Residential Loans - Activity of Residential Loans Held-for-Sale (Details) - Residential Loans - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Principal balance of loans acquired	$ 4,374,201	$ 5,732,699
Principal balance of loans sold	6,463,741	6,069,518
Gain (loss) on assets measured at fair value on a non-recurring basis	$ (15,477)	$ 3,267

For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612

Name:	us-gaap_FairValueOptionChangesInFairValueGainLoss1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration