SECURITIES - Schedule of Investments in Continuous Loss Positions (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Fair Value
Less than 12 Months	$ 4,411	$ 17,574
12 Months or Longer	20,043	5,634
Total	24,454	23,208
Gross Unrealized Losses
Less than 12 Months	(123)	(1,363)
12 Months or Longer	(3,013)	(1,099)
Total	(3,136)	(2,462)
Mortgage-backed securities
Fair Value
Less than 12 Months	3,796	13,433
12 Months or Longer	16,144	5,213
Total	19,940	18,646
Gross Unrealized Losses
Less than 12 Months	(111)	(1,144)
12 Months or Longer	(2,766)	(1,083)
Total	(2,877)	(2,227)
U.S. Treasury and other
Fair Value
Less than 12 Months	583	3,356
12 Months or Longer	3,142	0
Total	3,725	3,356
Gross Unrealized Losses
Less than 12 Months	(12)	(193)
12 Months or Longer	(239)	0
Total	(251)	(193)
Federal agencies and U.S. government sponsored entities
Fair Value
Less than 12 Months	3,796	13,353
12 Months or Longer	15,897	5,042
Total	19,693	18,395
Gross Unrealized Losses
Less than 12 Months	(111)	(1,136)
12 Months or Longer	(2,734)	(1,062)
Total	(2,845)	(2,198)
Other/non-agency
Fair Value
Less than 12 Months	0	80
12 Months or Longer	247	171
Total	247	251
Gross Unrealized Losses
Less than 12 Months	0	(8)
12 Months or Longer	(32)	(21)
Total	(32)	(29)
Collateralized loan obligations
Fair Value
Less than 12 Months	32	785
12 Months or Longer	757	421
Total	789	1,206
Gross Unrealized Losses
Less than 12 Months	0	(26)
12 Months or Longer	(8)	(16)
Total	$ (8)	$ (42)