SECURITIES - Schedule of Investments in Continuous Loss Positions (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Fair Value
Less than 12 Months	$ 7,250	$ 3,044
12 Months or Longer	19,935	20,505
Total	27,185	23,549
Gross Unrealized Losses
Less than 12 Months	(70)	(24)
12 Months or Longer	(2,362)	(1,999)
Total	(2,432)	(2,023)
Mortgage-backed securities
Fair Value
Less than 12 Months	5,990	2,939
12 Months or Longer	16,715	16,653
Total	22,705	19,592
Gross Unrealized Losses
Less than 12 Months	(56)	(24)
12 Months or Longer	(2,185)	(1,857)
Total	(2,241)	(1,881)
U.S. Treasury and other
Fair Value
Less than 12 Months	1,260	49
12 Months or Longer	3,209	3,245
Total	4,469	3,294
Gross Unrealized Losses
Less than 12 Months	(14)	0
12 Months or Longer	(177)	(139)
Total	(191)	(139)
State and political subdivisions
Fair Value
Less than 12 Months	0
12 Months or Longer	1
Total	1
Gross Unrealized Losses
Less than 12 Months	0
12 Months or Longer	0
Total	0
Federal agencies and U.S. government sponsored entities
Fair Value
Less than 12 Months	5,990	2,939
12 Months or Longer	16,462	16,398
Total	22,452	19,337
Gross Unrealized Losses
Less than 12 Months	(56)	(24)
12 Months or Longer	(2,164)	(1,833)
Total	(2,220)	(1,857)
Other/non-agency
Fair Value
Less than 12 Months	0	0
12 Months or Longer	253	255
Total	253	255
Gross Unrealized Losses
Less than 12 Months	0	0
12 Months or Longer	(21)	(24)
Total	(21)	(24)
Collateralized loan obligations
Fair Value
Less than 12 Months	0	56
12 Months or Longer	10	607
Total	10	663
Gross Unrealized Losses
Less than 12 Months	0	0
12 Months or Longer	0	(3)
Total	$ 0	$ (3)