SECURITIES - Summary of Residential Securities and CMBS (Details) $ in Thousands	6 Months Ended
Jun. 30, 2022 USD ($)
Debt Securities, Available-For-Sale [Roll Forward]
Beginning balance January 1, 2022	$ 63,655,674
Purchases	16,087,634
Sales and transfers	(9,563,655)
Principal paydowns	(5,711,774)
(Amortization) / accretion	31,235
Fair value adjustment	(5,456,380)
Ending balance June 30, 2022	59,042,734
Agency Securities
Debt Securities, Available-For-Sale [Roll Forward]
Beginning balance January 1, 2022	60,525,605
Purchases	14,731,945
Sales and transfers	(9,042,404)
Principal paydowns	(5,385,047)
(Amortization) / accretion	28,799
Fair value adjustment	(5,265,562)
Ending balance June 30, 2022	55,593,336
Residential Credit Securities
Debt Securities, Available-For-Sale [Roll Forward]
Beginning balance January 1, 2022	2,599,564
Purchases	1,243,293
Sales and transfers	(352,027)
Principal paydowns	(323,281)
(Amortization) / accretion	2,358
Fair value adjustment	(177,535)
Ending balance June 30, 2022	2,992,372
Commercial Securities
Debt Securities, Available-For-Sale [Roll Forward]
Beginning balance January 1, 2022	530,505
Purchases	112,396
Sales and transfers	(169,224)
Principal paydowns	(3,446)
(Amortization) / accretion	78
Fair value adjustment	(13,283)
Ending balance June 30, 2022	$ 457,026

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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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