Segment Information - Supplemental Information by Segment (Details) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Real estate securities	[1]	$ 1,285,426	$ 1,452,494
Other investments	[1]	347,707	438,518
Goodwill and intangible assets	[1]	49,121	0
Total Assets	[1]	15,476,283	11,937,406
Residential loans
Segment Reporting Information [Line Items]
Loans, at fair value		8,681,803	7,254,742
Business purpose residential loans
Segment Reporting Information [Line Items]
Loans, at fair value		336,035	141,258
Multifamily loans
Segment Reporting Information [Line Items]
Loans, at fair value		3,791,622	2,144,598
Operating Segments | Investment Portfolio
Segment Reporting Information [Line Items]
Real estate securities		1,285,426	1,452,494
Other investments		346,136	427,764
Goodwill and intangible assets		0
Total Assets		13,347,460	10,093,993
Operating Segments | Investment Portfolio | Residential loans
Segment Reporting Information [Line Items]
Loans, at fair value		7,326,757	5,685,983
Operating Segments | Investment Portfolio | Business purpose residential loans
Segment Reporting Information [Line Items]
Loans, at fair value		225,601	112,798
Operating Segments | Investment Portfolio | Multifamily loans
Segment Reporting Information [Line Items]
Loans, at fair value		3,791,622	2,144,598
Operating Segments | Mortgage Banking
Segment Reporting Information [Line Items]
Real estate securities		0	0
Other investments		1,571	0
Goodwill and intangible assets		49,121
Total Assets		1,166,639	1,103,090
Operating Segments | Mortgage Banking | Residential loans
Segment Reporting Information [Line Items]
Loans, at fair value		925,887	1,048,801
Operating Segments | Mortgage Banking | Business purpose residential loans
Segment Reporting Information [Line Items]
Loans, at fair value		110,434	28,460
Operating Segments | Mortgage Banking | Multifamily loans
Segment Reporting Information [Line Items]
Loans, at fair value		0	0
Corporate/ Other
Segment Reporting Information [Line Items]
Real estate securities		0	0
Other investments		0	10,754
Goodwill and intangible assets		0
Total Assets		962,184	740,323
Corporate/ Other | Residential loans
Segment Reporting Information [Line Items]
Loans, at fair value		429,159	519,958
Corporate/ Other | Business purpose residential loans
Segment Reporting Information [Line Items]
Loans, at fair value		0	0
Corporate/ Other | Multifamily loans
Segment Reporting Information [Line Items]
Loans, at fair value		$ 0	$ 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, 2019 and December 31, 2018, assets of consolidated VIEs totaled $9,596,537 and $6,331,191, respectively. At September 30, 2019 and December 31, 2018, liabilities of consolidated VIEs totaled $8,582,595 and $5,709,807, respectively. See Note 4 for further discussion.