XML 136 R64.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Fair Value of Financial Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013
Residential Subordinate Securities |  |
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] |  |
Fair value option elected aggregate carrying amount, asset | $ 9 rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod / invest_InvestmentSecuritiesClassAxis = rwt_ResidentialSubordinateSecuritiesMember | $ 4 rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod / invest_InvestmentSecuritiesClassAxis = rwt_ResidentialSubordinateSecuritiesMember
Residential Loans |  |
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] |  |
Fair value option elected aggregate carrying amount, asset | 8,810 rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialMortgageMember | 7,090 rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialMortgageMember
Mortgage Servicing Rights |  |
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] |  |
Fair value option elected aggregate carrying amount, asset | 96 rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod / invest_InvestmentSecuritiesClassAxis = rwt_MortgageServicingRightsMember | 48 rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod / invest_InvestmentSecuritiesClassAxis = rwt_MortgageServicingRightsMember
Guarantee Asset |  |
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] |  |
Fair value option elected aggregate carrying amount, asset | 7 rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod / invest_InvestmentSecuritiesClassAxis = rwt_AssetValueGuaranteesMember |
Senior Securities | Residential |  |
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] |  |
Fair value option elected aggregate carrying amount, asset | 77 rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember | 105 rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod / invest_InvestmentSecuritiesClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_InvestmentTypeAxis = rwt_SeniorSecuritiesMember
Senior Loans | Commercial Loans |  |
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] |  |
Fair value option elected aggregate carrying amount, asset | $ 935 rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod / invest_InvestmentSecuritiesClassAxis = us-gaap_CommercialLoanMember / us-gaap_InvestmentTypeAxis = us-gaap_SeniorLoansMember | $ 505 rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod / invest_InvestmentSecuritiesClassAxis = us-gaap_CommercialLoanMember / us-gaap_InvestmentTypeAxis = us-gaap_SeniorLoansMember
Mortgage Servicing Rights | Maximum |  |
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] |  |
Percentage difference of internal valuation than dealer marks | 2.00%rwt_PercentageDifferenceOfInternalValuationThanDealerMarks / us-gaap_InvestmentTypeAxis = rwt_MortgageServicingRightsMember / us-gaap_RangeAxis = us-gaap_MaximumMember |
Asset-backed Securities |  |
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items] |  |
Percentage difference of internal valuation than dealer marks | 1.00%rwt_PercentageDifferenceOfInternalValuationThanDealerMarks / us-gaap_InvestmentTypeAxis = us-gaap_AssetBackedSecuritiesMember |
Dealer marks of securities | 44.00%rwt_PercentageOfDealerQuotesReceivedOnSecurities / us-gaap_InvestmentTypeAxis = us-gaap_AssetBackedSecuritiesMember |

X
- Definition Fair Value, Option, Assets, Aggregate Carrying Amount During Period + References No definition available. + Details
Name: | rwt_FairValueOptionAssetsAggregateCarryingAmountDuringPeriod
Namespace Prefix: | rwt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage Difference Of Internal Valuation Than Dealer Marks + References No definition available. + Details
Name: | rwt_PercentageDifferenceOfInternalValuationThanDealerMarks
Namespace Prefix: | rwt_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of Third-party Dealer Quotes Received on Securities. + References No definition available. + Details
Name: | rwt_PercentageOfDealerQuotesReceivedOnSecurities
Namespace Prefix: | rwt_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | invest_InvestmentSecuritiesClassAxis=rwt_AssetValueGuaranteesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesClassAxis=rwt_MortgageServicingRightsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesClassAxis=rwt_ResidentialSubordinateSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesClassAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=rwt_MortgageServicingRightsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=rwt_SeniorSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_SeniorLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |