Components of Mortgage Servicing Rights Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Servicing income, net:
Income	$ 4,590	$ 3,008	$ 12,287	$ 5,820
Cost of sub-servicer	(437)	(355)	(1,040)	(767)
Net servicing income	4,153	2,653	11,247	5,053
Market valuation adjustments	2,321	460	(5,944)	9,628
MSR provision for repurchases	(653)		(653)
Income from MSRs, Net	$ 5,821	$ 3,113	$ 4,650	$ 14,681

Mortgage Servicing Expense

No definition available.

Name:	rwt_MortgageServicingExpense
Namespace Prefix:	rwt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Includes income from mortgage banking servicing real estate mortgages, net of subservicing costs, and market valuation changes of MSRs held at fair value.

+ References

No definition available.

+ Details

Name:	rwt_MortgageServicingRightsIncomeIncludingMarketValuationChangesOfMSRs
Namespace Prefix:	rwt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Provision for mortgage servicing rights repurchases.

+ References

No definition available.

+ Details

Name:	rwt_ProvisionForMortgageServicingRightsRepurchases
Namespace Prefix:	rwt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Total net change in market value related to mortgage servicing rights.

+ References

No definition available.

+ Details

Name:	rwt_TotalNetChangeInMarketValueRelatedToMortgageServicingRights
Namespace Prefix:	rwt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

All amounts that, per contract, are due to the servicer in exchange for servicing the financial asset and would no longer be received by a servicer if the beneficial owners of the serviced assets (or their trustees or agents) were to exercise their actual or potential authority under the contract to shift the servicing to another servicer. Depending on the servicing contract, those fees may include some or all of the difference between the interest rate collected on the asset being serviced and the rate to be paid to the beneficial owners of the asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 50

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122596-111746

+ Details

Name:	us-gaap_ContractuallySpecifiedServicingFeesAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The total amount of contractually specified servicing fees, late fees, and ancillary fees earned for each period for which results of operations are presented.

+ References

+ Details

Name:	us-gaap_ContractuallySpecifiedServicingFeesLateFeesAndAncillaryFeesEarnedInExchangeForServicingFinancialAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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