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Real Estate Securities - Components of Carrying Value (Which Equals Fair Value) of Residential Available for Sale Securities (Detail) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2015 | Dec. 31, 2014
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Schedule of Available-for-sale Securities [Line Items] |  |
Carrying Value | $ 1,178,406 us-gaap_AvailableForSaleSecurities | $ 1,267,624 us-gaap_AvailableForSaleSecurities
Senior Securities |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Carrying Value | 472,746 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember | 487,557 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember
Senior Securities | Prime |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Carrying Value | 297,872 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember | 307,813 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember
Senior Securities | Non-prime |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Carrying Value | 174,874 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember | 179,744 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember
Re-REMIC |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Carrying Value | 169,239 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember | 168,347 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember
Subordinate Securities |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Carrying Value | 536,421 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember | 611,720 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember
Subordinate Securities | Prime |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Carrying Value | 370,391 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember | 448,838 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember
Subordinate Securities | Non-prime |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Carrying Value | 1,000 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember | 1,000 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember
Residential |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Principal balance | 1,335,622 rwt_AvailableForSaleSecuritiesPrincipalBalance / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 1,445,079 rwt_AvailableForSaleSecuritiesPrincipalBalance / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Credit reserve | (63,584)rwt_AvailableForSaleSecuritiesCreditReserve / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (70,067)rwt_AvailableForSaleSecuritiesCreditReserve / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Unamortized discount, net | (286,382)rwt_AvailableForSaleSecuritiesUnamortizedDiscountsPremiums / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (296,342)rwt_AvailableForSaleSecuritiesUnamortizedDiscountsPremiums / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Amortized cost | 985,656 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 1,078,670 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Gross unrealized gains | 195,636 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 191,750 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Gross unrealized losses | (2,886)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (2,796)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Carrying Value | 1,178,406 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 1,267,624 us-gaap_AvailableForSaleSecurities / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Residential | Senior Securities | Prime |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Principal balance | 302,046 rwt_AvailableForSaleSecuritiesPrincipalBalance / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 311,573 rwt_AvailableForSaleSecuritiesPrincipalBalance / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Credit reserve | (2,830)rwt_AvailableForSaleSecuritiesCreditReserve / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (3,660)rwt_AvailableForSaleSecuritiesCreditReserve / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Unamortized discount, net | (32,645)rwt_AvailableForSaleSecuritiesUnamortizedDiscountsPremiums / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (34,782)rwt_AvailableForSaleSecuritiesUnamortizedDiscountsPremiums / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Amortized cost | 266,571 us-gaap_AvailableForSaleSecuritiesAmortizedCost / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 273,131 us-gaap_AvailableForSaleSecuritiesAmortizedCost / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Gross unrealized gains | 33,313 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 35,980 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Gross unrealized losses | (2,012)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (1,298)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Carrying Value | 297,872 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 307,813 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Residential | Senior Securities | Non-prime |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Principal balance | 190,790 rwt_AvailableForSaleSecuritiesPrincipalBalance / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 196,258 rwt_AvailableForSaleSecuritiesPrincipalBalance / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Credit reserve | (9,027)rwt_AvailableForSaleSecuritiesCreditReserve / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (9,644)rwt_AvailableForSaleSecuritiesCreditReserve / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Unamortized discount, net | (29,791)rwt_AvailableForSaleSecuritiesUnamortizedDiscountsPremiums / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (31,491)rwt_AvailableForSaleSecuritiesUnamortizedDiscountsPremiums / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Amortized cost | 151,972 us-gaap_AvailableForSaleSecuritiesAmortizedCost / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 155,123 us-gaap_AvailableForSaleSecuritiesAmortizedCost / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Gross unrealized gains | 22,984 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 24,682 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Gross unrealized losses | (82)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (61)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Carrying Value | 174,874 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 179,744 us-gaap_AvailableForSaleSecurities / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Residential | Re-REMIC |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Principal balance | 194,296 rwt_AvailableForSaleSecuritiesPrincipalBalance / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 195,098 rwt_AvailableForSaleSecuritiesPrincipalBalance / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Credit reserve | (12,667)rwt_AvailableForSaleSecuritiesCreditReserve / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (15,202)rwt_AvailableForSaleSecuritiesCreditReserve / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Unamortized discount, net | (79,401)rwt_AvailableForSaleSecuritiesUnamortizedDiscountsPremiums / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (79,611)rwt_AvailableForSaleSecuritiesUnamortizedDiscountsPremiums / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Amortized cost | 102,228 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 100,285 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Gross unrealized gains | 67,011 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 68,062 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Gross unrealized losses | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Carrying Value | 169,239 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 168,347 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = rwt_ResecuritizationOfRealEstateMortgageInvestmentSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Residential | Subordinate Securities |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Principal balance | 648,490 rwt_AvailableForSaleSecuritiesPrincipalBalance / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 742,150 rwt_AvailableForSaleSecuritiesPrincipalBalance / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Credit reserve | (39,060)rwt_AvailableForSaleSecuritiesCreditReserve / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (41,561)rwt_AvailableForSaleSecuritiesCreditReserve / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Unamortized discount, net | (144,545)rwt_AvailableForSaleSecuritiesUnamortizedDiscountsPremiums / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (150,458)rwt_AvailableForSaleSecuritiesUnamortizedDiscountsPremiums / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Amortized cost | 464,885 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 550,131 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Gross unrealized gains | 72,328 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 63,026 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Gross unrealized losses | (792)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (1,437)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Carrying Value | $ 536,421 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | $ 611,720 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = rwt_SubordinateSecuritiesMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember

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- Definition Balance of net unamortized discount on available-for-sale securities. + References No definition available. + Details
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- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563 + Details
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- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563 + Details
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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562 + Details
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- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.2) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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