Investment Securities - Summary of Unrealized Loss Positions on Investment Securities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	$ 2,357	$ 5,658
Less than Twelve Months, Unrealized Loss	84	122
Twelve Months or Longer, Fair Value	4,198	2,911
Twelve Months or Longer, Unrealized Loss	777	751
Fair Value	6,555	8,569
Unrealized Loss	861	873
Debt Securities | U. S. Treasury obligations
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	1,487
Less than Twelve Months, Unrealized Loss	0	4
Twelve Months or Longer, Fair Value	0	0
Twelve Months or Longer, Unrealized Loss	0	0
Fair Value	0	1,487
Unrealized Loss	0	4
Debt Securities | U.S. Government and GSE Obligations
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	181	243
Less than Twelve Months, Unrealized Loss	1	5
Twelve Months or Longer, Fair Value	1,362	1,156
Twelve Months or Longer, Unrealized Loss	290	346
Fair Value	1,543	1,399
Unrealized Loss	291	351
Debt Securities | GSE certificates
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	312	871
Less than Twelve Months, Unrealized Loss	5	46
Twelve Months or Longer, Fair Value	843	420
Twelve Months or Longer, Unrealized Loss	141	114
Fair Value	1,155	1,291
Unrealized Loss	146	160
Debt Securities | Private Label CMOs
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	29
Less than Twelve Months, Unrealized Loss	1
Twelve Months or Longer, Fair Value	0
Twelve Months or Longer, Unrealized Loss	0
Fair Value	29
Unrealized Loss	1
Debt Securities | GSE CMOs
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	1,835	2,219
Less than Twelve Months, Unrealized Loss	77	36
Twelve Months or Longer, Fair Value	1,312	925
Twelve Months or Longer, Unrealized Loss	304	264
Fair Value	3,147	3,144
Unrealized Loss	381	300
Debt Securities | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	61
Less than Twelve Months, Unrealized Loss	0	2
Twelve Months or Longer, Fair Value	228	262
Twelve Months or Longer, Unrealized Loss	5	12
Fair Value	228	323
Unrealized Loss	5	14
Debt Securities | Municipal bonds
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	9
Less than Twelve Months, Unrealized Loss	0	0
Twelve Months or Longer, Fair Value	6	7
Twelve Months or Longer, Unrealized Loss	0	0
Fair Value	6	16
Unrealized Loss	0	0
Debt Securities | Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	698
Less than Twelve Months, Unrealized Loss	0	27
Twelve Months or Longer, Fair Value	343	97
Twelve Months or Longer, Unrealized Loss	22	3
Fair Value	343	795
Unrealized Loss	22	30
Debt Securities | Foreign notes
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	20
Less than Twelve Months, Unrealized Loss	0	0
Twelve Months or Longer, Fair Value	9	0
Twelve Months or Longer, Unrealized Loss	1	0
Fair Value	9	20
Unrealized Loss	1	0
Debt Securities | Capital trust notes
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	46
Less than Twelve Months, Unrealized Loss	0	2
Twelve Months or Longer, Fair Value	81	34
Twelve Months or Longer, Unrealized Loss	12	10
Fair Value	81	80
Unrealized Loss	12	12
Equity Securities
Debt Securities, Available-for-sale [Line Items]
Less than Twelve Months, Fair Value	0	4
Less than Twelve Months, Unrealized Loss	0	0
Twelve Months or Longer, Fair Value	14	10
Twelve Months or Longer, Unrealized Loss	2	2
Fair Value	14	14
Unrealized Loss	$ 2	$ 2