2.4.0.81093 - Disclosure - Short-Term Debt - Additional Information (Detail)truefalseIn Millions, unless otherwise specifiedfalse1false USDfalsefalse$eol_PE798-----1310-Q0007_STD_91_20130630_0http://www.sec.gov/CIK0000930236duration2013-04-01T00:00:002013-06-30T00:00:00iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false USDfalsefalse$eol_PE798-----1310-Q0007_STD_91_20120630_0http://www.sec.gov/CIK0000930236duration2012-04-01T00:00:002012-06-30T00:00:00iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3false USDfalsefalse$eol_PE798-----1310-Q0007_STD_181_20130630_0http://www.sec.gov/CIK0000930236duration2013-01-01T00:00:002013-06-30T00:00:00iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$4false USDfalsefalse$eol_PE798-----1310-Q0007_STD_182_20120630_0http://www.sec.gov/CIK0000930236duration2012-01-01T00:00:002012-06-30T00:00:00iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$5false USDfalsefalse$eol_PE798-----1310-Q0007_STD_0_20121231_0http://www.sec.gov/CIK0000930236instant2012-12-31T00:00:000001-01-01T00:00:00iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 3us-gaap_ShortTermDebtLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Short-term Debt [Line Items]2false 4us-gaap_LoansPledgedAsCollateralus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse12000000001200USD$falsetruefalse2falsefalsefalse00falsefalsefalse3truefalsefalse12000000001200USD$falsetruefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryCarrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5086-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6467456&loc=d3e113888-111728 false2Residential loan pledged as collateral3false 4us-gaap_AvailableForSaleSecuritiesPledgedAsCollateralus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse455000000455USD$falsefalsefalse2falsefalsefalse00falsefalsefalse3truefalsefalse455000000455USD$falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe fair value of available-for-sale securities that serve as collateral for borrowings.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5086-111524 false2Securities pledged as collateral4false 4us-gaap_ShorttermDebtAverageOutstandingAmountus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse10500000001050USD$falsefalsefalse2truefalsefalse474000000474USD$falsefalsefalse3truefalsefalse954000000954USD$falsefalsefalse4truefalsefalse418000000418USD$falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryFor the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, average borrowings during the period.No definition available.false2Average balance of short-term debt5false 4us-gaap_InterestPayableCurrentus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse10000001USD$falsetruefalse2falsefalsefalse00falsefalsefalse3truefalsefalse10000001USD$falsetruefalse4falsefalsefalse00falsefalsefalse5truefalsefalse10000001USD$falsetruefalsexbrli:monetaryItemTypemonetaryCarrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Current Liabilities -URI http://asc.fasb.org/extlink&oid=6509677 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6935-107765 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.20) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e7018-107765 false2Accrued interest payable on short-term debt6false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6false truefalseeol_PE798-----1310-Q0007_STD_0_20130630_0_716819x751205http://www.sec.gov/CIK0000930236instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseCredit Agreementus-gaap_ShortTermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldirwt_CreditAgreementMemberus-gaap_ShortTermDebtTypeAxisexplicitMemberEntityStandardhttp://www.redwoodtrust.com/20130630Entityrwt0nanafalse0Credit Agreement7true 3us-gaap_ShortTermDebtLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Short-term Debt [Line Items]8false 4rwt_NumberOfBanksrwt_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse1111falsefalsefalse2falsefalsefalse00falsefalsefalse3truefalsefalse1111falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:integerItemTypeintegerNumber of BanksNo definition available.false256Number of bank counterpartiesfalseShort-Term Debt - Additional Information (Detail) (USD $)MillionsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.redwoodtrust.com/taxonomy/role/DisclosureShortTermDebtAdditionalInformation58