XML 45 R67.htm IDEA: XBRL DOCUMENT v2.4.1.9
Fair Value of Financial Instruments - Quantitative Information about Significant Unobservable Inputs Used in Valuation of Level 3 Assets and Liabilities Measured at Fair Value (Detail) (USD $)
 3 Months Ended
Mar. 31, 2015
Asset-backed Securities  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 1,239,065,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
Asset-backed Securities | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 4.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Prepayment rate 0.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Credit support 0.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Loss severity 20.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Default rate 0.00%us-gaap_FairValueInputsProbabilityOfDefault
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Asset-backed Securities | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 8.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Prepayment rate 31.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Credit support 65.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Loss severity 32.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Default rate 12.00%us-gaap_FairValueInputsProbabilityOfDefault
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Asset-backed Securities | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 5.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Prepayment rate 13.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Credit support 11.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Loss severity 26.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Default rate 6.00%us-gaap_FairValueInputsProbabilityOfDefault
/ us-gaap_FairValueByLiabilityClassAxis
= us-gaap_AssetBackedSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Commercial Secured Borrowings  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 68,077,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByLiabilityClassAxis
= rwt_CommercialSecuredLoanMember
Commercial Secured Borrowings | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Spread to swap rate 1.56%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByLiabilityClassAxis
= rwt_CommercialSecuredLoanMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Credit support 23.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByLiabilityClassAxis
= rwt_CommercialSecuredLoanMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Commercial Secured Borrowings | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Spread to swap rate 1.56%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByLiabilityClassAxis
= rwt_CommercialSecuredLoanMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Credit support 23.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByLiabilityClassAxis
= rwt_CommercialSecuredLoanMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Commercial Secured Borrowings | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Spread to swap rate 1.56%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByLiabilityClassAxis
= rwt_CommercialSecuredLoanMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Credit support 23.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByLiabilityClassAxis
= rwt_CommercialSecuredLoanMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Residential Loans Priced To Securitization and Whole Loan Market, Uncommitted to Sell  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 1,334,594,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
Residential Loans Priced To Securitization and Whole Loan Market, Uncommitted to Sell | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 4.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Prepayment rate 12.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Senior credit spread to TBA (usd per senior security) 3.13rwt_FairValueInputsSubordinateSpreadToSwap
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Spread to swap rate 3.15%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Credit support 8.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Whole loan spread to TBA (usd per loan) 3.10rwt_FairValueInputsWholeLoanSpread
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Residential Loans Priced To Securitization and Whole Loan Market, Uncommitted to Sell | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 5.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Prepayment rate 15.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Senior credit spread to TBA (usd per senior security) 3.13rwt_FairValueInputsSubordinateSpreadToSwap
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Spread to swap rate 3.15%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Credit support 8.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Whole loan spread to TBA (usd per loan) 4.50rwt_FairValueInputsWholeLoanSpread
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Residential Loans Priced To Securitization and Whole Loan Market, Uncommitted to Sell | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 420.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Prepayment rate 14.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Senior credit spread to TBA (usd per senior security) 3.13rwt_FairValueInputsSubordinateSpreadToSwap
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Spread to swap rate 3.15%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Credit support 8.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Whole loan spread to TBA (usd per loan) 4.35rwt_FairValueInputsWholeLoanSpread
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToSecuritizationAndWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Residential Jumbo Hybrid Loans Priced To Whole Loan Market Uncommitted To Sell  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 137,168,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialJumboHybridLoansPricedToWholeLoanMarketUncommittedToSellMember
Residential Jumbo Hybrid Loans Priced To Whole Loan Market Uncommitted To Sell | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Prepayment rate 15.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialJumboHybridLoansPricedToWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Spread to swap rate 1.25%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialJumboHybridLoansPricedToWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Residential Jumbo Hybrid Loans Priced To Whole Loan Market Uncommitted To Sell | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Prepayment rate 15.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialJumboHybridLoansPricedToWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Spread to swap rate 1.65%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialJumboHybridLoansPricedToWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Residential Jumbo Hybrid Loans Priced To Whole Loan Market Uncommitted To Sell | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Prepayment rate 15.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialJumboHybridLoansPricedToWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Spread to swap rate 1.34%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialJumboHybridLoansPricedToWholeLoanMarketUncommittedToSellMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Residential Loans Priced To Whole Loan Market and Committed to Sell  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 421,226,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToWholeLoanMarketandCommittedtoSellMember
Residential Loans Priced To Whole Loan Market and Committed to Sell | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Committed Sales Price 102rwt_FairValueInputsCommittedSalesPrice
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToWholeLoanMarketandCommittedtoSellMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Residential Loans Priced To Whole Loan Market and Committed to Sell | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Committed Sales Price 103rwt_FairValueInputsCommittedSalesPrice
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToWholeLoanMarketandCommittedtoSellMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Residential Loans Priced To Whole Loan Market and Committed to Sell | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Committed Sales Price 103,000rwt_FairValueInputsCommittedSalesPrice
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansPricedToWholeLoanMarketandCommittedtoSellMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Residential Loans Held For Investment at Fair Value  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 1,304,426,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansHeldForInvestmentAtFairValueMember
Residential Loans at Lower of Cost or Fair Value  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 1,103,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansAtLowerOfCostOrFairValueMember
Residential Loans at Lower of Cost or Fair Value | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Loss severity 13.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansAtLowerOfCostOrFairValueMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Residential Loans at Lower of Cost or Fair Value | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Loss severity 30.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansAtLowerOfCostOrFairValueMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Residential Loans at Lower of Cost or Fair Value | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Loss severity 20.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= rwt_ResidentialLoansAtLowerOfCostOrFairValueMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Commercial Loans at Fair Value  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 127,026,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByAssetClassAxis
= rwt_CommercialLoansAtFairValueMember
Commercial Loans at Fair Value | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Spread to swap rate 1.47%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByAssetClassAxis
= rwt_CommercialLoansAtFairValueMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Credit support 22.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByAssetClassAxis
= rwt_CommercialLoansAtFairValueMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Commercial Loans at Fair Value | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Spread to swap rate 1.56%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByAssetClassAxis
= rwt_CommercialLoansAtFairValueMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Credit support 23.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByAssetClassAxis
= rwt_CommercialLoansAtFairValueMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Commercial Loans at Fair Value | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Spread to swap rate 1.54%rwt_FairValueInputsCreditSpreads
/ us-gaap_FairValueByAssetClassAxis
= rwt_CommercialLoansAtFairValueMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Credit support 23.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByAssetClassAxis
= rwt_CommercialLoansAtFairValueMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Investment Securities  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 1,285,243,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
Investment Securities | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 4.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Prepayment rate 1.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Credit support 0.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Loss severity 20.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Default rate 0.00%us-gaap_FairValueInputsProbabilityOfDefault
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Investment Securities | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 12.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Prepayment rate 35.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Credit support 48.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Loss severity 64.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Default rate 35.00%us-gaap_FairValueInputsProbabilityOfDefault
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Investment Securities | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 6.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Prepayment rate 12.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Credit support 10.00%rwt_FairValueInputsCreditSupport
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Loss severity 34.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Default rate 8.00%us-gaap_FairValueInputsProbabilityOfDefault
/ us-gaap_FairValueByAssetClassAxis
= rwt_InvestmentSecuritiesMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Mortgage Servicing Rights  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 120,324,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByAssetClassAxis
= rwt_MortgageServicingRightsMember
Mortgage Servicing Rights | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 9.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_MortgageServicingRightsMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Prepayment rate 4.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_MortgageServicingRightsMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Per loan annual cost to service 72rwt_FairValueInputsPerLoanAnnualCostToService
/ us-gaap_FairValueByAssetClassAxis
= rwt_MortgageServicingRightsMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Mortgage Servicing Rights | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 11.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_MortgageServicingRightsMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Prepayment rate 60.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_MortgageServicingRightsMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Per loan annual cost to service 82rwt_FairValueInputsPerLoanAnnualCostToService
/ us-gaap_FairValueByAssetClassAxis
= rwt_MortgageServicingRightsMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Mortgage Servicing Rights | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 10.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_MortgageServicingRightsMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Prepayment rate 14.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_MortgageServicingRightsMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Per loan annual cost to service 77rwt_FairValueInputsPerLoanAnnualCostToService
/ us-gaap_FairValueByAssetClassAxis
= rwt_MortgageServicingRightsMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Guarantee asset  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 6,118,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByAssetClassAxis
= rwt_GuaranteeAssetMember
Guarantee asset | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 11.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_GuaranteeAssetMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Prepayment rate 5.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_GuaranteeAssetMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Guarantee asset | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 11.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_GuaranteeAssetMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Prepayment rate 27.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_GuaranteeAssetMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Guarantee asset | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Discount rate 11.00%us-gaap_FairValueInputsDiscountRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_GuaranteeAssetMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Prepayment rate 12.00%us-gaap_FairValueInputsPrepaymentRate
/ us-gaap_FairValueByAssetClassAxis
= rwt_GuaranteeAssetMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
REO  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 3,410,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByAssetClassAxis
= rwt_OtherRealEstateOwnedMember
REO | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Loss severity 31.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= rwt_OtherRealEstateOwnedMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
REO | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Loss severity 66.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= rwt_OtherRealEstateOwnedMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
REO | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Loss severity 46.00%us-gaap_FairValueInputsLossSeverity
/ us-gaap_FairValueByAssetClassAxis
= rwt_OtherRealEstateOwnedMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Loan Purchase Commitments  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
Fair Value 7,425,000us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_LoanPurchaseCommitmentsMember
Loan Purchase Commitments | Minimum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
MSR Multiple 0rwt_FairValueInputsMortgageServicingRightMultiple
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_LoanPurchaseCommitmentsMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Fallout rate 2.00%rwt_FairValueInputsFalloutRate
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_LoanPurchaseCommitmentsMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Loan Purchase Commitments | Maximum  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
MSR Multiple 6rwt_FairValueInputsMortgageServicingRightMultiple
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_LoanPurchaseCommitmentsMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Fallout rate 98.00%rwt_FairValueInputsFalloutRate
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_LoanPurchaseCommitmentsMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Loan Purchase Commitments | Weighted Average  
Fair Value Inputs, Assets, Quantitative Information [Line Items]  
MSR Multiple 3.5rwt_FairValueInputsMortgageServicingRightMultiple
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_LoanPurchaseCommitmentsMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember
Fallout rate 33.00%rwt_FairValueInputsFalloutRate
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_LoanPurchaseCommitmentsMember
/ us-gaap_RangeAxis
= us-gaap_WeightedAverageMember