Short-Term Debt - Outstanding Balances of Short-Term Debt by Type of Collateral Securing Debt (Detail)		6 Months Ended	12 Months Ended
		Jun. 30, 2015 USD ($) Contract	Dec. 31, 2014 USD ($) Contract
Short-term Debt [Line Items]
Number of Facilities | Contract		16	17
Outstanding	[1]	$ 1,367,062,000	$ 1,793,825,000
Residential Loans
Short-term Debt [Line Items]
Number of Facilities | Contract		5	5
Outstanding		$ 776,824,000	$ 1,076,188,000
Limit		$ 1,800,000,000	$ 1,550,000,000
Residential Loans | Minimum
Short-term Debt [Line Items]
Maturity		2015-04	2015-02
Residential Loans | Maximum
Short-term Debt [Line Items]
Maturity		2016-02	2015-12
Commercial Loans
Short-term Debt [Line Items]
Number of Facilities | Contract		3	3
Outstanding		$ 96,849,000	$ 109,128,000
Limit		$ 450,000,000	$ 400,000,000
Commercial Loans | Minimum
Short-term Debt [Line Items]
Maturity		2015-04	2015-04
Commercial Loans | Maximum
Short-term Debt [Line Items]
Maturity		2016-10	2016-10
Real Estate Securities
Short-term Debt [Line Items]
Number of Facilities | Contract		8	9
Outstanding		$ 493,389,000	$ 608,509,000
Real Estate Securities | Minimum
Short-term Debt [Line Items]
Maturity		2015-04	2015-01
Real Estate Securities | Maximum
Short-term Debt [Line Items]
Maturity		2015-06	2015-03

[1] Our consolidated balance sheets include assets of consolidated variable interest entities (“VIEs”) that can only be used to settle obligations of these VIEs and liabilities of consolidated VIEs for which creditors do not have recourse to the primary beneficiary (Redwood Trust, Inc.). At June 30, 2015 and December 31, 2014, assets of consolidated VIEs totaled $1,622,636 and $1,900,208, respectively, and liabilities of consolidated VIEs totaled $1,263,249 and $1,546,490, respectively. See Note 4 for further discussion.