SECURITIES - Unrealized Loss Position (Details) $ in Thousands		Sep. 30, 2024 USD ($) security	Dec. 31, 2023 USD ($) security
Unrealized Loss Position For:
Estimated Fair Value	[1]	$ 71,700,177	$ 69,613,565	[2]
Gross Unrealized Losses		(1,121,339)	(2,230,646)
Agency Mortgage-Backed Securities
Unrealized Loss Position For:
Estimated Fair Value		9,403,256	15,490,571
Gross Unrealized Losses		$ (718,345)	$ (1,340,450)
Number of Securities | security		1,440	1,763
Agency Mortgage-Backed Securities | Less than 12 months
Unrealized Loss Position For:
Estimated Fair Value		$ 13,122	$ 35,453
Gross Unrealized Losses		$ (638)	$ (418)
Number of Securities | security		11	16
Agency Mortgage-Backed Securities | 12 Months or more
Unrealized Loss Position For:
Estimated Fair Value		$ 9,390,134	$ 15,455,118
Gross Unrealized Losses		$ (717,707)	$ (1,340,032)
Number of Securities | security		1,429	1,747

[1] (3)Excludes $2.0 billion and $1.5 billion at September 30, 2024 and December 31, 2023, respectively, of non-Agency mortgage-backed securities in consolidated VIEs pledged as collateral and eliminated from the Company’s Consolidated Statements of Financial Condition. 

[2] (1)Derived from the audited consolidated financial statements at December 31, 2023.