Principles of Consolidation - Summary of Redwood's Interest in Third-Party Variable Interest Entity's (Details) - REO - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Assets	$ 1,175,616	$ 1,155,829
Senior
Variable Interest Entity [Line Items]
Assets	214,655	216,066
Mezzanine
Variable Interest Entity [Line Items]
Assets	538,847	508,010
Subordinate
Variable Interest Entity [Line Items]
Assets	$ 422,114	$ 431,753

Carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph a
-URI http://asc.fasb.org/extlink&oid=108788376&loc=d3e5728-111685

Name:	us-gaap_VariableInterestEntityNonconsolidatedCarryingAmountAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant