Fair Value of Financial Instruments - Valuation for Level 3 Assets (Details) $ in Thousands	3 Months Ended
Mar. 31, 2022 USD ($) securitization	Mar. 31, 2021 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 3,935,253	$ 3,471,854
Total (losses)/gains (realized/unrealized)
Included in earnings	(115,934)	4,929
Transfers out	(879)	(1,684)
Transfers to securitization trust	0
Funding/Contributions	19,191	161
Paydowns/Distributions	(330,853)	(197,727)
Sales	(320)	(6,633)
Purchases	782,477	347,283
Balance at the end of period	4,288,935	3,618,183
Consolidated SLST \| VIE, Primary Beneficiary \| Residential loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	1,070,882	1,266,785
Total (losses)/gains (realized/unrealized)
Included in earnings	(67,685)	(27,057)
Transfers out	0	0
Transfers to securitization trust	0
Funding/Contributions	0	0
Paydowns/Distributions	(33,344)	(28,220)
Sales	0	0
Purchases	0	0
Balance at the end of period	969,853	1,211,508
Residential loans \| Residential loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	1,703,290	1,090,930
Total (losses)/gains (realized/unrealized)
Included in earnings	(24,571)	9,386
Transfers out	(90)	(989)
Transfers to securitization trust	(598,430)
Funding/Contributions	0	0
Paydowns/Distributions	(126,575)	(125,646)
Sales	(320)	(4,257)
Purchases	767,914	347,283
Balance at the end of period	$ 1,721,218	1,316,707
Number of securitizations completed \| securitization	2
Residential loans held in securitization trusts \| Residential loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 801,429	691,451
Total (losses)/gains (realized/unrealized)
Included in earnings	(33,729)	14,123
Transfers out	(789)	(695)
Transfers to securitization trust	598,430
Funding/Contributions	0	0
Paydowns/Distributions	(117,548)	(24,436)
Sales	0	(2,376)
Purchases	14,563	0
Balance at the end of period	1,262,356	678,067
Multi-family loans \| Multi-family loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	120,021	163,593
Total (losses)/gains (realized/unrealized)
Included in earnings	3,258	5,077
Transfers out	0	0
Transfers to securitization trust	0
Funding/Contributions	0	0
Paydowns/Distributions	(13,071)	(16,834)
Sales	0	0
Purchases	0	0
Balance at the end of period	110,208	151,836
Equity investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period		259,095
Total (losses)/gains (realized/unrealized)
Included in earnings		3,400
Funding/Contributions		161
Paydowns/Distributions		(2,591)
Equity investments \| Equity investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	239,631	259,095
Total (losses)/gains (realized/unrealized)
Included in earnings	6,793	3,400
Transfers out	0	0
Transfers to securitization trust	0
Funding/Contributions	19,191	161
Paydowns/Distributions	(40,315)	(2,591)
Sales	0	0
Purchases	0	0
Balance at the end of period	$ 225,300	$ 260,065

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Funding/Contributions

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- Definition

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers Out of Level 3 to Out of Securitization Trust, Net

+ References

No definition available.

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Number Of Securitizations Completed

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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