SECURED FINANCING - Repurchase Agreements - Remaining Maturities, Collateral Types and Weighted Average Rate (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Repurchase Agreements:
Netted amounts	$ 51,364,097	$ 54,769,643	[1]
Weighted Average Rate	1.60%	0.17%
Repurchase agreements, remaining maturities, percentage	0.00%
CRTs
Repurchase Agreements:
Netted amounts	$ 723,574	$ 176,450
Non-Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	2,392,774	977,366
Residential Mortgage Loans
Repurchase Agreements:
Netted amounts	533,435	505,001
Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	47,293,951	52,724,923
Commercial Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	420,363	385,903
1 day
Repurchase Agreements:
Netted amounts	$ 14,686,762	$ 0
Weighted Average Rate	1.61%	0.00%
1 day | CRTs
Repurchase Agreements:
Netted amounts	$ 0	$ 0
1 day | Non-Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	35,360	0
1 day | Residential Mortgage Loans
Repurchase Agreements:
Netted amounts	0	0
1 day | Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	14,651,402	0
1 day | Commercial Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	0	0
2 to 29 days
Repurchase Agreements:
Netted amounts	$ 25,527,179	$ 27,013,474
Weighted Average Rate	1.58%	0.14%
2 to 29 days | CRTs
Repurchase Agreements:
Netted amounts	$ 2,406	$ 133,525
2 to 29 days | Non-Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	297,845	246,707
2 to 29 days | Residential Mortgage Loans
Repurchase Agreements:
Netted amounts	0	0
2 to 29 days | Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	25,217,859	26,435,408
2 to 29 days | Commercial Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	9,069	197,834
30 to 59 days
Repurchase Agreements:
Netted amounts	$ 1,590,972	$ 10,212,453
Weighted Average Rate	1.33%	0.19%
30 to 59 days | CRTs
Repurchase Agreements:
Netted amounts	$ 0	$ 38,854
30 to 59 days | Non-Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	531,852	270,377
30 to 59 days | Residential Mortgage Loans
Repurchase Agreements:
Netted amounts	0	159,350
30 to 59 days | Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	1,059,120	9,743,872
30 to 59 days | Commercial Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	0	0
60 to 89 days
Repurchase Agreements:
Netted amounts	$ 1,765,571	$ 6,377,347
Weighted Average Rate	1.55%	0.17%
60 to 89 days | CRTs
Repurchase Agreements:
Netted amounts	$ 244,947	$ 4,071
60 to 89 days | Non-Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	533,106	351,426
60 to 89 days | Residential Mortgage Loans
Repurchase Agreements:
Netted amounts	0	0
60 to 89 days | Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	936,214	6,021,850
60 to 89 days | Commercial Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	51,304	0
90 to 119 days
Repurchase Agreements:
Netted amounts	$ 1,770,550	$ 4,824,918
Weighted Average Rate	1.43%	0.15%
90 to 119 days | CRTs
Repurchase Agreements:
Netted amounts	$ 349,867	$ 0
90 to 119 days | Non-Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	648,369	12,573
90 to 119 days | Residential Mortgage Loans
Repurchase Agreements:
Netted amounts	0	0
90 to 119 days | Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	772,314	4,812,345
90 to 119 days | Commercial Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	0	0
Over 119 days
Repurchase Agreements:
Netted amounts	$ 6,023,063	$ 6,341,451
Weighted Average Rate	1.84%	0.27%
Over 119 days | CRTs
Repurchase Agreements:
Netted amounts	$ 126,354	$ 0
Over 119 days | Non-Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	346,242	96,283
Over 119 days | Residential Mortgage Loans
Repurchase Agreements:
Netted amounts	533,435	345,651
Over 119 days | Agency Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	4,657,042	5,711,448
Over 119 days | Commercial Mortgage-Backed Securities
Repurchase Agreements:
Netted amounts	$ 359,990	$ 188,069

[1] (1)Derived from the audited consolidated financial statements at December 31, 2021.