SECURITIES - Schedule of Investments in Continuous Loss Positions (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Fair Value
Less than 12 Months	$ 755	$ 3,044
12 Months or Longer	19,814	20,505
Total	20,569	23,549
Gross Unrealized Losses
Less than 12 Months	(4)	(24)
12 Months or Longer	(1,568)	(1,999)
Total	(1,572)	(2,023)
Mortgage-backed securities
Fair Value
Less than 12 Months	755	2,939
12 Months or Longer	16,504	16,653
Total	17,259	19,592
Gross Unrealized Losses
Less than 12 Months	(4)	(24)
12 Months or Longer	(1,489)	(1,857)
Total	(1,493)	(1,881)
U.S. Treasury and other
Fair Value
Less than 12 Months	0	49
12 Months or Longer	3,310	3,245
Total	3,310	3,294
Gross Unrealized Losses
Less than 12 Months	0	0
12 Months or Longer	(79)	(139)
Total	(79)	(139)
State and political subdivisions
Fair Value
Less than 12 Months	0
12 Months or Longer	0
Total	0
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	755	2,939
12 Months or Longer	16,244	16,398
Total	16,999	19,337
Gross Unrealized Losses
Less than 12 Months	(4)	(24)
12 Months or Longer	(1,476)	(1,833)
Total	(1,480)	(1,857)
Other/non-agency
Fair Value
Less than 12 Months	0	0
12 Months or Longer	260	255
Total	260	255
Gross Unrealized Losses
Less than 12 Months	0	0
12 Months or Longer	(13)	(24)
Total	(13)	(24)
Collateralized loan obligations
Fair Value
Less than 12 Months	0	56
12 Months or Longer	0	607
Total	0	663
Gross Unrealized Losses
Less than 12 Months	0	0
12 Months or Longer	0	(3)
Total	$ 0	$ (3)