Investment Securities - Securities at Cost (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
RMBS
Debt Securities, Available-for-sale [Line Items]
Cost of mortgage-backed securities	$ 482,824	$ 151,222
CMBS
Debt Securities, Available-for-sale [Line Items]
Cost of mortgage-backed securities	$ 10,875	$ 8,857

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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