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Fair Value of Financial Instruments (Level 3 Assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Excluded amount, unsettled purchases, residential whole loans, at fair value		$ 194,700
Residential whole loans held at fair value for which the closing price of the purchase transaction had not occurred	$ 70,600
Recurring basis | Level 3 | Residential whole loans, at fair value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	1,471,263	1,325,115
Purchases	234,979	500,004
Changes in unrealized gain/(losses)	47,848	36,725
Collection of principal	(152,011)	(199,203)
Repurchases	(1,337)	(1,807)
Transfer to REO	(219,159)	(189,571)
Balance at end of period	1,381,583	1,471,263
Recurring basis | Level 3 | Term Notes Backed by MSR-Related Collateral
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	538,499	381,804
Purchases	573,137	548,404
Collection of principal	(12,897)	(390,898)
Changes in unrealized gain/(losses)	5,391	(811)
Transfer to Level 2	(1,104,130)	0
Balance at end of period	$ 0	538,499
Residential whole loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Excluded amount, unsettled purchases, residential whole loans, at fair value		$ 194,700

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Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

+ References

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-Publisher FASB
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Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

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