Commercial Loans - Additional Information (Details)		1 Months Ended	3 Months Ended					12 Months Ended
		Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($) loan	Dec. 31, 2014 USD ($)
Commercial Loans [Line Items]
Transfers from loans held-for-investment to loans held-for-sale								$ 359,005,000	$ 154,012,000	$ 0
Senior commercial loans, held for sale								4,953,619,000	11,045,813,000	9,917,943,000
Sale of loan for third party, held for sale								4,192,671,000	9,761,010,000	8,126,249,000
Investment fair value changes, net								(28,574,000)	(21,357,000)	$ (10,202,000)
Yield maintenance fees received			$ 1,000,000	$ 1,000,000	$ 5,000,000	$ 2,000,000	$ 2,000,000	2,000,000
Commercial Loans Held-for-Investment, at Amortized Cost
Commercial Loans [Line Items]
Commercial loans financed through Commercial Securitization entity			0			166,000,000		0	166,000,000
Loan pledged as collateral			0			135,000,000		$ 0	$ 135,000,000
Number of loans | loan								0	59
Carrying value			0			295,849,000		$ 0	$ 295,849,000
Yield maintenance fees received								5,000,000	4,000,000
Senior commercial loans, held for Investment								0	22,000,000
Repayments received								70,000,000	57,000,000
Commercial loans, held-for-investment
Commercial Loans [Line Items]
Transferred commercial mezzanine loans, unpaid principal balance		$ 67,000,000
Transfers from loans held-for-investment to loans held-for-sale		70,000,000
Carrying value	[1]		0			363,506,000		0	$ 363,506,000
Commercial Loans Held For Sale
Commercial Loans [Line Items]
Number of loans | loan									4
Carrying value	[1]		2,700,000			39,141,000		2,700,000	$ 39,141,000
Principal value						$ 39,000,000			39,000,000
Senior commercial loans, held for sale								38,000,000	618,000,000
Sale of loan for third party, held for sale								76,000,000	741,000,000
Valuation adjustments								$ 400,000	$ 10,000,000
Commercial Loans At Lower Of Cost Or Market
Commercial Loans [Line Items]
Transferred commercial mezzanine loans, unpaid principal balance		237,000,000
Transfers from loans held-for-investment to loans held-for-sale		233,000,000
Number of loans | loan								1
Carrying value			3,000,000					$ 3,000,000
Principal value			3,000,000					3,000,000
Valuation adjustments		$ 4,000,000
Loans, at lower of cost or fair value			3,000,000					3,000,000
Net purchase discount			4,000,000					4,000,000
Principal balance of loans sold during period				218,000,000
Realized gains, net			1,000,000	5,000,000
Investment fair value changes, net				$ (300,000)
Yield maintenance fees received								16,000,000
Commercial Loans At Lower Of Cost Or Market | Fair Value
Commercial Loans [Line Items]
Loans, at lower of cost or fair value			$ 3,000,000					$ 3,000,000

[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 December 31, 2016 and December 31, 2015, assets of consolidated VIEs totaled $798,317 and $1,195,574, respectively. At December 31, 2016 and December 31, 2015, liabilities of consolidated VIEs totaled $773,980 and $1,050,861, respectively. See Note 4 for further discussion.