Short-Term Debt - Collateral for Short-Term Debt Facilities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Short-term Debt [Line Items]
Short-term Debt Pledged as Collateral	$ 1,817,322	$ 2,299,034
Facilities
Short-term Debt [Line Items]
Total real estate securities owned	357,237	178,070
Restricted cash and other assets	1,541	1,097
Short-term Debt Pledged as Collateral	1,564,945	2,017,062
Servicer advance financing
Short-term Debt [Line Items]
Short-term Debt Pledged as Collateral	252,377	281,972
Cash	18,073	12,713
Servicer advances	234,304	269,259
Held-for-sale residential loans \| Facilities
Short-term Debt [Line Items]
Market value of loans pledged as collateral under short-term borrowing agreements	192,910	775,545
Business purpose loans \| Facilities
Short-term Debt [Line Items]
Market value of loans pledged as collateral under short-term borrowing agreements	783,632	871,072
HEI \| Facilities
Short-term Debt [Line Items]
Market value of loans pledged as collateral under short-term borrowing agreements	229,625	191,278
On balance sheet \| Facilities
Short-term Debt [Line Items]
Available-for-sale securities pledged as collateral	17,205	72,133
Sequoia \| Sequoia securities \| Short Term Borrowing Agreement \| Facilities
Short-term Debt [Line Items]
Trading securities pledged as collateral	67,455	74,170
Freddie Mac SLST \| Sequoia securities \| Short Term Borrowing Agreement
Short-term Debt [Line Items]
Trading securities pledged as collateral	231,313	0
Freddie Mac K-Series \| Sequoia securities \| Short Term Borrowing Agreement \| Facilities
Short-term Debt [Line Items]
Trading securities pledged as collateral	32,514	31,767
CAFL \| Sequoia securities \| Short Term Borrowing Agreement
Short-term Debt [Line Items]
Trading securities pledged as collateral	$ 8,750	$ 0

Restricted Cash and Other Assets Pledged as Collateral

No definition available.

Name:	rwt_RestrictedCashAndOtherAssetsPledgedAsCollateral
Namespace Prefix:	rwt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Servicer Advances Collateral

+ References

No definition available.

+ Details

Name:	rwt_ServicerAdvancesCollateral
Namespace Prefix:	rwt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Short Term Debt, Restricted

+ References

No definition available.

+ Details

Name:	rwt_ShortTermDebtRestricted
Namespace Prefix:	rwt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Short-term Debt Pledged as Collateral

+ References

No definition available.

+ Details

Name:	rwt_ShorttermDebtPledgedasCollateral
Namespace Prefix:	rwt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of cash collateral held for borrowed securities, for which the cash is restricted as to withdrawal or usage.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

+ Details

Name:	us-gaap_CashCollateralForBorrowedSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481420/860-30-50-1A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 954
-SubTopic 210
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480632/954-210-45-4

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 954
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480602/954-210-50-2

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleRestricted
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of restricted investment in debt security measured at fair value with change in fair value recognized in net income (trading).

+ References

+ Details

Name:	us-gaap_DebtSecuritiesTradingRestricted
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of the securities pledged as collateral against securities loaned.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483444/210-20-55-12

+ Details

Name:	us-gaap_SecuritiesLoanedFairValueOfCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ShortTermDebtLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=rwt_ServicerAdvanceFinancingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=rwt_ResidentialLoansHeldForSaleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=rwt_BusinessPurposeLoansAtRedwoodAndCAFLBridgeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=rwt_HomeEquityInvestmentReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=rwt_RealEstateSecuritiesOnBalanceSheetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=rwt_SequoiaChoiceSecuritizationEntitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=rwt_SequoiaSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=rwt_ShortTermBorrowingAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=rwt_FreddieMacSLSTSecuritizationEntitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=rwt_FreddieMacKSeriesSecuritizationEntitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=rwt_CAFLSecuritizationEntitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: