Investment Securities Available for Sale, at Fair Value - Schedule of Investment Securities Available for Sale in Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Carrying Value Less Than 12 Months	$ 465,264	$ 25,507
Gross Unrealized Losses Less Than 12 Months	(33,607)	(124)
Carrying Value Greater Than 12 Months	23,600	222,390
Gross Unrealized Losses Greater Than 12 Months	(1,905)	(7,467)
Carrying Value	488,864	247,897
Gross Unrealized Losses	(35,512)	(7,591)
Agency RMBS
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Carrying Value Less Than 12 Months		0
Gross Unrealized Losses Less Than 12 Months		0
Carrying Value Greater Than 12 Months		222,286
Gross Unrealized Losses Greater Than 12 Months		(7,454)
Carrying Value		222,286
Gross Unrealized Losses		(7,454)
Non-Agency RMBS
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Carrying Value Less Than 12 Months	421,337	0
Gross Unrealized Losses Less Than 12 Months	(31,061)	0
Carrying Value Greater Than 12 Months	16,922	104
Gross Unrealized Losses Greater Than 12 Months	(1,280)	(13)
Carrying Value	438,259	104
Gross Unrealized Losses	(32,341)	(13)
CMBS
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Carrying Value Less Than 12 Months	43,927	25,507
Gross Unrealized Losses Less Than 12 Months	(2,546)	(124)
Carrying Value Greater Than 12 Months	6,678	0
Gross Unrealized Losses Greater Than 12 Months	(625)	0
Carrying Value	50,605	25,507
Gross Unrealized Losses	$ (3,171)	$ (124)

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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