Valuation (Significant Unobservable Inputs Rollforward) (Details) - Level 3 $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	$ 3,950,113	$ 2,181,112	$ 2,881,539	$ 1,959,802
Assets, Accreted Discounts/Amortized Premiums	(7,533)	(9,930)	(22,621)	(19,714)
Assets, Realized Gain (Loss)	237	11,996	10,978	15,710
Assets, Change In Net Unrealized Gain/(Loss)	(145,458)	(8,023)	(383,801)	40,536
Assets, Purchases	847,645	522,267	3,076,762	1,413,347
Assets, Sales	(411,990)	(325,302)	(1,332,677)	(1,001,333)
Assets, Transfers into Level 3	8,207	11,040	35,984	12,922
Assets, Transfers out of Level 3	(16,970)	0	(41,913)	(38,110)
Assets, Ending Balance	4,224,251	2,383,160	4,224,251	2,383,160
Liabilities, Begining Balance	(1,650,832)	(1,003,093)	(984,168)	(755,405)
Liabilities, Accreted Discounts/Amortized Premiums	(397)	0	(397)	0
Liabilities, Realized Gain/(Loss)	0	(67)	0	(1,428)
Liabilities, Change In Net Unrealized Gain/(Loss)	88,528	1,538	218,777	5,214
Liabilities Purchases/Payments	57,864	129,316	271,817	454,460
Liabilities, Sales/Issuance	(324,544)	0	(1,335,410)	(575,147)
Liabilities, Transfers into Level 3	0	0	0	0
Liabilities, Transfers out of Level 3	0	0	0	0
Liabilities, Ending Balance	(1,829,381)	(872,306)	(1,829,381)	(872,306)
Non-Agency RMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	105,785		105,785		$ 134,888
Non-Agency RMBS | Valuation, Income Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	43,127		43,127		45,544
Non-Agency RMBS | Valuation, Market Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	62,658		62,658		89,344
CMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	8,669		8,669		13,134
CMBS | Valuation, Income Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	554		554		268
CMBS | Valuation, Market Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	8,115		8,115		12,866
CLOs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	17,288		17,288		26,678
CLOs | Valuation, Income Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	6,533		6,533		8,014
CLOs | Valuation, Market Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	10,755		10,755		18,664
Asset-backed securities, backed by consumer loans | Valuation, Income Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	75,568		75,568		73,108
Residential mortgage loans | Performing Financial Instruments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets					952,656
Residential mortgage loans | Valuation, Income Approach | Performing Financial Instruments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	1,560,948		1,560,948		951,723
Residential mortgage loans | Measurement Input, Exercise Price | Valuation, Cost Approach | Performing Financial Instruments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets					933
Commercial mortgage loans | Valuation, Income Approach | Performing Financial Instruments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	432,740		432,740		310,735
Consumer loans | Valuation, Income Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	6,038		6,038		62,365
Corporate loan [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets					10,531
Corporate loan [Member] | Valuation, Income Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	3,534		3,534		3,531
Corporate loan [Member] | Valuation, Market Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets					7,000
Credit default swaps on asset-backed securities | Valuation, Income Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	77		77		303
Other secured borrowings, at fair value | Valuation, Market Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value	$ (1,635,829)		$ (1,635,829)		$ (984,168)
Other secured borrowings, at fair value | Measurement Input, Quoted Price | Valuation, Market Approach | Minimum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Debt instrument, measurement input	51.06		51.06		93.34
Other secured borrowings, at fair value | Measurement Input, Quoted Price | Valuation, Market Approach | Maximum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Debt instrument, measurement input	97.28		97.28		102.14
Other secured borrowings, at fair value | Measurement Input, Quoted Price | Valuation, Market Approach | Weighted Average
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Debt instrument, measurement input	88.76		88.76		99.94
Investment in unconsolidated entities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	$ 171,379		$ 171,379		$ 195,643
Investment in unconsolidated entities | Measurement Input, Net Asset Value | Enterprise Value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	87,864		87,864		57,828
Investment in unconsolidated entities | Measurement Input, Exercise Price | Valuation, Cost Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total assets	50,667		50,667		$ 14,036
Senior Notes | Valuation, Market Approach
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value	$ (193,515)		$ (193,515)
Senior Notes | Measurement Input, Quoted Price | Valuation, Market Approach | Minimum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Debt instrument, measurement input	92.15		92.15
Senior Notes | Measurement Input, Quoted Price | Valuation, Market Approach | Maximum
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Debt instrument, measurement input	92.15		92.15
Senior Notes | Measurement Input, Quoted Price | Valuation, Market Approach | Weighted Average
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Debt instrument, measurement input	92.15		92.15
Other secured borrowings, at fair value
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Payments		129,249		453,032
Liabilities, Issuances		0		(575,147)
Liabilities, Begining Balance	$ (1,448,182)	(1,003,037)	$ (984,168)	(754,921)
Liabilities, Accreted Discounts/Amortized Premiums	(397)	0	(397)	0
Liabilities, Realized Gain/(Loss)	0	0	0	0
Liabilities, Change In Net Unrealized Gain/(Loss)	79,430	1,482	202,329	4,730
Liabilities Purchases/Payments	57,864		271,817
Liabilities, Sales/Issuance	(324,544)		(1,125,410)
Liabilities, Transfers into Level 3	0	0	0	0
Liabilities, Transfers out of Level 3	0	0	0	0
Liabilities, Ending Balance	(1,635,829)	(872,306)	(1,635,829)	(872,306)
Change in unrealized gains (losses), liabilities	79,400	1,500	202,300	4,700
Financial Derivatives - Liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Change in unrealized gains (losses), liabilities	(37)	100	(37)
Financial Derivatives - Liabilities | Total return swaps
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	0		0
Assets, Accreted Discounts/Amortized Premiums	0		0
Assets, Realized Gain (Loss)	0		0
Assets, Change In Net Unrealized Gain/(Loss)	(37)		(37)
Assets, Purchases	0		0
Assets, Sales	0		0
Assets, Transfers into Level 3	0		0
Assets, Transfers out of Level 3	0		0
Assets, Ending Balance	(37)		(37)
Senior notes
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Begining Balance	(202,650)		0
Liabilities, Accreted Discounts/Amortized Premiums	0		0
Liabilities, Realized Gain/(Loss)	0		0
Liabilities, Change In Net Unrealized Gain/(Loss)	9,135		16,485
Liabilities Purchases/Payments	0		0
Liabilities, Sales/Issuance	0		(210,000)
Liabilities, Transfers into Level 3	0		0
Liabilities, Transfers out of Level 3	0		0
Liabilities, Ending Balance	(193,515)		(193,515)
Senior Notes
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Change in unrealized gains (losses), liabilities	9,100		16,500
Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Change in unrealized gain (loss), assets	(8,000)	3,100	(31,800)	13,600
Securities | Agency RMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	12,389	9,936	9,710	11,663
Assets, Accreted Discounts/Amortized Premiums	(751)	(1,285)	(1,595)	(2,570)
Assets, Realized Gain (Loss)	(723)	(15)	9	943
Assets, Change In Net Unrealized Gain/(Loss)	(62)	278	(1,421)	(1,408)
Assets, Purchases	0	2,038	840	2,039
Assets, Sales	(2,214)	0	(1,074)	(1,533)
Assets, Transfers into Level 3	1,094	780	3,393	5,093
Assets, Transfers out of Level 3	(1,914)	0	(2,043)	(2,495)
Assets, Ending Balance	7,819	11,732	7,819	11,732
Securities | Non-Agency RMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	131,449	114,464	134,888	127,838
Assets, Accreted Discounts/Amortized Premiums	(73)	612	743	1,926
Assets, Realized Gain (Loss)	216	680	2,167	2,993
Assets, Change In Net Unrealized Gain/(Loss)	(5,402)	(1,918)	(14,655)	(2,533)
Assets, Purchases	0	154	18,614	22,392
Assets, Sales	(13,789)	(9,005)	(26,541)	(42,009)
Assets, Transfers into Level 3	3,240	1,613	18,916	5,831
Assets, Transfers out of Level 3	(9,856)	0	(28,347)	(9,838)
Assets, Ending Balance	105,785	106,600	105,785	106,600
Securities | CMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	9,380	17,025	13,134	63,148
Assets, Accreted Discounts/Amortized Premiums	54	27	97	404
Assets, Realized Gain (Loss)	1,932	1,987	3,050	4,329
Assets, Change In Net Unrealized Gain/(Loss)	(581)	(468)	(2,142)	4,946
Assets, Purchases	0	0	620	0
Assets, Sales	(3,265)	(15,070)	(5,297)	(60,449)
Assets, Transfers into Level 3	3,230	8,647	5,470	397
Assets, Transfers out of Level 3	2,081	0	6,263	627
Assets, Ending Balance	8,669	12,148	8,669	12,148
Securities | CLOs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	23,378	33,989	26,678	111,100
Assets, Accreted Discounts/Amortized Premiums	(631)	(1,688)	(2,048)	(371)
Assets, Realized Gain (Loss)	3,324	2,689	6,231	934
Assets, Change In Net Unrealized Gain/(Loss)	(221)	3,007	(2,859)	19,782
Assets, Purchases	0	85	0	104
Assets, Sales	(6,086)	(7,961)	(13,659)	(77,879)
Assets, Transfers into Level 3	643	0	8,205	1,601
Assets, Transfers out of Level 3	(3,119)	0	(5,260)	(25,150)
Assets, Ending Balance	17,288	30,121	17,288	30,121
Securities | Asset-backed securities, backed by consumer loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	78,183	69,254	73,108	44,925
Assets, Accreted Discounts/Amortized Premiums	(2,376)	(1,813)	(4,528)	(3,796)
Assets, Realized Gain (Loss)	318	287	18	466
Assets, Change In Net Unrealized Gain/(Loss)	(2,618)	(1,598)	(8,250)	(3,181)
Assets, Purchases	13,063	15,853	49,300	61,665
Assets, Sales	(11,002)	(10,688)	(34,080)	(28,784)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	75,568	71,295	75,568	71,295
Securities | Corporate debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	1,767	5,444	5,198	4,082
Assets, Accreted Discounts/Amortized Premiums	0	0	0	0
Assets, Realized Gain (Loss)	133	1,271	1,666	1,497
Assets, Change In Net Unrealized Gain/(Loss)	(148)	(700)	(1,828)	(517)
Assets, Purchases	5,391	2,207	10,703	3,824
Assets, Sales	(3,541)	(3,803)	(12,137)	(4,467)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	3,602	4,419	3,602	4,419
Securities | Corporate equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	10,276	8,497	7,556	1,590
Assets, Accreted Discounts/Amortized Premiums	0	0	0	0
Assets, Realized Gain (Loss)	(80)	661	1,659	276
Assets, Change In Net Unrealized Gain/(Loss)	188	224	(1,176)	2,538
Assets, Purchases	785	351	5,768	5,329
Assets, Sales	0	(1,739)	(2,638)	(1,739)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	11,169	7,994	11,169	7,994
Loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Change in unrealized gain (loss), assets	(113,100)	(4,700)	(297,600)	(2,400)
Loans | Residential mortgage loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	2,995,584	1,445,651	2,016,228	1,187,069
Assets, Accreted Discounts/Amortized Premiums	(3,394)	(3,864)	(12,405)	(9,575)
Assets, Realized Gain (Loss)	(1,561)	277	56	738
Assets, Change In Net Unrealized Gain/(Loss)	(114,175)	(4,475)	(297,423)	(2,788)
Assets, Purchases	712,965	405,291	2,332,444	955,069
Assets, Sales	(240,609)	(186,179)	(690,090)	(473,812)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	3,348,810	1,656,701	3,348,810	1,656,701
Loans | Commercial mortgage loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	477,378	228,450	326,197	213,031
Assets, Accreted Discounts/Amortized Premiums	0	0	0	24
Assets, Realized Gain (Loss)	11	17	22	323
Assets, Change In Net Unrealized Gain/(Loss)	54	71	(1,170)	141
Assets, Purchases	77,888	72,415	411,693	219,914
Assets, Sales	(90,818)	(33,362)	(272,229)	(165,842)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	464,513	267,591	464,513	267,591
Loans | Consumer loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	7,410	52,016	62,365	47,525
Assets, Accreted Discounts/Amortized Premiums	(362)	(1,919)	(2,885)	(5,756)
Assets, Realized Gain (Loss)	(1,172)	(105)	(1,870)	(1,381)
Assets, Change In Net Unrealized Gain/(Loss)	986	19	615	476
Assets, Purchases	523	13,941	11,505	40,008
Assets, Sales	(1,347)	(8,276)	(63,692)	(25,196)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	6,038	55,676	6,038	55,676
Loans | Corporate loan [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	10,448	16,584	10,531	5,855
Assets, Accreted Discounts/Amortized Premiums	0	0	0	0
Assets, Realized Gain (Loss)	0	0	(1,000)	0
Assets, Change In Net Unrealized Gain/(Loss)	0	(267)	0	(267)
Assets, Purchases	100	254	2,425	10,985
Assets, Sales	(7,014)	(10)	(8,422)	(12)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	3,534	16,561	3,534	16,561
Investment in unconsolidated entities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	192,269	178,979	195,643	141,620
Assets, Accreted Discounts/Amortized Premiums	0	0	0	0
Assets, Realized Gain (Loss)	(1,317)	4,225	(177)	4,386
Assets, Change In Net Unrealized Gain/(Loss)	(24,196)	(1,676)	(54,107)	23,400
Assets, Purchases	36,928	9,674	232,838	92,008
Assets, Sales	(32,305)	(49,183)	(202,818)	(119,395)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	171,379	142,019	171,379	142,019
Change in unrealized gain (loss), assets	(27,000)	(2,700)	(61,000)	19,900
Financial Derivatives - Assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Change in unrealized gain (loss), assets	700	100	600	(100)
Financial Derivatives - Assets | Total return swaps
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance		520		9
Assets, Accreted Discounts/Amortized Premiums		0		0
Assets, Realized Gain (Loss)		26		167
Assets, Change In Net Unrealized Gain/(Loss)		(520)		(9)
Assets, Purchases		0		0
Assets, Sales		(26)		(167)
Assets, Transfers into Level 3		0		0
Assets, Transfers out of Level 3		0		0
Assets, Ending Balance		0		0
Financial Derivatives - Assets | Credit default swaps on asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, Beginning Balance	202	303	303	347
Assets, Accreted Discounts/Amortized Premiums	0	0	0	0
Assets, Realized Gain (Loss)	(844)	(4)	(853)	39
Assets, Change In Net Unrealized Gain/(Loss)	717	0	615	(44)
Assets, Purchases	2	4	12	10
Assets, Sales	0	0	0	(49)
Assets, Transfers into Level 3	0	0	0	0
Assets, Transfers out of Level 3	0	0	0	0
Assets, Ending Balance	$ 77	303	$ 77	303
Financial Derivatives - Liabilities | Total return swaps
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Liabilities, Payments		67		1,428
Liabilities, Issuances		0		0
Liabilities, Begining Balance		(56)		(484)
Liabilities, Accreted Discounts/Amortized Premiums		0		0
Liabilities, Realized Gain/(Loss)		(67)		(1,428)
Liabilities, Change In Net Unrealized Gain/(Loss)		56		484
Liabilities, Transfers into Level 3		0		0
Liabilities, Transfers out of Level 3		0		0
Liabilities, Ending Balance		$ 0		$ 0