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Commitments and Contingencies, Contractual Commitments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Agency Business Commitments
Cash collateral	$ 249,090	$ 94,847	$ 249,090	$ 94,847	$ 197,470	$ 210,875
Debt Obligations
2021 (six months ending December 31, 2021)	859,768		859,768
2022	2,496,580		2,496,580
2023	1,371,081		1,371,081
2024	1,017,797		1,017,797
2025	256,723		256,723
2026	340,026		340,026
Thereafter	463,903		463,903
Total	6,805,878		6,805,878
Minimum Annual Operating Lease Payments
2021 (six months ending December 31, 2021)	3,408		3,408
2022	8,257		8,257
2023	8,031		8,031
2024	7,926		7,926
2025	7,978		7,978
2026	8,282		8,282
Thereafter	26,098		26,098
Total	69,980		69,980
Total
2021	863,176		863,176
2022	2,504,837		2,504,837
2023	1,379,112		1,379,112
2024	1,025,723		1,025,723
2025	264,701		264,701
2026	348,308		348,308
Thereafter	490,001		490,001
Total	6,875,858		6,875,858
Operating lease expense	2,400	$ 1,500	4,700	$ 3,100
Unfunded CLO Commitments
Unfunded commitments related to structured loans and investments	524,700		524,700		$ 353,800
Fannie Mae
Agency Business Commitments
Minimum liquid assets to be maintained to meet operational liquidity requirements	19,100		$ 19,100
Period of funding for collateral requirement			48 months
Forward Contracts
Agency Business Commitments
Period of contractual commitment			60 days
Restricted liquidity arrangement - loans sold under the Fannie Mae DUS program \| Fannie Mae
Agency Business Commitments
Letter of credit assigned	45,000		$ 45,000
Cash collateral	14,600		14,600
Reserve required to fund additional restricted liquidity over the next 48 months	47,700		$ 47,700
Period of additional funding for collateral requirement			48 months
Cash collateral arrangement - purchase and loss obligations under Freddie Mac's SBL Program
Agency Business Commitments
Cash collateral per securitization	5,000		$ 5,000
Outstanding letters of credit	$ 5,000		$ 5,000