesMemberus-gaap_DebtInstrumentAxisexplicitMemberfalsefalseCertificates With Principal Valueus-gaap_InvestmentTypeAxisxbrldihttp://xbrl.org/2006/xbrldirwt_CertificatesWithPrincipalValueMemberus-gaap_InvestmentTypeAxisexplicitMemberfalsefalseContractual maturities of one to five yearsus-gaap_InvestmentSecondaryCategorizationAxisxbrldihttp://xbrl.org/2006/xbrldirwt_MaturityOneToFiveYearsMemberus-gaap_InvestmentSecondaryCategorizationAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 3us-gaap_DebtInstrumentLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Debt Instrument [Line Items]2false 4us-gaap_DebtInstrumentInterestRateTermsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00Substantially all ABS issued pay variable rates of interest, which are indexed to one-, three-, or six-month LIBOR.falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringDescription of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 false0Description of interest rate3false 4us-gaap_SecuredDebtus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3truefalsefalse22142960002214296000USD$falsetruefalse4truefalsefalse25299410002529941000USD$falsetruefalse5falsefalsefalse00falsefalsefalse6truefalsefalse21800000002180000000USD$falsetruefalse7truefalsefalse3800000038000000USD$falsetruefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryCarrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 20, 22 -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 false2ABS issued4false 4us-gaap_DebtInstrumentFaceAmountus-gaap_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:monetaryItemTypemonetaryFace (par) amount of debt instrument at time of issuance.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400 false2Principal value5false 4rwt_LongTermMarketableSecuritiesMaturitiesTermrwt_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse005 yearsfalsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaLong Term Marketable Securities Maturities TermNo definition available.false0Contractual maturities of ABS (in years)6false 4rwt_LongTermMarketableSecuritiesMaturitiesTermMinimumrwt_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse001 yearfalsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaLong Term Marketable Securities Maturities Term, MinimumNo definition available.false0Contractual maturities of ABS, minimum (in years)7false 4rwt_LongTermMarketableSecuritiesMaturitiesTermMaximumrwt_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse005 yearsfalsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaLong Term Marketable Securities Maturities Term, MaximumNo definition available.false0Contractual maturities of ABS, maximum (in years)8false 4us-gaap_AmortizationOfFinancingCostsus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2truefalsefalse10000001000000USD$falsetruefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5truefalsefalse10000001000000USD$falsetruefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of noncash expense included in interest expense to issue debt and obtain financing associated with the related debt instruments. Alternate captions include noncash interest expense.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=31042434&loc=d3e3602-108585 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 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 8 -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 8 -Article 9 false2Amortization of deferred ABS issuance costsfalseAsset-Backed Securities Issued - Additional Information (Detail) (USD $)NoRoundingUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.redwoodtrust.com/taxonomy/role/DisclosureAssetBackedSecuritiesIssuedAdditionalInformation118