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Summary of Significant Valuation Assumptions for Available for Sale Securities (Detail) | 12 Months Ended
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Dec. 31, 2014
Prime | Minimum |
Schedule of Available-for-sale Securities [Line Items] |
Prepayment rates | 8.00%rwt_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosurePrepaymentRates / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Loss severity | 20.00%rwt_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureLossSeverity / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Projected default rate | 1.00%us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureOtherDefaultRate / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Prime | Maximum |
Schedule of Available-for-sale Securities [Line Items] |
Prepayment rates | 15.00%rwt_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosurePrepaymentRates / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Loss severity | 52.00%rwt_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureLossSeverity / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Projected default rate | 22.00%us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureOtherDefaultRate / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialPrimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Non-prime | Minimum |
Schedule of Available-for-sale Securities [Line Items] |
Prepayment rates | 10.00%rwt_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosurePrepaymentRates / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Loss severity | 35.00%rwt_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureLossSeverity / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Projected default rate | 15.00%us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureOtherDefaultRate / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Non-prime | Maximum |
Schedule of Available-for-sale Securities [Line Items] |
Prepayment rates | 10.00%rwt_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosurePrepaymentRates / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Loss severity | 35.00%rwt_AvailableForSaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureLossSeverity / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Projected default rate | 15.00%us-gaap_AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureOtherDefaultRate / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialSubprimeFinancingReceivableMember / us-gaap_RangeAxis = us-gaap_MaximumMember

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- Definition This item represents a significant valuation assumption on loss severity, represented as a percentage, which was considered as one of the potential factors in reaching a conclusion that the available-for-sale investments are not other-than-temporarily impaired. + References No definition available. + Details
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- Definition This item represents a significant valuation assumption on prepayment rates, represented as a percentage, which was considered as one of the potential factors in reaching a conclusion that the available-for-sale investments are not other-than-temporarily impaired. + References No definition available. + Details
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- Definition This item represents the default rate of the underlying assets in the security that were considered as one of the potential factors in reaching a conclusion that the available-for-sale investments are not other-than-temporarily impaired. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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- Details
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