Commercial Loans - Additional Information (Details) $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
		Jun. 30, 2016 USD ($)	Sep. 30, 2016 USD ($) loan	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) loan	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transfers from loans held-for-investment to loans held-for-sale					$ 359,005	$ 66,918
Aggregate fair value			$ 30,400		30,400		$ 402,647
Senior commercial loans, held for sale					3,817,445	8,794,939
Sale of loan for third party, held for sale					2,930,641	7,741,024
Loans receivable, fair value			30,400		30,400		402,647
Carrying value of loans			4,311,164		4,311,164		3,928,803
Investment fair value changes, net			11,918	$ (14,169)	$ (18,686)	(17,105)
Commercial Loans Held-for-Investment, at Amortized Cost
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans financed through securitization							166,000
Loan pledged as collateral							$ 135,000
Number of loans | loan					0		59
Aggregate fair value			0		$ 0		$ 295,849
Recorded investment in loans			0		0		302,951
Loans receivable, fair value			0		0		$ 295,849
Commercial loans, held-for-investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transfer of loans held-for-sale to held-for-sale, principal balance		$ 67,000
Transfers from loans held-for-investment to loans held-for-sale		70,000
Number of loans | loan							3
Aggregate fair value	[1]		0		0		$ 363,506
Loans receivable, fair value			0		0		$ 67,657
Commercial Loans, Held-for-sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan							4
Principal balance							$ 39,000
Aggregate fair value	[1]		30,400		30,400		39,141
Senior commercial loans, held for sale				168,000	38,000	518,000
Sale of loan for third party, held for sale				254,000	76,000	602,000
Valuation adjustments				$ 4,000	400	$ 11,000
Loans, held-for-sale			0		0		39,141
Loans receivable, fair value			0		$ 0		39,141
Commercial Loans at Lower of Cost or Market
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transfer of loans held-for-sale to held-for-sale, principal balance		237,000
Transfers from loans held-for-investment to loans held-for-sale		233,000
Number of loans | loan					6
Principal balance			31,000		$ 31,000
Valuation adjustments		$ 4,000
Loans, held-for-sale			30,400		30,400		0
Net purchase discount on loans transferred to held-for-sale			4,000		$ 4,000
Principal balance of loans sold during period			203,000
Gain on sale of loans held at lower of cost or market			$ 5,000
Number of loans subject to sale agreements | loan			5		5
Carrying value of loans			$ 3,000		$ 3,000
Investment fair value changes, net			(300)
Fair Value | Commercial Loans Held-for-Investment, at Amortized Cost
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, fair value			0		0		300,824
Fair Value | Commercial Loans, Held-for-sale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, held-for-sale			0		0		39,141
Fair Value | Commercial Loans at Lower of Cost or Market
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, held-for-sale			$ 32,239		$ 32,239		$ 0

[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 Redwood Trust, Inc. or its affiliates. At September 30, 2016 and December 31, 2015, assets of consolidated VIEs totaled $847,399 and $1,195,574, respectively. At September 30, 2016 and December 31, 2015, liabilities of consolidated VIEs totaled $820,391 and $1,050,861, respectively. See Note 4 for further discussion.