SECURITIES - Summary of Residential Securities and CMBS (Details) $ in Thousands	9 Months Ended
Sep. 30, 2022 USD ($)
Debt Securities, Available-For-Sale [Roll Forward]
Beginning balance January 1, 2022	$ 63,655,674
Purchases	39,804,163
Sales and transfers	(21,163,009)
Principal paydowns	(7,791,831)
(Amortization) / accretion	(7,728)
Fair value adjustment	(7,657,916)
Ending balance September 30, 2022	66,839,353
Agency Securities
Debt Securities, Available-For-Sale [Roll Forward]
Beginning balance January 1, 2022	60,525,605
Purchases	37,900,732
Sales and transfers	(20,616,137)
Principal paydowns	(7,343,579)
(Amortization) / accretion	(12,815)
Fair value adjustment	(7,416,565)
Ending balance September 30, 2022	63,037,241
Residential Credit Securities
Debt Securities, Available-For-Sale [Roll Forward]
Beginning balance January 1, 2022	2,599,564
Purchases	1,655,685
Sales and transfers	(377,648)
Principal paydowns	(444,738)
(Amortization) / accretion	4,662
Fair value adjustment	(223,913)
Ending balance September 30, 2022	3,213,612
Commercial Securities
Debt Securities, Available-For-Sale [Roll Forward]
Beginning balance January 1, 2022	530,505
Purchases	247,746
Sales and transfers	(169,224)
Principal paydowns	(3,514)
(Amortization) / accretion	425
Fair value adjustment	(17,438)
Ending balance September 30, 2022	$ 588,500

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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