Principles of Consolidation - Assets and Liabilities of Consolidated Variable Interest Entity's (Details) $ in Thousands		Dec. 31, 2020 USD ($) investment		Dec. 31, 2019 USD ($) investment		Dec. 31, 2018 USD ($)
Variable Interest Entity [Line Items]
Other investments	[1]	$ 348,175		$ 358,130
Cash and cash equivalents		461,260	[1]	196,966	[1]	$ 176,000
Restricted cash		83,190	[1]	93,867	[1]	$ 29,000
Accrued interest receivable		39,445		71,058
Other assets	[1]	130,588		419,321
Total Assets	[1]	10,355,066		17,995,440
Short-term debt	[1]	522,609		2,329,145
Accrued interest payable		34,858		60,655
Accrued expenses and other liabilities	[1]	179,340		206,893
Asset-backed securities issued	[1]	7,100,661		10,515,475
Total liabilities	[1]	$ 9,244,167		$ 16,168,209
Number of VIEs | investment		50		49
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Other investments		$ 251,773		$ 184,802
Cash and cash equivalents		11,579		9,015
Restricted cash		23,368		21,936
Accrued interest receivable		30,587		45,772
Other assets		9,937		2,700
Total Assets		8,141,069		11,931,869
Short-term debt		208,375		152,554
Accrued interest payable		21,274		34,060
Accrued expenses and other liabilities		18,403		14,983
Asset-backed securities issued		6,900,362		10,515,475
Total liabilities		7,148,414		10,717,072
Residential loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		4,072,410		5,066,568
Business purpose loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		3,249,194		2,192,552
Multifamily loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		$ 492,221		$ 4,408,524
Legacy Sequoia
Variable Interest Entity [Line Items]
Number of VIEs | investment		20		20
Legacy Sequoia | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Other investments		$ 0		$ 0
Cash and cash equivalents		0		0
Restricted cash		148		143
Accrued interest receivable		305		655
Other assets		638		460
Total Assets		287,026		409,148
Short-term debt		0		0
Accrued interest payable		141		395
Accrued expenses and other liabilities		0		0
Asset-backed securities issued		282,326		402,465
Total liabilities		282,467		402,860
Legacy Sequoia | Residential loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		285,935		407,890
Legacy Sequoia | Business purpose loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		0		0
Legacy Sequoia | Multifamily loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		$ 0		$ 0
Sequoia Choice
Variable Interest Entity [Line Items]
Number of VIEs | investment		10		9
Sequoia Choice | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Other investments		$ 0		$ 0
Cash and cash equivalents		0		0
Restricted cash		0		27
Accrued interest receivable		6,802		9,824
Other assets		0		0
Total Assets		1,572,124		2,301,314
Short-term debt		0		0
Accrued interest payable		4,697		7,732
Accrued expenses and other liabilities		50		27
Asset-backed securities issued		1,347,357		2,037,198
Total liabilities		1,352,104		2,044,957
Sequoia Choice | Residential loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		1,565,322		2,291,463
Sequoia Choice | Business purpose loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		0		0
Sequoia Choice | Multifamily loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		$ 0		$ 0
Freddie Mac SLST
Variable Interest Entity [Line Items]
Number of VIEs | investment		2		2
Freddie Mac SLST | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Other investments		$ 0		$ 0
Cash and cash equivalents		0		0
Restricted cash		0		0
Accrued interest receivable		6,754		7,313
Other assets		646		445
Total Assets		2,228,553		2,374,973
Short-term debt		0		0
Accrued interest payable		4,846		5,374
Accrued expenses and other liabilities		0		0
Asset-backed securities issued		1,793,620		1,918,322
Total liabilities		1,798,466		1,923,696
Freddie Mac SLST | Residential loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		2,221,153		2,367,215
Freddie Mac SLST | Business purpose loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		0		0
Freddie Mac SLST | Multifamily loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		$ 0		$ 0
Freddie Mac K-Series
Variable Interest Entity [Line Items]
Number of VIEs | investment		1		5
Freddie Mac K-Series | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Other investments		$ 0		$ 0
Cash and cash equivalents		0		0
Restricted cash		0		0
Accrued interest receivable		1,337		13,539
Other assets		0		0
Total Assets		493,558		4,422,063
Short-term debt		0		0
Accrued interest payable		1,177		12,887
Accrued expenses and other liabilities		0		0
Asset-backed securities issued		463,966		4,156,239
Total liabilities		465,143		4,169,126
Freddie Mac K-Series | Residential loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		0		0
Freddie Mac K-Series | Business purpose loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		0		0
Freddie Mac K-Series | Multifamily loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		$ 492,221		$ 4,408,524
CAFL
Variable Interest Entity [Line Items]
Number of VIEs | investment		14		10
CAFL | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Other investments		$ 0		$ 0
Cash and cash equivalents		0		0
Restricted cash		0		0
Accrued interest receivable		13,055		9,572
Other assets		2,930		1,795
Total Assets		3,265,179		2,203,919
Short-term debt		0		0
Accrued interest payable		10,278		7,485
Accrued expenses and other liabilities		0		0
Asset-backed securities issued		3,013,093		2,001,251
Total liabilities		3,023,371		2,008,736
CAFL | Residential loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		0		0
CAFL | Business purpose loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		3,249,194		2,192,552
CAFL | Multifamily loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		$ 0		$ 0
Servicing Investment
Variable Interest Entity [Line Items]
Number of VIEs | investment		3		3
Servicing Investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Other investments		$ 251,773		$ 184,802
Cash and cash equivalents		11,579		9,015
Restricted cash		23,220		21,766
Accrued interest receivable		2,334		4,869
Other assets		5,723		0
Total Assets		294,629		220,452
Short-term debt		208,375		152,554
Accrued interest payable		135		187
Accrued expenses and other liabilities		18,353		14,956
Asset-backed securities issued		0		0
Total liabilities		226,863		167,697
Servicing Investment | Residential loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		0		0
Servicing Investment | Business purpose loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Loans, at fair value		0		0
Servicing Investment | Multifamily loans, held-for-investment | Variable Interest Entity, Primary Beneficiary
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 December 31, 2020 and December 31, 2019, assets of consolidated VIEs totaled $8,141,069 and $11,931,869, respectively. At December 31, 2020 and December 31, 2019, liabilities of consolidated VIEs totaled $7,148,414 and $10,717,072, respectively. See Note 4 for further discussion.