Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Mortgage-Backed Securities - Narrative (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Investment Holdings [Line Items]
Gross unrealized loss	$ 117,176,000			$ 117,176,000		$ 122,310,000
Gains (losses) on extinguishment of debt	(25,622,000)	$ (55,794,000)		(284,535,000)	$ (55,338,000)
Agency MBS
Investment Holdings [Line Items]
Gross unrealized loss	0			0		69,000
Non-Agency RMBS
Investment Holdings [Line Items]
Gross unrealized loss	$ 190,000			$ 190,000		$ 248,000
Non-Agency RMBS
Investment Holdings [Line Items]
Market value of investments transferred			$ 135,000,000
Servicing asset at amortized cost		196,000,000			$ 196,000,000
Repurchase of transferred investments		252,000,000
Gains (losses) on extinguishment of debt		$ (56,000,000)