Residential Whole Loans (Residential Whole Loans, at Carrying Value - Additional Information) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased performing loans	$ 5,367,871	$ 2,218,728
Purchased credit impaired loans	698,474	797,987
Non-QM loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased performing loans	3,706,857	1,354,774
Allowance for losses	388
Rehabilitation loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased performing loans	1,023,766	494,576
Single-family rental loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased performing loans	460,679	145,327
Allowance for losses	62
Seasoned performing loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased performing loans	176,569	$ 224,051
Certain rehabilitation loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for losses	$ 2,300
90 or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted average LTV ratio	89.69%	90.24%
Settled Whole Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residential whole loans, at carrying value, total or weighted average	$ 6,069,126
Unpaid Principal Balance (“UPB”)	$ 6,141,421
Weighted Average Coupon	5.96%
Weighted average contractual maturity	288 months
Settled Whole Loans \| Non-QM loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased performing loans	$ 3,707,245
Unpaid Principal Balance (“UPB”)	$ 3,592,701
Weighted Average Coupon	5.96%
Weighted average contractual maturity	368 months
Weighted average LTV ratio	67.00%
Weighted Average FICO Scores	716
Settled Whole Loans \| Rehabilitation loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased performing loans	$ 1,026,097
Unpaid Principal Balance (“UPB”)	$ 1,026,097
Weighted Average Coupon	7.30%
Weighted average contractual maturity	8 months
Weighted average LTV ratio	64.00%
Weighted Average FICO Scores	717
Settled Whole Loans \| Single-family rental loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased performing loans	$ 460,741
Unpaid Principal Balance (“UPB”)	$ 457,146
Weighted Average Coupon	6.29%
Weighted average contractual maturity	324 months
Weighted average LTV ratio	70.00%
Weighted Average FICO Scores	734
Settled Whole Loans \| Seasoned performing loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased performing loans	$ 176,569
Unpaid Principal Balance (“UPB”)	$ 192,151
Weighted Average Coupon	4.24%
Weighted average contractual maturity	181 months
Weighted average LTV ratio	46.00%
Weighted Average FICO Scores	723
Settled Whole Loans \| Purchased credit impaired loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased credit impaired loans	$ 698,474
Unpaid Principal Balance (“UPB”)	$ 873,326
Weighted Average Coupon	4.46%
Weighted average contractual maturity	294 months
Weighted average LTV ratio	81.00%
Settled Whole Loans \| Certain rehabilitation loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased performing loans	$ 269,200
Weighted average LTV ratio	69.00%
Settled Whole Loans \| Current \| Non-QM loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	$ 3,492,533
Settled Whole Loans \| Current \| Rehabilitation loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	868,281
Settled Whole Loans \| Current \| Single-family rental loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	432,936
Settled Whole Loans \| Current \| Seasoned performing loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	187,683
Settled Whole Loans \| 30-59 \| Non-QM loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	59,963
Settled Whole Loans \| 30-59 \| Rehabilitation loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	67,747
Settled Whole Loans \| 30-59 \| Single-family rental loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	15,948
Settled Whole Loans \| 30-59 \| Seasoned performing loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	2,164
Settled Whole Loans \| 60-89 \| Non-QM loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	19,605
Settled Whole Loans \| 60-89 \| Rehabilitation loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	27,437
Settled Whole Loans \| 60-89 \| Single-family rental loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	2,047
Settled Whole Loans \| 60-89 \| Seasoned performing loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	430
Settled Whole Loans \| 90 or more \| Non-QM loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	20,600
Settled Whole Loans \| 90 or more \| Rehabilitation loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	62,632
Settled Whole Loans \| 90 or more \| Single-family rental loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	6,215
Settled Whole Loans \| 90 or more \| Seasoned performing loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	1,874
Settled Whole Loans \| 90 or more \| Purchased credit impaired loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance (“UPB”)	$ 108,998

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Purchased Performing Loans

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The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount, before allowance for credit loss, of financing receivable.

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