Principles of Consolidation - Assets and Liabilities of Consolidated Variable Interest Entities Accounted for as Collateralized Financing Entities (Details) $ in Thousands		Sep. 30, 2020 USD ($) investment	Dec. 31, 2019 USD ($) investment
Variable Interest Entity [Line Items]
Other investments	[1]	$ 384,628	$ 358,130
Cash and cash equivalents	[1]	450,684	196,966
Restricted cash	[1]	73,594	93,867
Accrued interest receivable		39,330	71,058
Other assets	[1]	124,273	419,321
Total Assets	[1]	10,402,412	17,995,440
Short-term debt	[1]	482,761	2,329,145
Accrued interest payable		34,225	60,655
Accrued expenses and other liabilities	[1]	155,989	206,893
Asset-backed securities issued	[1]	7,172,398	10,515,475
Total liabilities	[1]	$ 9,348,948	$ 16,168,209
Number of VIEs | investment		49	49
Business purpose residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value	[1]	$ 3,670,552	$ 3,175,178
Legacy Sequoia
Variable Interest Entity [Line Items]
Number of VIEs | investment		20	20
Sequoia Choice
Variable Interest Entity [Line Items]
Number of VIEs | investment		10	9
Freddie Mac SLST
Variable Interest Entity [Line Items]
Number of VIEs | investment		2	2
Freddie Mac K-Series
Variable Interest Entity [Line Items]
Number of VIEs | investment		1	5
CAFL
Variable Interest Entity [Line Items]
Number of VIEs | investment		13	10
Servicing Investment
Variable Interest Entity [Line Items]
Number of VIEs | investment		3	3
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Other investments		$ 278,487	$ 184,802
Cash and cash equivalents		10,425	9,015
Restricted cash		20,795	21,936
Accrued interest receivable		30,644	45,772
Other assets		5,829	2,700
Total Assets		8,197,095	11,931,869
Short-term debt		228,998	152,554
Accrued interest payable		21,497	34,060
Accrued expenses and other liabilities		18,176	14,983
Asset-backed securities issued		6,969,376	10,515,475
Total liabilities		7,238,047	10,717,072
Variable Interest Entity, Primary Beneficiary | Residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		4,389,808	5,066,568
Variable Interest Entity, Primary Beneficiary | Business purpose residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		2,969,692	2,192,552
Variable Interest Entity, Primary Beneficiary | Multifamily loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		491,415	4,408,524
Variable Interest Entity, Primary Beneficiary | Legacy Sequoia
Variable Interest Entity [Line Items]
Other investments		0	0
Cash and cash equivalents		0	0
Restricted cash		146	143
Accrued interest receivable		402	655
Other assets		784	460
Total Assets		298,097	409,148
Short-term debt		0	0
Accrued interest payable		180	395
Accrued expenses and other liabilities		0	0
Asset-backed securities issued		292,484	402,465
Total liabilities		292,664	402,860
Variable Interest Entity, Primary Beneficiary | Legacy Sequoia | Residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		296,765	407,890
Variable Interest Entity, Primary Beneficiary | Legacy Sequoia | Business purpose residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | Legacy Sequoia | Multifamily loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | Sequoia Choice
Variable Interest Entity [Line Items]
Other investments		0	0
Cash and cash equivalents		0	0
Restricted cash		0	27
Accrued interest receivable		7,292	9,824
Other assets		0	0
Total Assets		1,843,653	2,301,314
Short-term debt		0	0
Accrued interest payable		5,652	7,732
Accrued expenses and other liabilities		47	27
Asset-backed securities issued		1,626,564	2,037,198
Total liabilities		1,632,263	2,044,957
Variable Interest Entity, Primary Beneficiary | Sequoia Choice | Residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		1,836,361	2,291,463
Variable Interest Entity, Primary Beneficiary | Sequoia Choice | Business purpose residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | Sequoia Choice | Multifamily loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | Freddie Mac SLST
Variable Interest Entity [Line Items]
Other investments		0	0
Cash and cash equivalents		0	0
Restricted cash		0	0
Accrued interest receivable		6,928	7,313
Other assets		887	445
Total Assets		2,264,497	2,374,973
Short-term debt		0	0
Accrued interest payable		5,009	5,374
Accrued expenses and other liabilities		0	0
Asset-backed securities issued		1,841,313	1,918,322
Total liabilities		1,846,322	1,923,696
Variable Interest Entity, Primary Beneficiary | Freddie Mac SLST | Residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		2,256,682	2,367,215
Variable Interest Entity, Primary Beneficiary | Freddie Mac SLST | Business purpose residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | Freddie Mac SLST | Multifamily loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | Freddie Mac K-Series
Variable Interest Entity [Line Items]
Other investments		0	0
Cash and cash equivalents		0	0
Restricted cash		0	0
Accrued interest receivable		1,342	13,539
Other assets		0	0
Total Assets		492,757	4,422,063
Short-term debt		0	0
Accrued interest payable		1,182	12,887
Accrued expenses and other liabilities		0	0
Asset-backed securities issued		464,865	4,156,239
Total liabilities		466,047	4,169,126
Variable Interest Entity, Primary Beneficiary | Freddie Mac K-Series | Residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | Freddie Mac K-Series | Business purpose residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | Freddie Mac K-Series | Multifamily loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		491,415	4,408,524
Variable Interest Entity, Primary Beneficiary | CAFL
Variable Interest Entity [Line Items]
Other investments		0	0
Cash and cash equivalents		0	0
Restricted cash		0	0
Accrued interest receivable		12,071	9,572
Other assets		4,158	1,795
Total Assets		2,985,921	2,203,919
Short-term debt		0	0
Accrued interest payable		9,337	7,485
Accrued expenses and other liabilities		0	0
Asset-backed securities issued		2,744,150	2,001,251
Total liabilities		2,753,487	2,008,736
Variable Interest Entity, Primary Beneficiary | CAFL | Residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | CAFL | Business purpose residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		2,969,692	2,192,552
Variable Interest Entity, Primary Beneficiary | CAFL | Multifamily loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | Servicing Investment
Variable Interest Entity [Line Items]
Other investments		278,487	184,802
Cash and cash equivalents		10,425	9,015
Restricted cash		20,649	21,766
Accrued interest receivable		2,609	4,869
Other assets		0	0
Total Assets		312,170	220,452
Short-term debt		228,998	152,554
Accrued interest payable		137	187
Accrued expenses and other liabilities		18,129	14,956
Asset-backed securities issued		0	0
Total liabilities		247,264	167,697
Variable Interest Entity, Primary Beneficiary | Servicing Investment | Residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | Servicing Investment | Business purpose residential loans, held-for-investment
Variable Interest Entity [Line Items]
Loans, at fair value		0	0
Variable Interest Entity, Primary Beneficiary | Servicing Investment | Multifamily loans, held-for-investment
Variable Interest Entity [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, 2020 and December 31, 2019, assets of consolidated VIEs totaled $8,197,095 and $11,931,869, respectively. At September 30, 2020 and December 31, 2019, liabilities of consolidated VIEs totaled $7,238,047 and $10,717,072, respectively. See Note 4 for further discussion.